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LOGAN WATER ALLIANCE

BEENLEIGH WWTP UPGRADE: PROCESS COMMISSIONING AND OPTIMISATION

PROGRAM

TASK NUMBER: 90-12-08

MARCH 2014

Beenleigh WWTP Upgrade: Process Commissioning & Optimisation Program

Document Number: 7600-000-P-REP-PL-8208

90-12-08 Date issued: 28/03/2014 of 37 Rev: 1

Approval Register

Date

Project Manager Submitted 30/01/2014

Planning & Project Management Team Review

Program Review

Controlled Document – Change Register

Revision Section

Changed Change Description Initial Date

A All Preparation of Draft Report LF 16/01/2014

B All Reviewed PG 26/02/2014

C All Draft report format SS 04/03/2014

D All Internal Review TP/LF 12/03/2014

E Executive

Summary, 4, 5, 7, 8

Program Review Comments Addressed LF 27/03/2014

1 All Final Report Format SS 27/03/014




TABLE OF CONTENTS

EXECUTIVE SUMMARY ................................................................................................................................. 6

1. INTRODUCTION ................................................................................................................................. 8

1.1 Objectives ........................................................................................................................................ 8

1.2 Scope ............................................................................................................................................... 8

1.3 Business Drivers .............................................................................................................................. 9

2. PLANNING CONTEXT ...................................................................................................................... 10

2.1 Background .................................................................................................................................... 10

2.2 Previous Studies ............................................................................................................................ 10

2.3 Amended DA limits ........................................................................................................................ 11

3. METHODOLOGY .............................................................................................................................. 13

3.1 Program timeline and key components ......................................................................................... 13

3.2 Site Meeting Attendees .................................................................................................................. 15

4. STUDY OUTCOMES ......................................................................................................................... 16

4.1 Study Overview .............................................................................................................................. 16

4.2 Current WWTP Capacity ............................................................................................................... 16

4.3 Improvements to Maintain 14 ML/d Capacity ................................................................................ 18

4.3.1 Operational Adjustments ........................................................................................................... 18

4.3.2 Outstanding Works .................................................................................................................... 21

4.4 Recommended Upgrades to Increase Above 14 ML/d Capacity .................................................. 21

4.4.1 Chemical Dosing ........................................................................................................................ 21

4.4.2 Ditch Velocity ............................................................................................................................. 22

4.4.3 Enhanced Aeration Control and Aeration System Upgrade ...................................................... 22

4.4.4 Summary of Upgrades and Controls ......................................................................................... 23

4.5 External Influences ........................................................................................................................ 24

4.5.1 Trade Waste Monitoring ............................................................................................................ 24

4.5.2 Network Flow Pacing ................................................................................................................. 25

5. CAPITAL WORKS IMPLICATIONS ................................................................................................. 29

6. PARALLEL VERSUS SERIES OPERATION ................................................................................... 31

7. CONCLUSIONS ................................................................................................................................ 32

8. RECOMMENDATIONS ..................................................................................................................... 34

9. REFERENCES .................................................................................................................................. 35




FIGURES

Figure 2-1: Release limits currently applied at Beenleigh WWTP (Schedule C Table 1 of the current DA) ..

................................................................................................................................................. 12

Figure 3-1: Key Phases in the Process Commissioning and Optimisation Program ................................. 14

Figure 3-2: Schematic of Process Commissioning and Optimisation Program Timeline .......................... 14

Figure 4-1: Capacity Limits at Beenleigh WWTP ....................................................................................... 17

Figure 4-2: Published Settling Characteristics Based on Effluent N Ratios and SRT (Hartley, 2014) ...... 19

Figure 4-3: Settling Characteristics (sSVI) during Study Period Based on averaged effluent N ratios ..... 20

Figure 4-4: Recommended upgrades and improvements (green boxes) that will enhance the WWTP

capacity, not including upgrades to tank sizes ................................................................................................ 24

Figure 4-5: Continuous Inflow Data for 3 Inlet Mains, showing variability in LCC Pump Stations ............. 26

Figure 4-6: Total Continuous Inflow Data for 3 Inlet Mains, showing near bypass trigger during peaks and

extremely low flows at night (moving average simulates 15 min average parameter) .................................... 27

Figure 4-7: Schematic of the Main Pump Station Contributors to the Beenleigh WWTP .......................... 28

TABLES

Table 2-1: Key amendments to Beenleigh WWTP DA limits .................................................................... 11

Table 3-1: Site Meetings - Key Attendees List .......................................................................................... 15

Table 4-1: Trade waste monitoring sample data (range: 5th percentile to 95

th percentile over week

sampled and over 3 lab analysts) .................................................................................................................... 25

Table 5-1: Proposed Works – Interim and Target Capacity for Beenleigh WWTP ................................... 29

Table 5-2: Capital Works Program Adjustment Summary ........................................................................ 30

Table 6-1: Estimated Capacity, Advantages and Disadvantages to Series versus Parallel Configuration at

Beenleigh WWTP ............................................................................................................................................ 31

Appendices

Appendix A Site Meeting Minutes

Appendix B Process Commissioning and Optimisation Report (Ken Hartley, 2014)




ABBREVIATIONS

ADWF Average Dry Weather Flow

BFP Belt Filter Press

BNR Biological Nutrient Removal

BOD Biological Oxygen Demand

COD Chemical Oxygen Demand

DA Development Approval

DO Dissolved Oxygen

LCC Logan City Council

LWA Logan Water Alliance

OD Oxidation Ditch

RAS Return Activated Sludge

SRT Sludge Retention Time

SVI Sludge Volume Index

sSVI Stirred Sludge Volume Index

VSD Variable Speed Drive

WAS Waste Activated Sludge

WWTP Waste Water Treatment Plant




EXECUTIVE SUMMARY

Strategic planning for Logan City has been based on the design capacity for the Beenleigh WWTP of

15 ML/d ADWF. Previous studies have indicated that the WWTP is operating at a reduced capacity of 10 to

13 ML/d ADWF (GCW, 2006; JWP, 2009). A peer review of the process analysis (LWA, 2010) suggested

that the limited flow capacity was impacted by the ‘oxidation ditches in series’ configuration. The objective of

this current study was to determine the maximum capacity of Beenleigh WWTP with a parallel ditch

configuration, and to outline possible optimisation opportunities.

The main strategy was to implement a parallel ditch configuration and then gradually reduce the sludge

retention time (SRT), while observing treatment capabilities. The plant was operated at an SRT of 15 to 20

days for 3.5 months, then SRT of 10-15 days and SRT of <10 days for one month each. The results showed

that effluent limits could be met with an SRT of 10-15 days, however below 10 days SRT it started to show

reduced ammonia removal capabilities.

The Beenleigh WWTP has a capacity of 14 ML/d ADWF in the parallel oxidation ditch configuration, with the

current controls in place. The key bottleneck is the aeration capacity which is also affected by the level of

chemical oxidation demand (COD) in the influent wastewater, currently measured at an equivalent median

750 mgCOD/L. This is 34% greater than the COD load the WWTP was designed for and is the main

determinant for the WWTP capacity reduction from 15 ML/d. The capacity could effectively be increased with

appropriate automation and controls in place, which will reduce process variability and an upgrade to the

aeration system capacity.

Overall, the series configuration accommodates more process variability but reduces overall capacity to 10-

13 ML/d ADWF. A parallel configuration allows more process control and increases capacity to at least

14 ML/d ADWF but can be more sensitive to process variability. This could be managed if appropriate

controls and automation were implemented.

A number of outstanding works and operational improvements are required to maintain a 14 ML/d capacity.

These works include repairing the aerator paddles, repairing downstream aerator baffles, implementing SRT

control and undergoing structural inspection and maintenance of the oxidation ditches. To gain a further

increase in capacity beyond to 14-15 ML/d, enhancing the aeration capacity and control, installing vertical

baffles and optimising the chemical dosing is required.

In total, these Stage 1 works are estimated to cost $1.7m. Stage 1 is recommended to be implemented

immediately and would effectively increase the capacity to the desired 15 ML/d. However, if a capacity of

15 ML/d is not achieved via enhancing the aeration processes, then a slight upgrade to the aeration system

(such as diffusers in between existing surface aerators) will achieve this upgrade. These additional Stage 2

works are estimated at $0.7m.




High instantaneous flow variability from the LCC operated catchments are causing issues in the WWTP

operation, especially in the form of triggering dry weather bypass alarms and other equipment issues at low

flows.

The Logan Water Alliance recommends that Logan City Council:

1. Retain the parallel oxidation ditch configuration to maintain a WWTP capacity of at least 14 ML/d

ADWF. This operational adjustment is to be based on the following:

a. Flow and aeration distribution – of 55%:45% OD1:OD2, where practicable with the current

operating constraints, to capitalise on volume capacities

b. Effluent N ratio– of 0.1 to 1 effluent ammonia to effluent nitrate ratio, where practicable to

improve settling performance and capitalise on volume capacities

2. Implement Stage 1 works in 2014/15 inclusive of the following:

a. Renewals/outstanding works: scum harvester adjustment, surface aerator paddle repair,

downstream baffle repairs and SRT control implementation,

b. Rectification/operational improvements: RAS pump refurbishment, sludge bin upgrade and

structural assessment and general clean of oxidation ditches

c. Capacity upgrade - enhanced aeration automation, installing upstream vertical baffles in

oxidation ditches and investigating chemical dosing for polishing only. This is recommended

to be carried out with the outstanding works, for the purposes of improving general operation.

3. Program Stage 2 works for implementation with the aim to increases the WWTP capacity to 15ML/d

pending the capacity improvements observed at the completion of Stage 1. Stage 2 works are

inclusive of the following:

a. Capacity upgrade - Upgrading the aeration system. This is recommended on the basis that

the Stage 1 works are insufficient to meet the 15 ML/d capacity.

4. Adopt proposed works as nominated to form part of Council’s Capital Works Program (refer

Section 5)

5. Undertake planning works to investigate LCC pump operation to reduce variability in flows entering

the WWTP, noting the impact of residential catchment diversions on the WWTP capacity

6. Continue trade waste investigations to determine any necessary changes to trade waste agreements

to reduce flow variability to the WWTP

7. Facilitate training of LCC operators and engineers to transfer knowledge and findings on the revised

plant operation

8. Facilitate the development of operational manuals to ensure that the adjusted operations of the

Beenleigh WWTP are documented to assist the future operation of the plant




1. INTRODUCTION

Beenleigh Wastewater Treatment Plant (WWTP) has undergone several augmentations and upgrades over

the 2012/13 financial year to deliver improved performance and regulatory compliance. The works were

staged based on urgency and prioritisation, and include:

1. Retrofitted inlet works, new bypass, upgraded dewatering area and other minor works (completed)

2. Process commissioning and optimisation (this study)

3. Disinfection and clarification upgrade, if required

Additional minor works such as relocating the DO probes and adjusting the inlet weirs to the oxidation

ditches were required and implemented to ensure a controlled sampling study as part of the optimisation

process.

The need for a process commissioning and optimisation study was the result of previous consultant studies

indicating the WWTP has a capacity of approximately 10 to 13 ML/d Average Dry Weather Flow (ADWF)

(GCW, 2006; JWP, 2009), compared to the strategic planning requirement of 15ML/d ADWF. A peer review

of the process analysis (LWA, 2010) suggested that the limited flow capacity was impacted by the ‘oxidation

ditches in series’ configuration. An increase in capacity to 15 ML/d was considered possible if the oxidations

ditches were operated in parallel. As a result, this current study addresses the operation of parallel oxidation

ditches.

1.1 Objectives

The current study objective is to undertake a process commissioning and optimisation study following recent

minor augmentation works at Beenleigh WWTP to confirm the design capacity of the WWTP and to

maximise the operational capacity of the WWTP.

1.2 Scope

The scope of this study includes:

Reviewing background data and operating set-points

Collecting and analysing data over the programme duration

Liaising with the WWTP operators and relevant stakeholders

Reviewing and refining operating set-points

Identifying optimised process for the WWTP

Fine tuning the process, including setting process controls

This study considers optimising the capacity of the WWTP within the current bioreactor and clarifier volumes.

Therefore, this study does not investigate any upgrades to tank volumes.




1.3 Business Drivers

Logan City Council (LCC) is committed to improving operational efficiencies and minimising the

environmental impact of its activities. The main business drivers that influence this study are: Improvement and

Compliance.

The key business driver for the Beenleigh WWTP Process Optimisation and Commissioning study is

improvement. This project offers the opportunity to increase the capacity of existing assets by improving the

current operation, and accommodating process improvement through the installation of automated controls.

The current wastewater flows are reaching the WWTPs capacity in series, with increasing non-compliances

largely due to the highly variable industrial flow contribution within the catchment. Although the installation of

a new bypass and other upgrades will assist in the operation of the WWTP, the capacity bottleneck of the

biological process remains.

A secondary business driver for the study is compliance. A legal obligation exists in the form of a

development approval (DA) or discharge licence and stipulates limits that ensure an environmental duty of

care to prevent or mitigate the risk of environmental harm under the Environmental Protection Act 1994.

Optimisation of the WWTP will also allow improved compliance. This optimisation study specifically focuses

on improving compliance for nutrient, solids and organics discharge limits by delivering improvements in the

biological and clarifier sections of the plant.




2. PLANNING CONTEXT

This section outlines the planning context for this study, including an overview of the WWTP history and

background, key previous studies and current DA amendments.

2.1 Background

The Beenleigh WWTP plant was upgraded to a Biodenipho operation in 1999/2001 and later converted to

two oxidation ditches in series. The 1999/2001 plant upgrades involved a new inlet structure, basin

reconfiguration and upgrade, a new clarifier, thermophilic anaerobic digester and UV disinfection. The plant

was operated by Veolia under contract to GCW until March 2004 (GCW, 2006).The Beenleigh WWTP was

transferred from Gold Coast City Council (GCCC) to Logan City Council (LCC) in 2008, as part of the

Queensland Government boundary changes.

The current contributing catchment for the Beenleigh WWTP includes inflow from Beenleigh (approximately

two-thirds) and a largely industrial inflow from Stapylton (approximately one-third). Poor plant performance

during dry weather has often been attributed to industrial loads. Other issues at the WWTP were also

attributed to a lack of peak wet weather by-pass and insufficient equipment and upgrades.

The most recent upgrade at the WWTP was completed in January 2013, and included a wet weather

bypass, a retrofit of the inlet works and an upgrade of the sludge dewatering area. These upgrades reduced

key bottlenecks in the process. Scum harvester commissioning and other minor works were also included as

part of the upgrade package.

Currently, the WWTP biological process operates with 2 oxidation ditches and 4 clarifiers. The anaerobic

digester has been decommissioned for more than 5 years.

Logan City Council (LCC) has indicated its intention to maintain a capacity and licence discharge of 15 ML/d

ADWF to support regional strategic planning. A number of modelling and planning assessments (GCW,

2006; JWP, 2009) indicate that the Beenleigh WWTP has a capacity of 10-13 ML/d ADWF, based on series

configuration of the two oxidation ditches. A peer review in the Beenleigh WWTP Performance Improvement:

Detailed Planning Concept Report (LWA, 2010 – Task No. 90-10-41) indicated that this capacity could

effectively be increased if the oxidation ditches were operated in a parallel configuration.

2.2 Previous Studies

Model-Based Analysis of the Beenleigh Sewage Treatment Plant (GCW, 2006)

Two software packages were used to simulate processes within the Beenleigh WWTP: Biowin and WEST.

Both models provided similar results, and indicated that the WWTP capacity is approximately 13 ML/d ADWF

in series configuration and 15 ML/d ADWF in the original BioDenipho design configuration. However, the

study mentions that this was based on an ammonia break-through of 5 mg/L and therefore may be based on

a less stringent DA limits for ammonia.




Beenleigh WWTP: Stormwater and Solids Handling Study (JWP, 2009)

Biological process modelling (including the clarifiers) was undertaken as part of the overall assessment to

determine unit capacities and the scope for upgrades. Detailed investigations were carried out based on a

superseded discharge licence which did not include bypassing directly to the river, and therefore

recommendations included bypassing peak flows to the clarifiers.

Model results indicated that if the plant was operated at a sludge retention time (SRT) of 15 days and a

stirred sludge volume index (sSVI) of 80 mL/g, the maximum ADWF achievable would be 10.6 ML/d (at sSVI

of 90 mL/g, the ADWF would drop further to 10 ML/d). At higher SRTs, this capacity would be reduced. It

was also stated that under the series configuration, the aeration system only had capacity for 7.6 ML/d

ADWF.

Beenleigh WWTP Performance Improvement Detailed Planning Concept Report (LWA, December

2010)

A peer reviewer (Ken Hartley) was engaged to review the biological treatment optimisation strategy. This

report concluded that parallel operation would simplify the process and allow improved sludge settle-ability

by appropriate aeration control. The study recommended that the WWTP undergo an optimisation study

(also known as EVOP) in a parallel configuration, to determine the maximum capacity, following the

installation of the new bypass.

2.3 Amended DA limits

New DA limits have been applied since the original peer review that accommodates parallel operation as an

alternative to increasing capacity. These changes have simplified the compliance analysis, which now

pertain only to nitrogen limits. As such, the capacity of the WWTP should be reviewed not only by the asset

volumes available, but also the limits applied in the DA.

Table 2-1 shows the amended DA limits as of August 2012, which have been adopted in the current study.

Table 2-1: Key amendments to Beenleigh WWTP DA limits

Parameter Previous DA

(2010) Current DA

(effective as of August, 2012)

Oxidised-N + ammonia-N

Short-term limit

Long-term limit

Maximum limit

Removed

Ammonia N Short-term limit

Long-term limit Removed

Total Nitrogen Median limit

Maximum limit

Reduced to 5 mg/L Reduced to 7.5 mg/L




Figure 2-1 shows the shows the release limits currently applied at Beenleigh WWTP (Schedule C Table 1 of

the current DA).

Figure 2-1: Release limits currently applied at Beenleigh WWTP (Schedule C Table 1 of the current DA)




3. METHODOLOGY

This section outlines the general methodology adopted for the study, including timeline profile and the key

stakeholders involved during the study period.

3.1 Program timeline and key components

The process commissioning and optimisation study is an ‘improve-as-you-go’ process that evolves as new

understandings of the WWTP are made, but based on a general implementation strategy.

The study is effectively categorised into five phases:

Phase A was the ‘baseline monitoring’ phase where data is collected and an extended sampling

regime is implemented. In this phase, historical data was also collected and a general understanding

of the WWTP developed.

Phase B was the start of parallel operation which commenced on the 17th of July 2013. The WWTP

was operated at a sludge retention time (SRT) of 15 to 20 days and the effluent monitored. During

this period, there was also a trial of ceasing all chemical dosing (for optimising biological nutrient

removal), improving the flow distributions between the ditches and improving the aeration control.

Phase C involved a reduction of the SRT at 10 to 15 days, with the effluent continued to be

monitored. At the end of this phase (November 2013), clarifier stress tests were undertaken over 3

days. This process included shutting down one clarifier at a time and throttling the return activated

sludge (RAS) pumps to determine the point of ‘stress’ and therefore establish an approximate

hydraulic capacity of the clarifiers.

Phase D was the further reduction of the SRT to <10 days. This coincided with the Christmas/New

Year period where additional wasting was carried out due to reduced biosolids truck movements. It

provided an opportunity to observe the WWTP behaviour under these limited conditions.

Phase E was the ‘post-analysis’ phase where the data was collated and final conclusions were

drawn to determine the likely capacity of the WWTP

A concurrent study was undertaken by the LCC Environmental Management Systems Team and the LCC

Trade Waste Department to determine the nutrient loading impacts from the three main catchments entering

Beenleigh WWTP.

Figure 3-1 and Figure 3-2 show the key phases of the study and an overview project timeline.




Figure 3-1: Key Phases in the Process Commissioning and Optimisation Program

Figure 3-2: Schematic of Process Commissioning and Optimisation Program Timeline




3.2 Site Meeting Attendees

Site meetings were conducted on a monthly basis during the study period to provide a general overview of

progress and ensure the involvement of key stakeholders. Meeting minutes are included in Appendix A.

Table 3-1 shows a list of site meeting attendees. The stakeholders mentioned in this list attended at least

one of the six general site meetings at Beenleigh WWTP over the study period.

Table 3-1: Site Meetings - Key Attendees List

Meetings Attendees Position

Leah Foley LWA Project Manager

Scott Francis LWA Project Director

Ken Hartley Technical Process Expert

Jason Lee Beenleigh WWTP Supervisor

David Wickman Beenleigh WWTP Operator

Bruce Willman Beenleigh WWTP Operator

Noel Robinson Beenleigh WWTP Operator

Kaja Thompson Beenleigh WWTP Operator

Imtiaj Ali LCC WWTP Process Engineer

Chitra Liyanage LCC WWTP Maintenance Engineer

Andrew Stevenson LCC Environmental Management Systems Coordinator

Kambez Akrami LCC Product Quality Systems Officer

Amy Flynn LCC Environmental Management System Officer




4. STUDY OUTCOMES

This section provides a summary of the study outcomes. Appendix B includes theBeenleigh WWTP

Upgrade Process Commissioning & Optimisation Report (Hartley, 2014), which provides a detailed overview

of the study outcomes. This section also outlines the key upstream influences on the WWTP, namely trade

waste discharges (i.e. high strength COD) and dry weather flow variances during the study period.

4.1 Study Overview

The process commissioning and optimisation study period occurred from June to December 2013, with

parallel operation initiated on the 17th of July 2013. During this period there was minimal rainfall, with some

wet weather bypasses occurring mid to late November and December. The data was limited in December

due to reduced WWTP staff and laboratory analysts, especially over the Christmas/New Year period.

An automated wasting control was approved mid-way through the study period; however, due to delays in

implementation (due to heavy contractor workloads at Loganholme WWTP) and some minor software faults,

the wasting control was not functioning by the end of the study period.

Some DA non-compliances occurred over the study period due to process adjustments. In the initial two

months, maximum total nitrogen and ammonia limits were exceeded; however, this did not occur for the

remainder of the study period. In the last two months of the study period, the long-term phosphorus limit was

exceeded and was attributed to nitrate recycling. The exceedance occurred due to an add-on effect to non-

compliances earlier in the year during the January 2013 flood events. The same occurred during the study

period for biological oxygen demand (BOD).

4.2 Current WWTP Capacity

There are multiple factors that limit the WWTP capacity. Apart from volume limitations of the oxidation ditch

and clarifiers, the following process-related limitations were determined:

The key capacity bottleneck of the plant is the aeration system, limiting the WWTP to a capacity of

approximately 14 ML/d

The clarifier and oxidation ditch volumes limited the WWTP to 15 ML/d, with the following

considerations:

o Clarifier volume limits (related to the RAS pumps capacity) was considered capable to

achieve 3 x 15 ML/d peak flow, but were noted to be operating at a capacity of

approximately 20% less than their original design flows (based on anecdotal evidence from

WWTP operators)

o The oxidation ditch capacity minimises the achievable SRT

It was found in the study that the WWTP could operate with the current DA limits at a minimum 10-15 day

SRT. Below 10 day SRT, the WWTP tended towards insufficient nitrification. A more accurate SRT could not




be determined during the study due to insufficient SRT controls in place. Sufficient controls will need to be

installed to ensure that process variability is minimised in future.

Figure 4-1 shows the capacity limits at Beenleigh WWTP.

Figure 4-1: Capacity Limits at Beenleigh WWTP

Aeration System and Chemical Oxygen Demand (COD) variability

The WWTP aeration capacity design of 15 ML/d average dry weather flow (ADWF) was based on a median

influent of 8.4 tCOD/d (equivalent to 560 mg COD/L). During the last two months of the study period, the

inflow median COD was 10.7 tCOD/d (equivalent to 750 mg COD/L). This increased load equates to a

reduced aeration capacity of 14 ML/d ADWF, and is the effective capacity of the WWTP with the current

control constraints.

The aeration capacity was identified as just sufficient for the current 90th percentile COD load (a peak load

parameter often used for design basis). As the aeration capacity is affected by the influent COD load, if the

influent load is reduced, such as reducing COD loads from industrial discharges, this would in turn increase

aeration capacity. A review of the trade waste agreement with Gold Coast (which currently limits COD

concentrations to 1000 mg COD/L) is recommended. In addition, regular monitoring is required of incoming

trade waste contributions to ensure compliance.




Clarifier Volumes and RAS Pump Capacity

The clarifier stress test performed in late November showed that the clarifiers have sufficient capacity for the

current 13 ML/d flows. Calculated clarifier performance at the peak hydraulic flow of 45 ML/d (i.e. 3 x

15 ML/d ADWF) was shown to be sufficient with the current clarifier volumes, based on the following

conditions for median influent COD concentrations of 750 mg/L:

o Settleability (sSVI) of 65 mL/g at SRT no greater than 19 days

o Settleability (sSVI) of 80 mL/g at SRT no greater than 16 days

An average settleability of 70 mL/g sSVI is considered achievable with the DA limits.

The clarifier capacity, is also limited by the RAS pump capacity. Operator anecdotal evidence suggests that

the RAS pumps are operating at 20% less than design capacity due to wear and tear.

4.3 Improvements to Maintain 14 ML/d Capacity

The following operational adjustments and completion of outstanding works are required to achieve a WWTP

capacity of 14 ML/d, in a parallel configuration.

4.3.1 Operational Adjustments

The following operational adjustments are recommended to optimise the capacity of the WWTP in parallel

operation:

Maintaining appropriate flow and aeration distribution

Maintaining optimal effluent ammonia to nitrate ratio for improved settleability

The study outcomes were limited by existing process constraints such as lack of automation (e.g. wasting

control, aeration control). All adjustments should be documented in the operational manuals and procedures

to ensure these assist future operation of the WWTP.

Flow and Aeration Distribution

Oxidation Ditch 1 (OD1) has a larger reactor volume than Oxidation Ditch 2 (OD2), due to OD2’s sloping

walls. Likewise, each surface aerator (i.e. rotor) has the same power consumption with multiple rotors fitted

throughout the ditches.

Operation should be modified, as best as practicable, so that:

A flow distribution of OD1:OD2 = 55%:45% is achieved. The OD2 inlet weir should be placed higher

by 14 mm (calculated to reduce flow to 45% towards OD2)

The number of operating rotors within each ditch is matched to the flow. For OD1, five aerators

should be running and for OD2, four aerators should be running




Effluent N Ratio and Settleability

Published oxidation ditch studies have shown that modification to the effluent N ratio (ammonia N: nitrate N)

affects the settleability performance in the clarifiers. Improving the setteability in the clarifiers effectively

increases the capacity of the WWTP.

Oxidation ditches have a different characteristic to fixed reactor biological nutrient removal (BNR) processes,

as the length of aeration zone can be extended or reduced based on DO set-points (i.e. operator settings),

as the oxidation ditch has no internal walls between zones. An extension of the aeration zone (where

nitrification occurs to reduce ammonia levels) will automatically create a reduction of the anoxic zone (where

denitrification occurs to reduce nitrate/nitrite levels), and vice versa.

As a result of this behaviour, greater control is available by adjusting effluent N ratios. Figure 4-2 illustrates

the relationship between settleability (measured in sludge volume index (SVI) or stirred sludge volume index

(sSVI)) and effluent N ratio. The relationship also changes based on SRT. This graph shows that there is an

ideal effluent N ratio range that will produce the best settleability for the wastewater sludge at each WWTP.

The key is to identify the optimal effluent N ratio range.

Figure 4-2: Published Settling Characteristics Based on Effluent N Ratios and SRT (Hartley, 2014)

Sampling during the study period was not performed to the same level of detail as in the published results;

however, the samples show a similar trend to the published data (refer Figure 4-2). Figure 4-3 shows the

study trends comparing sSVI with the effluent ammonia N:nitrate N ratio (Hartley, 2014). The sSVI

measurements were initiated just prior to the treatment configuration change to parallel for consistency, prior

to this change measurements were in SVI.

SRT 20d

SRT 10d

0

50

100

150

200

0.01 0.1 1 10 100

SS

VI o

r s

SV

I (m

L/g

)

Effluent NH3-N:NO3-N Ratio (3SRT average, Nrave)

Bucasia Ditch 1(SRT 17d)

Bucasia Ditch 2(10d)

Coolum(30d)-APT Online

Coolum(30d)-APT Offline

West Byron(20d)




Figure 4-3: Settling Characteristics (sSVI) during Study Period Based on averaged effluent N ratios

The study showed the following general characteristics:

At an effluent N ratio between 1 and 3, a sludge settling characteristic between 100 and 150 mL/g

was exhibited

At an effluent N ratio between 0.1 and 1, a sludge settling characteristic between 50 and 90 mL/g

was exhibited

The improvement to settleability was attributed to the effluent N ratio modifications as the reduction in SRT

did not occur until the weeks after the improved settleability.

A consistent sSVI of 70 mL/g is considered achievable if appropriate DO control for the ideal effluent

ammonia N to nitrate N is put in place. The ideal effluent ammonia N to nitrate N is between 0.1 and 1. This

should ideally be met in conjunction with adhering to DA limits.

Start sSVI

0.01

0.1

1

10

100

1000

0

50

100

150

200

250

01-May 01-Jul 01-Sep 01-Nov 01-Jan

Final Eff N

Ratio

(60d M

A)

sSV

I (m

L/g)

ML SVI / sSVI

Eff NH3-N:NO3-N Ratio

60 per. Mov. Avg. (Eff NH3-N:NO3-NRatio)

ParallelOperation Start

100 - 150 mL/g sSVI

50 - 90 mL/g sSVI General lowering = Improve settling




4.3.2 Outstanding Works

The conversion of the oxidation ditches to parallel was sufficient to inform the initial capacity assessment. To

maintain smooth operation of the WWTP, especially in parallel, several outstanding works still need to be

undertaken:

The scum harvesters have been installed and commissioned based on fixed weir operation (fully

closed). The parallel operation with the current method of aeration automation depends on moving

weirs to immerse aerators appropriately and maintain appropriate dissolved oxygen (DO) set points.

The water level is not high enough for the scum harvesters to appropriately remove scum in this new

configuration and there is a scum build up in the ditches. The scum harvester heights will need to be

adjusted to be submerged for effective operation.

Wasting automation controls were approved and installed at Beenleigh WWTP to improve the

stabilisation of SRT and provide more control over the process. Delays have occurred due to

software program errors which have recently been resolved. The control of SRT will need to be

implemented to improve WWTP stability.

The existing sludge bin is considered a bottleneck in the wasting process. Wasting is limited to the

amount the bin can hold, and the truck scheduling has been altered to accommodate and avoid

disruptions in the process (i.e. affecting SRT). The bin capacity is being addressed as part of the

Biosolids Management Strategy (LWA, 2013; Task No. 90-12-35).

The oxidation ditches and aerators are in need of maintenance works. The oxidation ditches have

not undergone a structural assessment or maintenance since 2000 and there are several aerators

with broken paddles and horizontal baffles. Maintenance and renewal works for these assets should

be undertaken and a regular preventative maintenance schedule reviewed.

4.4 Recommended Upgrades to Increase Above 14 ML/d Capacity

The following works are recommended to optimise the capacity of the WWTP in parallel operation:

Optimising chemical dosing usage

Reducing ditch velocities

Enhanced aeration control and aeration system upgrade

All upgrades and adjustments should be documented in the operational manuals and procedures to assist

future operation of the WWTP.

4.4.1 Chemical Dosing

Chemical dosing was ceased in the early stages of the study as a trial. Both ethanol and alum were

previously used, with:

ethanol used to improved denitrification (nitrate/nitrite removal)




alum used for phosphorus ‘trimming’ on top of biological phosphorus removal and to improve

settling characteristics when required (usually during wet weather events)

After 3 months, alum dosing recommenced to mitigate DA non-compliance, as phosphorus values were

starting to increase due to nitrate recycling inhibiting the biological P process.

Rather than chemically treating the phosphorus directly with alum dosing, ethanol dosing could be applied to

reduce the nitrate recycle and indirectly treat biological P inhibition caused by the nitrate (Appendix B,

Hartley, 2014). Further consideration and testing would be required to ensure no lag time for sludge uptake

of ethanol in the form of intermittent dosing. This is not expected to be an issue, however should be verified

with the Beenleigh sludge characteristics.

It is recommended that further internal investigations could be carried out by the operators to assist in

enhancing the process through chemical dosing optimisation.

4.4.2 Ditch Velocity

Ditch velocities were recorded by plant operators during the study period:

OD1 had a flow velocity of 0.74 m/s with 5 rotors running

OD2 had a flow velocity of 0.58 m/s with 4 rotors running

The minimum velocity required to maintain solids in suspension is 0.2 m/s. Reducing the velocity could

effectively increase nitrification rates by increasing DO concentrations, which will subsequently increase

capacity. Inclined downstream horizontal baffles are in need of repair and there are no vertical upstream

baffles. Repairing the broken horizontal baffles may sufficiently reduce the oxidation ditch velocity.

If more improvements to the velocity reduction exist after these improvements, then upstream vertical baffles

should be installed to further reduce the velocities. The design and placement of the baffles will need to be

designed to account for other constraining factors in the WWTP, such as possible implementation of diffused

aeration grids (see section 4.4.3).

4.4.3 Enhanced Aeration Control and Aeration System Upgrade

Aeration control can ideally be linked in with the continuous measuring system at the effluent sampling point,

and further investigations should be undertaken to investigate this potential operational control. The

enhanced aeration control would operate under fixed weirs (i.e. closed) and altering the DO set-point

accordingly with the effluent results. The scum harvesters would be able to operate as per original design

under these settings. This enhancement would require upgrading the surface aerators to allow variable

speed operation (i.e. variable speed drives (VSDs)).

Care should be taken not to depend on effluent values if chemical dosing is enhancing the nutrient removal

process, as the settleability is more dependent on the ‘zone’ ratio rather than the effluent results ratio.

An upgrade solution for the aeration system could accommodate the increased incoming COD loads and

remove the capacity bottleneck in the WWTP. This would increase the WWTP capacity to the desired




15 ML/d capacity. A simple solution involves installing diffused air grids between aerators (pers. comms, K

Hartley, 4 February 2014), rather than upgrading the surface aerator drives. This upgrade is highly

dependent on the future incoming COD assumptions, especially from the industrial portion of the catchment.

The upstream vertical baffles could pose a constraint to the removal of the diffuser grids during maintenance.

This conflict needs to be accounted for in the design. Additionally, the small spaces available between

surface aerators could exacerbate force on the diffuser grids at the location of the downstream baffles. This

may also affect equipment operation and integrity and needs to be reviewed in the design. There is also a

concern that the electrical supply to the site is currently insufficient to accommodate blowers for diffused

aeration. Due to all these concerns, care needs to be taken in the design of the aeration system upgrade.

The cost for upgrading the aeration system is expected to exceed the cost for converting surface aerators to

VSD operation. The enhancement of aeration control may be sufficient to increase the WWTP capacity to

15 ML/d. This needs to be trialled after installation. It is recommended that the installation of VSDs and

enhanced aeration control be implemented first and trialled before further aeration system upgrades are

considered.

4.4.4 Summary of Upgrades and Controls

Figure 4-4 shows the recommended upgrades (not including any upgrades to oxidation ditch or clarifier

volumes), which will assist in increasing the WWTP capacity. The figure also highlights alternative methods

to increase capacity which LCC has reduced control over, such as reducing influent COD concentrations or

less stringent DA limits.




Figure 4-4: Recommended upgrades and improvements (green boxes) that will enhance the WWTP capacity, not including upgrades to tank sizes

4.5 External Influences

A number of upstream influences were identified during the study period, including trade waste (known and

suspected), which produces variable strength nutrients and organics, and also variability in dry weather flows

from upstream pump stations.

4.5.1 Trade Waste Monitoring

A trade waste monitoring programme was initiated by the LCC Environmental Management Systems Team

and the LCC Trade Waste Department as a concurrent study to determine trade waste impacts and

influences. The initial study was carried out from the 28th September to the 4

th October, with monitoring

stations installed at each of the three inlet mains entering the Beenleigh WWTP, as well as a monitoring

station at BE35 pump station (located in Yatala, a GCW precinct). A trade waste agreement is in place

between LCC and GCW, which limits COD concentrations to 1000 mg/L.

The concurrent study:

Observed key industrial influences and determined if results met with agreed discharge terms

Identified any abnormal peak loads over the week (not normally captured on the DA sampling day)




Resolved any discrepancies between GCW and LCC test results (using QUU labs as an alternative

comparative)

Table 4-1 shows the trade waste monitoring sample data over the monitoring period. The data shows a

range of the 5th percentile to the 95

th percentile of data for the three inlet mains, and compared to definitions

of medium and high strength wastewater as outlined in Metcalf and Eddy (2005).

Table 4-1: Trade waste monitoring sample data (range: 5th

percentile to 95th

percentile over week sampled and over 3 lab analysts)

COD (mg/L) BOD (mg/L) TSS (mg/L) TN (mg/L) pH

BE35 line (Stapylton)

500 – 790 200 – 440 220 – 420 54 – 86 7.4 – 7.7

SPS106 line (BE48 - Bramley Court)

540 – 880 240 – 500 220 – 470 50 – 79 7.4 – 7.6

SPS134 (BE47 line – Spanns Rd)

400 – 590 190 – 320 130 – 230 52 – 78 7.4 – 7.6

High strength wastewater average (M&E, 2005)

800 350 400 70 -

Medium strength wastewater average

(M&E, 2005) 430 190 210 40 -

The total nitrogen (TN) for all three incoming mains is in a similar range; however, both the Stapylton and

SPS106 (BE48) pump stations show greater COD values than SPS134 (BE47). SPS134 (BE47) has

characteristics of medium-high strength wastewater, whereas the other two mains have characteristics of

high strength wastewater.

However, no COD exceedances were observed in the BE35 line or the BE35 pump station from Gold Coast

for this sampling period. Further testing will be required to verify this consistently.

Investigations are recommended to determine the cause of higher COD loads from SPS106 (BE48), and any

required mitigation measures. A possible pipework cross-connection between BE35 and SPS106 (BE48)

may allow mixing and could explain why the data from BE35 sampling point was higher than the data from

the BE35 inlet point at the WWTP.

Future strategic planning should consider a potential diversion of ‘domestic’ strength wastewater away from

Beenleigh catchment, effectively increasing the ‘industrial’ portion and thereby increasing COD loads.

Higher COD loads would ultimately lower the capacity of the WWTP.

4.5.2 Network Flow Pacing

Flow variability exists between the inlet mains at Beenleigh WWTP that originate from the Logan catchments

and the inlet from the Gold Coast (Staplyton). This fluctuation results in issues at the WWTP:

Dry weather peak flows:

o Cause infrequent dry weather bypass alarms and require manual prevention by operators,

and potentially resulting in non-compliance




Low night flows:

o Clarifier launder pump burn out, due to no flows in launder and fixed speed RAS pumps

o Lack of effluent washwater available for belt filter presses (BFP) & inlet band screens

(equipment automated to cease operations if no washwater available, to protect assets)

Figure 4-5 shows flow from the three inlet mains entering the WWTP for the period of 20th to 21

st December

2013. A high variance in fluctuations can be observed for the Logan operated pump stations, especially for

SPS106 (BE48). BE35 (Gold Coast) operates very consistently in comparison.

Figure 4-6 shows the total continuous wastewater flow entering the WWTP for the same period. A dry

weather bypass occurred on the 20th December at approximately 8am. The 15 minute averaging of the

instantaneous flows in the software did not reduce the value to lower than the bypass trigger of 400 L/s, and

therefore the alarm was triggered. This has happened on several occasions and also on weekends where

the WWTP has no on-site staff.

Figure 4-5: Continuous Inflow Data for 3 Inlet Mains, showing variability in LCC Pump Stations

0

50

100

150

200

250

300

6:00:00 AM 12:00:00 PM 6:00:00 PM 12:00:00 AM 6:00:00 AM 12:00:00 PM 6:00:00 PM 12:00:00 AM 6:00:00 AM

Flo

w (L

/s)

Incoming flow from PS BE35 (Gold Coast)

Incoming flow from SPS135 ( BE48 - Logan)

Incoming flow from SPS106 (BE47 - Logan)




Figure 4-6: Total Continuous Inflow Data for 3 Inlet Mains, showing near bypass trigger during peaks and extremely low flows at night (moving average simulates 15 min average parameter)

The inflow behaviour suggests that further planning and investigations should be undertaken for the Logan-

operated pump stations to determine possible improvements and minimise flow variability entering the

WWTP.

An immediate short-term solution to avoid unnecessary dry-weather bypass alarms is to increase the 15

minute average progressively by 5 minutes to no more than 30 minutes. It is expected that increasing to 20

minutes should reduce the number of alarms and avoid false bypassing but not delay triggering for a genuine

wet-weather event (pers. comms., S Rasmussen, LWA, 20th January 2014).

0

50

100

150

200

250

300

350

400

450

6:00:00 AM 12:00:00 PM 6:00:00 PM 12:00:00 AM 6:00:00 AM 12:00:00 PM 6:00:00 PM 12:00:00 AM 6:00:00 AM

Flo

w (L

/s)

Total inlet flow

Bypass trigger

3 per. Mov. Avg. (Total inlet flow)

Diurnal peak on dry weather day (20/12/2013)

Low flows (night period)




Figure 4-7: Schematic of the Main Pump Station Contributors to the Beenleigh WWTP




5. CAPITAL WORKS IMPLICATIONS

The total capital cost to maintain an interim 14 ML/d capacity and increase beyond is estimated as $2.4m.

The works for improving the Beenleigh WWTP capacity have been staged, as follows:

Stage 1 – Interim 14 ML/d Capacity and Target 14-15 ML/d Capacity

o Renewals and Outstanding Works: $0.5m

o Rectification/Operational Improvement: $0.7m

o Capacity Improvement: $0.5m

Stage 1 is estimated to cost in the $1.7m

Stage 2 – Target 15 ML/d Capacity: $0.7m (only required if 15 ML/d capacity not achieved by Stage

1 works)

Table 5-1 outlines the capital works items identified for Beenleigh WWTP.

Table 5-1: Proposed Works – Interim and Target Capacity for Beenleigh WWTP

Stage Proposed Works Estimated Cost

(2013$)

Stage 1 (FY14/15)

Renewals/Outstanding Works (Interim 14ML/d Capacity)

Scum harvester adjustment $- *

Implement SRT control $- *

Fix and/or renewal of surface aerator paddles (11 No.) $147,000

Repair and/or renewal of downstream baffles (11 No.) $242,000

30% Contingency $117,000

Stage 1 Renewals Sub -TOTAL $506,000

Rectification/Operational Improvement (Interim 14ML/d Capacity)

Refurbish RAS pumps $0**

Structural assessment and general clean of oxidation ditches*** $86,000

Sludge bin upgrade $438,000


Stage 1 Rectification Sub -TOTAL $682,000

Capacity Improvement (Target 14-15ML/d Capacity)

Enhanced aeration control $147,000

Install VSDs on surface aerators $104,000

Install upstream vertical baffles $100,000

Optimise chemical dosing NA




Stage Proposed Works Estimated Cost

(2013$)


Stage 1 Capacity Improvement Sub -TOTAL $457,000

Stage 1 Total $1,645,000

Stage 2 (FY15/16)

Capacity Improvement (Target 15ML/d Capacity)

Upgrade aeration system (with diffused air grids and blowers for both oxidation ditches)

$540,000


Stage 2 Capacity Improvement Sub -TOTAL $702,000

TOTAL (Stage 1 and 2) $2,347,000

NB: * Works to be implemented as part of plant operations by WWTP operators ** RAS pump refurbishment already included in maintenance budget.

*** Does not include cost of works from the outcomes of the structural assessment

Table 5-2 provides an overall summary of the capital works adjustment requirements. Overall the net change

to the program for the nominated works in 2014/2015 is $1.7m (Stage 1 works). Stage 2 works are not

recommended until an aeration capacity assessment has been undertaken after Stage 1 works have been

completed.

Table 5-2: Capital Works Program Adjustment Summary

CWP ID

Task Description Status Year Amendments Estimated

Cost (2013$)

New 90-12-08

Stage 1 – Renewals and Outstanding

Works:

Renewal of aerator paddles

Renewal of downstream baffles

Concept 2014/15 Add new item $506,000

New 90-12-08

Stage 1 – Rectification/ Operational Improvement:

Structural assessment and clean of oxidation ditches

Sludge bin upgrades


New 90-12-08

Stage 1 – Capacity Improvement (Target 14-15 ML/d Capacity)

Enhance aeration control

Install VSDs on surface aerators

Install upstream vertical baffles


New 90-12-08 Stage 2 – Beenleigh WWTP Target

15 ML/d Capacity

Concept 2015/16* Add new item $702,000

NB: Only recommended post an aeration assessment after Stage 1 works are completed.




6. PARALLEL VERSUS SERIES OPERATION

The Beenleigh WWTP has been operated in a series configuration in recent years to counter peak wet

weather flows passing through the WWTP and the nutrient variances due to the high industrial portion of the

catchment. This would have reduced the overall capacity of the WWTP; however inflows prior to recent years

have been below 12 to 13 ML/d ADWF, which was within the capacity limit with the ditches in series

configuration.

The installation of the bypass now protects the process from wash-out. However, the high COD

concentrations entering the WWTP remain and this decreases the overall capacity of Beenleigh WWTP.

The outcomes from this study have shown that in parallel configuration the WWTP capacity is estimated to

be 14 ML/d and could be more, if appropriate controls are put in place. This is achievable in conjunction with

the somewhat reduced total nitrogen limits in the DA and reduced chemical dosing. The additional capacity

is achievable through the ability to improve the settleability of sludge through more control of the effluent N

ratio.

The disadvantages of the parallel configuration is that it is sensitive to insufficient aeration distribution

between the ditches (i.e. 5 rotors required in OD1; 4 rotors required in OD2 and in the appropriate locations),

and therefore sensitive to aerator failure. There is also a current issue with the scum harvesters; however

this is not insurmountable.

Figure 6-1 outlines the estimated capacity, advantages and disadvantages of each configuration at

Beenleigh WWTP.

Table 6-1: Estimated Capacity, Advantages and Disadvantages to Series versus Parallel Configuration at Beenleigh WWTP

Series Configuration Parallel Configuration

Estimated Capacity Capacity 10 to 13 ML/d Capacity 14 ML/d+

Advantages

More operational buffer (less sensitive to changes in influent)

Better settleability (due to control over effluent N ratio)

Reduced chemical consumption (due to

better control over settleability)

Disadvantages

Unable to control settleability through effluent N ratio

Scum harvesters require more design/operational consideration due to

moving water levels*

More sensitive to aerator failure (effluent N

ratio control lost)

Note: * Fixed weir operation is an alternate possibility, if VSDs were installed on aerators and enhanced DO control installed. The scum

harvester could then operate according to original design.

It is recommended that the WWTP is continued in parallel operation and appropriate automations and

adjustments are delivered over the next six months.




7. CONCLUSIONS

As part of this current optimisation study, the capacity of the Beenleigh WWTP has been verified as

approximately 14 ML/d ADWF in the parallel oxidation ditch configuration. The key bottleneck is the aeration

capacity which is also affected by the level of chemical oxidation demand (COD) in the influent wastewater.

The reduced capacity is mainly due to the increased COD load of an equivalent median 750 mgCOD/L

(compared to a design load and flow of 560 mgCOD/L and 15 ML/d ADWF). The capacity could effectively

be increased with appropriate automation and controls in place, due to minimising process variability.

The WWTP was able to be operated to meet effluent limits with an SRT of 10-15 days, however below 10

days SRT, it started to show reduced nitrification (ammonia removal) capabilities.

In addition, some key operational adjustments will also assist in maintaining the 14 ML/d capacity, which

include appropriate flow and aeration distribution between ditches (OD1 55%; OD2 45%) and maintaining

appropriate effluent N ratio to improve settleability in clarifiers.

A number of outstanding and rectification works require completion at Beenleigh WWTP, to maintain

14 ML/d capacity and ensure good operation in the parallel configuration. This includes implementing SRT

process control automation, upgrading the sludge bin, structure assessment and maintenance of the ditches

and general repairs to the aeration equipment and ancillaries.

To target a capacity of 14-15 ML/d, the following works can be implemented: enhanced aeration control,

install upstream vertical baffles and optimising chemical dosing (ethanol and alum). These works are likely to

increase the capacity to the desired 15 ML/d and is expected to cost $0.5m.

In total, the outstanding, rectification and upgrade capacity works is estimated to cost $1.7m (Stage 1

works). This estimate is based on general cost estimates and includes 30% contingency. However, if a

capacity of 15 ML/d is not achieved via enhancing the aeration processes under Stage 1, then a slight

upgrade to the aeration system (such as diffusers in between existing surface aerators) will achieve this

upgrade, which estimated at $0.7m (optional Stage 2 works).

Overall, the series configuration accommodates more process variability but reduces overall capacity to 10-

13 ML/d ADWF. A parallel configuration allows more process control and increases capacity to at least

14 ML/d ADWF but can be more sensitive to process variabilities. This variability is a characteristic at

Beenleigh due to the high industrial portion of the catchment, however could be managed if appropriate

controls and automation were implemented.

Trade waste monitoring showed higher COD and other parameters from the Stapylton catchment but also

from the Mount Warren Park/Windaroo catchment area. A cross connection in the catchment between the

two inlet mains is suspected. Monitoring of the SPS134 (BE47) catchment exhibited residential wastewater

characteristics, as expected.




A high flow variability from the LCC operated catchments are causing issues in the WWTP operation, in the

form of triggering dry weather bypass alarms during peak flows and reduced effluent for equipment operation

during low flows.




8. RECOMMENDATIONS

The Logan Water Alliance recommends that Logan City Council should:

1. Retain the parallel oxidation ditch configuration to maintain a WWTP capacity of at least 14 ML/d

ADWF. This operational adjustment is to be based on the following:

a. Flow and aeration distribution – of 55%:45% OD1:OD2, where practicable with the current

operating constraints, to capitalise on volume capacities

b. Effluent N ratio– of 0.1 to 1 effluent ammonia to effluent nitrate ratio, where practicable to

improve settling performance and capitalise on volume capacities

2. Implement Stage 1 works in 2014/15 inclusive of the following:

a. Renewals/outstanding works: scum harvester adjustment, surface aerator paddle repair,

downstream baffle repairs and SRT control implementation,

b. Rectification/operational improvements: RAS pump refurbishment, sludge bin upgrade and

structural assessment and general clean of oxidation ditches

c. Capacity upgrade - enhanced aeration automation, installing upstream vertical baffles in

oxidation ditches and investigating chemical dosing for polishing only. This is recommended

to be carried out with the outstanding works, for the purposes of improving general operation

3. Program Stage 2 works for implementation with the aim to increases the WWTP capacity to 15ML/d

pending the capacity improvements observed at the completion of Stage 1. Stage 2 works are

inclusive of the following:

a. Capacity upgrade - Upgrading the aeration system. This is recommended on the basis that

the Stage 1 works are insufficient to meet the 15 ML/d capacity.

4. Adopt proposed works as nominated to form part of Council’s Capital Works Program (refer

Section 5)

5. Undertake planning works to investigate LCC pump operation to reduce variability in flows entering

the WWTP, noting the impact of residential catchment diversions on the WWTP capacity

6. Continue trade waste investigations to determine any necessary changes to trade waste agreements

to reduce flow variability to the WWTP

7. Facilitate training of LCC operators and engineers to transfer knowledge and findings on the revised

plant operation

8. Facilitate the development of operational manuals to ensure that the adjusted operations of the

Beenleigh WWTP are documented to assist the future operation of the plant




9. REFERENCES

GCW, 2006, Model-Based Analysis of the Beenleigh Sewage Treatment Plant. Prepared by Damien

Batstone (AWMC, UQ) and Michael Burns (GCW). Prepared in January 2006.

JWP, 2009, Beenleigh WWTP: Stormwater and Solids Handling Study – Consolidated Report. Prepared in

November 2009.

LWA, 2014, Biosolids Management Strategy. Task Number 90-12-35.

LWA, 2010, Beenleigh WWTP Performance Improvement Detailed Planning Concept Report. Task Number

90-10-41.



90-12-08 Date issued: 28/03/2014 Rev: 1

Appendix A Site Meeting Minutes

Meeting Minutes

7600-000-P-MOM-PL-8229

MOM-PL-8229 Date issued: 13.06.2013 Page 1 of 3 Rev: A

MEETING MINUTES

MEETING: Task Kick-Off Meeting

MEETING NUMBER: 1

DATE: 13/06/2013

START TIME: 9:00am END TIME: 10:00am


TASK NAME: Beenleigh WWTP Upgrade - Process Commissioning & Optimisation

LOCATION: Commitment Room (Ground Floor) – LWA Office (106 City Road, Beenleigh)

CHAIRMAN: Leah Foley

ATTENDEES / APOLOGIES

NAME (Present = YES) ABBR

Leah Foley LF

Scott Francis SF

Ken Hartley KH

Daryl Ross DR

Chris Pipe-Martin CPM

Sandy Veeren SV

Wijay Tilakumara WT

Imtiaj Ali IA

Jason Lee JL

Darren Moore DM

Jackie Clutten JC

MINUTES

NUMBER: ITEM:

1. General introductions. LF outlined briefly the objective of the project – to undertake process optimisation investigations to determine Beenleigh WWTP ultimate capacity while operating the oxidation ditches in parallel configuration. Strategic planning has allocated 15 ML/d ADWF to Beenleigh WWTP however this has been in conflict with previous planning reports.

2. Safety:

· A Job Safety and Environment Analysis (JSEA) is being prepared and is to be understood and signed by all LWA team members before undertaking site inspections.

Meeting Minutes

7600-000-P-MOM-PL-8229


· Site visits will be supervised by Water Operations staff where appropriate.

3.

Scope of project:

· Operating & sampling regime to reduce SRT from 25 days (current). Other set points include

20 days SRT and 15 days SRT

· Clarifier stress test

Deliverable:

· Ken Hartley report

4.

KH discussed possible constraints to the project:

· Weir inlets – one weir to be set lower than other for 45%:55% flow split

· Aerator control to be modulated with outlet weir

· Ensure RAS flow pacing with WWTP influent (pumps already VSDs – controls required)

· Internal plant recycling (from dewatering system)– review to ensure that it does not impact on

process

KH discussed possible additional requirements:

· Measure oxidation ditch velocity – floating object with stopwatch

· Ethanol dosing may need to be relocated (alum dosing to remain as is)

· Control of inflow – via pump stations?

Action: JL and KH to ensure DO probe and control requirements are met so sampling can commence. JL to organise controls and other requirements to help speed up start date of optimisation sampling.

5.

IA raised concerns of variability of influent concentrations. General discussion indicating the trade waste

impact on the WWTP. Testing of trade waste flows from Stapylton occur once a month from GC at the

pump station, to meet compliance limits. IA indicated that over the past 4 months there appeared to be

a spike in influent concentrations every 3rd week.

6.

General discussion regarding sampling personnel. JL indicated that sampling appeared to be a lot – KH

indicated that the sampling regime also includes current routine WWTP sampling. CPM raised concerns

regarding increase to drinking water sampling next month. IA raised likely requirement for dedicated

operator to observe carryover, especially during clarifier stress test.

Action: IA, WT and JL to organise any additional operators for sampling assistance. Risk assessment and resourcing plan suggested by DR.

7.

CPM queried about SVI and the impact on UV disinfection. Concerns regarding the sensitivity of the

WWTP. KH discussed that the likelihood of exceedences is not critical and carryover will be minimal. IA

indicated that clarifier stress tests were the section of the sampling programme where carryover might

occur – dedicated additional personnel suggested. KH and IA indicated that duration of the clarifier

stress test is likely 2 to 4 days.

Meeting Minutes

7600-000-P-MOM-PL-8229


8.

General discussion regarding involvement of EHP. IA shared previous process with Loganholme WWTP

– WT indicated that the process commissioning was part of the upgrade with EHP. CPM raised

concerns that an informal process may not be ideal, due to recent issues with lagoon overflow at

Jimboomba WWTP, where EHP was informed prior to the spill event yet still issued a claim to council.

There were issues in the past where EHP tried to put conditions on the Beenleigh WWTP

bypass/upgrade, LWA did not accept. There were no non-compliances – therefore, no current TEP for

bypass. Bypass is designed for >3 x ADWF, with current ADWF at 12 ML/d.

Action: CPM to start discussions with EHP

9. Monthly meetings will be held to report on progress for relevant people and those interested to attend.

Meeting Minutes

7600-000-P-MOM-PL-8229


MEETING MINUTES

MEETING: Monthly Meeting

MEETING NUMBER: 2

DATE: 01/08/2013




LOCATION: Beenleigh WWTP




Leah Foley LF

Ken Hartley KH

Jason Lee JL

David Wickman DW

Noel Robinson NR

Bruce Willman BW

Imtiaj Ali IA

Chitra Liyanage CL

Andrew Stevenson AS

MINUTES

NUMBER: ITEM:

1. General introductions. LF outlined briefly the meeting agenda.

2.

Changeover to parallel operations: · ODs were converted to parallel operation on · JL mentioned there has been issues with SCADA · JL/DW also indicated that the rotors (aerators) have been running too hard

o This issue is that during peak flows (dry weather) the water levels increases, requiring more energy input into the aerators – beyond the current motor limit

o DW pointed out that OD2 is maintaining DO better than OD1 o Rotor #5 is offline undergoing maintenance. Rotor #4 has undergone maintenance

Meeting Minutes

7600-000-P-MOM-PL-8229


and is back online now o Previous meeting between JL, CL & KH – it was decided to set an upper power limit

for the aerators, however this needs further consideration o Possible solution proposed by DW: extending level transmitter to avoid interference

from OD walls o Possible solution generally accepted: could override DO by lowering weirs – however

this needs controls set up o Need further discussion with LWA Engineer (Marlon Pritchard) – JL to action

3.

KH data analysis:

· KH presented trend plots of the previous 12 months of data (dated July 2012 to July 2013)

· Note that historical data for June was missing – JL to send

· From the KH analysis, the following was concluded:

o SRT currently 20 days

o The plant receives a high influent COD load, above the design load of Beenleigh

WWTP. This is attributed to industrial loads from Stapylton (BE35). KH informed that

WWTP COD design loads have been sourced from previous reports such as JWP.

The sample data is in the form of 24-hr composites and performed only on Tuesdays.

JL mentioned there has been occurrences in the past where effluent ammonia

mysteriously increases such as one event at 1am on a Saturday

o There has been a change of TN:TP ratios post-April, with influent TP spikes on

occasion

o Effluent ammonia increased, attributed to recent decrease in SRT

o TP appears to be decreasing over time. Alum may not be needed, based on the

current licence. AS notes that there is a continuous effluent improvement agreement

within the DA.

o Cycling of SRT, because waste control hasn’t been completed. Require Tenix sub-

contractor to complete control work. There are some interferences due to biosolids

truck scheduling. KH and JL have already worked out a possible schedule to avoid

intereferences.

o Regular spikes in effluent nitrate

o Changes from SVI to stirred SVI – date was 2/7/13

o BFP cake TS inversely proportional to SVI

Action: LF to see if Tenix sub-contractor sourcing could be sped up via LWA

4.

The following additional investigations have been identified:

· There is clearly no data available showing the loads entering from Gold Coast. AS informed

that there are sewer emission limits with industrial customers and GCC. There is also a

treatment agreement between GCC and LCC. Suggestions were raised to sample rising mains

to determine daily loads from the industrial catchment.

· A lot more alum is needed to reduce TP to lower than 1 mg/L. The current DA does not require

this, however there is a continuous effluent improvement agreement in the DA. KH proposes

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trialing no alum, for a few months (need 3 sludge ages). JL had concerns that this would

negatively affect effluent results. It was proposed that alum would be switched off for a couple

of week and if this showed no negative impacts, to trial longer for a couple of months.

Action: AS to propose sampling project with the Trade Waste Department, to determine levels of COD and other concentrations entering Beenleigh WWTP from industrial catchment (Gold Coast).

Action: JL to trial no alum dosing for a few weeks. If no adverse effect on plant performance, to increase trial to 2-3 months.

5. LF to organise data and spreadsheets for KH analysis prior to monthly meetings.

6. LCC job organised by Phil Rech – email sent to JL for operators to book to for their time on this

additional work on this project.

7.

Monthly meetings will be held to report on progress for relevant people and those interested to attend.

AS to attend future meetings so that he can produce informal reports to EHP, regarding progress of this

project.

Next meeting in 1 month. LF to coordinate.

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MEETING MINUTES


MEETING NUMBER: 3

DATE: 28/06/2013








Leah Foley LF

Scott Francis SC

Ken Hartley KH

Jason Lee JL

David Wickman DW

Noel Robinson NR

Bruce Willman BW

Imtiaj Ali IA

Chitra Liyanage CL

Andrew Stevenson AS

MINUTES

NUMBER: ITEM:

1.

WWTP performance review by JL, with input from NR & BW.

Changeover to parallel operations: · ODs were converted to parallel operation on 17th July · Some WWTP exceedances

o Ammonia & TN exceeded DA limits in first week of August (7th August) o Several faecal coliform exceedances (likely due to one microscreen of 3 units out of

action. Also may be issues with oxidation ditch outlet weirs moving to let more flow

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through however causing surging in microscreens & UV. There is also a potential side issue that network pumps may not be coordinating enough to ensure smooth flows to the WWTP)

o CL to ensure coordination of microscreen repairs · UV system may be inadequate during peak flows. Need to monitor whether upstream

microscreens are overflowing when samples are exceeding DA limits

Action: JL/BW/NR – to monitor whether microscreens are overflowing when faecal coliforms samples are high.

Action: AS – to report to EHP regarding surging likely causing faecal coliform issues, therefore is partially EVOP related. IA to continue providing information to AS.

2.

Trade waste side project - progress: · AS has been in communication with Gold Coast Trade Waste and Logan Water Trade Waste

regarding monitoring project location o Most optimal location is pump station BE35 (located near Yatala Pies), which will give

the best indication of trade waste influences o The BE35 pipeline entering the inlet works (within WWTP site boundaries) is not

considered suitable for this sampling programme. There is some mixing in the pipeline and most of the pipeline up to the inlet works is pressurised

o Note that the pipeline up to the flowmeter at the inlet works is Gold Coast’s responsibility – as written into the agreement between Logan and Gold Coast.

o Note that Gold Coast Trade Waste samples a 24-hr composite sample over a week on a quarterly basis

o Logan Water is considering sampling every hour over 24 hours to observe any fluctuations or changes

o AS to continue actioning (still requires approval through management) · AS has been gathering quotes

o Sampler could be Logan Water Trade Waste or if unavailable, likely Royce Water Technologies

o AS will require input regarding the parameters to be sampled at BE35, when project approval has been confirmed. COD monitoring will be adopted, preferably online.

o IA raised concerns regarding cost of sampling, therefore sampling regime needs to be budgeted appropriately

o KH/IA/LF to provide additional parameter input (parameters and number of samples required per week) – LF to coordinate

3.

Wasting control automation progress:

· BWG Automation (Bashier) has sent out a quote for $8.5k

· IA is waiting on a quote from AIT – AI to chase up

· JL noted that LWA/BWG Automation needs to cover for liability of defects, therefore LWA and

BWG Automation need to make back-up copies of the programming information prior to any

work that may be performed by AIT

4. KH data analysis:

· KH presented trend plots of the updated data

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· Note that some data was missing due to other heavy commitments at the WWTP, but will be

provided shortly

· From the KH analysis, the following was concluded:

o WWTP is receiving and handling above its COD design load

o There appears to be a weekly cycle in flows – as observed in the recent dry period

o TN:COD ratio – typical; TP:COD ratio – very low (attributed to trade waste with low

TP)

o Effluent SS – since March 2013 has been slowly trending upwards. Attributed to SRT

decrease from 30 to 25days. MLSS has crept downwards and SVI gradually trending

upwards

o Oxidation ditch 1 appears to be receiving a higher load than oxidation ditch 2

o Based on KH’s Figure 1 in report –it is more optimal to have 5 rotors operating in

oxidation ditch 1 based on aerator power, rather than 6 rotors. Oxidation ditch 2 has

been performing better at nitrification than oxidation ditch 1. This is correlated with

oxidation ditch 1 drawing less power per aerator than oxidation 2.

o The WWTP is exhibiting a low nitrification rate, which is likely due to the COD:TN ratio

· Suggests trial and error to operate OD1:OD2 at 5:4 ratio based on rotors (via aerator power –

which could be performed by measuring current on each aerator). This will produce an effluent

ammonia/nitrate level rough equal in concentration

o JL raised concerns regarding ensuring that rotors will not be electrically ‘tripped out’

(i.e. overloaded)

o JL to coordinate & liaise with KH

5.

Monthly meetings will be held to report on progress for relevant people and those interested to attend.

LF to be away on leave from mid to late September.

Next meeting in 1st week of October. LF to coordinate.

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MEETING MINUTES


MEETING NUMBER: 4

DATE: 03/10/2013








Leah Foley LF

Scott Francis SC

Ken Hartley KH

Jason Lee JL

David Wickman DW

Noel Robinson NR

Bruce Willman BW

Imtiaj Ali IA

Chitra Liyanage CL

Andrew Stevenson AS

Steffi Mavani (work experience) SM

MINUTES

NUMBER: ITEM:

1.

WWTP performance review by JL, with input from DW & BW.

In parallel operation: · ODs were converted to rotor operation of 5:4 in OD1:OD2 · Weirs adjusted to 100% open · 3 of the 4 RAS meters have had interface issues and have been incorrectly reporting flow data.

This is still being resolved.

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· No alum dosing in August or September · Microscreens have been repaired · Some WWTP exceedances

o Max effluent TN exceeded DA limits in third week of September, due to high nitrate o Long-term effluent phosphorus exceeded in third week of September (exceedance

contributed by high effluent phosphorus during January 2013 floods) o Max effluent BOD exceeded DA limits in 1st week of September o Faecal coliforms OK

· Effluent nitrate has been decreasing since reducing DO set points, slight effluent ammonia increase from zero

· Effluent phosphorus non-compliance due to nitrate recycling into anaerobic zone & switching off alum dosing

Action: AS to report to EHP regarding recent DA non-compliance, which have been EVOP related. IA to continue providing information to AS.

2.

Wasting control automation:

· No progress for funding

· From KH’s data: it can be observed that there has been cycling and variance of the SRT. This

is because wasting has been variable.

· Wasting so far has been based on operator decision and has also been affected by truck

scheduling in the past

· Note that Loganholme EVOP did not implement wasting control automation. However, there

were issues involved with the wasting and the solution was to use a spreadsheet instead to

estimate the wasting requirements. RAS is not flow paced at Loganholme WWTP

· Control of wasting will improve variance in the effluent and therefore help improve compliance

to DA limits

Action: SF – to begin discussions with Daryl Ross, regarding funding approval of wasting control automation.

3.

KH data analysis:

· KH presented trend plots of the updated data in his report sent out on 2nd October (Process

Review No. 4: Sept-13)

· The following was discussed:

o Optimising OD load distribution. KH suggests to maintain 55%:45% flow-split between

OD1:OD2

§ JL & operators to coordinate OD1:OD2 at 55%:45% split & liaise with KH accordingly

o Effluent ammonia to nitrate ratio has been decreasing over time (see graph D7 of KH

report). Ideally want effluent ammonia and nitrate to be the same and then observe

results.

§ JL/DW presented plant data performance showing DO & weir profiles. This

indicated that the weirs are still ‘hunting’ but generally OK, except when

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weirs ‘max out’ (reach top level) and then DO drops significantly

§ KH suggests aeration tuning control. Possible external resources are AIT.

§ JL to investigate further regarding aeration tuning control. Possible student project.

o Stabilising SRT will reduce effluent variability and theoretically give more capacity

o Effluent phosphorus has increased in the past month. This is consistent with nitrate

recycling and no alum dosing.

§ There is an aim to be purely biological phosphorus removal, however if

results show continual DA non-compliance, then alum dosing will resume.

§ Phosphorus exceedance occurred at the same time as the clarifier blanket

carryover. This occurred because of blockages in the riser, with

denitrification occurring in the clarifier and causing rising sludge flocs.

Operators have mitigated the issue and vacuumed clarifiers.

o Effluent suspended solids performance appears to affect UV performance

o There has been an increase of electricity consumption since change of rotor

operations. The correlation between power usage and rotor usage has not yet been

concluded.

§ Action: JL/DW/KH to discuss.

· Scope forward

o Recommended to decrease SRT to 18 days. Controlled wasting is important to

maintain this value. Truck scheduling needs to be resolved to ensure it is not the

bottleneck

o Measure OD circulating velocities. Check is OD2 is faster than OD1.

o Action: JL to coordinate, with wasting control to be based on IA’s spreadsheet in the interim

4.

Trade waste monitoring programme - progress: · A meeting was conducted between Gold Coast, Logan Water Trade Waste and key Logan

Water personnel. JL was present at the meeting. · Each inlet main has a 24hr composite sampler, measuring from Friday 27th September for 1

week. Pump station BE35 also has a 24hr composite sampler. · Each sample will be tested by Gold Coast, Logan Water and an external lab (ALS). Logan

Water is paying for the external lab results. This will determine any discrepancy between lab methods.

· The meeting also highlighted that, in the past, the Gold Coast field sampler did not shake the sample when collecting from BE35, therefore past samples (especially for COD/BOD) may not be representative.

o AS to send through sampling results when available


Next meeting in 1st week of November (Monday 4th November). LF to coordinate.

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7600-000-P-MOM-PL-8229


MEETING MINUTES


MEETING NUMBER: 5

DATE: 11/11/2013








Leah Foley LF

Scott Francis SC

Ken Hartley KH

Jason Lee JL

David Wickman DW

Noel Robinson NR

Bruce Willman BW

Imtiaj Ali IA

Chitra Liyanage CL

Andrew Stevenson AS

Kam Akroni KA


MINUTES

NUMBER: ITEM:

1.

WWTP performance review by JL, with input from DW & BW.

In parallel operation: · ODs already converted to rotor operation of 5:4 in OD1:OD2, but also inlet weir was raised to

14 mm higher to OD2 (to achieve optimum flow split OD1:OD2 of 55:45)

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· Alum dosing re-initiated due to high effluent P concentrations, approximately 18th October · Generally, the WWTP has been performing well, especially since alum dosing was re-instated.

It has also been a long dry period. Increased wasting has been carried out, to meet new SRT target.

2.


· Funding approved and purchase order raised

· AIT have not appeared onsite to complete task, due to high workload at Loganholme WWTP

inlet works

· Truck scheduling now organised for 2 loads on Tuesday and 2 loads on Thursday

Action: JL – to report when waste control automation has been completed.

3.

Trade waste monitoring programme - progress: · Results have been returned from each of the 3 labs (Logan, Gold Coast and Brisbane). · Each inlet main had a 24hr composite sampler, measuring from Friday 27th September for 1

week. Pump station BE35 also had a 24hr composite sampler, concurrently. · The trade waste agreement between Gold Coast and Logan has a limit of 1000 mgCOD/L.

Previous Gold Coast reporting was a quarterly analysis which was a composite over the 7 days, showing an average of 300 mgCOD/L. The average during this week of testing was 650 mgCOD/L.

· There was a clear discrepancy of COD and some other results between labs. · Further testing will be carried out accordingly, such as more focused monitoring on times

where there is an observed issue (such as on Saturdays). The trade waste department will also conduct a Catchment Monitoring Programme to investigate pump station BE48 catchment area.

o Action: KA/AS to send through any results or findings, when available

4.

KH data analysis:

· KH presented trend plots of the updated data in his report sent out on 8th November (Process

Review No. 5: Oct-13)

· The following was discussed:

o Noticeable cycling of flow during the recent long dry weather period

o During end of October to early November, COD was 8.6 tonnes/day, which is slightly

above the design of 8.4 tonnes/day

o TN:COD ratio fluctuations during dry period, due to fluctuations in COD

o Raw TP slowly increasing since July

o Uncertainty around long-term exceedance of effluent BOD. Need to the review

method of calculation (percentile function versus LARGE function in EXCEL)

§ Action: IA to liaise with KH to verify calculation procedures

o Effluent ammonia has decreased over this period with a corresponding nitrate

increase, whereas TN has remained the same. Recommendation to reduce DO – this

will increase effluent ammonia slightly to reduce TN, through balancing ammonia and

nitrate. Changes will fully stabilise after 3 sludge ages.

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§ A fixed DO set point is recommended rather ‘adjust-as- you-go’

§ Operators now only changing once per week. Was 0.8 mg/L, currently

0.6 mg/L. KH recommends changing to 0.3 mg/L.

§ Action: JL to organise and liaise with KH accordingly

o Clarifier stress test recommended in the next month before the high rain period

§ Action: JL and KH to organise

o Ethanol dosing still switched off

§ AS flagged concerns around national tonnage load reporting, which have

been low for the past few years due to high chemical dosing. Optimisation

(and possible cessation of chemical dosing) could report higher loads, even

though chemical dosing has been optimised.

o Median SRT for last week was 17 days. Stabilisation of SRT is required to observe

performance.

o Queries regarding accuracy of MLSS hand-held measuring device, which does not

always report the same value as filter-paper test.

o SVI shows that there has been some response in the WWTP performance with better

settleability, however needs further investigation

o Faecal coliform performance has improved. This is likely due to more consistent

clarifier cleaning, regular UV maintenance (by Aquatech), no rain and new stainless

steel screens (local supplier).

o OD velocity not yet measured

§ Action: JL to organise velocity measurements and liaise with KH accordingly

o Operators indicated that surges are more noticeable now after parallel operation

· Scope forward

o Continue SRT at 17 days. Maintain controlled wasting until wasting automation is

implemented

o Clarifier stress tests to be carried out over the next month

o Measure OD circulating velocities. Check if OD2 is faster than OD1.

o Continue to monitor effluent TP and any reduction in nitrate recycling, to optimise

alum dosing

o Action: JL to coordinate


Next meeting in a month’s time. LF to coordinate.

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7600-000-P-MOM-PL-8229


MEETING MINUTES


MEETING NUMBER: 6

DATE: 17/12/2013








Leah Foley LF

Scott Francis SC

Ken Hartley KH

Jason Lee JL

David Wickman DW

Noel Robinson NR

Bruce Willman BW

Imtiaj Ali IA

Chitra Liyanage CL

Andrew Stevenson AS

Kam Akroni KA

Amy Flynn AF

Kaja Thompson KT


MINUTES

NUMBER: ITEM:

1. KH sends his apologies to the group.

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2.

WWTP performance review by JL, with input from operators.

In parallel operation:

· Current WWTP under heavy wasting to accommodate Christmas period where there will be only one operator attending and biosolids trucking expected to be slow

· MLSS – 3000 to 4000 mg/L · Trucking will likely be only 4 loads over the Christmas period · Ammonia has been fluctuating due to the high wasting – has been up to 6 mg NH4/L · DO levels were 0.3 mg/L for both ODs at the previous meeting (1 month ago). Currently, OD2

has a significantly higher set point whereas OD1 is maintaining OK. However, due to heavy wasting, the switching off of one rotor in OD2 has been delayed (ammonia issues)

· Oxidation ditch velocities measured: o OD1 - ~0.5 m/s o OD2 - ~0.7 m/s o KH has suggested vertical baffles to help slow down the velocity. This should

effectively increase the WWTP capacity o JL indicated that CL and Gary Goodliffe are intending to drain the ODs and inspect

the baffles in future. The last time this occurred was likely in 2000.

3.


· Completed, however not in operation due to issues with the ‘maximum tonnes wasted’

parameter

· Waiting until after Christmas period to complete

Action: JL – to report when waste control automation has been completed.

4.

Trade waste monitoring programme - progress: · Improvement in the trade waste quality received from catchment has been observed, without

any measures put in place. This is likely due to trade waste customers becoming aware that wastewater is being monitored

o For example, there appears to be a reduction in COD inflow from Teys Brothers Abattoir

· An auto-sampler has been set up for composite sampling at pump station BE35 (pump station directing flow from Yatala/Stapylton catchment to the WWTP). KA hopes to receive some data after the Christmas period

· Chris Pipe-Martin is intending to organise a further COD monitoring trial for a couple of weeks, to better capture any significant peaks from trade wastes

· A catchment survey for pump station BE48 is going ahead for a couple of weeks by the Trade Waste Department

Action: KA/AS to send through any results or findings, when available

5.

Issues with catchment flows from pump stations:

· Issues are still existing from Loganholme mains (BE47 and BE48 mains entering the inlet

works) which show to fluctuate heavily during dry weather, whereas the BE35 mains have a

tendency to be consistent

· This is attributed to the pump set up in the catchment (Logan Water operations versus Gold

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Coast Water operations)

· Alarms are still activated in the bypass, which operates based on 15 minute average intervals

and has occurred a couple times per week. This has required operator manual adjustment to

avoid dry weather discharge (potential for DA non-compliance)

· The process risk is possible dry weather exceedances during peaks in the flow, as well as

clarifier draw down issues during troughs in the flow (RAS pump still operating during low

flows). Faecal coliform results have also been affected by this. A stabilised flow is most ideal

for WWTP operation

· AF indicated that there was an Environmental Impact Assessment process already carried out

which involved the Operations Department. The risk to the WWTP due to pump station

operations was flagged during this process

Action: LF to re-flag issue via recommendations for further investigations in final report

6.

Clarifier stress tests:

· The tests have shown that Clarifier #3 discharge launder needs upgrading (the discharge

downpipe), even with the recent repairs/upgrades already performed on this clarifier

· Clarifier #1 and 2 are suction lift and may be drawing directly off the bottom of the clarifier

· Process of clarifier shut down for clarifier stress tests were as follows:

o Turned off Clarifier #4 (at this point, noted that Clarifier #3 was weaker)

o Turned off Clarifier #4 and #2

o Turned off Clarifier #4, #2 and #1

Action: KH to analyse and draw conclusions from clarifier stress test data

7.

Other notable information:

· Operators are generally satisfied with the operation of ODs in parallel, even though there are some final adjustments to be carried out to improve operation. They generally believe that operations have best benefited from the operational adjustments such as the stabilising of wasting (including improving truck schedule) and optimising the aeration – although the recent upgrades such as installation of the bypass would be a large contributor to the improvements

· The scum harvesters installed during the recent upgrade were designed for fixed weir operation. The new operation which requires moving outlet weirs is impeding the scum harvester operation

· Previous suggestion by KH was to perhaps control the aeration through power usage monitoring of rotors. However, JL communications with CL indicates that there is no equipment existing to record kW usage from each rotor

8. There will be no more monthly meetings as we are now at the end stages of the programme. The final

presentation will be held at the Logan Water Alliance office, expected in early February.



90-12-08 Date issued: 28/03/2014 Rev: 1

Appendix B Process Commissioning and Optimisation Report (Ken Hartley, 2014)

KEN HARTLEY PTY LTD

LOGAN WATER ALLIANCE

90-12-08

BEENLEIGH WWTP UPGRADE

PROCESS COMMISSIONING & OPTIMISATION

January 2014

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BEENLEIGH WWTP UPGRADE

PROCESS COMMISSIONING & OPTIMISATION

CONTENTS

ABBREVIATIONS

SUMMARY

1. PURPOSE

2. METHOD

3. RESULTS

3.1 Overview

3.2 Oxidation Ditch Flow Distribution

3.3 SRT Control

3.4 Aeration Control: N / sSVI

3.5 Phosphorus Removal / Alum Dosing

3.6 Nitrogen Removal / Ethanol Dosing

3.7 Clarifier Capacity

4. CONCLUSIONS & RECOMMENDATIONS

4.1 Conclusions

4.2 Recommendations

APPENDICES

1. References

2. Process Details

3. Clarifier Capacity Diagrams

4. Trend Plots

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ABBREVIATIONS

ADWF average dry weather flow

DEHP Department of Environment Protection

DO dissolved oxygen

EVOP evolutionary operation

MLSS mixed liquor suspended solids

OD oxidation ditch

RAS return activated sludge

SC secondary clarifier

SP setpoint

SRT solids retention time

sSVI stirred sludge volume index

WWF wet weather flow

WWTP wastewater treatment plant

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24-Jan-14

SUMMARY

The Beenleigh WWTP was originally a conventional oxidation ditch (OD) plant but at a

subsequent augmentation it was converted to a proprietary BioDenipho format with

anaerobic reactors for bio-P removal. Later, it was further converted to a two-stage

conventional BNR format with the two ODs operating in series and supplementary alum and

ethanol dosing.

Plant design capacity is 15 ML/d ADWF at a median load of 8.4 tCOD/d (560 mg/L); WWF

above 45 ML/d is bypassed. Operating experience suggested that the operating capacity may

be only 10-11 ML/d ADWF and two theoretical studies, both assuming retention of the

series OD format, rated the capacity at 11-13 ML/d ADWF. The main capacity bottleneck

identified was the reactor and clarifier volumes, combined with the historical sludge

settleability, which limited the maximum SRT achievable at the design load.

A subsequent review concluded that reversion to conventional parallel OD operation may

allow the design capacity to be achieved. Parallel OD operation would provide a greater

degree of operating flexibility which may allow improvement of sludge settleability and

reduction of chemical dosing.

An upgrade recently completed (2013) by the Logan Water Alliance has provided new

pretreatment, bypassing, scum harvesting and sludge dewatering facilities. However, before

deciding whether an upgrade may be required for the main biological process it was decided

to conduct an evolutionary operation (EVOP) program, similar to a 2012 program at the

Loganholme WWTP, to assess the actual operational capacity of the plant.

The EVOP program ran over the period Jul-Dec 2013. Regular process reviews were

undertaken and plant operational procedures adjusted progressively to improve

understanding of the plant operating characteristics, optimise performance and define the

operational capacity of the liquid stream process.

The main conclusions of the program are as follows:

1. The operational capacity of the plant is limited almost equally by the oxidation ditch and

clarifier volumes, oxidation ditch aeration capacity and RAS pumping capacity (20%

below its original capacity due to pump deterioration). Plant median capacity is 11

tCOD/d, equivalent to an ADWF of 14 ML/d at the current median influent strength of

750 mgCOD/L. The plant is currently operating close to its capacity, with a median flow

of 13 ML/d.

2. Operationally, the maximum capacity is also governed by the minimum SRT at which the

process can be reliably run. A process SRT of 10-15 days is the minimum at which the

effluent standards can be reliably met. It was not possible to determine an accurate SRT

during the study; over the last two months the calculated SRT was 14 days based on

wasting data and 10 days based on dewatered sludge cake produced. Improved RAS

wasting controls have been implemented.

3. It was demonstrated that appropriate oxidation ditch aeration control allowed both

effluent nitrogen and sludge settleability to be optimised. For the last two months of the

study the median values for effluent TN and sSVI were 4.7 mg/L and 68 mL/g

respectively. Ethanol dosing for denitrification was discontinued.

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4. A clarifier stress test confirmed that the clarifier behaviour conformed with theoretical

expectations.

5. The oxidation ditch scum harvesters are at a fixed level. Modifications are required to

enable them to function properly with a variable water level.

6. The oxidation ditch circulating velocity is significantly higher than the minimum necessary

to maintain the biomass in suspension. Installation of vertical baffles upstream of the

aerators to reduce the velocity would raise the dissolved oxygen profiles and enhance

nitrification. This would increase capacity by allowing operation at lower SRT.

7. It may be possible to reduce process variability and further increase capacity through a

range of modifications such as aeration control from ammonia probes, renewed use of

ethanol dosing to facilitate operation at shorter SRT and possibly reduce the need for

alum dosing, installation of vertical baffles to reduce circulating velocity and increase DO

concentration, and refurbishment of RAS pump.

8. Pursue a trade waste program aimed at reducing the variability of the plant influent.

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1. PURPOSE

The Beenleigh WWTP was originally a conventional oxidation ditch (OD) plant but at a

subsequent augmentation it was converted to a proprietary BioDenipho format with

anaerobic reactors for bio-P removal. Later, it was further converted to a two-stage

conventional BNR format with the two ODs operating in series and supplementary alum and

ethanol dosing.

Plant design capacity is 15 ML/d ADWF at a median load of 8.4 tCOD/d (560 mg/L); WWF

above 45 ML/d is bypassed. Operating experience has suggested that the operating capacity

may be only 10-11 ML/d ADWF and two theoretical studies, both assuming retention of the

series OD format, rated the capacity respectively at 13 ML/d (Gold Coast Water, 2006) and

11 ML/d (WorleyParsons, 2009). The main capacity bottleneck identified was the reactor

and clarifier volumes, combined with the historical sludge settleability, which limited the

maximum SRT achievable at the design load.

A subsequent peer review (Hartley, 2010) concluded that minor modifications and reversion

to parallel OD operation may allow the design ADWF capacity of 15 ML/d to be achieved.

Parallel OD operation would provide a greater degree of operating flexibility which may

allow improvement of sludge settleability and reduction of chemical dosing.

An upgrade recently completed (2013) by the Logan Water Alliance has provided new

pretreatment, bypassing, scum harvesting and sludge dewatering facilities. However, before

deciding whether an upgrade may be required for the main biological process it was decided

to conduct an evolutionary operation (EVOP) program, similar to that recently completed at

the Loganholme WWTP (Hartley, 2012), to assess the actual operational capacity of the

plant.

EVOP is a technique developed in the chemical process industries for maximising the rate of

learning during routine operation (Box & Draper, 1969). This is a structured method for

deliberate learning in which a continuous investigative routine becomes the basic mode of

operation and replaces normal static operation. It is based on the principle that it is

inefficient to run a plant in such a way that only a product is produced, rather, a process

should be operated so as to produce not only a product but also information on how to

improve the product.

This method of operation involves the operators in an ongoing process of continuous

improvement through planned variation of operating parameters and evaluation of results.

Understanding of the plant’s behaviour improves and the plant is continuously moved

towards the optimal operating regime. In the short term, for the purpose of determining a

practical capacity rating, the plant is operationally stressed to determine its response and

assess the load at which the effluent licence limits are likely to be exceeded.

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2. METHOD

During the test period the plant was operated in the parallel OD mode with the flowsheet

shown in Figure 2.1. Process details are listed in Appendix 2.

The operational capacity of the liquid stream processes is the maximum load the plant can

handle while reliably meeting the DEHP performance limits. The key performance limits are

summarised in Table 2.1.

The operational capacity of a treatment plant is generally different from the original design

capacity because of design and construction margins, differences between the design and

actual sewage qualities (strength, constituent ratios, variability), and operating skill levels.

Process failure is caused by the single component of the plant, referred to as the bottleneck,

which first exceeds its capacity. The capacity of the bottleneck governs the capacity of the

whole plant. The main potential bottlenecks at Beenleigh are as follows:

Table 2.1 Liquid Stream Key Effluent Limits (weekly monitoring)

Parameter

(mg/L)

50%ile

Long Term

80%ile

Short Term

90%ile

Long Term

Maximum

BOD mg/L

SS mg/L

NH3-N mg/L

TN mg/L

TP mg/L

pH units

Faecal coliforms cfu/100 mL

---

---

---

5

---

---

1502

15

23

---

---

3

---

6002

10

15

---

---

2

---

---

15

30

3

7.5

4

6.5-8.51

--- 1. Range of pH.

2. For faecal coliforms, the median of five consecutive grab samples taken over 24 hours shall not

exceed 150; four of the five samples shall not exceed 600.

Figure 2.1 Plant flowsheet with parallel oxidation ditch operation.

Effluent

Lagoon

AlumAlum

P P P P

Washwater

BFP BFP

Poly

WAS

RAS

Biosolids

Sludge Storage Tanks

Outlet

Weirs

Inlet

Weirs

Flow

Distributor

OD1

OD2

C1 C2 C3 C4

F

F

F

Septage

Scre

en

s

Grit T

an

ks

Anaer’bic

Reactor

Biofilter

Wet Weather Bypass > 3ADWF

Scum

Wetland

Alb

ert

Riv

er

Mic

roscre

en

s

UV

Dis

infe

ctio

n

Wa

sh

wa

ter

Scu

m

To be diverted to

Loganholme

Filtrate

7

16117:Ken Hartley

24-Jan-14

Flow distribution between the two ODs – theoretically, the optimum distribution

matching the relative volumes and aeration capacities (OD1:OD2 loads 55:45) will

minimise the required SRT and maximise treatment capacity.

Clarifier capacity – RAS flow governs thickening capacity and potential gross solids loss;

overflow rate governs effluent SS produced by clarification.

Biomass settleability (sSVI) – settleability is a key factor governing clarifier capacity.

SRT control – SRT also governs clarifier capacity: maximum capacity is achieved at the

minimum SRT (minimum MLSS for a given load) at which the effluent standards can be

met; steadiness of SRT control is important to minimise the average operating value

required.

OD aeration control – can be adjusted to minimise sSVI, and to minimise the

concentration and variability of effluent ammonia and TN.

The keys to achieving optimum results from the biological process are as follows:

Parallel (rather than series) operation of the two oxidation ditches with an optimum load split

(theoretically A:B 55:45 based on volumes and aeration capacities): Potentially, parallel

operation will maximise aeration capacity, facilitate improvement of sludge settleability,

reduce chemical consumption and improve tune-ability (Hartley, 2-Jul-13).

Minimising effluent variability so as to minimise the SRT at which the effluent standards can be

met: Theoretical SRTs at which the clarifiers reach their capacities at the design peak

load of 45 ML/d and 8.4 tCOD/d are: sSVI 110 mL/g – 15d; sSVI 95 – 18d; sSVI 80 – 22d;

sSVI 65 – 26d.

Close monitoring and control: Operators need to have a good understanding of the plant

behaviour at all times so they are not taken by surprise. Tuning transcends

troubleshooting.

Good understanding of the plant operating characteristics: Every experience with the plant

provides opportunity to move up the learning curve.

Attention to bottlenecks as they are discovered: Performance and capacity are limited by

bottlenecks which come into play during periods of duress. These can often be

overcome by operational measures.

The EVOP methodology implemented to assess the actual operational capacity of the plant

liquid stream processes is as follows:

1. Parallel (rather than series) operation of the two ODs with an optimum OD1:OD2 load

split (theoretically 55:45, but nominally 50:50). Aeration control by modulation of the

OD outlet weirs.

2. Systematically vary the plant control variables.

3. Measure the outcomes - data collection program.

4. Interpret the data and develop ideas for improvement through production of plant trend

plots, periodic process reviews, technical memos and EVOP meetings.

5. Re-adjust the process.

6. Conduct specific trials and tests on individual processes or the whole plant.

An overview of the whole program is set out in Table 2.2.

8

16117:Ken Hartley

24-Jan-14

Table 2.2 EVOP Strategy

Item

No.

Aim

Action Comments

1

Overall Strategy

Maximise plant capacity at which the

effluent licence limits can be reliably met.

At current load, test by defining the minimum SRT & sSVI at

which the licence can be met. To maximise capacity:

1. Operate ODs in parallel. This provides a degree of control

over sSVI and minimises reliance on ethanol. Shift ethanol

dosing to OD inlet channel.

2. Gradually decrease SRT to determine the minimum value at

which the effluent licence can be met.

3. Adjust the DO SP step-wise to determine the minimum sSVI

at which the effluent licence can be met.

4. Adjust the OD and clarifier flow distributions and the RAS

flow ratios such that parallel units potentially fail at the same

time.

5. Maintain steady operating conditions to minimise effluent

variability.

Goals:

Capacity: ADWF 15 ML/d @ 8.4 tCOD/d

requiring-

SRT 20d @ sSVI 90 mL/g, or 15d @ 110

mL/g

with effluent 90:50%ile variability limited

to:

NH3-N TN

SRT 20d 2:1 4:1

SRT 15d 1.5:1 2:1

2

OD 1-2 Flow Distribution

Distribute load between the two ODs to

match their relative operating aeration

capacities & volumes.

Theoretically:

OD1: 55% of total inflow

OD2: 45% of total inflow

Operate OD1 influent weir full down

Set OD2 influent weir 14mm above OD1

weir, or at same level as OD1 for a 50:50

split

3

SRT / WAS Control

Maintain a steady daily wasting rate to

hold SRT constant and minimise

variability of effluent quality.

Implement improved wasting control strategy to enable the same

fraction of the solids mass to be wasted each day. Allow for

effluent SS loss and solids recycle via the BFP filtrate return.

Monitor the daily OD SRT value calculated from the 7d MA

(moving average) WAS flow & the daily MLSS concentration.

9

16117:Ken Hartley

24-Jan-14

4

OD 1-2 Aeration Control: N / P /

sSVI

Positive control of aerobic & anoxic

fractions. To achieve in-spec N and P

and lowest sSVI with minimum doses of

ethanol and alum, tune aeration to

achieve optimum effluent

ammonia:nitrate ratio.

OD1: operate Aerators 2, 3, 4, 5 & 6 (1 & 7 off); control DO just

upstream of the OD inlet. OD2: operate Aerators 10, 11, 12 &

13 (8 & 9 off); control DO just upstream of the OD inlet. Shift

DO probes & control DO by modulating the outlet weirs. Tune

the DO control loops. Measure the OD velocities to determine

the potential for increase of average DO (nitrification

enhancement).

5

Phosphorus Removal / Alum Dosing

Alum dosing reduces pH and tends to

increase effluent SS concentration and

should be minimised.

Dose at one location only (anaerobic zone). Maintain a steady

dose rate at the minimum level required to meet the effluent P

limits. May not be needed. Can use ethanol to reduce nitrate if

bio-P removal is limited by nitrate.

6

Nitrogen Removal / Ethanol Dosing

Minimise or eliminate ethanol dosing.

Adjust DO setpoints to minimise effluent ammonia & nitrate.

Dose ethanol to the OD inlets (anoxic zones) to meet the

effluent N or P limits if necessary - the need is more likely at the

shorter SRTs.

7

Secondary Clarifier Flow

Distribution / Stress Test

Distribute flows so all clarifiers fail

simultaneously.

Distribute flow in close proportion to the RAS flows:

SC1:2:3:4 = 15:15:21:49 (as per existing clarifier inlet structure).

Conduct testing to assess the actual behaviour & capacity of the

clarifiers at the prevailing sSVI.

8

BFP Operation

Control BFP operation to maintain the

filtrate quality and daily return volume as

steady as possible over the week.

Operators to maintain as practicable through the investigation

period.

9 Load Variation

Minimise process disturbances.

Review and optimise control of plant flow streams - influent rising

mains, septage receival, BFP filtrate recycle (Item 8).

10

16117:Ken Hartley

24-Jan-14

10

Monitoring / Recording

Monitor the plant closely to identify

trends and respond appropriately.

Collect EVOP data. Record plant observations and comments.

11

Reviews / Reporting

Provide ongoing reviews and

documentation.

Prepare monthly process reviews and technical memos on

specific issues.

Conduct monthly operations meetings to review progress and

decide direction.

11

16117:Ken Hartley

24-Jan-14

3. RESULTS

3.1 Overview

Plant trend plots for the overall operating period Jul-12 to Dec-13, including the specific six-

month EVOP period 17-Jul-13 to 31-Dec-13, are shown in Appendix 5 (Plots A1 – E1, 20

plots trending 60 parameters). Parallel OD operation began on 17-Jul-13.

Plant operating data for the final two months, 1-Nov to 31-Dec-13, are summarised in Table

3.1. Features of note are as follows.

Loading

The median influent flow was 13 ML/d, 87% of the design ADWF. Rainfall was low and

the maximum day flow was only 65% of the design peak of 45 ML/d. See Trend Plot A1.

In contrast the plant median daily COD load of 10.7 t/d was 27% above the design value

of 8.4 t/d and the 90 percentile daily load was 55% above the design median (Trend Plot

A2). This arose because the median and 90 percentile COD concentrations were 34%

and 68% above the design figures. The median COD concentration was 750 mg/L

compared with the design strength of 560 mg/L.

The median influent TN:COD and TP:COD ratios were only 0.089 and 0.015, somewhat

lower than typical sewage values of 0.10 and 0.02 because of the significant industrial

inputs at Beenleigh. TN and TP concentrations were less variable than COD (Trend

Plot A3).

Trend Plot D1 shows that over the Nov-Dec period flow was distributed to OD1/OD2

in the proportions 55/45 in November (inlet weir levels 0mm/14mm above the concrete

weir sill) and 50/50 in December (0mm/0mm).

Effluent Quality

Effluent quality is trended in Plots B1-B4. All parameters conformed with the key

licence standards listed in Table 2.1 except for total phosphorus (90 percentile 2.6 mg/L,

above the limit of 2 mg/L - see Trend Plot B3).

Operation

SRT was calculated by two methods, (a) from the waste activated sludge (WAS) flows

extracted from the RAS system and the associated RAS SS analyses, and (b) from the

mass of dewatered sludge cake transported and the associated cake TS analyses. Trend

Plot D2 shows that the two SRT trends have similar patterns although for uncertain

reasons the cake value is generally lower than the WAS value with the gap increasing

over the EVOP period; an improved method of WAS SRT control was implemented

near the end of the EVOP period (Hartley, Oct-13; AIT, 2013). Over the November-

December period the SRT was reduced to determine the effect on plant performance;

median values were 14 days calculated from the WAS and 10 days calculated from the

dewatered cake.

Median MLSS concentration was 6.5 g/L (Trend Plot D2).

Median sSVI was 68 mL/g (Plot D7).

12

16117:Ken Hartley

24-Jan-14

Table 3.1 Plant Operating Data for Final Two Months of EVOP Period Parameter Key Targets Data for EVOP Period

1-Nov to 31-Dec-13

50%ile

Variability

90:50%ile

Plant Load

Sewage flow ML/d

COD conc mg/L

COD load t/d

TN conc mg/L

TP conc mg/L

TN:COD

TP:COD

ADWF 15

Process max 45

560

8.4

56

11

0.10 typical

0.02 typical

13.0

29.2 max

750

10.7

70

9.8

0.089

0.015

1.29

---

1.25

1.22

1.32

1.22

1.84

1.43

Effluent Quality

BOD mg/L

SS mg/L

NH3-N mg/L

TN mg/L

TP mg/L

F.cols cfu/100mL

10, LT 90%ile

15, LT 90%ile

3, max

5, LT 50%ile

7.5 max

2, LT 90%ile

150 max (50%ile of sample)

5

8

1.0

4.7

5.6 max

0.75

8

1.40 (90%ile 7)

1.38 (90%ile 11)

2.10 (max 2.5)

1.12

---

3.47 (90%ile 2.6)

1.60 (max 8)

Operation

SRT d

MLSS g/L

sSVI mL/g

ML pH units

Alum dose: mg solid/L

Ethanol dose mg/L

See footnote1

14 (WAS data)

10 (cake data)

6.5

68

7.4

44 (anaerobic reactor)

0

1.31

1.39

1.21

1.21

1.04

1.36

---

1. The theoretical bottleneck is clarifier capacity (Section 3.7). Theoretically, for sewage COD 560

mg/L, maximum SRTs at which design flows can be achieved are sSVI 65 mL/g, 26d SRT; sSVI 80

mL/g, 22d SRT; sSVI 95 mL/g, 18d SRT; sSVI 110 mL/g, 15d SRT. For sewage COD 750 mg/L, the

maximum SRTs at which design flows can be achieved are sSVI 65 mL/g, 19d SRT; sSVI 80 mL/g,

16d SRT; sSVI 95, 13d SRT; sSVI 110, SRT 11d.

2. Calculated from WAS data.

3. Calculated from dewatered cake data.

The various plant operating characteristics explored during the EVOP program (as listed in

Table 2.2) are discussed in the following Sections with reference to both the trend plots

appended and, for convenience, a key selection of trends shown in Figure 3.1.

3.2 Oxidation Ditch Flow Distribution

The flow distribution applied over the EVOP period is summarised in Trend Plot D1

appended. For the theoretical OD1:OD2 flow split of 55:45, the OD2 inlet weir should be

14 mm higher than for OD1 and the respective number of aerators operated in the two

ditches should be 5 and 4 with DO profiles as depicted in Figure 3.2 (Hartley, 2-Jul-13).

Trend Plot D1 shows the various inlet weir and aerator settings used over the test period.

Given the significant degree of data variability, it is difficult to discern in the trend plots any

direct effects of the different aerator and weir settings used. It is recommended that the

theoretical settings be adopted.

13

16117:Ken Hartley

24-Jan-14

Figure 3.1 Key trends from the EVOP program.

0

5

10

15

20

25

0

10

20

30

40

50

01-Jul 01-Sep 01-Nov 01-Jan 01-Mar 01-May 01-Jul 01-Sep 01-Nov 01-Jan 01-Mar 01-May

ML

SS

-14d

MA

(g

/L)

Re

acto

r S

RT

(14d

MA

, d)

ML

Te

mp

(d

egC

)

D2. SRT, MLSS, ML Temperature SRT(WAS, Sc 0.98) SRT(cake trucked) MLSS (g/L)

Start sSVI

0.01

0.1

1

10

100

1000

0

50

100

150

200

250


Fin

al E

ff N

Rat

io (

60

d M

A)

sS

VI (

mL

/g)

D7. sSVI , Effluent N Ratio ML SVI / sSVI Eff NH3-N:NO3-N Ratio 60 per. Mov. Avg. (Eff NH3-N:NO3-N Ratio)

0

4

8

12

16

20

0

100

200

300

400

500


Eth

an

ol D

os

e (m

gC

OD

/L)

Alu

m D

os

e(m

g s

olid a

lum

/L)

C. CHEMICALSC1. Plant Alum & Ethanol Consumption

Alum-Anaerobic Zone Alum-Total Ethanol

Licence TP90 LT 2mg/L

6.6

7

7.4

7.8

8.2

0

1

2

3

4


pH

TP

(m

g/L

)

B3. Effluent P & pH Effluent TP Effluent pH

Licence TN50 LT 5mg/L

Licence NH3 max 3mg/L

0

2

4

6

8

10

0

2

4

6

8

10


NH

3-N

, N

Ox-N

(mg

/L)

TN

(m

g/L

)

B2. Effluent N TN NH3-N NOx-N

0.1

1

10

100

0

1

2

3


Fin

al E

ff N

Rat

io (

60

d M

A)

Daily A

ve

Pro

be

DO

(m

g/L

)

D8. Aeration, Effluent N Ratio Ave Probe DO - OD1 Eff NH3-N:NO3-N Ratio 60 per. Mov. Avg. (Eff NH3-N:NO3-N Ratio)

14

16117:Ken Hartley

24-Jan-14

Figure 3.2 Operating DO profiles in Oxidation Ditches 1 and 2. The slopes of the lines

represent the average respiration rate at the design load (15 ML/d at 560

mgCOD/L). The solid lines show the DO profiles for an anoxic fraction of 0.4

with the feed entering at or close to the start of the anoxic zones. For OD1,

the dashed line shows the DO profile at the end of the aerobic zone for an

anoxic fraction of 0.33. The DO is controlled by the outlet weirs, using DO

Probe 1 in OD1 and Probe 2 in OD2. For effective control, at the start of the

EVOP program the probes were shifted from their original positions to the

locations shown.

3.3 SRT Control

As mentioned in 3.1 above, Trend D2 (Figure 3.1) shows that the separate SRT values

calculated from the WAS data and the cake data diverged significantly from September

onwards. The associated MLSS concentration is consistent with the cake-based SRT and the

variable influent COD concentration (Plot A2 appended). SRT ran at 15-20 days for the first

three months of the EVOP period and was then gradually decreased to about 10 days over

the last two months.

Possibly the SRT was higher when calculated from WAS because the periodic WAS SS

sample was collected at a time of day when the SS concentration was lower than the average

over the full wasting period. The improved method of WAS wasting control mentioned in

Section 3.1 above (Hartley, Oct-13; AIT, 2013) accounts for the variation in WAS

concentration over the wasting period.

3.4 Aeration Control: N / sSVI

Nitrogen Refer to Figure 3.1, Plot B2. After changeover to the new operating configuration, effluent

ammonia declined because of a high aerobic fraction in the ODs – daily average probe DO

was around 1.5 mg/L (Plot D8).

OD1

INL

ET

, 9

2

R6

, 6

1

R5

, 4

9R4

, 2

4

R3

, 1

2

Ro

tor

2,

0

R2

, 1

55

DO

2 E

xg

, 3

7

OU

TL

ET

, 4

0

DO

1 E

xg

, 9

7

DO

1 N

ew

, 8

6

R1

, 1

02

R7

, 7

3

0

1

2

0 155

Circuit distance (m)

DO

(m

g/L

)

Anoxic fraction 0.4 Anoxic fraction 0.33

OD2

R1

0, 1

56

R9

, 1

20

R6

, 6

1

R1

3, 5

8

R1

1, 1

6

Ro

tor

10

, 0

R1

2, 4

2

DO

1 E

xg

, 2

9

OU

TL

ET

, 3

3

DO

2 E

x'g

, 9

0

R8

, 9

4

INL

ET

, 8

6

DO

2 N

ew

, 8

0

0

1

2

0 155

Circuit distance (m)

DO

(m

g/L

)

15

16117:Ken Hartley

24-Jan-14

Conversely, nitrate increased because of the low anoxic fraction and the cessation of ethanol

dosing (Plot C1). Downward adjustment of the DO setpoints (Plot D8) increased the OD

anoxic fraction and reduced the nitrate.

The ammonia concentration rose again in Nov-Dec (Plot B2) when the SRT was reduced

(Plot D2) and the DO setpoint (SP) was further reduced (Plot D8). Overall, Plot B2 shows

that the effluent ammonia and TN licence limits can be met, without ethanol dosing, at an

SRT of 15 days by appropriate DO control.

Sludge Settleability Plot D7 (Figure 3.1) shows the relationship between the sludge settleability and the effluent

ammonia:nitrate ratio (60d or nominal 3SRT moving average). Both the nitrogen ratio and

the settleability are governed by the OD anoxic fraction and can therefore be controlled by

the DO setpoint. With appropriate DO control, it should be possible to hold the sSVI

below 70 mL/g.

The Beenleigh settleability characteristics are consistent with published data - see Figure 3.3

(Hartley, 2013). The Bucasia curve for an SRT of 10 days has an optimum sSVI of 65 mL/g at

an effluent ammonia:nitrate ratio between 0.1 and 1. The Beenleigh optimum matches this

precisely. Therefore, for maximum capacity, operate at an SRT of 10-15 days (based on

cake production or using the enhanced RAS wasting control system, AIT 2013).

Figure 3.3 Published oxidation ditch settleability characteristics.

3.5 Phosphorus Removal / Alum Dosing

Referring to Figure 3.1, Plots B3 and C1 show that when chemical dosing ceased in Jul-13,

effluent P increased excessively. There are two reasons for this: alum phosphorus

precipitation ceased and bio-P removal decreased due to greater nitrate recycle to the

anaerobic reactor (Plot B2). Alum dosing was restarted in October (Plot C1).

SRT 20d

SRT 10d

0

50

100

150

200

0.01 0.1 1 10 100

SS

VI o

r s

SV

I (m

L/g

)

Effluent NH3-N:NO3-N Ratio (3SRT average, Nrave)

Bucasia Ditch 1(SRT 17d)

Bucasia Ditch 2(10d)

Coolum(30d)-APT Online

Coolum(30d)-APT Offline

West Byron(20d)

16

16117:Ken Hartley

24-Jan-14

An alternative approach would be to dose ethanol to reduce nitrate recycle to the anaerobic

zone. Potentially, this approach could have two advantages – effluent TN and TP would

both be reduced, and the chemical cost may be lower. Total dewatered cake production

would be unchanged – cessation of alum dosing would reduce the total dry solids production

but this would be counterbalanced by an equivalent reduction in the cake solids

concentration (Hartley, 2013).

3.6 Nitrogen Removal / Ethanol Dosing

Plot B2 shows that the effluent TN and ammonia limits can be met by appropriate aeration

control with minimal need for ethanol dosing. However, as mentioned in 3.5 above, ethanol

dosing may offer advantages as an alum replacement.

Velocity measurements gave average circulating velocities in ODs 1 and 2 of 0.74 and 0.58

m/s (with five and four operating aerators respectively). These velocities are quite high given

the practical minimum to maintain MLSS in suspension is 0.2 m/s, and occur because the

aerators are fitted with inclined downstream baffles but no vertical upstream baffles.

Installation of vertical baffles to reduce the circulating velocity would increase the DO

concentration downstream of the aerators and enhance nitrification, potentially increasing

capacity.

3.7 Clarifier Capacity

Theoretical clarifier capacities are shown graphically in Appendix 3. Graphs are provided for

sewage mean COD concentrations of 190 mg/L at peak daily flow (560 mg/L at design

ADWF) and 250 mg/L (the wet weather strength associated with the actual median strength

of 750 mg/L during the EVOP program). The graphs show that RAS capacity is the limiting

factor; with the current stronger influent characteristics, the design peak flow capacity of 45

ML/d (3ADWF) can be met with an sSVI value of 65 mL/g and an operating SRT of up to 19

days, or 80 mL/g and 16 days (Table 3.1).

The current capacity would be slightly lower than this given the RAS pump capacities are

some 20% below their original values (Appendix 2).

A clarifier stress test was conducted over the three days 27 to 29-Nov-13 (average plant

inflow 13.5 ML/d). On 27-Nov the plant was operated with Clarifiers 1, 2 and 3 (Clarifier 4

off-line). Clarifiers 1-3 were each receiving 33% of the plant load compared with their

normal shares of 22%. On 28-Nov Clarifier 2 was first reduced to about 70% of its normal

flow, then taken off-line, increasing the Clarifier 1 & 3 loads to 50% each. From early on 29-

Nov, flow was distributed to Clarifiers 1 and 3 in the approximate proportions 0.25:0.75; in

other words, Clarifier 3, with 22% of the plant total clarifier area, was handling 10 ML/d, 75%

of the total plant dry weather flow, equivalent to its design maximum hydraulic load, at a

total plant COD load 27% above design (Table 3.1). Plant SRT at the time was about 10

days based on cake production (Trend Plot D2).

The behaviour of Clarifier 3 is shown in Figure 3.4. The overflow rate increased from about

0.5 m/h during the peak period on the 27th to 0.75 m/h on the 28th and to 1.1 m/h on the

29th. Effluent SS did not exceed 5 mg/L. At the highest loading the clarifier underflow SS

concentration reached about 2.5 g/L and the measured blanket height reached about two

thirds of the side water depth or 2m. This transfer of solids to the clarifiers reduces the

reactor MLSS concentration and increases the clarifier capacity.

The results of this clarifier stress test show that (a) the clarifier capacity is sufficient for the

current plant load - median flow 13 ML/d, median COD load 10.7 t/d (Table 3.1), (b)

Clarifier 3 RAS pumping capacity proved sufficient for the current load despite its

17

16117:Ken Hartley

24-Jan-14

Figure 3.4 Behaviour of Secondary Clarifier 3 during a stress test 27 to 29-Nov-13. Dia

27m, SWD 3m, bottom of feedwell 1.7m below surface. Fixed RAS flow 64 L/s

(5.5 ML/d). MLSS 6.7 g/L, sSVI 64 mL/g. Uo/Vs = overflow rate based on 30

minute moving average flow / mixed liquor settling rate. Parameters 1, 2 & 5

were measured, other parameters were calculated.

deterioration in capacity from 75 L/s to 64 L/s (Appendix 2), and (c) the clarifier behaviour

accords with theoretical expectations (Hartley, 2013).

3.8 Aeration Capacity

In their optimum configuration (Figure 3.2), the oxidation ditches have nine 45 kW aerators

operating. Table 3.2 shows that the aeration capacity is just sufficient for the current 90

percentile load day. Aerator capacity can be rated at a median plant load of 10.7 tCOD/d,

equivalent to 14 ML/d at 750 mgCOD/L. This is slightly less than the clarifier capacity

discussed in Section 3.7 above and represents the primary capacity bottleneck in the plant.

Table 3.2 Oxidation Ditch Total Aeration Capacity1

Aerators: 9 no. ea 45 kW

Field oxygen transfer rate at 1 kg/kWh: 9,700 kgO2/d

Oxygen demand at 15d SRT: 0.68 kgO2/kgCOD

Nov/Dec-13 50%ile COD load: 10,700 kg/d

Nov/Dec-13 90%ile COD load: 12,800 kg/d

Nov/Dec-13 90%ile oxygen demand: 8,700 kg/d

Aeration capacity peaking available on 90%ile load day: 9700 / 8700 = 1.11 1See Table 3.1 for plant loads.

3.9 Practical Issues

Two practical issues arose in relation to the aerators and the scum harvesters.

Aerators For optimum OD performance the single aeration and anoxic zones need to be contiguous,

with the DO probe controlling the anoxic fraction and the influent being fed near the start

of the anoxic zone as shown in Figure 3.2. However, if one of the aerators fails and a

standby unit needs to operate, the ideal reactor zonation is disrupted. This may increase the

effluent nitrogen level to some degree and necessitate temporary ethanol dosing. In the

event of an extended aerator outage the failed unit could be physically replaced by one of

the spare units.

1.RAS ratio

2.Blanket Level

4.Underflow Zone SS

5.Effluent SS

6.Overflow Rate 0

1

2

3

4

5

6

0

1

2

3

4

5

6

27/11 0:00 28/11 0:00 29/11 0:00

4.U

nd

erfl

ow

Zo

ne

SS

(g/L

)5

.Eff

luen

t S

S (m

g/L)

6.O

verf

low

Rat

e (m

/h)

1.R

AS

Rat

io2

.Bla

nke

t Le

vel (

dep

th f

ract

ion

) 3

.Uo

/Vs

Date & Time of Day

18

16117:Ken Hartley

24-Jan-14

Scum Harvesters The scum harvesters recently installed are set at a fixed level and are above the water

surface during low load periods. One way to address this operational problem would be to

modify the aeration controls so as to raise the water level to the appropriate value for scum

removal for a short period each day.

19

16117:Ken Hartley

24-Jan-14

4. CONCLUSIONS & RECOMMENDATIONS

4.1 Conclusions

The design median capacity of the Beenleigh WWTP is 15 ML/d ADWF at 8.4 tCOD/d (560

mg/L) with WWF above 45 ML/d bypassed. Operating experience and two previous studies

have suggested that the plant in its then series oxidation ditch configuration had an

operational capacity less than design. However, a more recent theoretical review concluded

that minor modifications and reversion from series to parallel oxidation ditch operation may

allow the design capacity to be achieved. The current six month EVOP program (17-Jul to

31-Dec-13) was therefore undertaken to assess the actual operational capacity of the plant

when operated in a parallel oxidation ditch format..

The specific aims of the EVOP program were to:

1. Optimise operational procedures for the plant liquid stream processes.

2. Determine the minimum SRT at which the effluent nitrogen targets can be reliably

achieved.

3. Define the operational capacity of the plant liquid stream processes.

The conclusions of the program are as follows.

Influent 1. During the last two months of the program (Nov/Dec-13) the median and peak influent

flows were 13 ML/d and 29 ML/d, 13% and 35% below the design values of 15 ML/d

ADWF and 45 ML/d peak.

2. The design median influent strengths for COD:TN:TP were 560:56:11 mg/L. However

the plant has a significant industrial load and over the last two months of the program

the corresponding median strengths were 750:67:11 mg/L. The median COD load was

10.7 t/d, 27% above the design value. Influent variability was high with a maximum COD

load of 13.7 t/d.

Effluent Quality 3. Over the last two months of the program all effluent quality parameters were within

licence limits except for the effluent 90 percentile TP concentration of 2.6 mg/L which

exceeded the licence limit of 2 mg/L. This can be controlled easily with increased

chemical dosing.

Operation 4. The plant was operated with the two oxidation ditches in parallel. Ethanol and alum

dosing were turned off at the start of the EVOP period, however alum was re-

introduced for the last two months to reduce TP. An alternative approach could be to

exchange alum dosing for ethanol dosing to reduce nitrate in the effluent and in the

recycle to the anaerobic zone.

5. The biological process was operated at a reactor SRT of 15-20 days during the first four

months. Over the last two months the SRT was decreased below 10 days, leading to a

rise in effluent ammonia.

6. SRTs calculated from biosolids cake produced were lower than those calculated from

RAS wasting data. The biosolids values are considered more reliable. An improved

method of RAS wasting control has been implemented. More effort is needed to

achieve reliable steady SRT control.

20

16117:Ken Hartley

24-Jan-14

7. It was demonstrated that oxidation ditch effluent ammonia and TN, and process sludge

settleability (sSVI), can be controlled through adjustment of the process anoxic fraction

using the DO control system. The sSVI control characteristics were demonstrated to

be consistent with published results from other plants.

8. The results of the clarifier stress test show that (a) the clarifier capacity is sufficient for

the current plant load - median flow 13 ML/d, median COD load 10.7 t/d (Table 3.1), (b)

Clarifier 3 RAS pumping capacity is sufficient for the current load despite its

deterioration in capacity from 75 L/s to 64 L/s (Appendix 2), and (c) the clarifier

behaviour accords with theoretical expectations (Hartley, 2013).

9. The scum harvester is fixed in level and is not compatible with DO control by varying

water level (rotor immersion).

Capacity 10. Despite the high COD load (Table 3.1), the plant was able to meet the effluent

standards. The plant is currently operating near its practical capacity. The biological

process capacity is limited by the oxidation ditch and clarifier volumes, oxidation ditch

aeration capacity and RAS pumping capacity (20% below the original capacity). Aeration

capacity appears to be the primary factor, limiting plant capacity to a median of 11

tCOD/d, equivalent to an ADWF of 14 ML/d at 750 mgCOD/L.

11. Operationally, the maximum capacity is also governed by the minimum SRT at which the

process can be reliably run. Control for minimum SRT variability will reduce effluent

variability and maximise capacity. A process SRT of 10-15 days is the minimum at which

the effluent standards can be reliably met. During the study it was not possible to

determine the operating SRT accurately.

12. The oxidation ditch circulating velocity is significantly higher than the minimum necessary

to maintain the biomass in suspension. Installation of vertical baffles upstream of the

aerators to reduce the velocity would raise the dissolved oxygen profiles and enhance

nitrification. This would increase capacity by allowing operation at lower SRT.

13. It may be possible to reduce process variability and further increase capacity to some

degree through control enhancements and improved tuning of controls. For example,

oxidation ditch aeration could be controlled from the ammonia probes rather than the

DO probes; in conjunction with this, ethanol dosing to reduce nitrate may allow

operation at shorter SRT, reducing MLSS and increasing clarifier capacity.

4.2 Recommendations

It is recommended that consideration be given to the following in order to optimise

performance and capacity:

1. Tune the SRT control system to reduce variability.

2. Tune the aeration control system to minimise SRT while meeting the effluent nitrogen

standards.

3. Control oxidation ditch aeration from ammonia, rather than oxygen, probes.

4. Improve tuning of all other process control systems to reduce variability.

21

16117:Ken Hartley

24-Jan-14

5. Reduce the minimum operating SRT by ethanol dosing to reduce oxidation ditch nitrate.

6. Investigate the interchangeability of ethanol and alum for supplementary nitrogen and

phosphorus removal at minimum cost.

7. Install vertical baffles in the oxidation ditches to reduce circulating velocities and

increase DO concentrations.

8. Investigate methods to achieve a practical scum harvesting capacity, possibly through

periodic oxidation ditch water level management integrated with DO control.

9. Refurbish the RAS pumps to restore their original capacities.

10. Pursue a trade waste program aimed at reducing the variability of the plant influent.

22

16117:Ken Hartley

24-Jan-14

APPENDIX 1: REFERENCES

AIT (2013), Beenleigh WWTP – Solids Retention Time (SRT), J3307-LCC-Beenleigh WWTP, Rev

B.

Box GEP & Draper NR (1969), Evolutionary Operation - A Statistical Method for Process

Improvement, John Wiley.

Gold Coast Water (2006), System Assessment Report for Beenleigh WWTP: Functional Area 2 -

Biological Treatment [with UQ modelling report appended].

Hartley Ken (2010), Beenleigh Wastewater Treatment Plant Upgrade: Peer Review, Logan Water

Alliance.

Hartley Ken (2012), Loganholme WWTP, Stage 7 Process Commissioning, Logan Water Alliance.

Hartley Ken (2013), Tuning Biological Nutrient Removal Plants, IWA Publishing, London.

Hartley Ken (2-Jul-13), Beenleigh WWTP EVOP Program, Technical Memorandum 1: Process

Tuning Strategy, v2.

Hartley Ken (4-Oct-13), Beenleigh WWTP EVOP Program, Technical Memorandum 2 – SRT

Control Strategy, v5.

Hartley Ken (19-Apr-13), Beenleigh WWTP EVOP Program, Technical Memorandum 3: Capacity

Envelopes.

WorleyParsons (2009), Beenleigh WWTP: Stormwater & Solids Handling Study - Consolidated

Report, Logan CC.

23

16117:Ken Hartley

24-Jan-14

APPENDIX 2: PROCESS DETAILS

Process Unit

Total reactor volume, ML

Anaerobic reactor volume, ML

Oxidation Ditches OD1 OD2 Total

Volume @ TWL, ML 5.20 4.58 9.78

Volume fraction 53% 47%

Circuit length, m 155 156

Max water depth, m 3.5 3.0

Aerators

No. 7 6 13

Length, m 9 9

Drive power, kW ea 45 45 585

Mixers

No. 2 2 4

Power, kW 5.5/4.0 5.5/4.0

Inlet weirs, length, m 5 5 10

Outlet weirs, length, m 5 5 10

Secondary Clarifiers 1-4 SC1 SC2 SC3 SC4 Total

Dia, m 27 27 27 33 ----

Surface area, m2 573 573 573 855 2573

SWD, m 3 3 3 4.5 ----

Feedwell dia, m 5.9 5.9 4.4 4.3 ----

Feedwell depth, m 1.7 1.7 1.7 1.8 ----

Underflow volume (below feedwell), m3 744 744 744 2309 4542

RAS capacity, L/s (VS pumps manually set)

DESIGN 75 75 75 244 469

CURRENT (Dec-13) 63 70 64 180 377

RAS drawoff

Influent flow split (based on RAS capacity) 15% 15% 21% 49% 100%

Suction lift From centre well

Details

BEENLEIGH WWTP - BIOPROCESS DETAILS

1.29

11.1

24

16117:Ken Hartley

24-Jan-14

APPENDIX 3: CLARIFIER CAPACITY DIAGRAMS

Based on the design RAS pump capacities listed in Appendix 2.

Sewage mean COD 190 mg/L at peak flow Sewage median COD 250 mg/L at peak

flow

SC 1-3 (ea)

SC 4

Settling LimitsTotal

SC 1-3 (ea)

SC 4

RAS LimitsTotal

Design 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 65 mL/g

Sewage COD 190 mg/L at peak flow

SC 1-3 (ea)

SC 4


SC 1-3 (ea)

SC 4

RAS LimitsTotal

Design 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 80 mL/g

SC 1-3 (ea)

SC 4


SC 1-3 (ea)

SC 4

RAS LimitsTotal

Design 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 95 mL/g

SC 1-3 (ea)SC 4


SC 1-3 (ea)

SC 4

RAS LimitsTotal

Design 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 110 mL/g

SC 1-3 (ea)

SC 4


SC 1-3 (ea)

SC 4

RAS LimitsTotal

Design 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 65 mL/g

Sewage COD 250 mg/L at peak flow

SC 1-3 (ea)SC 4


SC 1-3 (ea)

SC 4

RAS LimitsTotal

Design 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 80 mL/g

SC 1-3 (ea)SC 4

Settling Limits

Total

SC 1-3 (ea)

SC 4

RAS LimitsTotal

Design 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 95 mL/g

SC 1-3 (ea)SC 4


SC 1-3 (ea)

SC 4

RAS Limits

TotalDesign 3ADWF

0

10

20

30

40

50

60

70

80

90

10 15 20 25 30

Cla

rifi

er

Ca

pa

cit

y (

ML

/d)

SRT (d)

sSVI 110 mL/g

25

16117:Ken Hartley

24-Jan-14

APPENDIX 4: TREND PLOTS

PLOTS: Jul-12 to Dec-13

EVOP PERIOD: 17-Jul-13 to 31-Dec-13

A. PLANT LOADING

A1. Influent Flows

A2. Influent Strength

A3. Influent Nutrients

A4. Influent Nutrient Ratios

B. EFFLUENT QUALITY

B1. Effluent Organics

B2. Effluent N

B3. Effluent P & pH

B4. Effluent Faecal Coliforms

C. CHEMICALS

C1. Plant Alum and Ethanol Consumption

D. OPERATION – LIQUID STREAM

D1. OD Loading

D2. SRT, MLSS, ML Temperature

D3. RAS, WAS

D4. Aeration – OD1

D5. Aeration – OD2

D6. Electricity Consumption

D7. sSVI, Effluent N Ratio

D8. ML pH, Alkalinity

D9. Clarifier Effluent SS

E. OPERATION – SOLIDS STREAM

E1. BFP Cake TS

26

16117:Ken Hartley

24-Jan-14

Design ADWF 15 ML/d

Process Peak 45 ML/d

Influent Peak 75 ML/d

0

40

80

120

160

200

0

20

40

60

80

100


Rain

fall (m

m/d

)

Infl

ue

nt Flo

w (M

L/d

)

BEENLEIGH WWTP Jul-12 to Apr-14A. PLANT LOADING

A1. Influent FlowsRainfall Total Inf Influent Treated Start EVOP/Parallel OD Op'n 17-Jul

Design COD50 Conc 560 mg/L

Design COD50 mass 8.4 t/d

0

6

12

18

24

30

0

300

600

900

1200

1500


CO

D M

as

s (t/

d)

Co

nce

ntr

atio

n (m

g/L

)

A2. Influent Strength COD conc COD Mass

0

6

12

18

24

30

0

40

80

120

160

200


TP

(m

g/L

)

TN

(m

g/L

)

A3. Influent Nutrients TN TP

Licence BOD90 LT10 mg/L

Licence SS90 LT15 mg/L

0

10

20

30

40

0

10

20

30

40


SS

(m

g/L

)

BO

D (

mg

/L)

B.EFFLUENT QUALITYB1. Effluent Organics BOD SS

Typical Sew age TN:COD, 0.1

Typical Sew age TP:COD, 0.02

0.00

0.02

0.04

0.06

0.08

0.10

0.00

0.05

0.10

0.15

0.20

0.25


TP

:CO

D

TN

:CO

D

A4. Influent Nutrient Ratios TN:COD TP:COD

27

16117:Ken Hartley

24-Jan-14

Licence TN50 LT 5mg/L

Licence NH3 max 3mg/L

0

2

4

6

8

10

0

2

4

6

8

10


NH

3-N

, N

Ox-N

(mg

/L)

TN

(m

g/L

)

B2. Effluent N TN NH3-N NOx-N

Licence TP90 LT 2mg/L

6.6

7

7.4

7.8

8.2

0

1

2

3

4


pH

TP

(m

g/L

)

B3. Effluent P & pH Effluent TP Effluent pH

0

4

8

12

16

20

0

100

200

300

400

500


Eth

an

ol D

os

e (m

gC

OD

/L)

Alu

m D

os

e(m

g s

olid a

lum

/L)

C. CHEMICALSC1. Plant Alum & Ethanol Consumption

Alum-Anaerobic Zone Alum-Total Ethanol

Licence Max(50%ile) 150

1.E-02

1.E+00

1.E+02

1.E+04

1.E+06

1.E+08


F. co

lifo

rms (cfu

/100m

L)

B4. Effluent Faecal Coliforms Effluent F.coliforms

0

2

4

6

0

10

20

30

40


No

. o

f R

oto

rs O

pe

rati

ng

Inle

t W

eir

Level (

mm

ab

ove s

ill)

D. OPERATION - LIQUID STREAMD1. OD Loading

Inlet Weir Level - OD2 Inlet Weir Level - OD1 Rotors - OD2 Rotors - OD1

28

16117:Ken Hartley

24-Jan-14

0

5

10

15

20

25

0

10

20

30

40

50


ML

SS

-14d

MA

(g

/L)

WA

S F

low

(0.0

1xk

L/d

)

Re

acto

r S

RT

(14d

MA

, d)

ML

Te

mp

(d

egC

)

D2. SRT, MLSS, ML Temperature SRT(WAS, Sc 0.98) SRT(cake trucked) ML Temp MLSS (g/L) WAS Flow with 7d MA(brown)

0

6

12

18

0

3

6

9


RA

S / W

AS

Co

nc (g

/L)

RA

S R

ecycle

Rati

o

D3. RAS, WAS RAS Ratio (at design RAS flow) RAS Ratio (calc from MLSS & RAS SS) RAS Conc (measured) RAS Conc (calc from design RAS flow)

Des ign RAS f low 440 L/s

0

2

4

6

8

10

0

2

4

6

8

10


No

. o

f R

oto

rs O

pe

rati

ng

Daily A

ve

Pro

be

DO

(m

g/L

)

Eff

lue

nt N

(m

g/L

)

D4. Aeration - OD1 [Shows FE till 17-Jul-13]

Effluent NH3-N Effluent NO3-N Ave Probe DO OD1:NH3-N OD1:NO3-N Rotors Op.

0

2

4

6

8

10

0

2

4

6

8

10


No

. o

f R

oto

rs O

pe

rati

ng

Daily A

ve

Pro

be

DO

(m

g/L

)

Eff

lue

nt N

(m

g/L

)

D5. Aeration - OD2[Shows FE till 17-Jul-13]

Effluent NH3-N Effluent NO3-N Ave Probe DO OD2:NH3-N OD2:NO3-N Rotors Op.

0.0

0.5

1.0

1.5

2.0

2.5


kW

h /

kg

CO

D

D6. Electricity Consumption

29

16117:Ken Hartley

24-Jan-14

Start sSVI

0.01

0.1

1

10

100

1000

0

50

100

150

200

250


Fin

al E

ff N

Rat

io (

60

d M

A)

sS

VI (

mL

/g)

D7. sSVI , Effluent N Ratio ML SVI / sSVI Eff NH3-N:NO3-N Ratio 60 per. Mov. Avg. (Eff NH3-N:NO3-N Ratio)

0

50

100

150

200

250

6.0

6.4

6.8

7.2

7.6

8.0


Eff

lue

nt T

A (m

gC

aC

O3/L

)

ML

pH

D9. ML pH, Alkalinity ML pH OD1 ML pH OD2 Effluent TA

Start sSVI

0

50

100

150

200

25010

12

14

16

18

20


SV

I (m

L/g

)

Cak

e T

S (%

)

E. OPERATION - SOLIDS STREAME1. BFP Cake TS

Cake TS, BFP1 ML SVI / sSVI

0

5

10

15

20


Eff

lue

nt S

S (m

g/L

)

D10. Clarifier Effluent SS Final Eff-Comp SC1-Grab SC2-Grab SC3-Grab SC4-Grab

0.1

1

10

100

0

1

2

3


Fin

al E

ff N

Rat

io (

60

d M

A)

Daily A

ve

Pro

be

DO

(m

g/L

)

D8. Aeration, Effluent N Ratio Ave Probe DO - OD1 Eff NH3-N:NO3-N Ratio 60 per. Mov. Avg. (Eff NH3-N:NO3-N Ratio)

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