Process Monitoring and Automation of Water Resource Recovery

Facilities (WRRF)

What’s Inside?

• Online process monitoring instrumentation – what’s new?

• Dissolved Oxygen measurement (optical) • DO aeration control

• Nitrogen measurement (ISE) • Ammonium based aeration control

• TSS • SRT (Solids Retention Time) control

• Nitrogen, COD, phosphate

Online Process Monitoring Instrumentation

• Solid-state in-situ sensors • Multiparameter universal controllers • Digital communications • Measurement

• New parameters – NH4, NOx

• New methods – DO, TSS • Better performance

What’s new

Solid-State In-Situ Sensors

Signal processing in sensor

• Auto-recognition (plug & play)

• Calibration

• Multiple measurements

• Self-diagnostics

IQSN Sensors

Multiparameter, Universal Controllers

Brain of the system

• Up to 20 channels

• Measurement display

• Internal communications

• Operating functions

IQ SensorNet Controller Digital

Expandable Multi-location System

Model 2020XT: 1 – 20 parameters

Customized solutions, happy customers… Units are separated and encased in standardized modules, adaptable to local conditions

Power supply

Analog outputs / inputs

Interfaces

System extension

Controller in a module

Modules

Digital Communications

Enhanced signal stability

• Simultaneous and 2-way communication

• Convenient placement of components

• Large distances

• Less cabling

• RS-485, Modbus, profibus, Ethernet IP, Modbus TCP/IP

Dissolved Oxygen (Optical)

Optical insulation

Filter

Detector

Optical DO Sensor - FDO

Gas selective membrane with fluorescence dye

Step 1: Excitation flash

Step 2: Fluorescence flash: Starting time and intensity depend on O2 concentration

Oxygen Measurement

Oxygen Measurement

Time or intensity • Time • Highly

accurate • No

interferences from ambient light / bleaching

• Check: some signal must be detected

Effect of DO Concentration on Biological Treatment Basis for maintaining DO at or below 2 mg/L setpoint

D.O. Reaction

0.75

D.O. : Reaction

D.O. ~ 2 mg/l sufficient for nitrification

COD removal

Nitrification

0.5 1.0 2.0 1.5 2.5 3.0 O2 (mg/l)

1/2 vmax

vmax

Rea

ctio

n ra

te

0.3

Automated DO Control Alternatives

• On-off • Mixing required • Never at setpoint

• Direct control of airflow • Difficult control problem - DO vs. airflow non-linear

Cascade Control

Most effective / most complicated

PI

FDO 700 IQ

Optical DO Sensor

Intelligent Sensor Cap (Replaceable)

• Data stored on memory chip • Automatic transfer of

calibration constants

Individual factory calibration

Interferences

Bubbles & coatings cause overestimate and erratic measurements

Interferences

Nitrogen Removal – The Traditional Way

1 mole Ammonia (NH3 / NH4

+)

1 mole Nitrite (NO2

-)

1 mole Nitrate (NO3

-)

1 mole Nitrite (NO2

-)

1/2 mole Nitrogen gas (N2)

75% O2

25% O2 40% Carbon

60% Carbon

Nitrification / Denitrification

Aerobic Anoxic

Ion Selective Measurement System

Nitrification - Denitrification

Pre denitrification (MLE) • Anoxic zones – denitrification

• Oxic zones (DO control) – nitrification

• Mixers to uncouple aeration/mixing (anoxic)

• Recirculation – IMLR • Readily degradable C

– ww or methanol ($$) • Sensors & control

system

Ingildsen, P, Wendelboe, H., “Improved nutrient removal results using in situ

continuous on-line sensors with reduced response time”, WEFTEC 2003

Ammonium-Based Aeration Control

Feedback control

• Direct control on ammonium • DO not controlled at all

• Direct control w/ DO limit (ceiling)

• DO changes faster – control authority?

• Cascade control • Ammonium controller

calculates DO setpoint

VARiON Plus 700 IQ, AmmoLyt Plus 700 IQ, NitraLyt Plus 700 IQ - Nitrogen Measurement

VARiON® Plus 700 IQ AmmoLyt® Plus 700 IQ

NitraLyt® Plus 700 IQ

ISE Sensors for Ammonium (NH4), Nitrate (NO3)

ISE Sensor Design

Four individual electrodes

• NH4, NO3, K, Cl • 1-yr. warranty • Automatically recognized in

system

AmmoLyt Plus 700 IQ NitraLyt Plus 700 IQ

VARiON Plus 700 IQ

3 slots 3 slots

Sensor Types

Total Suspended Solids

Optical Measurement of Solids

Particles absorb, reflect, scatter light

Inte

nsity

Turbidity / Suspended Solids

90° (DIN, ISO, US EPA) < 90°

180° (or back scatter)

Effect of Measuring Angle on Measuring Range

0.0

4.0

8.0

12.0

16.0

5 10 15 20 25

Nit

rifi

cati

on

SR

T, d

SRT (Solids Retention Time) Required for Nitrification

Design SRT; SF=1.5

Operating Range

Change SRT by changing wasting rate

Min. SRT

Temperature, °C

Approaches to SRT Control

Qe, Xe

V, MLSS

Qr, Xr Qw, Xr

Qi, Xi

SRT setpoint

Qw

Sensor Maintenance

Ultrasonic cleaning with UltraClean technology & sapphire windows

• No wipers • No moving parts

without cleaning system (30 days) with cleaning system (30 days)

UltraClean Ultrasonic Cleaning

Nitritation - Anammox

1 mole Ammonia (NH3 / NH4

+)

1 mole Nitrite (NO2

-)

1 mole Nitrate (NO3

-)

1 mole Nitrite (NO2

-)

1/2 mole Nitrogen gas (N2)

75% O2

25% O2 40% Carbon

60% Carbon

Aerobic Anoxic

Anaerobic

1 mole Ammonia (NH3 / NH4

+)

1 mole Nitrite (NO2

-)

1 mole Nitrate (NO3

-)

1/2 mole Nitrogen gas (N2)

Aerobic Anoxic

Deammonification

Anaerobic

37.5% O2

2013 WEF/IWA Nutrient Removal & Recovery Conference

UV Sensor – Principle of Measurement

• Absorbance depends on • Concentration (what you are measuring) • Optical path length (distance from lamp to detector) • Transmission characteristics of sample (everything in

the water that absorbs or reflects light)

lamp detector

I0 I Light gets absorbed / weakened by sample

sample

What Different Wavelengths Tell You About What is in the Sample Measurement & compensation

Difference Between UV and UV-VIS Sensors

Measurement of NO2 and NO3

• 256 wavelengths measured • 200 – 390 nm • 0.74 nm resolution

wavelength [nm]

COD, TOC, BOD, NO3-N, TSS mg/l mathematics

Calculation

• Measurement procedure 1. Record spectra 2. Calculate concentrations from model

Models stored in instrument

Deammonification

• Sidestream treatment (DEMON®, MBBR)

• Mainstream treatment

Applications

46

CarboVis, NitraVis, NiCaVis, NiCaVis NI

UV-VIS and UV Spectral Measurement

200 nm 720 nm

Immersible Spectrophotometer

256 wavelengths

Low Maintenance

Durable / low ownership cost

• Integrated UltraClean ultrasonic cleaning

• Very hard, smooth sapphire window

• No wipers • Titanium / PEEK

• NitraVis: NOx, (TSS) • CarboVis: SAC, CODtotal, CODsoluble, BOD, DOC, TOC,

(TSS) • NiCaVis NI: NO3, NO2, SAC, CODtotal, CODsoluble, BOD,

DOC, TOC • 200 nm to 390 nm (UV only)

• Measuring gap

• 1 mm (high concentrations) • 5 mm (low concentrations)

Sensor Types

Up to 5 parameters on one sensor

Phosphate

Chemical P Removal

• Effluent monitoring • Feedback control

• Pre-precipitation • Post-precipitation

• Feed forward control • Feedback feed forward

P 700 IQ

P 700 IQ

P 700 IQ

Features

• Low reagent consumption • Optional outdoor climate package • Automatic calibration • Integrated permeate pump • Filter module

Application Example Chemical Dosing

Flocculating agent

Phosphate [mg/l]

time

Use of P700 IQ for regulation of

flocculating agent dosage

Resources YSI.com/IQ bit.ly/IQwin (win an IQ instrument) bit.ly/IQanimation (IQ overview video) bit.ly/IQfeatures (IQ features video) bit.ly/IQcolorado (IQ installed in WWTP in Colorado) blog.ysi.com/IQ-SensorNet (related blog posts about IQ)

Contact Us +1 (937) 767-7241 (800) 765-4974 info@ysi.com YSI.com @YSIinc