2016-020 - weao - stop chasing the solids
TRANSCRIPT
STOP CHASING THE SOLIDS REDUCED DESIGN FLOWS FOR THE NEW WAS THICKENING FACILITY AT
ASHBRIDGES BAY TREATMENT PLANT
1
S. Liver*, S. Atlin**, P. Coleman*, and R. McKinley**
* Black & Veatch**City of Toronto
AG
END
A
1. Project Overview 2. Why Consider Reduced Design Flows3. Operational Approach4. Analytical Approach5. Findings
AGENDA
1
PR
OJE
CT
OV
ERV
IEW
• Driver: Stop co-thickening in PCs as part of City‘s overall Wet
Weather Flow Strategy and abandon aged DAF thickening
• Objective: Construct WAS Thickening Facility with sufficient
capacity so that all future WAS flows can be thickened through a single process.
PROJECT OVERVIEW
1
WAS Pumps and WAS Piping •Automate WAS pumps•Replace 12 PLCs with GE RX31 PLCs
Incineration Facility Conversion to TWAS•Demolish Incineration and Waste Heat Recovery Facility•Construct new facility on existing pile foundations• Integrate TWAS facility with adjacent buildings•Design basis: 26 MLD•Preselect centrifuges, relocate 2 centrifuges from HTP•New workshop, administration space, storage areas
2
3
1
1
2
DAF Building •Convert to Storage Building•Remove equipment, piping, pumps•New main floor to cover DAF tanks•Perform work after TWAS Facility is
commissioned
3
ASHBRIDGES BAY TREATMENT PLANT
PR
OJE
CT
O
VER
VIE
W
DRIVERS
• 37 MLD future peak• 6,500 mg/L • Based on historical data
ORIGINAL DESIGN CRITERIA
5
WH
Y C
ON
SID
ER R
EDU
CED
DES
IGN
FLO
WS
• Quantities measured didn’t match CAS theory• Contribution of solids from Humber and North
Toronto confounded data• Historical dataset affected by biosolids “outlets”• Requirement to Nitrify• “Phantom RAS”
DRIVERS FOR CONSIDERING REDUCED DESIGN FLOWS
6
WH
Y C
ON
SID
ER R
EDU
CED
DES
IGN
FLO
WS
MASS BALANCE - SIMPLIFIED
7
Influent: 818 MLDSecondary ClarifierBOD RemovalPrimary Clarifier
Thickening
Co-Thickening
WAS Flow Rate
North Toronto
Humber
Sewer Shed
Splitter Box“Phantom RAS”
OP
ERA
TIO
NA
L A
PP
RO
AC
H
1. Improved flexibility in biosolids contracts
2. Weekly process control meetings
3. Use of a Business Intelligence Tool
OPERATIONAL APPROACH
8
AN
ALY
TIC
AL
AP
PR
OA
CH
1. Statistical Analysis2. Mass Balance
ANALYTICAL APPROACH
9
AN
ALY
TIC
AL
AP
PR
OA
CH
1. Statistical Data Review of 2012 and “New Operating Regime” August-December 2013
2. Factors affecting WAS volume3. Development of Mass Balance4. Reconciling 2011 Engineering Study Report
proposed design point
STATISTICAL ANALYSIS
10
AN
ALY
TIC
AL
AP
PR
OA
CH
• findings
DATA REVIEW - THE BOX AND WHISKER PLOT
11
Maximum
Half of the values are within this box
Minimum
MedianHalf of the values are above and below this value
AN
ALY
TIC
AL
AP
PR
OA
CH
12
DATA REVIEW - TOTAL WAS FLOW RATE
0
10
20
30
40
50
60
70
2007-2009 Feb 2012 to Dec 2012 Aug 2013 to Dec 2013
WAS
Flow
Rat
e (M
LD)
2011 Engineering Study Report Data
2012 Data
New Operating Regime Data
AN
ALY
TIC
AL
AP
PR
OA
CH
DATA REVIEW – CO-SETTLING FLOW
130
5
10
15
20
25
30
35
40
45
50
2007-2009 Feb 2012 to Dec 2012 Aug 2013 to Dec 2013
Co-S
ettlin
g Fl
ow (M
LD)
2011 Engineering Study Report Data
2012 Data
New Operating Regime Data
AN
ALY
TIC
AL
AP
PR
OA
CH
DATA REVIEW – DAF FLOW
140
5
10
15
20
25
30
2007-2009 Feb 2012 to Dec 2012 Aug 2013 to Dec 2013
WAS
Flow
to D
AF (M
LD)
2011 Engineering Study Report Data
2012 Data New Operating Regime Data
AN
ALY
TIC
AL
AP
PR
OA
CH
DATA REVIEW – WAS THICKNESS
150.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Feb 2012 to Dec 2012 Aug 2013 to Dec 2013
WAS
Con
cent
ratio
n (%
w/w
)
2012 Data
New Operating Regime Data
AN
ALY
TIC
AL
AP
PR
OA
CH
DATA REVIEW – FLOW VS. CONCENTRATION
16
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000
WAS
Flo
w R
ate
(MLD
)
WAS Concentration (mg/L)
Y axis: Flow in MLD
X Axis: Concentration in mg/L
AN
ALY
TIC
AL
AP
PR
OA
CH
HISTORICAL DATA
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000
WAS
Flo
w R
ate
(MLD
)
WAS Concentration (mg/L)
Yr 2012 25th-75th %ile
Yr 2013 - Aug-Dec25th-75th %ile
What is difference?Nitrifiying (longer SRT)
Better Control of WAS ConcentrationLess Co-Settling
17
AN
ALY
TIC
AL
AP
PR
OA
CH
• Thickening‐ Co-Thickening‐ DAF or Centrifuge
• Solids Load from Humber & NTP• Impact of Nitrification• Evaluation at current flows• Evaluation at plant-rated flow (818 MLD)
MASS BALANCE USED TO EVALUATE:
18
TEC
HN
ICA
L A
PP
RO
AC
H
19
MASS BALANCE
AN
ALY
TIC
AL
AP
PR
OA
CH
20
MASS BALANCE: 2012 – 2013 PRODUCTION
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000
WAS
Flo
w R
ate
(MLD
)
WAS Concentration (mg/L)
Yr 2012 25th-75th %ile
Yr 2013 - Aug-Dec25th-75th %ile
Average 2012 -2013 Sludge Production~ 88,070 kg/d
52% of WAS to Co-Settling
AN
ALY
TIC
AL
AP
PR
OA
CH
21
FACTORS AFFECTING VOLUME – CO-SETTLING
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000
WAS
Flo
w R
ate
(MLD
)
WAS Concentration (mg/L)
Yr 2012 25th-75th %ile
Yr 2013 - Aug-Dec25th-75th %ile
Impact of No Co-Settling88,070 kg/d -> 68,156 kg/d
23% less WAS as mass
The New NormalNo need to co-settle when new facility is built
52% Co-Settling
0% Co-Settling
AN
ALY
TIC
AL
AP
PR
OA
CH
22
FACTORS AFFECTING WAS VOLUME - SRT
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000
WAS
Flo
w R
ate
(MLD
)
WAS Concentration (mg/L)
Yr 2012 25th-75th %ile
Yr 2013 - Aug-Dec25th-75th %ile
SRT 6 days -> 3 days = 10% more WAS massSRT 6 days -> 9 days = 5% less WAS mass
3 day SRT
9 day SRT
AN
ALY
TIC
AL
AP
PR
OA
CH
23
FACTORS AFFECTING WAS VOLUME - HUMBER
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000
WAS
Flo
w R
ate
(MLD
)
WAS Concentration (mg/L)
Yr 2012 25th-75th %ile
Yr 2013 - Aug-Dec25th-75th %ile
Why can't you use textbook numbers?28% of the WAS Mass is due to the Humber TP
With HTP
Without HTP
FIN
DIN
GS
24
NEW DESIGN ENVELOPE
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000
WAS
Flo
w R
ate
(MLD
)
WAS Concentration (mg/L)
Yr 2012 25th-75th %ile
Yr 2013 - Aug-Dec25th-75th %ile
576 MLD
1.3 X 818 MLD
26 MLD X 5,000 mg/L = 130,000 kg/d
818 MLD
2011 Engineering Study
FIN
DIN
GS
• 26 MLD WAS‐ 818 MLD (ABTP rated capacity)‐ Humber at rated capacity‐ No co-thickening‐ 6 day SRT (SRT impact is less than 10%)‐ Peaking Factor 30% on mass basis‐ 5,000 mg/L WAS concentration (minimum at peak flow)
DESIGN POINT - RECOMMENDATION
25
FIN
DIN
GS
• Recommend Reducing Design Flow from 37 MLD to 26 MLD- Peaking Factor 30% on mass basis - 5,000 mg/L WAS Concentration
• 5 Duty – 2 Standby “40-inch bowl” centrifuges
• Key Reasons:- Installing centrifuges eliminated co-settling and
“recycle of solids”- Improved solids control vs. 2007-2009 operation
IMPLICATIONS
26
THANK YOU !
QUESTIONS ?