WEF SDC 2011
Expansion of Acton WWTP
University of Guelph Team:
Alexandra Chan
Adam Erb
Cynthia Mason
Julia Veerman
October 16, 2011
Outline
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Introduction
Population Analysis
Process Selection
Phase 1 Design
 Modeling
 Noise & Odour Control
 Construction
 Phase 2 Design
 Economic Evaluation
 Conclusions and Recommendations
Review of Existing Facility
Problem Statement
 Current WWTP operating near peak
capacity
 Need to increase capacity to
accommodate projected growth in two
phases
 Meet projected effluent criteria
Design Basis
Parameter
Average Daily Flow (dry weather)
Maximum Daily Flow (dry
weather)
Instantaneous Peak Flow (wet
weather)
Current
(m3/day)
4610
Phase 1 Given
(m3/day)
5600
Phase 2 Given
(m3/day)
7000
6160
9690
14307
15980
14955
21452
Parameter
Existing
Effluent
Objective/Limit
Proposed
Effluent
Objective/Limit
BOD5 (mg/L)
2/5
2/5
TSS (mg/L)
3/5
3/5
0.2/0.3
0.1/0.2
1.0/2.0
1.0/4.0
-/0.1
1.0/2.0
1.0/4.0
-/0.016
-/0.08
100/150
100/150
Total Phosphorus (mg/L)
(Ammonia + Ammonium) Nitrogen (mg/L)
Non-freezing period (May 1 to Nov 31)
Freezing period (Dec 1 to April 30)
Unionized Ammonia (monthly average) (mg/L)
Unionized Ammonia (any single sample) (mg/L)
Escherichia Coli (monthly geometric mean
density) (#of organisms/100mL)
Population Analysis
 Predicted linear growth
 Assumed water saving devices at 10%
 Infiltration/Inflow at 204 L/c/d
Parameter
Current
Phase 1
Given
Phase 1
Calculated
Phase 2 Phase 2
Given
Calculated
ADF
4610
5600
7628
7000
8574
MDF
6160
9690
10193
14307
11456
Peak
15980
14955
26442
21452
29721
Process Selection
 Constraints
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Accommodate design flows
Meet effluent discharge limits
Use available land
Be compatible with existing facility
 Criteria
 Cost effectiveness
 Integration with existing facility
 Environmental impact and footprint
minimization
Phase 1 Design
Process Flow
Primary Clarifier
Primary Clarifier
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Add two rectangular clarifiers
New volume 256 m3
ADF SOR of 27.5 m3/m2/day
Maximum day flow
 62.5% TSS removal
 40.3% BOD removal
 Chain & scraper sludge collector and
scum removal system
Secondary Treatment
Aeration System
 Two conventional plug flow
activated‐sludge system with
nitrification
 Accommodate 1275 m3/d required
 Target MLSS = 4000 mg/L
 SRT = 12 days
 Fine bubble aeration
 Positive displacement blower
 Designed for max day flow + additional
feedback flow
Secondary Clarifier
 Two additional secondary clarifiers
 Limiting solid flux concept
 MLSS = 6620 mg/L
 Overflow = 31 m3/m2d
 Chain & scraper sludge collector and
scum removal system
 Max day flow design
Tertiary Treatment
Chemical Addition
 85 mg/L liquid alum with 45% purity –
824 kg/d
 Addition point in activated sludge tank
Plant B Alum Dose Determination
1,000
Alum Dose (mg/L)
At 95%, alum
dose = 85
mg/L
100
10
1
10
Percent of values equal to or less than indicated
value
100
Filtration
 Dual media deep bed filtration
 Existing filters work well to meet limits
 Widely accepted in WWT
 Easily retrofit
 Leopold™ Type S™ Underdrain
 Air scour + surface wash backwash
 Max day flow design with one filter out
of commission
 SLR of 7.2 m3/m2/h
http://www.wateronline.com/product.mvc/Universal-Type-S-Underdrain-0002
UV Disinfection
 UV selected as best disinfection
method
 Trojan UV3000Plus™ system
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LP/HI lamp
Automatic and continuous dose pacing
Automated mechanical/chemical cleaning
Automatic level controller
 Sized for peak flow
Solids Handling
Bio-Solids Digester
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Sequential dual-stage digester series
Add new series in parallel
Methane gas collected for heating
Thermophillic Stage 1
 SRT 2 days
 Recirculation pump mixing
 Mesophillic Stage 2
 SRT 8 days
Sludge Drying
 Belt press drying after digester
 Polymer addition
 Increases solids concentration from
~3% to ~25%
 Cost-effective in disposal
 Reduces footprint
Mass Balance
System Controls and Instrumentation
 Control strategy
 Increased control and monitoring
 Small relative capital cost
 Significant efficiency improvements
 Biological treatment
 Aeration accounts for up to 50% energy
consumption
 Matched oxygen demand profile
 Intelligent feedback control for aeration,
RAS, WAS
System Controls and Instrumentation
 Clarifiers
 Monitoring
 Sludge pumping control mechanisms
 Digesters
 Control for feeding rates, recirculation,
heating, withdrawal
 Tertiary Treatment
 Flow splitting
 SCADA
 Interfacing with SCADA for remote
monitoring
Hydraulic Profile
Phase 1 – Model Inputs
 Projected peak influent concentrations
and flows
 Proposed plant sizing
 Clarifier modeling based on Lessard
and Beck dynamic model
 Activated sludge modeling completed
using the IAWQ1 model
Phase 1 – Model Results
 BOD and NH3 water quality
requirements met
 Model Shortcomings:
 Chemical phosphorous treatment or
tertiary filtration not accounted for
Odour and Noise Control
 Currently no odour or noise issues
 Reduce odour and noise
 Buffer zone
 Housing potential equipment
Construction
 Completion in 24 months
 Best management practices:
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Construct in phases
Protect waterways
Provide training
Conduct inspections
Phase 2 Conceptual Design
Phase 2 Conceptual Design
 Modify Plant B aeration basin
configuration to plug flow + BNR
 Investigate:
 Membrane technology
 Phosphorus extraction
Phase 1 – Capital Cost
Total Capital Cost Estimate
= $24M
Phase 1 – O&M Cost
Annual O&M Cost Estimate
= $1.2M
Phase 2 – Capital Cost
Total Capital Cost Estimate
= $12M
Conclusions
 Expansion design to increase the Acton
WWTP capacity
 Preliminary Phase 1 design
 Additional clarifier, disinfection, and
anaerobic digestion trains
 CAS + nitrification
 Deep bed dual media filter
 Belt press
 Conceptual Phase 2 design
Recommendations
 Implement sewer system improvement
plan
 Conduct more simulations
 Obtain more cost-specific information
from manufacturers
 Conduct pilot tests
Acknowledgements
Dr. Hongde Zhou, P.Eng., University of
Guelph – Faculty Advisor
David Arsenault, P.Eng., CH2M Hill –
Consulting Advisor
Rafiq Qutub, P.Eng., WEAO – SDC SubCommittee Chair
Lauren Zuravnsky, P.E., WEF – Design
Competition Sub-Committee Chair