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Comox Valley Wastewater Treatment Facility Upgrades:Biological Nutrient Recovery and Biogas Production
Group B5: Xrystos Bhegani, Luke Privett, Anand Samra, Marisa Tellis, Ariel Zheng
Introduction
Raw Sewage
Mechanical Screening
Grit Removal
Grit
Primary Clarification
SecondaryTreatmentAeration
Secondary Clarification
Biological Nutrient Recovery System
System Effluent
-TSS reduced by 98%-BOD reduced by 95%-P reduced by 99%-N reduced by 90%
Retrofitted System UpgradesExisting Treatment ProcessExisting Treatment Process
SludgeThickening
Water Recycle
Water Recycle
Water Recycle
Sludge Recycle
SludgeBlending
The Comox Valley is a growing community on northern Vancouver Island surrounded by breathtaking nature and a thriving ecosystem. The residents of the Comox Valley take pride
in the surrounding environment and are passionate to maintain its integrity. The Comox Valley Water Pollution Control Centre (CVWPCC) treats the wastewater of a majority of the
population which includes over 44,000 residents. The objective of this capstone project is to use the technology of biological and chemical engineering to provide a series of
upgrades to assist the CVWPCC in maintaining the environment as the community continues to expand in the years to come. These upgrades go above and beyond what is expected
from a wastewater treatment plant and include a Biological Nutrient Removal (BNR) system and a Sludge Digestion System. The BNR system employs both biological nitrogen (N)
removal and enhanced biological phosphorus (P) removal to lower the nutrients of the system effluent with the ultimate goal of water reclamation. The sludge digestion system
utilizes the nutrient rich sludge to create biogas used to power the plant and fertilizer sold to the local community to offset the energy and cost requirements of the plant. .
Plant Layout & Location
A very special thanks to Zoe Berkey, the engineer at the CVWPCC that helped make this project possible; to all the other
engineers at the CVWPCC who provided input to this project; to Josh Torry and the other operators who helped facilitate
a tour of the centre; to Mr. Sergio Beretta who provided a tremendous amount of inputs for our process diagrams; and
our instructors and assistants Dr. Jonathon Verret, Lee Rippon, and Dr Sue Baldwin.
AcknowledgmentsSludge trucked toComposting Facility
Blended SludgeDewatering
N itrogen Removal P hosphorus Removal
1) Nitrification: the ammonia (NH4) is oxidized to nitrite
(NO2-) by Nitrosomonas then to oxidized to nitrate (NO3
-) by
Nitrobacter ; occurs under Aerated conditions
NH4 + + O2 → NO2- + H2O + H+
NO2- + O2 → NO3
-
2) Denitrification: the nitrates are reduced to nitrogen gas
(N2) by Pseudomonas ; occurs under Anoxic conditions
NO3- + H+ → N2 + H2O
A high flow rate recycle line from the Aerated zone to the
Anoxic zone allows the system achieve ammonia < 0.5mg/L
and nitrate <2mg/L
P removal is made possible by the incredible ability of
phosphate accumulating organisms (PAOs). PAOs are able
to store more polyphosphate than required for growth.
Anaerobic conditions: PAOs use stored polyphosphates,
release phosphorus, consume organics, and store energy.
Aerated conditions: PAOs use stored energy to uptake
phosphorus, store polyphosphates, and grow.
Anaerobic Digestor
Screw Press
Pre-Anoxic Anaerobic Anoxic Aerated
The Johannesburg ConfigurationIncludes the standard Anaerobic, Anoxic, and Aerated zones, necessary for N and P removal with the addition
of the Pre-Anoxic zone. Nitrates present in returned sludge disrupt Anaerobic conditions, reducing energy
stored by PAOs reducing their ability to reabsorb P in the Aerated zone. The Pre-Anoxic zone removes these
nitrates improving the removal of both N and P. With proven to be success operating in colder climates and
with dilute wastewater this was the best option to ensure our system maintains nutrient removal year round.
Why Thermal Hydrolysis?
● Increases the amount of biogas produced
by 50% by accelerating the solubilization
of particulate organic matter
● Operates at elevated temperatures,
reducing potential pathogens present in
wastewater
On-Site Sludge Digestion System
Biogas
CAPEX
92MOPEX
4.7M
Water Recycle
Water Recycle
Fertilizer
Equipment20.9%
Installation8.2%
Instrumentation, Piping & Electrical
11.3%
Building & Service Facilities17.6%
Yard Improvements
2.1%
Engineering & Construction
13.8%
Contractors Fee3.7%
Contingency7.4%
Working Capital15.0%
Raw Materials3.8%
Labour12.7%
Utilities6.2%
Maintenance & Supplies
38.0%
Laboratory Charges
2.2%
Insurance11.6%
Plant Overhead
10.0%
General Expenses
6.0%
Biogas Upgrading
9.6%
PAOsPAOs
Organics P
EnergyStorage
Poly PEnergyStorage
PP
Poly P
P
Growth
Anaerobic Conditions Aerated Conditions
PAOsPAOs
Organics P
EnergyStorage
Poly PEnergyStorage
PP
Poly P
P
Growth
Anaerobic Conditions Aerated Conditions
Environmental Benefits
Economic Breakdown
Advantages of using high-rate continuously fed stirred anaerobic digesters:
● Good mixing results in no stratification or loss of capacity due to supernatant, scum, or dead pockets
● Continuous addition of raw sludge and using thickened sludge results in a significant reduction of retention times
● Achieves 50% destruction of volatile solids allowing the digestate to be used in
fertilizer applications
Benefits of the Screw Press over
other dewatering equipment
● 70% reduced energy consumption
● 90% reduced water consumption
● Low operator attention
● No noise or vibrations
Thermal Hydrolysis
Reactor
Thermal Hydrolysis
Reactor
Victoria
VancouverComox Valley
Victoria
VancouverComox Valley
Thermal Hydrolysis
ReactorAnaerobic Digester
Digestate Dewatering
BNR System
Supporting pumps and heat
exchangers
Primary Clarifiers
Aerated Basins
Sludge Thickening
Secondary Clarifiers
Produced by biogas reducing demand of fossil fuels
Energy Production
72000GJ/year
By displacing the production of artificial fertilizers
Reduced CO2 Emissions
-175 tonnes/day
CO2
Reduced CO2 Emissions
-175 tonnes/day
CO2
By displacing the production of artificial fertilizers
Reduced CO2 Emissions
-175 tonnes/day
CO2
Nutrient removal is a step towards additional applications for water reclamation, reducing
the communities water consumption
Water ReclamationWater Reclamation
Nutrient removal is a step towards additional applications for water reclamation, reducing
the communities water consumption
Water Reclamation
BNR system replaces
the aerated basin
No need to truck
sludge with on-site
processing!
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