Wastewater Treatment & Collection
Petawawa’s Wastewater Treatment Facility was upgraded in 1998. In keeping with the Town’s ‘dynamic by nature’ outlook, Town officials chose to upgrade the facility to a full secondary treatment process. This upgraded plant includes primary treatment, secondary treatment, Sequencing Batch Reactivator (SBR) technology, UV disinfection, sludge thickening process, as well as a full biosolids utilization program.
The facility uses cutting edge technology that is completely biological, meaning that no chemicals are used in the treatment process, therefore no chemicals or chemical by-products are passed on to the receiving stream, which is the Ottawa River.
The disinfection process uses Ultraviolet light, which again is a completely environmentally friendly technology.
The facility serves the Town and both Garrison Petawawa town sites, encompassing a population of over 17,500.
The plant is rated at 8730 cubic meters/day, with a peak day flow of 17460 cubic meters/day. Presently, the facility is operating at approximately 5400 cubic meters/day, which gives the Town ample capacity to handle its projected growth and community requirements, with no foreseeable upgrades required until the year 2018.
The Town of Petawawa has contracted the services of the Ontario Clean Water Agency (OCWA) to maintain and operate both the Wastewater Facilities and the Water Treatment Facilities.
Town of Petawawa Waste Water Treatment Facility
P.O. Box 128
560 Abbie Lane
Petawawa, Ontario
K8H 2X2
Tel: 613-687-2141
Fax: 613-687-7138
Anaerobic Sludge Digestion
Anaerobic sludge digestion is a process typically employed at many wastewater treatment plants to treat (or stabilize), the various primary and secondary sludges produced. Anaerobic sludge digestion also reduces odours and bacteria levels, decreases the amount of solids present in the sludge (and hence hauling costs), and produces energy in the form of methane and carbon dioxide gases which can be utilized as an energy source at the facility.
As the name implies, stabilization of sludges occur in the absence of oxygen. Digestion occurs in three stages. In the first stage, complex solid organics, cellulose, proteins, lignins and lipids are broken down by extracellular enzymes into soluble organic fatty acids, alcohols, carbon dioxide and ammonia. In the second stage, the products of the first stage are converted into various organic acids and alcohols by acid forming microorganisms. In the third stage, two forms of methane-forming bacteria convert hydrogen and carbon dioxide to methane and acetate to methane and carbon dioxide.
The rate limiting stage (i.e. the stage which is the slowest) controls the process. This is usually stage three since the methane forming bacteria reproduce very slowly. These methane bacteria are also very sensitive to environmental factors such as pH, alkalinity, temperature and toxins and, therefore, the control of these factors is very important to control the digestion process.
Anaerobic sludge digestion can involve a conventional standard-rate single stage process; a high rate continuous-flow stirred process or; a two-stage process.
The two stage process (utilized at the Petawawa WPCP) incorporates a first stage (primary) digesters and a second stage (secondary) digesters. Digestion occurs in the primary digester vessel. Raw sludges are sent to the primary digester where they are mixed and heated usually through circulation lines and by gas mixing equipment.
Digested sludge is then transferred to the secondary digesters. The secondary digester serves four purposes: as a storage vessel for digested solids, as a standby primary tank, as a source for seed, and, as a quiescent basin for supernatant withdrawal. Sludge from the primary digester is conveyed by gravity to the secondary digester where it settles and stratifies into gas, scum, supernatant and digested sludge layers. Gas is withdrawn from the top of the digesters and can be used as an energy source (or alternatively wasted), and supernatant is decanted to minimize sludge haulage costs. Digested sludge and scum can be transferred to a storage facility or directly to hauling trucks.
Environmental Compliance - Renewable Energy
The Town of Petawawa applied in accordance with Section 47.4 of the Environmental Protection Act for approval to engage in a renewable energy project in respect of a Class #3 Anaerobic Digestion Facility consisting of the following:
The construction, installation, use, operation, maintenance, and retiring of a Class 3 anaerobic digestion facility with a nameplate capacity of 200 kilowatts of electricity (kW) as outlined in Schedule “A” to:
- receive, temporarily store and process a maximum 36,135 tonnes of liquid Organic Waste per year;
- generate a maximum of 200 kilowatts of electicity (kW) per year.
Environmental Compliance - Wastewater
General
In Ontario, sewage systems are approved either under the Ontario Water Resources Act (OWRA) or under the Environmental Protection Act (EPA). In general, a sewage system which discharges treated effluent to a surface water requires approval under Section 53 of the OWRA (formerly Section 24).
The Ministry of the Environment’s (MOE’s) legislative authority to manage the quality of Ontario’s water resources is provided under the Act and includes specifying sewage treatment works effluent requirements which are typically presented in the form of a Certificate of Approval (a legal instrument).
The purpose of issuing a Certificate of Approval (C of A) for sewage treatment system is to ensure adequate protection of Ontario’s surface waters. Effluent limits are incorporated into the Certificate of Approval to ensure minimal impact to the receiving stream.
Effluent Quality
The Petawawa WPCP is operated under C of A #1276-5YFSZH, issued on June 24, 2006. Conditions placed in this C of A address a number of issues associated with the operation and maintenance of the Petawawa WPCP and also specify effluent “requirements” and “objectives” along with sampling requirements. Table 1 presents a summary of the effluent requirements and objectives specified in the C of A.
Table 1: Certificate of Approval Effluent Requirements/Objectives
| Parameter | Effluent Requirements | Effluent Objectives | ||
|---|---|---|---|---|
| Concentration (mg/L) | Total Loading (kg/day) | Con-centration (mg/L) | Total Loading (kg/d) | |
| CBOD5 | 25.0 | 218 | 15.0 | 131 |
| Suspended Solids | 25.0 | 218 | 15.0 | 131 |
| Total Ammonia | 5.0 | 43.5 | <5.0 | <43.5 |
| Total Phosphorous | 1.0 | 8.7 | 1 | 8.7 |
| pH | 6.0-9.5 units | - | - | |
| Escherichia Coli (E.Coli) | 200 organisms/100mL |
The effluent “requirements” represent the concentrations which indicate noncompliance. The effluent “objectives”are intended as target concentrations which should be set as goals to be achieved under most operating conditions.
Noncompliance with the C of A occurs if:
- the annual average BOD5 or SS concentrations (i.e. 12 consecutive months of all samples take) exceeds the effluent “requirement”.
- the daily concentration of total ammonia (i.e. Ammonia-Nitrogen + Ammonium-Nitrogen) for any composite sample taken exceeds the effluent “requirement”.
- the monthly average Total Phosphorous concentration of all samples taken during a calendar month exceeds the effluent “requirement”.
- any annual average BOD5, SS or Total P loading (i.e.12 consecutive months of all samples taken) exceeds the effluent “requirement”.
- any daily concentration of Total Ammonia multiplied by the average daily flow over the seasonal period the sample was taken exceeds the effluent “requirement”.
- the pH is outside the 6.0 to 9.5 range.
Also set out in the C of A are the minimum requirements for determining effluent quality. These sampling requirements are presented in the next table.
| Parameter | Location | Type of Sample | Min. Frequency |
|---|---|---|---|
| CBOD5 | Raw/Final | Composite | Monthly |
| SS | Raw/Final | Composite | Monthly |
| Free Ammonia Nitrogen | Raw | Grab | Monthly |
| Total Kjeldahl Nitrogen (TKN) | Raw | Composite | Monthly |
| Total Ammonia | Final | Composite | 3 times/week |
| Total P | Raw/Final | Composite | 3 times/week |
| pH | Final | Grab | 3 times/week |
| Alkalinity | Final | Composite | 3 times/week |
| Temp. | Final | Grab | 3 times/week |
History
In 1963, the Ontario Resources Commission entered into an agreement with DND for the Base Water Pumping Station to supply 2,050 m3/d to the Village of Petawawa.
In 1968 a Water Treatment Plant was constructed by DND, a class 3 direct filtration plant.
In 1976, the Ministry of the Environment requested the water quota to the Village of Petawawa be increased to 3,180 m3/d of its 14,500m3/d capacity. This request initiated several studies into the need for system expansion.
In 1989, the Department of National Defense announced an expansion to Garrison Petawawa and their intent to recall the water quota allocated to the Village of Petawawa. The Village of Petawawa was then given the option to own and operate the plant and pay for the upgrading needed to provide the additional capacity for their use.
October 30,1992, the contract was awarded for the expansion of the Water Treatment Plant.
The present plant has a rated capacity of 21,500 m3/d and is located on Lot 26, Lake Range, Town of Petawawa on the southern shore of the Ottawa River surrounded by Garrison Petawawa.
Plant Capacity
The incoming flows to a Water Pollution Control Plant fluctuate throughout any given day. Higher “base” flows occur in the morning, noon and night when domestic water usage is high, while lower base flows occur in between these peak periods. Groundwater infiltration and direct inflows (I/I) into the collection system (i.e. extraneous flows) also contribute to the overall sewage flow received by a treatment plant.
The average day flow represents the total quantity of sewage received by the Water Pollution Control Plant over the course of a year divided by the number of days in a year. The peak day flow represents the highest volume of sewage received over a given 24 hour day period.
The Petawawa WPCP has been designed to accommodate an average day flow of 8,730 cubic metres per day (2:1 peaking factor). These flows are based on a 20 year design period which takes into account population growth within the community as well as CFB Petawawa requirements.
Sewage flows also tend to fluctuate over the course a year (i.e. seasonal variations). For example, flows during the spring thaw are usually much higher than during other time periods of the year due to higher infiltration and direct inflows into the collection system. The magnitude of these flows largely depend on the condition of the collection system, surrounding soil, groundwater table and direct connections ( e.g. roof drains, weeping tiles, etc.).
A maximum day design flow usually accounts for very high 1/1 flows which typically occur during the spring thaw. The maximum day flow allows for very high I/I rates occurring concurrent with the maximum 24 hour domestic flows. This flow is intended to represent “worst case” conditions and the design of hydraulic devices and controls in a plant is usually based on maximum day flows. However, the treatment process is not normally designed to handle such high flows and must be by-passed.
Based on the Operating Certificate of Approval (C of A), the Petawawa WPCP is “approved” to treat sewage at an average daily flow of 8,730 cubic metres per day and a peak daily flow of 17,460 cubic metres per day. The plant is not permitted to accept flows in excess of 17,460 cubic metres per day, and any flows larger should be by-passed.
Petawawa Net Zero Project
The Petawawa Net Zero Project will transform the existing Petawawa Water Pollution Control Plant (WPCP) into a Resource Recovery Facility by upgrading its anaerobic digesters to divert waste from landfill and boost biogas production for use as electricity, making the plant energy neutral or positive (Net Zero), and reducing GHG emissions. This will involve the utilization of biogas in a Combined Heat and Power (CHP) unit for the purpose of making the WWTP Net Zero. The project also aims to find beneficial usage of remaining biogas as clean fuel in the future.
The Project has previously undergone stakeholders outreach under the name of “Petawawa Co-digestion and Energy Generation Feasibility Study” in 2019. The project received a grant of $2.7 Million from Low carbon Economy Challenge Fund in November 2019 under name “Petawawa Wastewater Treatment Plant (WWTP) Energy Recovery and Waste Diversion Net Zero Project”.
The Project is situated within the Petawawa Water Pollution Control Plant, located at 560 Abbie Lane, Petawawa, County of Renfrew, K8H 2E6 (Site). The Site has an area of 75.3 acres and is registered as Range Lake Lot 17 RP, Petawawa, and County of Renfrew; roll number 477907902006900.
Private Septic Systems
You may have a septic system if you live in a rural or older home or cottage in Petawawa. Septic systems are onsite wastewater treatment units that fulfill the role of municipal sewers in rural areas. Anything that goes down the drain — every shower drip and toilet flush — flows to the septic system.
Get information about how your septic system works and how to keep it working properly here.
Contact the Town of Petawawa Municipal Offices at 613-687-5536 for septic permitting requirements and other questions.
Primary Wastewater Treatment
The objective of primary wastewater treatment is to remove the readily settleable and floatable solids from the raw wastewater stream.
Primary treatment at the Petawawa WPCP includes chemical addition, screening, grit removal, preaeration, scum removal (skimming) and sedimentation (or primary clarification).
The purpose of these processes are outlined below:
Chemical Addition – To improve settling performance in sedimentation tanks by increasing floc formation. Also used to precipitate and remove phosphorous and to control odors.
Screening – To remove larger solids which could interfere with other components of the wastewater treatment system.
Grit Removal – To remove discrete granular particles such as sand, cinders, rocks and other substances which could interfere with other components of the wastewater treatment system.
Pre-aeration – To provide a more uniform distribution of suspended and floating solids to sedimentation facilities and to a lesser extent to provide grease separation, odour control, and increase BOD removal rates.
Scum Removal – To remove grease and other floatable materials from the wastewater. Typically carried out in sedimentation tanks.
Sedimentation – To remove flocculent particles and hence remove a portion of the BOD and SS from the wastewater. This is typically accomplished in sedimentation tanks or clarifiers which allow settleable materials to accumulate at the bottom of the tank and supernatant to overflow into a collection system. Solids thicken at the bottom and are drawn off for further treatment and disposal. Supernatant is conveyed to further treatment processes and/or discharged to a receiving water body.
Secondary Wastewater Treatment
The objective of Secondary wastewater treatment is to remove the non-settleable solids from the wastewater stream.
Secondary wastewater treatment is accomplished at the Petawawa WPCP by utilizing a Sequencing Batch Reactor (SBR) activated sludge process, which incorporates Biological Nutrient Removal (BNR). This treatment method incorporates a proprietary system referred to as ICEAS@ (Intermittent Cycle Extended Aeration System).
Traditional Activated Sludge
The traditional activated sludge process combines biological and physical treatment methods with the objectives of coagulating and removing the nonsettleable solids and stabilizing the organic matter contained in the raw sewage. In general, organic matter (typically measured as Biochemical Oxygen Demand and referred to as substrate or food), and nutrients in the raw sewage are utilized by microorganisms (e.g. bacteria) to grow and reproduce into a settleable cellular mass. The activated sludge process involves the removal of organic matter using suspended biological growth under aerobic conditions (accomplished in a reactor). The term “activated” refers to the microbial mass formed by the process, which serves to stabilize (or consume) the waste.
Note: The removal of organic matter from the waste stream is important since organic matter exerts oxygen demand which would deplete the natural oxygen content of a receiving water.
The biological portion of the process involves the introduction of organic matter (raw sewage) into a reactor which contains microorganisms. This biological slurry is referred to as “mixed liquor”. The microbes (e.g.. bacteria) convert the colloidal (i.e. very small) and dissolved organic matter into various gases and cell tissue as described by the following chemical reaction: