An anaerobic pretreatment upgrade helped a growing city manage high-strength industrial wastewater while restoring capacity and reducing long-term operating demands.
Rising demands from industrial growth
Industrial growth has brought both economic benefits and new challenges to the City of Portage la Prairie. Although the City has a small population, most of the load entering its wastewater treatment plant, the Water Pollution Control Facility or WPCF, comes from industrial sources — mainly three food processing plants. As industrial activity increased, so did pressure on the plant, making it harder for the City to manage operations and plan for future growth.
The City needed a reliable solution that would remove much of the organic material and solids from industrial wastewater before the next stage of treatment. The new system had to work with the City’s existing facilities, help keep long-term costs manageable, and be delivered in a low-risk way that the City could operate and maintain utilizing existing WPCF staff.
Supporting the City as Owner’s Engineer
As the Owner’s Engineer, we supported the City from concept through commissioning of a new low-rate anaerobic reactor or LRAR: a treatment system that uses naturally occurring bacteria to break down high-strength wastewater in large tanks, without oxygen. This type of system is simple to run, produces much less sludge than conventional treatment, and works well for industrial wastewater with high organic content. As the waste breaks down, it also creates biogas, which can be captured and beneficially used.
Our work began with the preparation of the preliminary design, followed by the development of performance-based Request for Proposals (RFP) documents for the delivery of a new anaerobic pretreatment system under a design-build contract.
The pretreatment system was designed to treat an average flow of 8.4 megaliters per day of high-strength industrial wastewater, prior to combining with municipal flows for secondary treatment.
Following a competitive procurement process, a design-build contractor was selected, and we continued to provide Owner’s Engineer services during detailed design, construction, and commissioning.
In parallel, we acted as the design consultant for the balance of plant, focusing on the integration of the new pretreatment facilities with existing infrastructure. This included the detailed design and construction services for two design-bid-build packages: a new pumping station near the new industrial processing plant and an approximately 11-kilometer wastewater conveyance system delivering industrial wastewater to the treatment plant. We also coordinated interfaces between the design-build and design-bid-build contractors.
Beyond capital delivery, we also assisted the City in updating its Industrial Service Agreements to reflect the upgraded treatment system and associated lifecycle costs, with industry contributions based on wastewater flows, loads and temperature. We also supported longer-term planning for future plant expansion, including evaluation of alternative project delivery models.
Improving performance and restoring capacity
The new pretreatment system has delivered strong results for the City, which took over without adding operations or maintenance staff.
The system was designed to remove 85 percent of organic matter and 70 percent of solids from incoming industrial wastewater. Since it began operating, it has consistently performed better than expected, removing about 97 percent of both.
By reducing the amount of organic material and solids reaching later treatment stages, the City has been able to operate only three of its four sequencing batch reactors or SBRs: the treatment tanks that clean the wastewater in a step-by-step cycle. This has reduced the strain on the plant, as well as lowered energy, maintenance and operating demands, while creating additional capacity for future growth. The system also produces less sludge, allowing sludge thickening operations to be reduced from five days per week to two. This also reduced how often the City had to dispose of liquid biosolids on land — from twice a year to once a year.
Building on these results, the City is now looking at ways to use the biogas generated by the system. This could further improve energy efficiency and create added value for both City operations and the industries that send wastewater to the plant. These outcomes show how effective pretreatment planning can deliver economic, operational and environmental benefits — for communities and generations to come.