Saskatchewan community seeks affordable & sustainable biosolids management solution
The city of North Battleford is an urban municipality located in west central Saskatchewan, Canada. It is located approximately 85 miles northwest of the city of Saskatoon, just off Highway 16, and directly across the North Saskatchewan River from the town of Battleford. Together, the two communities are known as “The Battlefords.” North Battleford has a population of approximately 14,000 residents.
In 2012, the city produced more than 649 million gal of potable water and treated approximately 5.6 million gal of domestic wastewater. More than 3,747 wet tons of dewatered biosolids, (with a solids content of approximately 19%) were disposed of in the main cell of its North Battleford Waste Management Facility (landfill). The city utilized a drum thickener with dewatering by centrifuge and polymer to stabilize the biosolids for disposal. The material then was conveyed into a truck loading area, where it was loaded via a discharge chute for transportation to the city’s landfill. This was far from ideal, as the material takes up valuable space, creates problems for landfill equipment and was a major source of odor. There was no beneficial use of the city’s biosolids.
As a result of these disposal issues, the Water Security Agency mandated that the “The Permittee [city] shall have in place a Water Security Agency authorized and approved sewage works biosolids treatment and disposal process by Nov. 1, 2015.” The solution also would need to be built and operated in accordance with applicable Water Security Agency standards, permits to construct and engineering best practices. Therefore, the city sought to implement a new biosolids management solution that would allow it to meet these directives.
In addition to the ability to meet the requirements of the regulator, however, the city also had a few other challenges and goals that had to be considered. Not only would the new system need to be environmentally responsible, but council and staff also decided that it would have to be fiscally prudent, while providing the city with a proven, year-round management program, ultimately resulting in a marketable, Class A-quality end product with real commercial value.
Meeting all of these objectives, however, was proving to be a challenge. Not only would the end result have to satisfy the critical requirements and deadline set out by the Water Security Agency, but it also would need to meet the city’s criteria—all while remaining in line with its tight budget constraints. Therefore, in 2013, a formal Request for Proposal (RFP) process was undertaken by the city with a submission deadline of January 2014.
The key requirements outlined in the RFP were as follows:
- The proposed treatment process would convert the wastewater treatment plant (WWTP) biosolids to a Class A fertilizer (or equivalent);
- The process should be acceptable to the Saskatchewan Water Security Agency;
- Each proposal should estimate the capital and operating costs for their treatment process, including any costs required to modify the existing WWTP;
- Each proposal should include commissioning and training services in its capital costs, as well as provide ongoing operational support for a five-year period after commissioning; and
- The awarded firm selected to construct the process for treating the biosolids would enter into a cost-share profit contract with the city to market the Class A (or equivalent) fertilizer.
The city ultimately received three responses. The first proposal called for the use of a traditional “in vessel” composting methodology to convert the biosolids into a soil amendment product. This method would require seven additional WWTP staff to operate the treatment facility, as well as approximately 10 acres of city lands to house the treatment facility, which was not included in the capital costs for this proposed solution. In addition, in order to reduce the high cost per ton and make the project economically feasible, the compost approach would require the city to bring additional biosolids into the operation from other municipalities. Finally, in order to construct the facility, hire the appropriate staff and produce a saleable end product, this approach would take more time and costs than the city could afford.
The second option proposed to utilize an alkaline stabilization process to take the biosolids and, over an approximately 12-hour period, convert the city’s biosolids into a dry soil amendment product. Although this proposed approach would require no additional staff, it would have required a truck and a front-end loader to transport and handle the treated material from the WWTP into an additional storage silo and then again to transport vehicles in order to go to market. The cost for the additional storage silo was included in the proponent’s capital cost submission; however, the required truck and front-end loader were not. There also was an estimated construction timeline of at least one to two years before the facility could be in operation.
The third submission was from Lystek and involved the installation of a patented thermal hydrolysis processing system that could fit into the city’s existing biosolids management building. A lined and covered product storage reservoir was also included, to hold and protect the biofertilizer product between usage cycles.
This solution was chosen as the right fit for North Battleford. It was the only solution that would be able to meet the Water Security Agency’s looming deadline, as well as the city’s tight capital and operating budget constraints. It also was the only system that could be easily retrofitted into the city’s existing plant with little to no disruption to existing infrastructure or operations and that required no additional staff or special skills to operate.
The city also was impressed by the speed at which the Lystek system can covert the raw material inputs into finished product—less than an hour per cycle. The proposal further offered a revenue-sharing agreement that would allow the city to generate revenue (further offsetting costs over time) from sales of the federally registered, organically rich liquid fertilizer product. This would allow North Battleford to take something that once was considered waste and turn it into a valuable resource.
An agreement to initiate the project was executed in February 2014 and North Battleford’s new biosolids management system was commissioned in December 2014, making the city the first municipality in Western Canada to adopt and successfully implement this system, on budget and almost a year ahead of schedule.