Opportunities to increase capacity for biosolids processing include either WBPF plant expansion or the implementation of anaerobic digestion. Through the anaerobic digestion process, biosolids volume is reduced which may allow the WBPF to operate beyond 2030 without capacity increase.
The anaerobic digestion of biosolids may eliminate the need for the WBPF in the future depending on the quality and marketability of the product leaving the digesters.
Co-mingling of Organics and Sewage Sludge
As per the EOI submissions, treatment options for co-mingled organics and sewage sludge are limited to advanced composting technologies and anaerobic digestion. The design of either of these technologies must include consideration of both streams from the start of the project to maximize community benefit and reduce duplication of efforts.
The results of EOI#114-20 included a wide range of available technologies for processing of various types of waste, including food and organic household waste, biosolids from the wastewater treatment plants, commercial, industrial and institutional sector waste and leaf and yard waste. Based on the EOI submissions, the City has various processing and treatment options to consider that range from transporting the waste streams to existing processing facilities outside the region to construction of a new facility to manage the waste. Alternative service delivery models could be considered from a standard design-bid-build project to a more complex private-public-partnership arrangement.
The City must identify its goals and priorities related to overall management of organic waste in order to identify next steps. While the main objective of this project is to comply with legislation, there are opportunities to address other municipal priorities including management of wastewater biosolids, energy and greenhouse gas (GHG) emission targets. This project provides an opportunity to evaluate available options through both Life Cycle Costing (Capital and Operating Costs) and through Triple Bottom Line considerations (Economic, Social and Environmental). Some examples of additional considerations are identified below.
Capital and Operating costs
Capital and operating costs associated with a new facility will depend on a number of factors, including technology, feedstock, site selection, revenue from end products and service delivery model.
Community and Environmental Impacts
For a new build, selection of a site within the City’s limits would reduce collection costs and mitigate GHG emissions. However, consideration will have to be given to the elimination of odour, noise, traffic and other nuisance to the surrounding community. Some modern processes claim zero odour impacts through the use of closed systems, negative pressure, scrubbers and/or biofilters to reduce odour. Other considerations include air quality, impact on vegetation and wildlife, groundwater and drainage.
Depending on the site selected there may be additional environmental and planning requirements such as environmental assessments, species at risk permit, archeological assessment, planning applications and servicing studies.