Biosolids in wastewater
When is is Waste?
When produced by wastewater treatment plants
Collect and landfill, or apply to industrial landscaping
Recover nutrients through regulator-approved use of residuals
collect and divert to composting or anaerobic digestion
How It Works
Nutrients can be recovered from wastewater with chemical and/or physical processes to yield stable commercial fertilizers. Another approach is to integrate biogas digesters with wastewater treatment plants to generate energy.
Reduce the amount of rainwater/stormwater entering the municipal liquid waste stream by enhancing green stormwater infrastructure.
Since sewage biosolids can be dewatered and used as a feedstock in a biogas plant or gasification plant, it is worth considering if they can be used as a source of energy
What are the Costs?
Costs for reclaiming nutrients from wastewater vary depending on the degree of wastewater treatment used. The capital expenditure needs to be weighed against future reduced maintenance costs and revenue from sales of soil amendments.
Where is it Happening?
Comox Valley Regional District Composting from Wastewater Biosolids
Comox Valley Regional District Water Pollution Control Centre
The Comox Valley Water Pollution Control Centre processes wastewater from 40,000 households in the Comox Valley region. Solids are removed by screening and degritting, then the water undergoes aeration to ensure it is meeting safety standards before being discharged. Biosolids from the treatment process are transported to CVRD’s compost facility at the Comox Valley Waste Management Centre. The resulting compost, SkyRocket, is sold as a soil amendment for large-scale landscaping and planting projects as well as residential uses.
SkyRocket is a high-nitrogen soil amendment that is composed of wood chips and bio-solids and cured over time. Biosolids have organic matter and are nutrient rich, which helps to replenish soil and retain its moisture. Due to its high nitrogen content, the most appropriate use of SkyRocket is as a soil conditioner or supplement rather than a topsoil or fertilizer. It can be applied to orchards, flower gardens, lawns and landscaping projects. SkyRocket undergoes frequent testing to ensure it meets the regulations for Class A compost, the most stringent
level for compost production.
The Comox Valley Water Pollution Control Centre has been in operation since 1984, and originally included on-site composting. A history of odour complaints resulted in several odour controls measures over the years and the relocation of the composting facility in 2002. In 2014, the Regional District initiated an evaluation of odour control equipment and a review of available technologies. The Comox Valley Sewage commission approved additional upgrades to the Water Pollution Control Centre in 2017 and work began in 2018. The Regional
District will continue composting biosolids at the Waste Management Centre.