Long-Term Biosolids Management Strategy

At the Residuals Treatment Facility, the residual solids undergo anaerobic digestion in which microorganisms break down biodegradable material in the absence of oxygen and produce biogas. The water is removed, and the solid materials are heated to a very high temperature creating the highest standard of biosolids for use as fertilizer or energy generation. Biogas produced during the treatment process is collected and used to fuel the facility. There is no plan to replace the current residuals treatment process. 

The cost to use the biosolids beneficially varies with the end destination of the product and can be anywhere between $60,000 to $240,000 per month. 

In July 2011, prior to introducing wastewater treatment in the core area, the CRD Board passed a resolution to ban the production and land application of biosolids at CRD facilities and parks, and on farmland in the CRD, based on public health and environmental concerns raised by members of the public.

If you want to learn more about the current biosolids production and how it is being used from month to month you can find that information here: https://www.crd.bc.ca/about/data/biosolids-production

Every biosolids management option will have some level of risk, but risks for most options can be minimized. The safety of land application of biosolids has been evaluated by senior levels of government and is promoted by the Canadian Council of Ministers of the Environment (CCME) and the BC Ministry of Environment and Climate Change Strategy as a low-risk way to beneficially use biosolids. Risk can be managed by following best management practices, like setting appropriate application rates, applying at the appropriate time of year, and ensuring application is set-back a minimum distance from water courses and property lines.

The CCME has published a Guidance Document, which can be found here. 

The provincial government has published a literature review on the risks of land application of biosolids that can be found here. 

A literature review on the risks of applying biosolids to agricultural lands, prepared by Toronto Metropolitan University, can be found here.

Biosolids are analyzed regularly for metals and pathogens. Results are published monthly on our website here.

The last stage of the treatment process is drying. Biosolids are heated to over 90 °C in a fluidized bed dryer. As a result, CRD biosolids contain almost no detectible levels of pathogens. 

CRD biosolids have been analyzed for contaminants such as pharmaceuticals, and PFAS, and results show that concentrations are low, and that the potential for risk to human health and the environment is small.

CRD biosolids were analyzed for 58 of the most common pharmaceuticals. Of the 58, 28 were not detected. Of the 30 pharmaceuticals detected, all were reported in the parts-per-billion (ppb) range. In 2017, Metro Vancouver commissioned a risk assessment evaluating human exposure to eleven common pharmaceuticals through biosolids. The study concluded that the presence of low concentrations (parts-per-billion) of pharmaceuticals in biosolids was very unlikely to result in adverse health effects, and that it would take many thousands of years of working with biosolids to be exposed to the amount in a standard dose. 

CRD biosolids were analyzed for 38 of the most common types of polyfluoroalkyl substances (PFAS) or “forever chemicals”. 24 types were not detected. Fourteen types of PFAS were detected in the parts-per-billion range. The Canadian Food Inspection Agency (CFIA) has announced its intention to protect farmland from PFAS contamination by setting a limit for PFOS, one of the most common type of PFAS, in biosolids used as fertilizer. The limit chosen by the CFIA as appropriate to protect agricultural land is 50 ppb. The concentration of PFOS in CRD biosolids is approximately 6 ppb.

The most effective way to reduce the amount of contaminants such as PFAS and microplastics in biosolids is to prevent these contaminants from entering wastewater in the first place. The Canadian government is currently considering limiting the use of PFAS in Canadian consumer products; some types of PFAS have already been phased out of production. Microplastics in biosolids can be reduced using microfibre filters on clothes washing machines to prevent this common type of microplastic from entering wastewater. France has introduced a requirement for all washing machines to include these filters from 2025. 

The safety of land application of biosolids has been evaluated by senior levels of government and is promoted by the Canadian Council of Ministers of the Environment (CCME) and the BC Ministry of Environment and Climate Change Strategy as a low-risk way to beneficially use biosolids. Risk can be managed by following best management practices, like setting appropriate applications rates, applying at the appropriate time of year, and ensuring application is set-back a minimum distance from water courses and property lines.

CRD biosolids have been analyzed for contaminants such as pharmaceuticals, and PFAS, and results show that concentrations are low, and that the potential for risk to human health and the environment is small.

CRD biosolids were analyzed for 58 of the most common pharmaceuticals. Of the 58, 28 were not detected. Of the 30 pharmaceuticals detected, all were reported in the parts-per-billion (ppb) range. In 2017, Metro Vancouver commissioned a risk assessment evaluating human exposure to eleven common pharmaceuticals through biosolids. The study concluded that the presence of low concentrations (parts-per-billion) of pharmaceuticals in biosolids was very unlikely to result in adverse health effects, and that it would take many thousands of years of working with biosolids to be exposed to the amount in a standard dose. 

CRD biosolids were analyzed for 38 of the most common types of polyfluoroalkyl substances (PFAS) or “forever chemicals”. 24 types were not detected. Fourteen types of PFAS were detected in the parts-per-billion range.  The Canadian Food Inspection Agency (CFIA) has announced its intention to protect farmland from PFAS contamination by setting a limit for PFOS, one of the most common type of PFAS, in biosolids used as fertilizer. The limit chosen by the CFIA as appropriate to protect agricultural land is 50 ppb. The concentration of PFOS in CRD biosolids is approximately 6 ppb.

While biosolids contain energy, we have found they are not a particularly good fuel for a typical small-scale biomass boiler. They would need to be combusted in a large system that has emissions control technology, like a cement kiln or a hog fuel boiler at a pulp mill. 

Additionally, to qualify as a beneficial use, the ash from combustion needs to be used, which disqualifies most pulp mills, as their ash is typically landfilled. These requirements leave just two nearby facilities (both cement kilns in the lower mainland). 

Our current plan for biosolids is to bring them to one of these cement kilns for combustion, displacing fossil fuels. Operational difficulties have limited the amount of biosolids that we can send them. Combustion for energy at the cement kiln could remain one of the long-term options, but given the ongoing challenges, the CRD requires a range of options to ensure redundancy. 

The CRD is planning a demonstration project that will use gasification or pyrolysis technology to process biosolids to produce energy and biochar. While gasification has been successfully used on feedstocks like wood and coal, applying this technology to biosolids is still emerging, with few examples worldwide.

One of the goals of the demonstration project is to work out the best way to use the excess energy generated from an advanced thermal process. Gasification and pyrolysis produce a hydrogen-rich synthetic gas. There are few facilities processing biosolids worldwide for reference, but generally synthetic gas is burned on-site to create the heat used to sustain the thermal process, and to dry the biosolids enough to be processed.

Funding for this project is expected to come from the Core Area Wastewater Treatment and Hartland Landfill budgets. Synergies with other projects, like the Landfill Gas upgrade project currently being constructed at Hartland landfill, will be explored during the demonstration project. 

Trace contaminants and emerging contaminants of concern are top of mind for the CRD Board, staff and the regulatory agencies that oversee the management and safe use of biosolids. Biosolids may contain trace amounts of pharmaceuticals and metals, generally in the parts-per-billion range for pharmaceuticals, and the parts-per-million range for metals.

In 2017, Metro Vancouver commissioned a study assessing the potential ways that humans might be exposed to eleven common pharmaceuticals through biosolids. The study concluded that the presence of pharmaceuticals in biosolids was very unlikely to result in adverse health effects. Fentanyl was not specifically assessed but is likely present in biosolids at much lower concentrations than the compounds studied.  

Biosolids are sampled regularly and compared to standards for metals and pathogens contained within the Organic Matter Recycling Regulation. These results are published monthly on our website here. CRD biosolids also meet the Canadian Food Inspection Agency’s metal standards for fertilizers.   

The last stage of the treatment process is drying. Biosolids are heated to over 90 °C in a fluidized bed dryer. As a result, CRD biosolids contain almost no detectible levels of pathogens. 

At this time, the cost estimates do not account for the sale of energy or biochar, as these are not well understood, and will depend on a number of factors, including the location of any potential facility and the quality of the biochar. If the advanced thermal facility was co-located with the Residuals Treatment Facility, heat from the pyrolysis or gasification process could be used to dry the biosolids, allowing more of the digester biogas to be upgraded to RNG.  The CRD is committed to finding a use for our biosolids that provides the best financial and environmental benefits to the region.  

"Natural” systems like these can work well, but are intended more for wastewater treatment as opposed to biosolids.  They are typically only employed at smaller systems, and often only as a final polishing step. Our flows are large and would require a lot of land area for such a system, which we do not have.