Aerial view of Clover Bar biosolids lagoons and compost curing site
All municipalities that provide sanitary drainage services treat wastewater in order to return water to its source and manage the biosolids that remain. In the City of Edmonton, biosolids are generated by the Gold Bar Wastewater Treatment Plant (GBWWTP) and the Alberta Capital Region Wastewater Commission (ACRWC).
Biosolids are the nutrient-rich organic by-product of domestic wastewater treatment that contains essential plant nutrients and organic matter. When properly treated and managed as a beneficial resource they can be recycled and applied as a fertilizer and soil amendment.
- Average annual production for Gold Bar Plant: 20,800 dry tonnes (2006-2010 average)
- Average annual production for ACRWC Treatment Plant is: 4,430 dry tones (2006-2010 average)
- Total solids content from the treatment plants: 2-4%
- Ammonia Nitrogen: 21,000 mg/kg (average)
- Total Phosphorus: 30,500 mg/kg (average)
- TKN (Total Kjeldahl is the combination of organically bound nitrogen and ammonia in wastewater): 55,600 mg/kg (average)
Composting is a process of mixing biosolids with a carbonaceous bulking agent such as sawdust, woodchips, ground woody yard debris and residential solid waste. Finished compost products are refined and sold for various uses. It is one of the recommended options for the beneficial reuse of biosolids by Canadian Council of Ministers of the Environment (CCME).
Agricultural Land Application (NutriGold Program)
NutriGold is a program for using liquid biosolids from the City’s Clover Bar Lagoons on agricultural lands. Biosolids provide macronutrients (nitrogen and phosphorus) and micronutrients (calcium and magnesium) to the agricultural farm lands, which reduces the requirements for chemical fertilizers.
Non-Agricultural Land Application (Pilot Studies)
The City of Edmonton started utilizing biosolids in Non-Agricultural Lands as Pilot Studies since 2008 and results of pilot studies would be available by the end of 2012 for evaluation by The Provincial Regulators. Biosolids provide a source of nutrients and organic matter to promote soil development and vegetation establishment. They assist in achieving multiple reclamation objectives if they are utilized in Non-Agricultural Land such as degraded sites, gravel pits, marginal land conversion and mine reclamation.
Biosolids Use in New Technologies
Drainage Services is investigating the use of dewatered biosolids in future biofuel production as a pilot project study with Waste Management services in its Waste to Biofuels Facility. The process will include utilizing dewatered biosolids in combination with residential solid waste to produce next generation biofuels (methanol and ethanol).
Biosolids Management Strategy
In 2011 and 2012, the City of Edmonton developed the Early Action Plan and Long Term Strategy for biosolids. The strategies were developed to deal with short and long term biosolids accumulation, related processes and options to better manage biosolids at the City-owned Clover Bar Lagoons.