Biosolids Management/Organic Residuals Energy & Resource Recovery (031-DP-3)
Discussion Paper Summary
Resource recovery is a priority for the CRD in planning for wastewater treatment. By investigating the options for resource recovery in the wastewater treatment process the CRD has created a short list of possible alternatives. The short list contains detailed Integrated Resource Management (IRM) strategies that could be applied in the Core Area. The short list includes:
- Energy Recovery and reuse technology, including:
- Anaerobic digestion, biogas use and composting
- Energy recovery application, including:
- Co-combustion in a municipal solid waste-to-energy facility
- Fluidized bed combustion, gasification/plasma, cement kilns and capacity of thermal destruction units
- Reuse application, including
- Residuals landfill application
- Residuals land application, either within or outside urban areas
Part of the process of producing a short list of alternatives included a detailed overview of the technology and options open to the CRD and creation of a long list. Further study of the short list will help the CRD make the best decision for resource recovery.
Energy & Reuse Potential
Energy and reuse potential in the CRD involves:
- The measurement of energy units. This includes the heat generating power of different types of wastewater sludges and biogas. With proper treatment, biomethane (converted biogas) can be used in place of natural gas.
- The potential to reuse biosolids. This includes regulations governing the use of biosolids, solid waste organic matter and compost in BC.
- Regional potential. This examines the potential use of biogas and biosolids produced within the CRD. Biogas produced from digestion of sludge and converted to natural gas as a fuel for transit buses may be a viable alternative, with the potential to power up to 65 vehicles and offset $5.4 million per year of fuel costs.
The CRD’s Short List of Alternatives
The short list presents a number of alternatives, which the CRD will continue to study for suitability with the wastewater treatment project. Each option takes into account public acceptability, technological, financial and climate change risk factors. Option 3 was eliminated after consideration.
1. Organics would be composted at Hartland; digested residuals would be processed at Macaulay for land application. No thermal destruction would take place; digested solids would be sent to Hartland for landfilling and landfill cover. Biogas would be used to fuel a co-gen system for on-site power use.
2. Co-digested residuals would be processed with organics at Hartland; biosolids would be burned, producing heat and power; the ash from burning would be reused as a soil nutrient. Gas from co-digestion would be cleaned and used as vehicle fuel.
3. (Eliminated option) Similar to option 2, but organics processing and sludge processing would be completed at separate locations (Macaulay and Hartland).
4. Similar to option 3, but digested organics would be land applied for beneficial use rather than burned.
5. Organics would be composted at Hartland; undigested raw biosolids would be dewatered and burned at Macaulay, with ash used as a soil nutrient. Some electricity would be produced and used by the treatment plant.
© Image courtesy of Evan Leeson