Resource
Wet Organic Waste from residential, commercial and agricultural uses
When is it Waste?
When produced by farming and food production, retail, preparation and consumption
Conventional Approach
Collect and landfill
Regenerative Approach
Recover nutrients through regulator-approved use of residuals
Collect and divert to aerobic composting
Collect and divert to anaerobic digestion to produce biomethane (waste to gas) and compost
Collect and divert to appropriate treatment before use as a supplemental nutrient source in agricultural settings
- Diversion of organic waste from landfill
- Reduced methane emissions, the most potent greenhouse gas
- Reduced leachate
- Reduced need for land for landfill
- Production of compost for application to landscaping and in some cases food production
Aerobic Digestion
How it Works
Aerobic composting of wet organic waste (including residential kitchen waste, restaurant waste, food processing waste, wastewater treatment plant biosolids, and manure) is a common practice and considered a traditional method of resource recovery. Diverting wet organic waste from landfills and aerobic composting can result in a significant reduction in greenhouse gas emissions (methane) from landfills. Composting also recovers nutrients and soil-building materials for agriculture.
In aerobic composting, micro-organisms digest the organic materials, giving off metabolic heat and carbon dioxide (CO2). Since the CO2 is from atmospheric rather than fossil sources, it is considered greenhouse gas-neutral. The goal in composting is to expose organic materials to air as effectively as possible, in order
to accelerate the decomposition process and to prevent anaerobic
decomposition.
Local governments can set up community curbside organic waste collection and divert it to a centralized composting facility.
But first
Encourage localized, onsite backyard composting by subsidizing composting bins and providing community education and outreach about the benefits of backyard composting.
What are the Costs?
Adding curbside collection of organic waste to existing solid waste collection systems can be achieved at incremental costs. The resulting compost can be used in municipal landscaping and/or sold to generate revenue that offsets these incremental costs.
Where is it Happening?
Regional District of Kitimat Stikine Compostable Waste Collection
Anaerobic Digestion
How it Works
In anaerobic digestion, waste decomposes without oxygen in an anaerobic digester. Like in aerobic composting, the nutrients are still concentrated in the residues to produce compost. In aerobic composting, chemical energy in the organic matter is lost as
heat in the process, whereas in anaerobic digestion the absence of oxygen results in bacteria converting the waste into "biogas" (more in the Recover and Generate Energy & Heat section).
But first
Communities have two options for recovering nutrients from organic waste: aerobic composting or anaerobic digestion. Aerobic and anaerobic digestion both recover nutrients and divert organic waste away from landfills; anaerobic digestion has the added benefit of providing greenhouse gas-neutral energy. The digestate from anaerobic digestion typically takes the form of wet slurry, while the residuals from composting contain less water and are therefore less costly to de-water and transport.
What are the Costs?
Capital costs depend on the technology, size of digester, and the extent of odour control measures required. Depending on the project, there is a minimum amount of feedstock required on an ongoing basis to ensure the anaerobic digester is economically viable. Another cost consideration is that to achieve adequate inputs for a digester, curbside collection of organic waste will likely be necessary.
Where is it Happening?
Surrey Biofuel Facility