Anaerobic digestion is the process by which microorganisms break down biodegradable material in the absence of oxygen. The process is used in both industrial and domestic applications to manage organic waste and produce biogas, which is largely composed of methane and carbon dioxide. This biogas can be used to generate heat, electricity, and vehicle fuel in the form of Compressed Natural Gas (CNG)
The organic materials fed to the anaerobic digester are often referred to as feedstocks. Feedstocks can be categorized into Low Solids (<1% solids), Medium Solids (up to 15% solids), and High Solids (>15% solids). Lows solids typically includes feedstocks such as whey, juice, and process wastewater. Medium solids typically includes feedstocks such as municipal wastewater biomass, liquid streams, and slurries. High solids will typically include feedstocks such as municipal solid waste, solid food waste, and manure.
Wastewater treatment plants have traditionally utilized anaerobic digestion to stabilize the sludge (biomass) byproduct produced during the wastewater treatment process. The stabilization of the biomass involves reducing the biological activity of the organic matter and reducing the concentration of pathogens. As previously stated, municipal wastewater biomass is in the medium solids category as they are generally between 2-6% solids. The wastewater contains organics typically referred measured as Biological Oxygen Demand or BOD. This BOD is treated and captured in the primary and secondary treatment processes, pumped out, dewatered, and then sent on to the anaerobic digester.
Today, many wastewater treatment plants have begun to use their anaerobic digesters to produce biogas, which they can then convert to electricity, heat, or even fuel for vehicles. Some wastewater treatment plants have even begun to import food waste from the surround community to further boost their onsite energy production.
ClearCove’s Harvester solution increases the biogas production of wastewater treatment plants anaerobic digesters but up to 3 times by capturing more of the high value organics before they are broken down in secondary treatment.