Enhanced Transportation Biomethane Production From Municipal Sludge Digesters

The goal of this Agreement is to develop, demonstrate, and deploy an innovative approach to enhancing biogas production. The project team seeks to produce a biomethane transportation fuel that reduces greenhouse gas emissions, petroleum demand, and the environmental impacts associated with co-digestion of waste water, sludge, food waste and other organic wastes. The main objective of this project is to enhance anaerobic digestion of organic biosolids at wastewater treatment plants using a modified version of Argonne National Laboratory's patented process (US 8,247,009 and US Patent Application No.14/540,393). This new process has the potential to increase the productivity of anaerobic digestion process by a factor of five and reduce the amount of carbon dioxide. Biogas from anaerobic digestion of organic materials consists of methane (CH4), carbon dioxide (CO2) and other trace components, which can be upgraded for use in combined heat and power systems or as vehicle fuel.

Argonne achieved this breakthrough process by using a waste material (biochar) with high concentrations of mono- and divalent cations such as potassium, calcium and magnesium which can stimulate accelerated carbonation for CO2 sequestration. Biochar is a waste product from thermochemical conversion of biomass via gasification and pyrolysis. Anaerobic digestion of food waste was conducted in batch and two-stage semi-continuous configurations at two different scales bench- (0.5 L), pilot- (14 L) and field-scale (100,000 gallons). The bench- and pilot-scale tests were conducted at Argonne National Laboratory while the field-scale tests were conducted at the American River Packaging (ARP) Plant in Sacramento.

Results from bench and pilot scale tests at Argonne National Laboratory showed methane content increasing up to 1.1 times and carbon dioxide decreasing up to 3.3 times. Field scale tests in Sacramento showed methane content increasing up to 1.2 times and carbon dioxide decreasing up to 1.8 times. These positive results led to increased production of transportation fuel and electricity. Overall, this new process could provide an economic waste-to-energy process, reduce GHG emissions, reduce demand for fossil fuels, and reduce environmental impacts associated with major California's waste sources.