Feasibility and pilot study of coupled anaerobic digester and pyrolyzer for co-processing organic waste to renewable natural gas and biochar

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Anaerobic digestion (AD) technologies can produce carbon-neutral renewable natural gas (RNG) thatsignificantly decarbonizes the energy system and reduces GHG emissions. Additional benefits include reducinglocal atmosphere pollution from animal waste storage and land spreading, maximizing the value of biomasswaste and producing organic fertilizers from digestate to reduce the overall cost of RNG production. There aresome small-scale facilities in British Columbia for anaerobic digestion of agricultural waste and urbansource-separated organics for biogas production. However, to deploy AD system broadly for the production ofRNG in large quantity at large scale to meet the government's RNG blending target, several challenges stillneed to be overcome to improve the AD system efficiency in treating various organic waste feedstock, reducecarbon footprint, and better manage the waste digestate streams. Integrated AD-pyrolysis system was arelatively new approach to increase the stability of AD reactor and biogas production, and it has shown a greatpromise in increasing the overall energy conversion from 33-50% of single AD reactor to more than 80% in thecombined AD-pyrolysis system. Majority of studies to date have been performed in components in laboratoryor small pilot units without integration. We propose to systematically evaluate the feasibility of an integratedanaerobic digestion and microwave pyrolysis system based on environmental and techno-economic analysesand the test of a small pilot AD reactor and a microwave-assisted fluidized bed pyrolysis reactor. The focus ison the AD reactor performance for co-digestion of crop residues, yard waste, food waste and animal waste withthe addition of pyrolysis aqueous liquid (APL) and biochar, microwave catalytic pyrolysis of solids digestatefor biochar production and the optimization of biochar properties as an additive to the AD reactor to improveAD performance and for other applications. The overall objective of this project is to provide stakeholders anAD+pyrolysis technology to meet the renewable natural gas blending demands and greenhouse gas emissionsreduction targets in British Columbia and Canada.