Use of ADM1 To Evaluate Anaerobic Digestion of Food Waste

Anaerobic digestion and biomethane production is a promising method for management of food wastes from military establishments and other institutions. We have found over 80% conversion of food waste from the United States Air Force Academy (USAFA) to biomethane in lab anaerobic digesters. Of concern for successful field digester operation is the effect of operating methods and loading conditions on digester stability. Dynamic simulation modeling provides a useful tool to evaluate transient loadings and operating conditions that can lead to unstable operation with volatile fatty acid accumulation, pH drop, and decreased methane production. The International Water Association anaerobic digester model 1 (ADM1) was incorporated into Mathcad 15 software to provide a useful tool to evaluate digester design and performance. The model was calibrated from operating data from two parallel lab digesters. Batch bottle tests were also done with spiked feeds to digesters to evaluate food waste hydrolysis kinetics. Model modifications were done to facilitate the calibration of hydrolysis kinetics, to provide more accurate alkalinity and ammonia production predictions, to allow stable model runs under transient conditions, and to account of the biomass debris composition from endogenous decay.