Anaerobic Co-Digestion of Products from Biosolids Pyrolysis – Implementation in ADM1

Abstract

Pyrolyzing biosolids can decrease volume and increase value of solids while anaerobic digestion of gas and liquids from the process could increase overall methane production. Prediction of process behavior and biogas yield through simulation is valuable when considering new substrates for anaerobic digestion. In this study, gas and liquids from biosolids pyrolysis were implemented in Anaerobic Digestion Model No 1 (ADM1) together with a stream of thermally hydrolyzed sludge/food waste used in an industrial biogas plant. Average operational data from the industrial plant was used to calibrate the base scenario in ADM1, achieving a good fit. Simulation scenarios evaluating two hydrolysis constants for the pyrolysis liquid showed minor differences at the load simulated and simulated variations in composition of the liquid showed minor differences. Simulation of adding a relevant stream of pyrolysis liquid and gas together increased methane production by 7 % but decreased overall methane yield from 63 % to 61 % compared to the base scenario.