Simulation study for optimising the operating conditions of anaerobic co-digestion for sewage sludge

Abstract

Anaerobic digestion (AD) is a process that converts biodegradable wastes into methane (CH4) gas, reducing the waste's size efficiently. The methane gas can be used as biofuel for power generation due to its explosive properties. The biogas could be upgraded to bio-compressed natural gas (Bio-CNG), which could be utilised as a fuel in the community. Biogas or methane yield from the AD process of sewage sludge (SS) usually is undesirable due to the lack of vital components, such as carbohydrates, proteins and fats, with higher inert substances or moisture content. Therefore, the optimisation of the AD process for SS feedstock is needed to increase its biogas yield. In this study, the anaerobic co-digestion (ACoD) with other wastes, such as corn silk (CS), food wastes (FW), cattle manure (CM), and palm oil mill effluent (POME), is investigated through a simulation model in SuperPro Designer. The biogas upgrading technologies, namely chemical and water scrubbing, are studied in this model to investigate the biogas purification efficiency for producing methane-rich biogas gas that meets international standards (>90 % CH4 and <1,000 ppm H2S).