Using Digestate Compost as a Substrate for Anaerobic Digestion

Abstract

Anaerobic digestion (AD) of separately collected biowaste is an ecologically and economically interesting waste treatment technology due to the production of utilizable biogas and coeval reduction of waste mass fractions. The combination of AD with subsequent composting leads to a higher degree of overall biowaste carbon utilization compared to single composting. Compost may also be of interest for an anew digestion step, since carbon, e.g., of lignocellulose, is made available by the aerobic composting process. The possibility to redigest liquid digestate and/or digestate compost was evaluated using batch reactors. It could be shown that compost is an interesting substrate for AD that might be used for stabilization of the digestion process, e.g., in times of deteriorating reactor performance due to changes in quantity and quality of the feed material.