Anaerobic digestibility of two processed municipal-solid-waste materials

Municipal solid waste (MSW) has been demonstrated to be highly heterogeneous in composition and poses a significant disposal problem. Processing MSW recycles important materials such as aluminum, ferrous metals, and glass, as well as decreasing the heterogeneity. The composition and anaerobic digestibility of products from two different MSW processing operations were compared. Compositions of the two processed MSW materials were found to be similar, with cellulose constituting approximately 50% by weight. This processed MSW was determined to be nutritionally deficient for stable anaerobic-digestion studies. Adding synthetic formulations or pre-anaerobically digested municipal sewage sludge to the processed MSW supplies adequate nutrients for stable anaerobic digestion. The anaerobic digestibility of the two processed MSW feedstocks was compared using laboratory-scale semi-continuously stirred tank reactors. Using the synthetic or pre-digested sludge nutrient additions, at retention times of 14–20 days, resulted in similar digestion performance and 67–81% digestion of the biodegradable cellulose.