High-solids anaerobic digestion for the recovery of energy from municipal solid waste (MSW)

Anaerobic digestion of municipal solid waste (MSW) was studied in 'high solids digesters' (HSDs) for generating energy (as methane). Three kinds of HSDs were employed in which the waste along with inoculum (consisting of pre-digested cow dung slurry) were subjected to anaerobic digestion. The first type (HSD-I) was provided with two chambers; the upper chamber served as a solid phase in which only the solid portions of vegetable waste were subjected to digestion, while the lower chamber served as liquid phase where the leachates were allowed to ferment. The second type (HSD-II) was similar to HSD-I but had no partition The third type (HSD-III) had two distinct units, one for solid phase and the other for the liquid phase; the units were connected by a tap with a flow regulator valve. The reactor performance was assessed in terms of biogas yield. The results of the study indicate that the performance efficiency (in terms of biogas yield) of the HSDs increased with the increase in the degree of phase separation. The performance of the digesters was further enhanced by providing additional props to facilitate biodegradation, such as biofilm support systems (BSS) in the liquid phase unit/chamber of the HSDs.