Biogas and Methane Yields from Paper Sludge by Anaerobic Digestion

Abstract

We measured the biogas and methane yield from two types of paper sludge and three types of organic waste (food waste, vegetable scraps, and pruning branches) by anaerobic digestion. Batch digestion was carried out under mesophilic and thermophilic conditions at volatile solid loads between 0.18 and 0.60 w/v% per reactor. The volume of methane produced from paper sludge from virgin paper pulp (PS-1) was comparable to that from vegetable scraps. However, the other type of paper sludge, from recycled paper (PS-2) was barely digested, owing to the high aluminum content. A kinetic analysis of the gas yields from PS-1 and food waste was carried out using a first-order kinetics model. The gas production rates were constant at a temperature adequate for the inoculum used. Consequently, co-digestion at the mesophilic temperature might be possible, and the deficiency of nitrogen could be compensated for by the addition of food waste to PS-1.