Co-digestion of waste activated sludge and agricultural straw waste for enhanced biogas production

Abstract A method for waste management and valorization of waste activated sludge (WAS) was developed using co-digestion. Biogas and methane production were used as indicators of efficiency for analyzing biochemical methane potential (BMP) of co-digestion of waste activated sludge with three agricultural wastes (i) wheat straw, (ii) rice straw, and (iii) soybean straw. Results infer that co-digestion system of waste activated sludge with wheat straw or rice straw or soybean straw gave higher cumulative specific methane production of 223, 218, and 197 ml/g VS, which produced 2.57, 2.52, and 2.27 times higher methane yield compared to the mono-digestion of WAS respectively. In addition, the use of rumen as inoculum was found to enhance biogas and methane production. The kinetic analysis further confirmed that the inclusion of agricultural straws could abbreviate the lag phase and increase the degradation of the substrates, which in turn enhances methane production potential.