Renewable electricity generation from biogas of anaerobic co-digestion of sludge, cattle manure and water

Abstract

This study reported the viability of energy supply from the energetic conversion of biogas generated by the anaerobic co-digestion in biodigester of rural properties with different sizes of the herd. Indian model benchtop biodigesters were filled with sewage sludge (SS), cattle manure (CM) and deionized water (DW). The energy conversion calculation was based on the cumulative biogas yield (CBY), amount of cattle manure and one cubic meter equivalence of gas with electricity. In the SS co-digestion biogas production was accelerated and 25:50:25 SS:CM:DW presented higher cumulative production. Experimental data on the cumulative production of this ratio fitted to the exponential model, in which 28.15 L were obtained. The efficiency of anaerobic co-digestion of SS and CM was proved with a higher cumulative biogas production than in the single substrate digestion of SS and the single substrate digestion of CM. High immediate production was only observed with SS. There was a long lag-phase for digestion of only CM. An intermediate production profile to the previous ones was noticed when balancing the three co-digesters. The CBY was 16.56 L kg -1 , 0.48 L gTS added -1 and 0.59 L gVS added -1 to 25:50:25 SS:CM:DW. The implement of biodigesters in rural properties for electricity generation provided monthly 2600 kWh and economy of US$ 7669.19. It was concluded that the implantation of biodigesters with 25:50:25 SS:CM:DW to produce electric energy from biogas allows energy self-sufficiency of the property, enabling the sustainable development of the activity through the proper disposal of waste and economic gains to the producer.