ENERGY PRODUCTION FROM SEWAGE SLUDGE BY ANAEROBIC CO-DIGESTION AND GRASS CULTIVATION

Abstract

 Anaerobic co-digestion of sewage sludge and grass cultivated using the digested sludge as liquid fertilizer is a promising energy production system in small facilities, where oxidation ditch processes are widely applied. Applicability of this system is experimentally evaluated. Grass cultivation performance in 2 months is 0.24 kg(dry)/m². Components of the cultivated grass are similar to those of grass collected at river and road sides. Mesophilic anaerobic digestion experiments show that biogas production from grass is 0.5 NL/gVS-grass-added, and it is upgraded to 0.6 NL/gVS-grass-added by pretreatment at 80°C for 24 hr. Increase in biogas production by the cultivated grass addition and required cultivation area are within a feasible range. These results show that energy production by grass cultivation using digested sludge can be acceptable.