High Solid Thermophilic Anaerobic Co-digestion of Oxidation Ditch Sludge and Rice Straw

摘要

Thermophilic anaerobic co-digestion of waste sludge from an oxidation dich process (OD sludge) and rice straw (RS) was investigated in a laboratory scale digester. Several concentrations of RS were mixed to 6% of OD sludge, and the mixture was fed to the digester in the condition of SRT 15 days and 55 °C. Biogas yield increased, and ammonium nitrogen and organic acids concentrations in the supernatant decreased by the addition of RS. when 3% RS was mixed to 6 % OD sludge, stable performance and the highest biogas production yield (0.27 NL/g TS) was achieved. Biogas yield and COD conversion rate was almost the same as the theoretical value obtained from the batch experiment of each biomass. When total amount of input TS was increased to 11.7 % (OD sludge 7% and RS 3.5%) in the same mixing ratio, ammonium nitrogen rapidly increased to 3.3g/l and biogas production yield decrease to 0.20 NL/g TS.