Anaerobic Co-digestion of Food waste and Sewage sludge using Combined Thermal-Alkali Pre-Treatment and Anaerobic Digestion Elutriated Phased Treatment

This study was performed to evaluate the efficiency of the anaerobic co-digestion of food waste (FW) and sewage sludge(SS) using thermal-alkali pre-treatment and anaerobic digestion elutriated phased treatment(ADEPT). Through the evaluation of solubilization rate and methane yield, optimum thermal-alkali pre-treatment conditions were determined as follows: reaction temperature 140°C, NaOH concentration 60 meq/L, reaction time 60 min, mixture ratio 5:1(FW:SS=Wt.:Wt.). The removal efficiency of total chemical oxygen demand(TCOD), Soluble COD and volatile solid(VS) in the thermal-alkali pre-treatment ADEPT were 89%, 90% and 76%, respectively. The VS removal rate was 39% higher than that ADEPT at the same hydraulic retention time(HRT) of 7 days. Methane yield was estimated to be 0.378 L/g CODadded, which was 14% higher than that of phase II. As a result, it is considered that the application of combined pre-treatment and ADEPT is effective increasing the biogas and methane yield due to increasing the biodegradability of FW and SS.