LAB-SCALE STUDY ON CO-DIGESTION OF KITCHEN WASTE, SLUDGE AND SEWAGE

Abstract

Anaerobic digestion is widely used for biodegradable solid organic wastes in order to recover bio-energy in the form of biogas. Some previous studies presented that co-digestion of various substrates can improve biogas yields as well as enhanceperformance of organic wastes digestion, in comparison with digestion of sole solid waste. This study aimed to evaluate the performance of anaerobic mono-digestion and anaerobic co-digestion of the following mixtures: (a) sole kitchen waste (KW), (b) KW and sewage (SW), (c) sole sludge (SL)and (d) KW and SL. This study was conductedby four lab-scale anaerobic complete mixing reactors (numbered MH1 – MH4) in 4,5 liters working volume atorganic loading rate (OLR) 2,0 g(VS).L-1.d-1. The KW was collected from canteen B4 and SW was collected from effluent from septic tank C6 Building in Ho Chi Minh University of Technology (HCMUT). The results show that the reactor of sole KW obtained average total chemical oxygen demand (tCOD), soluble chemical oxygen demand (sCOD), total solid (TS), volatile solid (VS), total phosphorus (TP) and total Kjeldahl nitrogen (TKN) of 62 %, 62 %, 71 %, 72 %, 73 % and 45 %, respectively, whereas reactor of KW and SW co-digestion had were tCOD, sCOD, TS, VS, TP and TKN removal of 73 %, 78 %, 75 %, 79 %, 59 % and 57 %, respectively. Thus co-digestion of KW and SW revealed an efficient enhancement of digestion, instead of sole KW digestion. Similarly, TS (74 %) and VS removals (75 %) of co-digesting mixtures of SL and KW were higher than those of sole SL digestion (67 %). Furthermore, co-digestion of SL and KW obtained better performance in tCOD and sCOD removals (70 % and 76 %, respectively).