Abstract

The aim of this study was to investigate the effect of substrate loading rate on anaerobic digestion using composite biogas tank with the climate of Vietnam. The study was done in three trails with fresh material was faecal sludge (FS) and organic waste (OW) mixed at ratio FS:OW = 3:1 about weight. The fesh material was loaded batch and kept for digestion in 30 days after that the reactor was operated at three different loading rates VS = 1.0±0.1 kgVS/m³.day in trail 1, 1.5±0.1 kgVS/m³.day in trail 2 and 2.0±0.1 kgVS/m³.day in trail 3. The obtained results during anaerobic digestion indicated that when increased loading rate from 1.0±0.1 kgVS/m³.day to 1.5±0.1 kgVS/m³.day the yeild biogas also rised from 284 Nl/kgVS of the feed to 490.32 Nl/kgVS of the feed with CH₄ content higher than 60%. However, at loading rate 2±0.1 kgVS/m³.day the yield of biogas product reduced to 236.11 Nl/kgVS of the feed with CH4 content lower than 50 %. It can see that the organic loading rate 1.5±0.1 kgVS/m³.day is suitable for anaerobic co-digestion of faecal sludge and organic waste.