A Two-Stage Anaerobic Digester of Pig Manure and Food Waste for Biogas Production with Heat Exchanger

Pig manure is one of the most significant causative agents of environmental pollution in swine farm areas. To reduce this problem, research has suggested the use of piggery waste for sustainable energy production. The aim of the present study was to investigate the effects of feedstock ratio on the efficiency of 2-stage anaerobic co-digestion. A 100-L capacity digester was built with the variation of mixing ratios of pig manure to food waste to water of 50:20:30, 35:35:30 and 20:50:30, respectively. Biogas production at high temperature using hot water heating system was also investigated. The effluent in fermentation tank was collected every 5 day and analyzed for the following parameters: total solid (TS), suspended solid (SS), total dissolved solid (TDS), amount of fat oil and grease, and biological oxygen dissolved (BOD). The results revealed that feedstock with the mixing ratio of 50:20:30 and 35:35:30 produced high volume of biogas. The anaerobic digester under hot water treatment (40 degrees C) exhibited higher biogas volume than that under normal temperature (30 degrees C). The ratios of feedstock also affect the efficiency of anaerobic digester as indicated by the difference in the reduction of TS, SS, TDS, COD, BOD and fat oil and grease.