Anaerobic co-digestion of food waste and septage – A waste to energy project in Nashik city

Abstract

The samples for food waste (FW) and septage were collected from six localities of Nashik city. Physical and chemical characterizations of the wastes were carried out. A Biomethanation potential (BMP) assay was developed to determine the ultimate biodegradability and associated methane yield during the anaerobic methanogenic fermentation of organic substrates. BMP assays of individual substrate, FW and septage were carried out by taking into account the volatile solids/total solids (VS/TS) ratio of each while keeping the inoculum’s VS constant. BMP of FW and septage mixture was carried out in different ratios (1:1, 1.5:1, 2:1, 1:1.5 and 1:2) to find the optimum mixing ratio for maximum biogas production. The average methane yield for different locality FW was found to be 503±17.6 ml/g VS and for septage it was 56 ±10.8 ml/g VS. Based on the above results, the total biogas yield and total methane yield for 10 tons of FW would be 2178 m3/d and 1306 m3/d respectively. The total biogas yield and total methane yield for 20 m3 of septage would be 65m3/d and 39m3/d respectively. From our co-digestion studies we also conclude that the mixture of FW to septage at 1:2 ratio gives 2896 m3/day of biogas. The role of septage is to provide essential trace elements that are required for methanogens.

Keywords

• Food waste
• anaerobic
• co-digestion
• energy
• biogas
• methane