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Abstract

This research aimed to study the efficiency of biogas production from fruit waste and chicken manure by co-digestion process. The fruit wastes used were pineapple, papaya and mango at ratio of 1:1:1 by wet weight. The experiments were divided into 2 parts. Firstly, the biochemical methane potential test was conducted by varying the carbon to nitrogen (C/N) ratio, i.e. 15, 20, 25 and 30, in order to determine the suitable C/N ratio for biogas production. Result showed that C/N ratio of 20 rendered the highest specific methane yield (0.54 L CH4/g VSadded). The second part of experiment was carried out in order to study the effect of organic loading rates (OLRs) on specific methane yield using two Anaerobic Sequencing Batch Reactors (ASBRs). Chicken manure was used as the co-substrate in the first rector, while urea was used in the second rector. These two reactors were operated at different OLR, i.e. 0.5, 0.8, 1, 1.5, 2, 2.5 and 3 kgVS/m3-day, respectively. Result showed that the highest specific methane yield of the first rector (fruit wastes + chicken manure) was 0.30+0.01 L CH4/gVSadded at the OLR of 0.8 kgVS/m3-day while the highest specific methane yield of 0.14+0.01 L CH4/gVSadded was obtained from second reactor (fruit wastes + urea) at the OLR of 1.5 kgVS/m3-day. It was found that fruit wastes were very acidic and was the main cause of pH reduction in the reactor. Alkalinity addition was required to maintain pH level of the reactor at the workable range.