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Elaiyaraju P., Partha N. (2016): Studies on biogas production by anaerobic process using agroindustrial wastes. Res. Agr. Eng., This study investigated the effect of factors namely temperature, pH, substrate concentration on sago and tannery effluents by the anaerobic digestion process for biogas production. Response surface methodology with the Central Composite Design (CCD) experiments verified that the biogas production rates were mainly affected by operating temperature, pH, and substrate concentration. The experiments were carried out by two distinct effluents at different organic loading rate under mesophilic range of temperature 31-33°C. Co-digestion was carried out for a period of 21 days. The gas produced was measured by the liquid displacement system. Meanwhile, the highest biogas yields -80% of CH 4 and 20% of CO 2 -produced in the combined effluent were confirmed by the Gas Chromatography (GC) analysis.

In the present study, we have developed a batch reactor setup to monitor the formation of biogas using sago (cassava) wastewater for the first time. The experimental parameters like pH, COD, BOD, volatile solids, have been tested to optimize the production of biogas. The liberated biogas was analyzed and found that, about 65 – 70 % of methane and remaining 20–25 % of CO2. Sago effluent contains large amount of organic material which has a potential to cause water pollution. In order to reduce this problem, an experiment was conducted to remove organic material and biogas recovery from sago effluent using lab scale batch reactor. The biogas produced in the first reactor of 750 ml feed was 3393 ml per liter of liquid waste and similarly the biogas produced in the second reactor of 1250 ml feed was 3068 ml per liter of liquid waste.

Anaerobic co-digestion of jatropha deoiled cake and orange peel waste for biogas production was carried out in the batch scale (500 ml serum bottle) under anaerobic condition at ambient temperature (at various mixing ratios of two substrate). The experimental data showed a maximum gas output of 1140 ml of gas production at (1:2) ratio of jatropha deoiled cake with orange peel waste obtained for a period of 17 days. The modified Gompertz equation was used to adequately describe the cumulative biogas production for this reactor. The CH 4 content was 75%, CO 2 content was 16% and CO content was 9%. The biogas production was measured by liquid displacement system on daily basis. The digested slurry can be used as a fertilizer for agricultural purpose.

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