Chiang Mai Journal of Science

The optimum proportions of cassava starch wastewater, hydrogenic effluent and anaerobic sludge for batch methane production were determined using D-optimal mixture design. The optimum percentage ratio of cassava starch wastewater: hydrogenic effluent: anaerobic sludge was 7.60 : 16.67 : 75.73 at volatile solid (VS) of 60 g/L which resulted in the highest methane yield (MY) of 108.3 mL CH4/g-VS. Enhancement of methane production was attempted by supplementing with modified basal medium and modified basic anaerobic (BA) medium. Addition of modified BA medium enhanced MY by 8.28% (113.7 mL CH4/g-VS) in comparison to a control (without media addition). However, no improvement in MY was observed when using modified basal medium. Replacement of yeast extract by soybean and fish meal at the same total nitrogen concentration in modified BA medium, the differences on MY were only 3.58 % and 4.36% , respectively, indicating that soybean and fish meal can be used as cheaper alternative organic nitrogen sources for methane production.