Biogas production from cassava waste: effect of concentration

Abstract

In the lactic acid production from cassava, there is cassava waste generated from saccharification process. This study intends to investigate the effects of substrate concentration on fermentative methane and carbon dioxide from cassava waste using activated sludge obtained from the cassava production plant and the biogas production was determined in batch experiments. The ratio between cassava waste and sludge of 1:1, 1:2, 2:1 and 1:0 at 34°C were used in this investigation. The rate of fermentation and methane yield were observed during the fermentation. First, we investigated whether the biogas can occur without the additional microorganism. It was found that methane can occur within 6 days for the batch adding the biological sludge, while it cannot be observed in the case of the reactor free of adding the microflora. The suitable ratio in this study was found that cassava waste and sludge of 1:1 can produce the greatest biomethane in biogas. The quality of biogas occurred in batch reactor composed of 63.1% CH4, 34.4% CO2, 2.2% of oxygen and 0.3% of other gases. It is noted that at this ratio, the hydrogen sulfide (H2S) was not detected while it was 4 ppm in the case of higher sludge added in the reactor.