Volatile fatty acids production from anaerobic treatment of cassava waste water: effect of temperature and alkalinity

The production of volatile fatty acids (VFAs), intermediates in the anaerobic degradation process of organic matter from waste water, was evaluated in this work. A batch reactor was used to investigate the effect of temperature, and alkalinity in the production of VFAs, from the fermentation of industrial cassava waste water. Peak production of total volatile fatty acids (TVFAs) was observed in the first two days of acidogenesis. A central composite design was performed, and the highest yield (3400mgL(-1) of TVFA) was obtained with 30 degrees C and 3gL(-1) of sodium bicarbonate. The peak of VFA was in 45h (pH 5.9) with a predominance of acetic (63%) and butyric acid (22%), followed by propionic acid (12%). Decreases in amounts of cyanide (12.9%) and chemical oxygen demand (21.6%) were observed, in addition to the production of biogas (0.53cm(3)h(-1)). The process was validated experimentally and 3400gL(-1) of TVFA were obtained with a low relative standard deviation.