Combined toxicity effects of free fatty acids (FFAS) and detergent in the anaerobic treatment of oleochemical industrial effluent (OCIE) / Izham Bakar

The effect of combined toxicity of free fatty acid such as caproic acid (C6), caprylic acid (C8), capric acid (C10), lauric acid (C12) and detergent in anaerobic digestion was examined both in batch and continuous experiments. The objectives of the study were to determine the effect of combined toxicity effects of FFAs and detergent and also the optimum threshold inhibition concentration of FFAs and detergent. Methanogenesis was inhibited more when FFAs and detergent were mixed together then the individual FFAs or detergent. In the batch experiment, mixtures of detergent and FFAs at concentrations 20 mg/l and 40 mg/l respectively resulted in significant inhibition of methanogenesis. On the other hand, individual concentration of FFA or detergent up to more than 100 mg/l was showed only slight inhibition. The continuous experiment at HRT at 5.6 day, 4.0 day and 2.2 day with the concentration of detergent at 40 mg/l and original FFAs in the OCIE did not effect the reactor. The efficiency of TOC removal was about 90 to 95 %. However, the gas production was very low.