IMPACTS ON THE PH LEVELS FOR THE CONVERSION OF VOLATILE FATTY ACIDS IN AN INTEGRATED ANAEROBIC BAFFLED REACTORASHA B., N. SIVARAMAN AND S. RAJKAMAL
The real time institutional wastewater was used during the experimental study period. Institutional wastewater contains high levels of organics as evidenced by Chemical Oxygen Demand (COD), Volatile Suspended Solids (VSS), Volatile Fatty Acid (VFA), Nitrogen, Potassium and Phosphorus and large amount of suspended solids. A laboratory scale Anaerobic Migrating Blanket Reactor was designed and fabricated. AMBR was accomplished with both suspended and attached growth process. The reactor has been continuously operated at mesophilic range. A low initial organic loading rate was beneficial for the growth of anaerobic active sludge and the low COD organic loading resulted in low production of gas rate and low wastewater up-flow velocity. The reactor has five compartments and accomplished with both suspended and attached growth processes. Temperature of the reactor was maintained under mesophilic range. The influence of VFA for the growth of acidogenic and methanogenic organisms with respect to the reduction of organic substance was analysed. The entire experimental work was carried out with the Hydraulic Retention Times of 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 5.0 and 6.0 days with six average influent Chemical Oxidation Demand of 888, 768 and 656, 1064, 1168 and 1304 mg/L. Increased level of VFA in the second compartment was due to the production of acetic acids and acetate during the digestion process. The anaerobic path way from the first to fifth compartment in terms of COD reduction was estimated due to the influence of ph. The influent in the compartment 1 had hydrolyzed to simple organics. This results demonstrated that the VFA had been converted to acetate and hydrogen gas by acetogens in the compartment (1 and 2), and these intermediates were then further converted to methane by methanogens in the subsequent compartments (3, 4 and 5). The behaviour of the VFA concentration in the 5th compartment demonstrated that hydrolysis and acidogenesis were the important biochemical activities occurring in the first 2 compartments, whereas methanogenesis dominated in the last 2 compartments. The maximum and minimum VFA concentration is 336 to 45 mg/L respectively. It may be the result of acclimatization of methanogenic bacteria which partly began to degrade organic acid.