A CSTR-anaerobic filter process with the phase separation technique was employed in treating monosodium glutamate fermentation waste of high strength to avoid the difficulties of process instability and long hydraulic detention time in conventional anaerobic wastewater treatment.
A 40 l capacity CSTR was used for the first stage acidogenesis reaction carried out at 30 ℃ and a 31.3 l filter packed with square channel type packings of polypropylene was for the second stage methanogenesis reaction at 38 ℃.
Two sets of steady state experiments were run. The first experiment was performed with the detention time of 14 h for CSTR and 20 h for filter and the second one with the detention time of 16.7 h for CSTR and 40 h for the filter. The anaerobic filter was operated with the loading rates of 4.5 ㎏-COD/㎥/day and 2.24 ㎏/㎥/day. The treatment efficiencies were 57.4 % and 85.3 % respectively on the basis of filtrate COD. Methane production rates were 25 l/day and 15 l/day respectively. Sludge Volume Index of the over flow from the CSTR was 18.4 far less than 100. During the operation, no external pH control was required and any part of the anaerobic filter did not fail to maintain the optimum pH range from 6 to 8 for the growth of methane generating bacteria.