Abstract
Low strength soybean processing wastewater (BOD=1, 000mg·l-1, VSS=690mg·l-1) was treated, using an anaerobic two-phase membrane reactor process, in which an acidification fixed-bed reactor was combined with an ultrafiltration membrane module. A fixed-bed reactor reduced SS loading for membrane to ensure a high flux and enhanced solubilization rate with high attached soybean SS and bacteria. Studies on solubilization and acidification were conducted in the labratory scale and the continuous field tests. The following results were obtained :
1) In the batch solubilization test of soybean protein SS, under the condition of pH ranged from 5.0 to 8.3, the result showed the maximum solubilization rate constant was 0.7 d-1 in the proximity of pH 6.0.
2) The ultrafiltration membrane concentrated both substrate soybean protein SS and bacterial SS. The permeate supplied to the methane reactor contained mainly volatile atty acids.
3) A composition analysis of SS attached on the carriers in an acidification reactor clarified 41% to 56% of total SS attached was the soybean protein SS. The field test results estimated the solubilization rate constant was 0.28 d-1 to 0.33 d-1.
