[Effect of salinity on immobilized microorganisms in biological aerated filter (BAF)]

Based on the satisfactory treatment effect of synthesized oil field wastewater with salinity of 0 - 3%, the salinity effect on the immobilized microorganism in the biological aerated filter (BAF) was further investigated. It was shown that the quantity of live microorganisms could rise to 1.3 x 10(7) per cm3 as the influent salinity was less than 1%, whereas it would decline to 1.1 x 10(6) per cm3 as the salinity increased to 2%, accompanied with the small and cracked cells running out in effluent in the domesticated system. Dehydrogenase activity (DHA) was the highest of 14.4 microg/(mg h) at salinity of 0.5%, which means the greatest degradation capability. And the extra cellular polysaccharide (ECP,) excreted by microorganisms to immobilize themselves on the carriers was the most of 209.9 microg/mg at the salinity of 2%. Although extra cellular polymers (ECP(s)) and microorganisms weight accumulated during the react system operation, the macro-pore diameter of patented FPUFS was from 0.3 to 0.7 mm, which could avoid the clog caused by the microorganisms and their ECP(s), and retained agreeable air and water condition for microorganisms under high salinity.