Abstract
Microbial community of thermophilic contact oxidation process batch reactors treating waste metal working fluids (MWFs) was analyzed through culture-independent techniques in this study. We investigated the correlation between treatment capacity and microbial community, particularly focusing on dicyclohexylamine (DCHA), a persistent compound in waste MWFs. The treatment reduced oil content by 60 to 70%. The reduction of fatty acids and p-t-butyl-benzoic acid was almost 100%, whereas DCHA reduced by 80%. DCHA reduction capacity was maintained even when DCHA concentration was tripled. Clone library of 16S rRNA gene showed that Bacillus species were dominant (72%) and the clones related to B.thermozeamaize and B.thermoamylovorans were abundant among them. A combination of PCR-Denaturing Gradient Gel Electrophoresis (DGGE) and clone library suggested that the relatives of Bacillus sp. BGSC W9A92 and B. polygonumi functioned for the DCHA decomposition.
