Assessment of toxicity of tetrahydrofuran on the microbial community in activated sludge.

Activated sludge is widely used to treat industrial wastewater, but its efficiency is affected by a variety of factors, including toxic substances such as tetrahydrofuran (THF). In this study, we examined the toxicity of THF at different concentrations (0-320 mM) on the microbial community in activated sludge. A remarkable dose-dependent decrease in the total organic compound removal rate and culturable bacteria and fungi was observed. At THF concentrations higher than 160 mM, a decrease in pH to 3.0 was observed. The activities of five enzymes (catalase, dehydrogenase, urease, phosphatase and protease) analyzed were all significantly inhibited (p<0.01) at THF concentrations higher than 160 mM, especially dehydrogenase activity, which lost 95.4% of its activity at 320 mM THF. Microbial community analysis by PCR-DGGE revealed a substantial shift in the community structure and a reduction in diversity at a low THF concentration (20mM). These results suggest that THF is much more toxic than reported in the literature, indicating its acute toxicity to microorganisms.