Survival of a non-flocculating bacterium, Thiobacillus thioparus TK-1, inoculated to activated sludge

The survival of a non-flocculating bacterium inoculated to activated sludge and the development of the bacterial activity were examined. Thiobacillus thioparus TK-1, which degrades O,O-dimethyl phosphorodithioate (DMDTP) contained in the wastewater of pesticide manufacturers, shows no flocculation property. This strain was inoculated to activated sludge at the concentration of 5 × 107, 105 and 103 cfu/ml, and a wastewater containing DMDTP was treated with this sludge. No degradation was observed for the first 3, 5 and 7 days, respectively. However, after this lag time the activated sludge developed the stable degradation activity. The population of the inoculated strain in the activated sludge decreased at first, but then increased very rapidly up to 108 cfu/ml and remained stable at this level.