Abstract
Wastewaters from oil refinery factories often contain high concentrations of sulphide and the pH is over 12. Sulphide in wastewater causes the problems of the odor, toxicity and oxygen demand. We have studied an efficient biological process to oxidize sulphide to sulphate at neutral pH. A method to acclimate sulphur bacteria from activated sludge of sewage treatment plant at neutral pH by synthetic wastewater containing thiosulphate and the thiosulphate removal rate by the sulphur bacteria were examined.
Sulphur bacteria could be acclimated from activated sludge of sewage treatment plant for about 10 days. The thiosulphate removal rate by the sulphur bacteria was from 350 to 600 mg S2O32-·g VSS-1·h-1 under the neutral pH when the water temperature was from 20°C to 35°C. And the thiosulphate removal rate was 150 mg S2O32-·g VSS-1·h-1 at 5°C. The sulphur bacteria are thought to be bacillus and maintained good settleability even at 5°C. The biological process using the sulphur bacteria acclimated from activated sludge could remove both sulphide of 200 mg·l-1 and thiosulphate of 600 mg·l-1under the HRT of 3 hours and the water temperature of 5°C.
