The Study Of Sulfide Bio-oxidation To Sulfur

Sulfide in water could affect the wastewater treatment. If sulfide escapes from the water in the form of H2S, not only can cause the nerve poisoning, but also make reaction of ozone to form sulfuric acid, and acid rain. It is an effective way to use CSB to oxidation sulfide to sulfur. Screened CSB from the soil, determination of the bacteria growth curve, then optimized its growth conditions and preliminary studied on the effects of the desulfurization of bacteria in shaking flask. Influent concentration of sulfide, pH changes, HRT and QAIR in the process of sulfide bio-oxidation to sulfur were studied after inoculating CSB in the airlift loop reactor(ALR). Then focused on the study of ORP role and the main influencing factors in the process of sulfide bio-oxidation to sulfur.The experimental results showed that: CSB had the best growth at initial pH of 7.0 and at a temperature between 28℃and 30℃. While its best sodium thiosulfate concentration for growth is 10 g/L, and the best nitrogen source is ammonium chloride, at the concentration of 400 mg/L. The preliminary desulfurization results showed that sulfide can be well used by the CSB. PH in the reactor increase makes sulfate production rate increase, and the operation is better when pH is between 7.85-8.5. Under the condition of QAIR 2000 L/h, HRT 2.78 h, the sulfide removal rate and sulfate formation rate decrease with the increase of concentration of sulfide influent. The reaction system would be paralyzed if influent concentration of sulfide is 550 mg/L. Sulfide removal rate decreases with the decline of HRT and HRT controlled 2.0-3.0 h is appropriate. In certain influent concentration and HRT sulfide conditions, QAIR too small made sulfide removal rate not high, while QAIR too large made much of sulfate. ORP is controlled by adjusting the size of the aeration, and the results show the sulfide removal and sulfate producing rate decrease with the decline of ORP under the 350 mg/L influent concentration condition. In different volumetric loading rate(VLR), the respective maximum of sulfur forming efficiency could be attained if ORP controlled -380～-340 mV. If the influent concentration are 230 and 465 mg/L, the best ORP is also -380～-340 mV.