| Nowadays,the sulfur-containing wastewater is a large portion in the totalemissions of industrial wastewater.Besides there are many industries discharging thiskind of water,such as printing and dyeing, pharmaceutical, leather,paper-making andothers. Sulfide has a strong toxicity. It can penetrate inside cells when adhering to thecell wall,bringing the cell out of its activity or even to death. It also can be oxidized toform acid under the action of bacteria causing the corrosion of the pipeline and metalequipment.In anaerobic reactors,the sulfur compound can inhibit the survival of themethanogens, causing the failure of reactors when operated in severe conditions.Due to the hazard of sulfide in wastewater, the environmental factors of sulfatetransforming to sulfide in the anaerobic system were studied in this paper as well asthe formed sulfide how to work on the following aerobic biochemical course.Moreover, magnetic flocculation separation technology－a chemical method was usedto remove sulfur compound by orthogonal experiment.The results show that:1. The production of sulfide is easily and mainly transformed by sulfate reduction inan anaerobic environment.There is a direct relationship between sulfide formation andanaerobic time,reaction temperature and pH value. Results showed that theconcentration of sulfate should not be higher than1500mg/L. When anaerobicreaction time was36h,temperature about33℃,and pH7.0,the sulfide production wasthe highest(23.6mg/L).Therefore,these laboratory points were avoided as most aspossible in practical application.2.Sulfide can hurt the wastewater biochemical system.The influence factors ofsulfide on the aerobic biochemical system contain the sulfide concentration, hydraulicretention time,temperature and so on.The higher the sulfide concentration and ambient temperature,the longer hydraulic retention time,the more obvious that inhibitory ofsulfide on biochemical system. The experiment results showed that the sulfideconcentration should not be higher than200mg/L,hydraulic retention time should notexceed24h, and the temperature should not exceed30℃.3. The results show that the magnetic flocculation separation technology cangreatly remove sulfide. Several flocculant factors were studied using a orthogonalmethod to remove the sulfur compound, including species, flocculant dosage and pHvalue.The results showed that FeCl3was the best flocculant.When the sulfideconcentration in the wastewater was about100mg/L,it has a very good removal rate atthe FeCl3dosage of400mg/L under the pH6.0,PAM added6.67mg/L and magneticpowder added3.33g/L.And the rate can reach89.04%. |
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