次氯酸钠电解工艺动力学调控及在污水处理中消毒效果

Kinetic control of sodium hypochlorite electrolysis process and disinfection effect in sewage treatment

  • 摘要: 为提升次氯酸钠电解工艺的产氯量和满足城镇污水处理站深度处理单元出水的消毒要求,从反应动力学角度,探究次氯酸钠电解工艺的电解参数如盐水浓度、电流密度和电解温度对次氯酸钠生产过程的影响,分析深度处理单元出水水质对次氯酸钠消毒效果的影响,明晰电解参数和出水水质的影响机制。结果表明:当盐水浓度、电流密度、电解温度和电解时间分别为40 g/L、20 A/dm2、32 ℃和2.5 h时,能够有效控制温度影响、析氯电位、歧化反应和活化能,并使次氯酸钠产量提高到9.28 g/L。当次氯酸钠的投加量至少为5 mg/L和控制接触反应时间为5 min时,次氯酸钠对粪大肠杆菌群的灭菌性比其对COD和氨氮的氧化性更占竞争优势,并将水样中粪大肠杆菌群数减少至102.97个/L,达到了GB 18918—2002《城镇污水处理厂污染物排放标准》一级A排放标准中细菌学指标要求。

     

    Abstract: In order to increase the chlorine production of sodium hypochlorite electrolysis process and meet the disinfection requirements of effluent from the advanced treatment unit in township sewage treatment station, from the perspective of reaction kinetics, the influence of electrolytic parameters such as saline concentration, current density and electrolytic temperature on the production process of sodium hypochlorite was investigated, and the influence of effluent quality of the advanced treatment unit on the disinfection effect of sodium hypochlorite was analyzed, to clarify the influence mechanism of electrolytic parameters and effluent quality. The results showed that the temperature effect, chlorine evolution potential, disproportionation reaction and activation energy could be effectively controlled by adjusting the saline concentration, current density, electrolytic temperature and time to 40 g/L, 20 A/dm2, 32 ℃ and 2.5 h, respectively, and then the yield of sodium hypochlorite could be increased to 9.28 g/L. When the dosage of sodium hypochlorite was at least 5 mg/L and the contact reaction time was 5 min, the sterilization performance of sodium hypochlorite against fecal coliform groups in denitrification filter effluent was more competitive than its oxidation performance of COD and ammonium, and could reduce the number of fecal coliform groups in water samples to 102.97 L-1, and finally meet the bacteria index requirements of A-level standard of Discharge Standard of Pollutants for Municipal Waste-water Treatment Plant (GB 18918-2002).

     

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