响应面法优化硫酸根自由基高级氧化深度处理渗滤液生化尾水

针对垃圾渗滤液生化尾水中仍含有较高浓度的难生物降解COD、NH4+-N和NO2--N,无法满足现行排放标准的问题,采用基于硫酸根自由基的高级氧化技术(SR-AOP)对生化尾水进行深度处理.考察了pH值、温度、FeSO4和过硫酸钠浓度对TOC和TN去除效果的单独作用及交互作用.结果表明,影响因子对于处理效果的贡献排序为:pH值>温度>过硫酸钠浓度,各因素对TOC的去除有显著性影响,而对TN的去除没有显著性影响.各因素的复合效应为:TN去除效果影响:温度+过硫酸钠浓度>pH+过硫酸钠浓度>温度+pH, TOC去除效果影响:温度+pH>pH+过硫酸钠浓度>温度+过硫酸钠浓度.实验最终确定SR-AOP的最佳条件为:pH=5,温度为30℃,过硫酸钠浓度为0.5g/L,催化剂FeSO4剂量为3.8g/L,该条件下TOC去除率为35.5%,TN去除率为16.9%,同时可以显著提高出水BOD5/COD.因此,通过SR-AOP深度处理可以去除生化处理尾水大部分COD和TN,并大幅提高B/C比,为后续与适当的生化处理工艺组合进行达标处理奠定了良好的基础.

Optimization of sulfate radical-based advanced oxidation process using response surface methodology for treating effluent from biological treatment of landfill leachate

Generally the quality of the effluent from biological treatment of landfill leachate couldn’t meet the national discharge standard due to the relatively high concentrations of recalcitrant COD, NH4+-N and NO2--N. In this study, sulfate radical-based advanced oxidation process (SR-AOP) was adopted for the advanced treatment of the effluent. Single factor and combined effects of pH, temperature (T) and sodium persulfate concentration (SPC) on SR-AOP in removing TOC and TN from the effluent were evaluated using response surface methodology. Results showed that each factor alone could significantly influence the TOC removal but not TN. The influential extent on the TOC removal was more significant with pH, followed by T and SPC. On the other hand, both TOC and TN removal rate could be significantly impacted by the combined effect. The order in TN removal efficiency was T+SPC>pH+SPC>T+pH, whereas that in TOC removal was T+pH>pH+SPC>T+SPC. The highest TOC and TN removal rate, 35.5% and 16.9%, respectively, was obtained under the optimal condition of 0.5g/L SPC and 3.8g/L FeSO4at pH 5and 30℃ for SR-AOP in treating biological effluent from landfill leachate. In addition, BOD5/COD ratio of the effluent could also be significantly improved after SR-AOP. These results indicated that SR-AOP could be an effective method for advanced treatment of the effluent derived from biological treatment of landfill leachate.