混凝+芬顿法对中晚期垃圾渗滤液色度去除

垃圾渗滤液经一般生化处理后色度很大。对混凝和芬顿法结合深度处理垃圾渗滤液对色度去除进行了研究。混凝段通过中心复合设计(简称CCD)和响应面方法(简称RSM)分析了混凝的色度去除率的响应特征,建立了实际因素的最终方程模型:Y(色度去除率,%)=-553.40+73.74A+229.06B+0.38AB-34.16A2-22.67B2,(Y、A、B分别代表色度去除率、投加量和pH)并对絮凝条件进行优化,得到混凝反应的最佳优化条件:投加量1.11 g/L,pH 5.06,及在此条件下的去除率67.2%。在芬顿段,将芬顿反应对水中亲水性有机物相对含量(UV254)与对色度的去除特征相结合进行了研究,证明色度的去除跟该类有机物的去除有关,色度去除率最优值条件选择为H2O2/COD=1.0,Fe2+/H2O2=0.35∶1,而初始pH=2.5时对色度的去除达到99%以上。整个工艺出水可达到达标排放标(GB16889-2008)。     

Chemical oxygen demand reduction in coffee wastewater through chemical flocculation and advanced oxidation processes

The removal of the natural organic matter present in coffee processing wastewater through chemical coagulation-flocculation and advanced oxidation processes （AOP） had been studied. The effectiveness of the removal of natural organic matter using commercial flocculants and UV/H202, UV/O3 and UV/H2O2/O3 processes was determined under acidic conditions. For each of these processes, different operational conditions were explored to optimize the treatment efficiency of the coffee wastewater. Coffee wastewater is characterized by a high chemical oxygen demand （COD） and low total suspended solids. The outcomes of coffee wastewater treatment using coagulation-flocculation and photodegradation processes were assessed in terms of reduction of COD, color, and turbidity. It was found that a reduction in COD of 67% could be realized when the coffee wastewater was treated by chemical coagulation-flocculation with lime and coagulant T-1. When coffee wastewater was treated by coagulation-flocculation in combination with UV/H2O2, a COD reduction of 86% was achieved, although only after prolonged UV irradiation. Of the three advanced oxidation processes considered, UV/H2O2, UV/O3 and UV/H2O2/O3, we found that the treatment with UV/H2O2/O3 was the most effective, with an efficiency of color, turbidity and further COD removal of 87%, when applied to the flocculated coffee wastewater.     

絮凝法预处理高浓度垃圾渗滤液的实验研究

在用絮凝法对CODCr高达19 200～22 500 mg·L-1的垃圾渗滤液进行预处理当中,以垃圾渗滤液的CODCr去除率为考察指标,通过不同混凝剂对CODCr去除效果的比较,确定了最佳混凝剂.通过单因素实验和正交实验确定了最佳混凝剂用量以及最佳反应条件.研究结果表明,采用自制聚合氯化铁絮凝剂在投药比为1 000:3,pH值为10.5左右,搅拌时间为5.0 min,沉降时间为20 min时,能够使垃圾渗滤液的CODCr去除率达到64%以上,减轻了下一步生物处理的负荷.     

Evaluation and remediation of organics,nutrients and heavy metals in landfill leachate – a case study in Beijing

Leachate pollution in landfill sites is a major source of environmental concern. This study evaluates organics, nutrients and heavy metals in a landfill site in Beijing, and introduces a method combining coagulation–flocculation with filtration for the advanced treatment of leachate. The results confirm that COD_Cr, TN, NH₄⁺ ? N, TP, Mn and As in leachate treated by an anaeobic–oxic biological method are unable to meet discharge or surface water quality standards. When treated with coagulation–flocculation combined with filtration under optimal conditions (cationic polyacrylamide dosage of 8.0 mg/L; polyaluminium chloride dosage of 350 mg/L; 0.4–0.6 mm ceramsite media in the filtration process), the residual NH₄⁺? N, TN, Mn and As in the leachate meet the maximum allowed values for landfill leachate discharge or surface water quality standards in China; the exceptions are chemical oxygen demand and total phosphorus. Leachate treatment processes could be further strengthened or improved.