电化学组合工艺削减垃圾渗滤液毒性的综合评价

Comprehensive evaluation of the toxicity reducing rates of the landfill leachate through combined electrochemical processing

以某垃圾填埋场的垃圾渗滤液为样本,将其在实验室以电化学氧化为主要工艺的废水处理装置出水作为研究对象。选择发光细菌、斑马鱼胚胎和斑马鱼仔鱼为受试生物,以发光抑制率及生物体死亡为观察指标,研究不同处理过程出水对3种受试生物的急性毒性效应。试验结果以半数效应浓度(Median Effective Concentration,EC50)和半数致死浓度(Median Lethal Concentration,LC50)表征。通过毒性单位(Toxicity Unit,TU)法、平均毒性(Average Toxicity,Av Tx)法、毒性指数(Toxic Print,Tx Pr)法、最敏感的测试(Most Sensitive Test,MST)法和潜在毒性效应指数(Potential Ecotoxic Effects Probe,PEEP)法等生物毒性评价方法对不同处理过程进行毒性削减评估。结果表明,出水对发光菌、斑马鱼幼鱼和胚胎的TU分别为0.63、9.82和8.55,与原水相比分别削减了81.52%、88.41%和89.65%。Av Tx、Tx Pr和MST法评价结果显示,经混凝沉淀-厌氧-电化学氧化-好氧组合工艺处理的出水仍具有一定的生物毒性,即现行的废水排放标准下不能完全阻止有毒废水的排放。此外在考虑废水排放量的基础上,PEEP评价法虽然表明出水无毒,但排放时需注意单项指标毒性。与成组生物试验相结合的PEEP评价方法可以反映垃圾渗滤液的综合生物毒性及评价其对生态系统的潜在影响。

The present paper is inclined to make a toxicity evaluation of the effluents of the landfill leachate to be treated via a combined process of coagulation and sedimentation,in addition to the anaerobic,electrochemical oxidation and aerobic oxidation.For the study purpose,we have chosen the luminescent bacteria,zebrafish embryos and zebrafish larvae as the organism testing subjects,for they are representative aquatic organisms at different tropic levels in the aquatic ecosystem. In the experiment,we have adopted the luminescence inhibition rate and the death rate of the living organisms as the observation indexes to study the acute toxicity effects of the effluents from the different treating processes. The experimental results have been characterized by means of the median effective concentration（ EC50） and the median lethal concentration（ LC50）. In addition,we have also investigated and measured the toxicity reduction in the different treating processes in different methods and units,including the toxicity unit（ TU）,the average toxicity（ Av Tx） rate,the toxic print（ Tx Pr）,the most sensitive tests（ MST） and the potential ecotoxic effects probe（ PEEP）. The testing results we have gained demonstrate that the toxicity units of the luminescent bac-teria,the zebrafish larvae and the zebrafish embryos are respectively equal to 0. 63,9. 82 and 8. 55. At the same time,the combined process proves to be able to result in the decreasing rates of81. 52%,88. 41% and 89. 65%,respectively,as compared with the original data. Besides,the Av Tx,Tx Pr and MST methods can also be used to evaluate the synthetic biological toxicity of the sewage. The evaluation results of Av Tx,Tx Pr and MST indicate that the combined biological toxicity can be reduced by 88. 88%,88. 88% and 88. 41% through the combined process,respectively,though they may remain to be biologically toxic with the effluent from the said combined process. What is more,it is also necessary to point out that the current discharge standards cannot be made to avoid the discharge of the toxic sewage. And,in terms of the sewage discharge amount,the mixed toxicity of the sewage can be remarkably reduced by 37. 11% as compared with the original water by using the PEEP evaluation method. Therefore,though the treated effluent can be taken as non-toxic according to the PEEP method,the single index toxicity evaluation method can also be brought about into application. In conclusion,the PEEP evaluation method in combination with the biological toxicity testing approach can be used to reflect the synthetic biological toxicity of the landfill leachate,as well as the evaluation of the potential impact of the landfill leachate on the ecosystem.