冻融法处理垃圾渗滤液初探

PRELIMINARY STUDY ON TREATMENT OF LANDFILL LEACHATE BY FREEZE-THAWING

利用冻融法处理垃圾渗滤液,研究冷冻温度、稀释倍数及种冰量对冷冻、融化阶段渗滤液电导率和COD的影响,并对两个阶段污染物的变化规律进行对比分析。结果表明:冷冻阶段:在-6,-13,-20,-26℃4组冷冻温度中,-13℃为渗滤液的最佳冷冻温度,此温度下渗滤液电导率和COD的下降效果最明显;渗滤液稀释倍数对冷冻阶段电导率和COD的变化无明显影响;不同种冰量的结果表明,冰晶不分离更有利于后续产生高纯度的冰晶。融化阶段:将渗滤液原水-13℃下完全冷冻后进行融化,发现电导率和COD浓度均呈指数形式下降,6 h后电导率和COD的分配系数均降到0.04。对冷冻、融化阶段渗滤液中污染物浓度变化规律进行对比分析,发现经冻融法处理后,垃圾渗滤液中电导率和COD浓度均显著下降,且融化阶段的处理效果好于冷冻阶段。因此,冻融法作为一种减量化处理方法在渗滤液预处理领域具有广阔的应用潜力。

In the study, landfill leachate was treated by freeze-thawing, and the effects of freezing temperature, dilution ratio and amount of ice on leachate conductivity and COD during freezing-thawing stages were investigated. Moreover, the changes of leachate pollutants in these two stages were compared and analyzed. The results showed that among the freezing temperature of-6,-13,-20 and-26 ℃, the treatment efficiency of leachate was better at-13 ℃ than others. Thus,-13 ℃ was considered as the optimal leachate freezing temperature. However, the dilution ratio of leachate had no significant effect on the conductivity and COD during the freezing stage. Studies on the treatment effect of different amounts of ice indicated that keeping the ice crystals in leachate was more beneficial to the subsequent freezing process. During the thawing process, the raw leachate was completely frozen at-13 ℃, then melted at room temperature. We found that the levels of conductivity and COD were exponential declined, and the distribution coefficient of conductivity and COD both dropped to 0.04 after 6 h. By comparing the changes of conductivity and COD in freezing and thawing process, it was found that the treatment effect in thawing stage was better than that in freezing stage. Therefore, as a reduction treatment method, freeze-thawing may have a great application prospect in leachate pretreatment.