新鲜渗滤液与长填埋龄渗滤液的Fenton处理过程特征

Comparison of the Treatment Performance in Fresh and Mature Landfill Leachates by Fenton Process

以新鲜渗滤液和长填埋龄渗滤液为对象,采用Fenton法对其进行处理,通过相对分子质量（Mr）分布、COD、总有机碳（TOC）、COD/TOC等表征手段,比较分析渗滤液性质对Fenton处理效果的影响.结果表明,长填埋龄渗滤液的有机物平均Mr高于新鲜渗滤液,其Mr〉105的组分占到了总量的64%,但在Fenton法作用下其更易转化为可溶性小分子有机质（Mr〈103）;新鲜渗滤液的COD去除率（61%-84%）高于长填埋龄渗滤液（31%-60%）,而长填埋龄渗滤液的TOC去除率（85%-91%）高于新鲜渗滤液（52%-80%）;无论是处理新鲜渗滤液还是难降解的长填埋龄渗滤液,Fenton法的氧化作用对COD去除的贡献均大于絮凝作用.絮凝作用的COD（CODcoag）去除率受氧化作用的COD（CODoxid）去除率影响,CODoxid去除率越大,CODcoag去除率越低;物料平衡结果显示,长填埋龄渗滤液的TOCoxid去除量大于CODoxid去除量,而新鲜渗滤液的的TOCoxid去除量小于CODoxid去除量;长填埋龄渗滤液和新鲜渗滤液的初始COD/TOC分别为1.17和1.58,在Fenton处理的氧化作用下,COD/TOC分别变为1.96和0.68,表明长填埋龄渗滤液发生的是完全氧化,而新鲜渗滤液同时发生了部分氧化和完全氧化;2种渗滤液的CODcoag和TOCcoag变化说明,长填埋龄渗滤液中受絮凝作用去除的有机物的氧化态明显低于新鲜渗滤液.

The experiments focused on comparing the removal efficiencies of organic matters in fresh and mature landfill leachate by Fenton treatment. The changes in dissolved organic matter before and after Fenton treatment were assessed using gross organic parameters such as organic compound relative molecular mass （Mr） distribution, chemical oxygen demand （COD）, total organic carbon （TOC） and the ratio of COD to TOC. The results from this study demonstrate that high Mr fractions of mature landfill leachate are more easily converted into dissolved small Mr fractions （ Mr 〈 10^3 ） by Fenton reaction than those of fresh landfill leachate, since the average Mr of mature landfill leachate is higher than that of fresh landfill leaehate and the Mr 〉 105 fraction of the mature leachate account for 64% of the total mass. Operating parameters such as p H[Fe^2＋] and [ H2O2 ]/[ Fe^2＋ ] demonstrate that the COD removal efficiency of the fresh landfill leachate （from 61% to 84% ） is higher than that of the mature landfill leachate （from 31% to 60% ） ,while it is converse for TOC （from 85% and 52% to 91% and 80% for the mature and fresh landfill leachate, respectively）. Oxidation seems to play a more active role in COD reduction than coagulation whatever for the mature or fresh landfill leachate. Oxidation efficiency apparently controls coagulation efficiency, so that high oxidation efficiency may cause relatively low coagulation. The mass balances indicate that TOC removal by oxidation （TOCoxid） is more than COD removal by oxidation （ CODoxid ） for the mature landfill leachate while TOCoxid is less significantly than CODoxid for the fresh landfill leachate. The COD/TOC ratios are 1.17 and 1.58 for the initial mature landfill leachate and fresh landfall leachate, respectively, but they are 1.96 and 0.68 after Fenton treatment by oxidation, respectively. This phenomenon suggests that complete oxidations occur in the mature landfill leachate while both partial and complete oxidations occur in the fresh landfill leachate. The changes of CODcoag and TOCoag illustrate that the oxidation state of the organic matters removed by coagulation in the mature landfill leachate is significantly lower than in the fresh landfill leachate.