【作者】 刘卫华；

【导师】 季民；

【作者基本信息】 天津大学 ， 环境工程， 2007， 博士

【摘要】 针对垃圾渗滤液中有机物难降解、毒性大、难以达标排放的问题,选取两种在垃圾渗滤液中普遍存在的污染物为研究对象:(1)在垃圾渗滤液中微量存在,但具内分泌干扰性的难降解有机物-邻苯二甲酸异辛酯(di(2-ethylhexyl) phthalate,简称DEHP);(2)垃圾渗滤液中的主体有机物,且难于生化降解-高浓度腐殖质(TOC>100mg/L)。采用液-液萃取,色谱-氢火焰离子化检测(GC-FID)方法分析天津市两个主要垃圾填埋场渗滤液中酞酸酯(phthalic acid esters,简称PAEs)的存在情况,均检出不同浓度的邻苯二甲酸二丁酯(di-n-butyl phthalate,简称DBP)和DEHP,未检出其他PAEs有机物;DBP浓度范围为3.8～9.3μg/L,DEHP浓度范围为65.3～1212.0μg/L,渗滤液中DEHP含量远远高于DBP含量。采用XAD大孔树脂吸附分离技术对渗滤液中腐殖质进行分离与提取,试验结果表明渗滤液经过充分生物处理后,残余的有机物绝大部分为难以生物降解的可溶性腐殖质。考察了臭氧对DEHP及腐殖质氧化降解去除的效能和可能的氧化机理,系统探讨了臭氧初始浓度、污染物初始浓度、pH值、温度、抑制剂等因素对臭氧氧化降解DEHP和腐殖质反应的影响,分析了不同臭氧氧化条件下污染物的降解特征。结果表明臭氧氧化对DEHP具有较好的降解效果,确定了较优的反应条件限值为:臭氧浓度16.8mg/L,温度不宜超过35.5℃,pH值不宜超过10。试验中加入·OH抑制剂叔丁醇,阻碍DEHP的臭氧氧化反应,间接证明了反应遵循羟基自由基反应机理。采用紫外可见光谱(UV-Vis)、气相色谱-质谱(GC/MS)等分析方法,对DEHP臭氧氧化中间产物进行分析,得出DEHP可能的降解途径。研究了Fe(II)、Mn(II)、Cu(II)对高浓度腐殖质的臭氧催化降解的可能性,对其催化作用机制进行了考察。结果表明,无论是臭氧氧化还是催化臭氧氧化都具有显著的脱色作用,并可有效去除以UV254表征的有机物。在去除TOC及COD表征的有机物时,催化臭氧氧化法降解腐殖质的效率比单独臭氧氧化法有显著提高,氧化60min时,TOC的去除率从28.6 %增加到57.9%(Fe(II)催化)、68.9%(Mn(II)催化)、74.5%(Cu(II)催化),Cu(II)催化效果最优。Fe(II)、Mn(II)、Cu(II)的最佳投加浓度均为0.6mg/L。溶液初始pH值、温度、羟基自由基抑制剂叔丁醇等因素对腐殖质去除率均有一定影响。对Fe(II)和Cu(II)而言,催化作用机理主要是通过各物质与溶液中溶解的臭氧发生反应而产生·OH,进而显著提高氧化过程对腐殖质的降解能力。Mn(II)对臭氧氧化的催化作用,则主要是它与臭氧反应生成水合态MnO2再进一步形成具有催化活性的MnO2-OH·所致。最后对垃圾填埋场渗滤液生化处理出水进行了小试研究,用Cu(II)催化臭氧氧化生化处理后的渗滤液,仅需投加0.6mg/L Cu(II)即可达到理想效果,并且出水中Cu的浓度远远低于污水排放标准的要求值。更多还原

【Abstract】 How to dispose the landfill leachate which was consisting of a lot of refractory and toxic materials is one of most difficult issues. Di(2-ethylhexyl) phthalate (DEHP) was an endocrine disrupting pollutant in the landfill leachate, even at low concentration. And humic substance was the main organic matter in landfill leachate, which was refractory organic. This thesis focused on the oxidation of DEHP and humic substance in landfill leachate.Liquid-phase extraction method and GC-FID were used to analyse phthalic acid esters (PAEs) in landfill leachate from two municipal solid wastes (MSW) landfill sites in Tianjin. DEHP and di-n-butyl phthalate (DBP) were found in all the leachates. DEHP was the most abundant of the PAEs, which concentration was 65.3~1212.0μg/L. The concentration of DBP was 3.8~9.3μg/L. Other PAEs were not detected. Natural organic matter in landfill leachate was fractionated into hydrophobic compouds and other hydrophilic organics by XAD resin. Results showed that dissoluble humic substance was the main organic matter in landfill leachate treated by biological process.The efficiency of ozonation on removing DEHP and humic substance was studied. The effects of ozone concentration, DEHP concentration, pH, temperature, quenching agent on the removal rate of DEHP were evaluated. Results showed that DEHP was effectively degraded by ozonation. The optimum condition was the concentration of O3 with 16.8mg/L, temperature under 35.5℃, and pH under 10. The mechanism of removing DEHP and humic substance by ozonation were proved that radical reaction took the main role. In addition, UV-Vis, GC-MS were utilized to analyze the oxidation intermediates in ozonation process of DEHP, and the detailed degradation path was illuminated.Homogeneous catalysed ozonation of high concentration humic substance was investigated with the existence of Fe(II), Mn(II) and Cu(II). The results showed that both ozonation and catalytic ozonation achieved chroma and UV254 removal well. All catalytic ozonation processes resulted in a significant increase on the removal of TOC and CODCr. The removal efficiency of TOC increased from 28.6% to 57.9% by Fe(II), 68.9% by Mn(II) and 74.5% by Cu(II) at 60min. Cu(II) was found to be the most effective among the three catalysts. All the optimum dose of the three catalysts was 0.6mg/L. Initial pH, temperature, quenching agent influenced humic substance removal also. Ozonation efficiency was improved by ?OH induced by Fe(II) and Cu(II) catalysed ozonation, but the catalytic effect was shown by MnO2-OH? created in Mn(II) catalysed process.A bench-scale study had been undertaken on the catalytic ozonation of landfill leachate treated by biological process from a MSW landfill site in Tianjin. It was proved that organic materials in leachate could be successfully removed by catalytic ozonation on the presence of Cu(II) with 0.6 mg/L. And the concentration of Cu in the effluent was lower than that in the Integrated Wastewater Discharge Standard.更多还原