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混凝和Fenton工艺深度处理渗滤液时反应条化优化和DOM分析

Optimization of Operational Conditions During Leachate Treatment by Coagulation and FENTON Processes and DOM Analyses

【作者】 张静

【导师】 赵庆良;

【作者基本信息】 哈尔滨工业大学 , 环境科学与工程, 2010, 硕士

【摘要】 垃圾渗滤液水质复杂,难于处理,其中主要是由于垃圾渗滤液中含有较高的溶解性有机物(DOM)。DOM的组成和特征可以影响到渗滤液处理工艺的选择。为了更有效地去除垃圾渗滤液中DOM,本文选用混凝法和Fenton法两种典型的渗滤液深度处理工艺,对渗滤液SBR出水进行处理,利用非离子吸附树脂将混凝和Fenton的进出水分别进行DOM分级,确定了不同组分的难易去除程度,通过荧光光谱和红外光谱确定了混凝和Fenton反应过程中不同组分的去除特性和结构变化规律。首先,通过单因子实验确定混凝工艺在投加0.772 mmol/L的聚合三氯化铁(PFC)(以Fe计)时,SBR出水pH=8.89的情况下,DOC的去除率为67.21%。Fenton工艺在H2O2的投加量为1.2 mL/L,Fe2+的投加量为6.44 mmol/L,pH为3.5,反应时间30 min时,DOC去除效果可以达到64%。此时,两种工艺出水的COD均小于100 mg/L,符合“生活垃圾填埋场污染控制标准(GB 16889-2008)”规定的一级排放限值。可以看出,混凝工艺比Fenton工艺的药剂投加量少,从而产生的沉淀量也少。因而,混凝工艺在深度处理中的经济成本和环境效益均优于Fenton工艺。在混凝过程中大分子有机物去除效果较好,主要是由于混凝工艺更容易通过吸附、拦截和网捕机制去除水中物质。在Fenton过程中,小分子烃类物质去除的较好,因此反应终止时Fenton出水的分子量有明显增大的趋势。混凝法对于各个组分的去除率从大到小依次为:HPO-N(83.47%),TPI-A(78.55%),HPO-A(72.22%),TPI-N(60.89%),HPI(0.49%);Fenton法对于各个组分的去除率从大到小依次为:HPO-N(84.78%),TPI-A(73.99%),TPI-N(67.57%),HPO-A(60.43%),HPI(17.10%)。HPO-A发射荧光的强度最大,远远高于其他组分,而HPO-A的SUVA也比其他几个组分大,说明其内部含有的芳香性组分较多,主要是腐殖酸和富里酸。HPI则主要是亲水性物质组成,并不属于腐殖质的范畴,主要是糖、氨基酸等的混合物,多为脂肪烃类物质。HPO-N和TPI-N两个组分的荧光物质主要是由芳香性蛋白质组成,并且具有较高的分子量。通过红外光谱的分析,可以得知HPO-A和TPI-A中有明显的羧酸基团的吸收峰。HPO-N和TPI-N则主要是脂肪烃的吸收峰,说明虽然HPO-N和TPI-N含有一定的芳香性蛋白质,但是其内部仍然是烃类物质占绝大部分,因为含有酰胺类震动峰,说明HPO-N和TPI-N是微生物体降解得到的糖蛋白等产物。

【Abstract】 Landfill leachate contains the higher content of dissolved organic matter (DOM), and the composition and characteristics of DOM can affect the leachate treatment options. Therefore, this paper focus on two typical advanced treatment processes: coagulation and Fenton. Effluent of the SBR was treated by Fenton and coagulation processes, and after that the effluent from both processes was fractionated into five classes using non-ionic adsorption resin, in order to characterize the removal of DOC during Fenton and coagulation. Fluorescence EEMs was applied to characterize the transformations of DOM fractions and IR spectroscopy was used for gross characterization of DOM and can provide valuable information on the structural and functional properties of DOM molecules.The optimum operational conditions for coagulation was dosage of poly-ferric chloride (PFC) 0.772 mmol/L (Fe) without adjusted pH (8.89). DOC removal rate was 67.21%. The maximum amount of DOC that could be removed by the Fenton’s post-treatment was about 64% of the initial value. Such a maximum removal was achieved with dosages of H2O2 and Fe2+ respectively 1.2 mL/L and 6.44 mmol/L, pH=3.5 and reaction time=30 min. The residual COD of both effluents from coagulation and Fenton were less than 100 mg/L, which meet the correlative discharge standard (GB 16889-2008). Compared with Fenton process, coagulation showed a better performance for using less precipitant and producing less sludge. The cost of leachate treatment was lower and environmental benefit was obvious in coagulation process.Fenton process was good at removing organics of small molecules, thus the residual organics in the effluent of Fenton were of large molecular weight. In the coagulation process, complex organic matters of large molecular weight were removed, because mechanism of coagulation was adsorption and interception. The removal rates of different fractions during coagulation process in decreasing order was as following: HPO-N (83.47%), TPI-A (78.55%), HPO-A (72.22%), TPI-N (60.89%), HPI (0.49%); so was Fenton process: HPO-N (84.78%), TPI-A (73.99%), TPI-N (67.57%), HPO-A (60.43%), HPI (17.10%).The peaks in the fluorescence EEMs of HPO-A were the highest ones, which showed that there were more fluorescing materials in HPO-A, while SUVA of HPO-A was also higher than other fractions, which meant that its internal components containing more aromatic substances. HPI, mainly composed of hydrophilic material which is not in the range of humus, was properly derived from carbohydrate and amino acids and contained mainly of aliphatic hydrocarbons. There were more aromatic proteins in HPO-N and TPI-N, and these organic matters were with large molecular weight.The IR spectrum effectively indicated that carboxylic acids existed as a major functional group in the influent HPO-A and TPI-A. The FT-IR spectra of the HPO-N and TPI-N were very similar, with greater hydrocarbon character and less carboxylic acid character than other fractions. Moreover, both contained a significant amide-1 or amide-2 peaks. HPO-N and TPI-N were enriched in hydrocarbon and amide-1 or amide-2 functional groups, indicating bacteria-derived glycoprotein material.

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