【作者】 薛爽；

【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， 2008， 博士

【摘要】 将城市污水处理厂二级处理出水用于人工地下水回灌逐渐成为补充地下含水层和储存水资源的有效途径,土壤含水层处理(SAT)是地下回灌流程中一个重要组成部分。在SAT系统中,溶解性有机物(DOM)一直备受关注。本研究采用XAD树脂分离技术将DOM分级成疏水性有机酸(HPO-A),疏水性中性有机物(HPO-N),过渡亲水性有机酸(TPI-A),过渡亲水性中性有机物(TPI-N)和亲水性有机物(HPI)等5种组分,并通过氯化实验、红外光谱、紫外光谱、核磁共振波谱、元素分析等多种实验手段考察了城市污水处理厂二级处理出水中的DOM各组分的分布特征和化学特性,并考察了DOM在SAT系统中的去除和变化,以及回灌对土壤有机物的影响。利用XAD树脂对二级处理出水中的DOM进行分级分离,并对各DOM组分进行特性表征。结果表明,HPO-A和HPI是二级处理出水的主要有机组分,HPO-A是加氯消毒时产生三卤甲烷(THMs)的主要前体物质。每种DOM组分的单种THM生成量随溴离子浓度增加的变化趋势相同:CHCl3单调递减;CHCl2Br和CHBr2Cl先升后降;CHBr3单调递增。氯化反应导致HPO-A, HPO-N, TPI-A和TPI-N在250–280 nm范围内的紫外吸收的降低。氯化反应导致HPO-A、HPO-N、TPI-A和TPI-N中O—H、C=C和苯环含量的降低,C—O含量的升高,以及C=O和C—Cl的生成。氯化反应中溴离子的存在导致这4种DOM组分中出现C—Br。通过土壤柱模拟实验考察了DOM在SAT系统中的去除及其卤代活性的变化。结果表明,SAT系统对HPO-A、HPO-N、TPI-A、TPI-N和HPI的三卤甲烷生成势(THMFP)的去除率分别为27.24%, 34.43%, 26.24%, 35.85%和36.08%。DOM各组分的三卤甲烷生成活性(STHMFP)在SAT系统中均升高。对于HPO-A、HPO-N和HPI来说,THMFP与UV-254的相关性较强,而对于TPI-A和TPI-N来说,THMFP与UV-254的相关性较弱。通过可生物降解溶解性有机碳(BDOC)反应柱实验,以及进水分别为未添加NaN3和添加了NaN3的二级处理出水的2个土壤柱系统的模拟实验,研究了好氧生物降解作用、SAT系统、以及SAT系统中非好氧生物降解和吸附的联合作用对DOM的去除效果。结果表明,好氧生物降解作用、SAT系统和SAT系统中非好氧生物降解和吸附的联合作用对总DOC的去除率分别约为57.3%、70%和27.5%。中性DOM组分(HPO-N和TPI-N)比酸性DOM组分(HPO-A和TPI-A)更容易被好氧生物降解作用所去除,而酸性DOM组分比中性DOM组分更容易被SAT系统中非好氧生物降解和吸附的联合作用所去除。好氧微生物显著降解酸性DOM组分中的C=O官能团而SAT系统中非好氧生物降解和吸附的联合作用显著降解中性DOM组分中的C=O官能团;好氧微生物降解酸性DOM组分中的C―O官能团,而SAT系统中非好氧生物降解和吸附的联合作用则导致C―O官能团在HPO-A,HPO-N,TPI-A和TPI-N中的相对含量的升高;好氧微生物显著降解酰胺类有机物,而SAT系统中非好氧生物降解和吸附的联合作用则导致酰胺类有机物的生成。通过比较进水分别为未进行和已经过活性炭吸附处理后的二级处理出水的2个土壤柱系统对DOM的去除效果,研究了进水预处理程度对SAT系统性能的影响。结果表明,当SAT系统进水中DOM的浓度降低时,SAT系统出水中DOM的浓度也降低,并且SAT系统对DOM的去除率下降。通过比较回灌前的土壤,以及回灌后不同深度土壤中水可提取DOM的含量和官能团特征考察了回灌对土壤中水可提取DOM的影响。结果表明,回灌导致了表层土(0-12.5 cm)中水可提取DOM含量的升高,以及深度在12.5 cm以下的土壤中水可提取DOM含量的降低。回灌导致土壤中HPO-A和TPI-A的含量的下降,以及HPO-N、TPI-N和HPI的含量的升高。回灌对顶部和底部土壤中水可提取DOM组分的官能团的影响不同。更多还原

【Abstract】 Groundwater recharge with municipal wastewater is an increasingly valued practice for replenishing aquifers used for domestic supply. Soil-aquifer treatment (SAT) is the import component of groundwater recharge engineers. Dissolved organic matter (DOM) is of concern during SAT. DOM was fractionated using XAD resins into five fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). The distribution and chemical characters of these DOM fractions in secondary effluents from the wastewater treatment plant were examined by many experimental analysis ways such as chlorination experiments, infrared spectroscopy, ultraviolet (UV) spectroscopy, nuclear magnetic resonance spectroscopy and elemental analysis. Moreover, the removal and transformation of DOM during SAT, as well as the effect of the recharge on the soil DOM, were investigated.DOM in secondary effluents was fractionated and isolated using XAD resins, and each DOM fraction was characterized. The results showed that HPO-A and HPI dominated in the secondary effluent. HPO-A was the main precursors for trihalomethanes (THMs) following chlorination. The patterns of individual THM species with increased bromide concentrations were similar for all DOM fractions, which were as follows: CHCl3 decreased exponentially; CHCl2Br and CHBr2Cl increased initially and then decreased; CHBr3 increased continuously. Chlorination resulted in decreased UV absorbance across wavelengths from 250 to 280 nm for HPO-A, HPO-N, TPI-A and TPI-N. Chlorination resulted in the decreasing content of C—H, C=C and aromatic rings, the increasing content of C—O, and the production of C=O and C—Cl in HPO-A, HPO-N, TPI-A and TPI-N. The presence of bromide in chlorination led to the occurrence of C—Br for these four fractions.The removals and changes in the chlorine reactivity of DOM during SAT were investigated by soil-column simulation experiments. The results showed that the reduction of THMFP from HPO-A, HPO-N, TPI-A, TPI-N and HPI during SAT was 27.24%, 34.43%, 26.24%, 35.85% and 36.08%, respectively. Specific THMFP (STHMFP) for each DOM fraction increased across the soil columns. THMFP was strongly correlated to UV-254 for HPO-A, HPO-N and HPI, while the relationship between THMFP and UV-254 for TPI-A and TPI-N was significantly poor.The removals of DOM by the aerobic biodegradation, SAT system and a combination of sorption and anaerobic biodegradation during SAT were examined by the BDOC reaction column tests, as well as the simulation experiments using two soil-column systems, whose influents were the secondary effluent without and with NaN3 addition, respectively. The results showed that the removals of bulk DOC by the aerobic biodegradation, the SAT system and the combination of sorption and anaerobic biodegradation during SAT were 57.3 %, 70% and 27.5%, respectively. Neutral DOM fractions (HPO-N and TPI-N) were more readily removed than acid DOM fractions (HPO-A and TPI-A) by aerobic biodegradation, while acid DOM fractions were more readily removed than neutral DOM fractions by the combination of sorption and anaerobic biodegradation during SAT. The C=O functional groups in acid DOM fractions were significantly reduced by the aerobic biodegradation, whereas those in neutral DOM fractions were significantly reduced during SAT. The C―O functional groups in acid fractions were reduced by aerobic biodegradation while the combination of sorption and anaerobic biodegradation during SAT resulted in the increased relative content of C―O functional groups in HPO-A, HPO-N, TPI-A and TPI-N. The aerobic biodegradation significantly reduced amides, while the combination of sorption and anaerobic biodegradation during SAT resulted in the production of amides.The effect of influent pre-treatment on the performance of SAT systems was investigated by a comparison between the removals of DOM by two soil-column systems, whose influents were the secondary effluents without and with activated carbon adsorption treatments, respectively. The results showed that the effluent DOM concentrations as well as the DOM removals for the SAT system would decrease when the influent DOM concentrations decrased.The effect of recharge on water extractable DOM in soils was examined, by comparing the content and functional properties of water extractable DOM in soils after recharge at the different depths with those in the soils before recharge. The results showed that the recharge resulted in the increased content of water extractable DOM in the top soils (0-12.5 cm), as well as the decreased content of water extractable DOM in the soils below 12.5 cm. The recharge resulted in the decreased content of HPO-A and TPI-A as well as the increased content of HPO-N, TPI-N and HPI. The effects of recharge on functional groups of water extractable DOM fractions in the top and bottom soils were not similar.更多还原