城市不同水体表观特征污染物及污染类型识别

选择苏州市区河网为研究对象,经过为期近3年的广域布点采样,选取DO,温度,p H,CODMn,S2-,浊度,Chl-a,UV254等作为水质监测指标,通过对各指标累计频率分布及其变化趋势的统计分析,识别出不同污染水体的主要表观特征污染物,并依此对水体污染类型进行了划分界定。结果表明:监测指标UV254值、浊度与ρ(CODMn)的比值、ρ(S2-)和ρ(Chl-a)对不同污染水体有很好的区分度,可作为表观特征污染物指标;将污染水体分为4种类型:有机主导型、无机主导型、营养主导型和混合型,前3种类型的主要筛选条件分别为UV254值·ρ(S2-)·1 000大于10 cm-1·(mg/L)、浊度与ρ(CODMn)的比值大于15 NTU/(mg/L)和ρ(Chl-a)20μg/L;利用该条件对6条定点监测河流污染类型进行初步划分。     

北运河生态健康快速评价研究

为进一步探究现阶段北运河健康现状,采用北运河河流快速评价方法和SPSS多元统计方法中相关性分析,对北运河山区和平原段河流健康进行评价,结果表明:河流快速评价方法可操作性强、便捷高效,在本研究中基本能够简洁、准确地反映北运河健康状况,适合专业、非专业人员对城市河流生态健康评价的早期快速判断,具有一定的推广应用价值;SPSS相关性统计结果显示北运河健康指数(RHI)与河流快速评价体系中一级指标生物、物理化学、水文地貌指标显著相关(P0.01),与二级指标中植被、河道、物理、化学指标显著相关(P0.01),表明该快速评价指标体系能很好地识别北运河表征河流健康的影响因子;北运河属于亚健康河流,表现出山区河流生态等级较高、平原河流生态等级较低的特征,山区河流后期生态修复指标应以水量、水质及生物多样性等为主,平原河流生态修复指标多考虑水生指示性物种、水质、植被及景观。该研究可为流域河道管理部门提供参考。     

西江下游流域水质与不同空间尺度土地利用的响应关系

基于西江下游流域2005—2017年11个监测断面水质数据和2005年、2010年、2018年遥感影像数据,通过不同空间尺度和土地利用类型的划分,利用Spearman秩相关系数法、冗余分析等方法分析了不同空间尺度下土地利用结构对西江下游流域水质的影响。结果表明:2005—2017年西江干流、贺江及罗定江水质较为优良,新兴江、南山河水质恶化明显,西江干流汛期总磷浓度明显高于非汛期;流域尺度下,河流水质指标与城镇用地呈显著正相关关系,与水体呈显著负相关关系;河岸缓冲区尺度下,河流水质指标与林地、水体呈负相关关系,城镇用地对河流中COD解释度较高,800 m缓冲区城镇用地对氨氮和总磷解释度最高,河流水质指标与旱地相关性在缓冲区达到 1 500 m后显著上升,800 m缓冲区内水田坑塘对河流水质指标影响较大。建议对西江下游流域河岸800 m宽度范围内城镇用地、水田坑塘以及1 500 m缓冲区外旱地加强污染管控。     

苏子河流域景观格局指数对流域水质的影响

文章基于苏子河流域的ALOS影像数据和景观指数统计结果,对景观指数与苏子河水质之间进行了相关性分析,结果显示景观格局指数与苏子河水质的主要指标间存在不同程度的相关性,能够在一定程度上反映景观格局对苏子河水质的影响。     

筑坝河流不同尺度土地利用结构对库区水质的影响——以平寨水库为例

为了分析筑坝河流域人类活动与库区水质的响应关系,以平寨水库为例,选取子流域、河流缓冲区及监测点圆形缓冲区三种尺度,基于2017年Landsat8 OLI遥感影像解译结果所反映的土地利用结构特征,结合实测监测点水质指标数据,运用GIS空间分析及统计分析的方法,探讨筑坝河流流域土地利用结构对库区水质的影响。结果表明:(1)在三种尺度上,土地利用结构与库区水质都有显著相关性,河流缓冲区和子流域尺度相关规律基本一致,但与圆形缓冲区尺度相关规律差异较大;(2)不同土地利用类型面积比例对水质的影响存在尺度效应,不同尺度上表现出不同的"源"与"汇";(3)土地利用相对合理指数R与水质指标呈显著负相关,说明土地利用结构越合理,越有利于减少土壤侵蚀,水体中污染物浓度就越低。     

强化混凝超滤组合工艺对有机污染物去除效能的研究

为了进一步提高水质处理效果,采用强化混凝超滤的组合工艺对湖水进行处理,考察该组合工艺对有机物的去除效能,及影响有机物去除效能的因素。试验结果表明:①强化混凝超滤组合工艺对原水浊度的去除效果较好,对TOC和UV254的去除效果也明显优于传统水处理工艺;②原水中UV254含量的波动,对UV254的去除率和滤后水UV254含量影响并不大。原水中TOC含量的波动,对TOC的去除率有很大的影响,对滤后水TOC含量的影响并不大。TOC的去除率普遍高于UV254的去除率;③根据原水和滤后水SUVA值的变化发现,强化混凝超滤组合工艺对亲水性有机物的去除率大于该工艺对疏水性有机物的去除率。在一定范围内,pH的变化对TOC和UV254去除率变化趋势相反。     

活性炭吸附性能新指标在实际水处理工艺中的应用

以单宁酸和腐殖酸吸附值作为活性炭吸附性能新指标进行生产性试验的验证,在建立生物活性炭吸附作用模型的基础上,对工艺运行60 d内活性炭的有机物吸附值(UV254和CODMn)进行了曲线拟合,结果较好地符合吸附模型,相关系数R2为0.606 4~0.786 1。对工艺中选取的5种活性炭进行有机物吸附试验,将吸附容量与传统选炭指标碘吸附值和亚甲基蓝吸附值,以及新指标单宁酸和腐殖酸吸附值进行相关性分析。结果表明传统指标与5种活性炭生产试验中的吸附容量之间不存在明显的相关性,而新指标与5种活性炭的吸附容量之间有较好的相关性:以UV254的变化值表示活性炭的吸附容量时,单宁酸及腐殖酸吸附值与其的相关系数R2分别为0.705 4和0.816 9;以CODMn的变化值表示活性炭的吸附容量时,单宁酸及腐殖酸吸附值与其的相关系数R2分别为0.632 5和0.701 3。     

粉末活性炭应急处理原水静态模拟试验研究

采用静态模拟试验,研究了粉末活性炭应急投加技术中存在的碳种优选、最佳投加量和投加点确定等问题。结果表明,投加粉末活性炭作为头部原水水质变化的应急处理手段是完全可行的,能够保证给水厂的供水安全;PICA煤质碳为粉末活性炭应急处理原水的最佳碳种;结合UV254、CODMn和色度三项指标以及给水厂的实际情况得出,吸水井处为粉末活性炭应急投加的最佳点;在水质急剧变化时,粉末活性炭投量为20～30mg/L是适宜的,其中UV254的去除率净增加20%左右,CODMn的去除率净提高10%左右;当水质极端变差时可考虑将粉末活性炭的投加量增加至50mg/L。     

污染河流水质净化与生态修复技术及其集成化策略

如何选用和集成适宜的技术实施污染河流的水质净化与生态修复,以及如何评价其工程措施的效果,是污染河流治理实践中面临的难题。分析了我国河流水质污染及生态破坏的现状、特点及其成因,总结了污染河流水质净化与生态修复技术的国内外研究进展。并对各种技术的特点及其对不同类型河流的适用性进行了剖析。探讨了污染河流水质净化与生态修复技术的选择原则与集成化策略,在分析我国北方河流的物理结构与生态特点的基础上,提出了以生物/生态技术为核心的污染河流水质净化与生态修复综合技术方案。还就污染河流水质净化与生态修复工程效果的评价方法和健康河流评价指标进行了探讨。     

长江常熟段水溶解性有机物分子质量分布特性

采用超滤膜法对水溶解性有机物进行物理分级,研究长江常熟段水源水中不同分子质量区间DOC和UV254分布的变化特征及其原因。结果表明,长江常熟段水源水总体水质较好,高锰酸盐指数、氨氮、总磷等指标均未超过地表Ⅲ类水体水质标准,符合饮用水源地卫生要求。2008年11月至2009年9月期间,水源水中分子质量小于1kDa的DOC所占比例平均为64.3%,分子质量小于1kDa的UV254所占比例平均为45.2%,表明长江水源水中水溶解性有机物主要以小分子质量的有机物为主,汛期水源水中分子质量在3～10 kDa区间的DOC和UV254比例较枯水期有显著提高。     

Characterizing natural dissolved organic matter in a freshly submerged catchment (Three Gorges Dam, China) using UV absorption, fluorescence spectroscopy and PARAFAC

This study applied parallel factor analysis (PARAFAC) to fluorescence excitation-emission matrices (EEMs) of natural water samples in a freshly submerged catchment in the upper reach of Three Gorges Dam (China). Two fluorescent natural dissolved organic matter (NDOM) components (humic/fulvic-like) were uncovered and were positively correlated with selected water quality parameters, i.e. dissolved oxygen concentration, dissolved organic carbon concentration, dissolved Kjeldahl nitrogen concentration and total (dissolved plus particulate) phosphorus concentration, respectively. To other water quality parameters (i.e. total nitrogen, particulate nitrogen, particulate phosphorus, dissolved phosphorus, dissolved nitrate, pH, and chemical oxygen demand), either the two components did not show any correlation or only one component showed correlation. In particular, particulate N correlated significantly to the fulvic acid, but not to the humic acid. Meanwhile, two conventional spectroscopic indices i.e. specific UV absorbance at 254 nm (SUVA254) and fluorescence index (FI) indicated that the whole NDOM in the waters were low in aromaticity and predominantly derived from aquatic microbial processes. Given together, it concludes that N and P did not function equally in the NDOM production, and the two components were not derived from the same microbial processes. The EEMs-PARAFAC has proven to be of potential as an effective tool in investigation of the interlink between NDOM and nutrients which may be utilized as an indicator of water environment.     

Activation of solgel titanium nanofilm by UV illumination for NOM removal.

The control of natural organic matter (NOM) in drinking water treatment plants is required in order to control (i) the formation of potentially harmful disinfection byproducts (DBPs), (ii) the regrowth of bacteria and (iii) pipe corrosion in the distribution system. Photocatalysis is a promising advanced oxidation technology due to its ability to mineralise chlorinated byproduct precursors such as humic acids (HAs) to carbon dioxide and water. In this study, the efficiency of HAs and NOM removal in terms of UV absorbance at 254 nm (UV254) was tested by means of a new photocatalytic reactor made of stacked polymethylmethacrylate (PMMA) rings coated by TiO2 nanofilm. Three different sets of rings were coated with TiO2 gel one, two and three times respectively to optimise the coating thickness according to UV254 removal efficiency. The titania sol was immobilised on the substrate by a low temperature procedure and after 8 months the reactors were reactivated by means of UV radiation before the experiments. The photocatalytic removal efficiency of humic acid in terms of UV254 was significantly higher after 1 hour for the reactor employed with high thickness TiO2 nanofilm (around 20%) compared to middle and low thickness reactors (6 and 1.4%, respectively). However, during the same reaction time only 10% of UV254 was removed with high thickness TiO2 nanofilm using raw surface water, probably owing to ionic species naturally occurring in the raw water sample. Finally, the activation of the TiO2 nanofilm may be effectively accomplished by means of UV radiation where calcination cannot be applied (e.g. thermally sensitive substrates).     

Implementing Treatment Sequences to Promote Reduction of DBPs in Small Drinking Water Systems

The performance of three drinking water treatment sequences found in small community systems in reducing disinfection by-product precursor concentrations and the corresponding disinfection by-product formation potential was evaluated. Raw water quality and its potential for effective removal were characterized by the specific ultraviolet absorbance (SUVA) components of absorbance of ultraviolet light at 254 nm wavelength (UV254) and dissolved organic carbon (DOC). The results demonstrate that, for the source water qualities tested (hydrophobic SUVA with moderate DOC content, 2.0 to 4.8 L/(mg.m) and 4.1 to 6.3 mg DOC/L), there was a tendency to produce a higher percentage of total trihalomethane (TTHM) over the five regulated species of haloacetic acid (HAA5). The treatment sequence and chemical selection play a critical role in the ability of a small community system operator to achieve compliance with the concentration of regulated disinfection by-products. For the waters tested ferric chloride coagulants perform better at reducing the higher molecular weight, hydrophobic organic precursors. Powdered activated carbon does not perform as well with these source waters unless its application is followed by a clarification process that effectively forms a sludge blanket. This research provides additional criteria for linking source water quality with treatment sequence for sustainable management of disinfection by-product (DBP) compliance.     

AOPs with ozone and UV radiation in drinking water: contaminants removal and effects on disinfection byproducts formation.

In this study, the advanced oxidation with ozone and UV radiation (with two low pressure UV lamps, at 254 and 185 nm wavelength) were experimented on a surface water in order to study the removal of two odorous compounds (geosmin and 2-methylisoborneol) and a pesticide (metolachlor), the influence on organic compounds (UV absorbance and THM precursors) and bromate formation. Different batch tests were performed with ozone concentration up to 10 mg/L, UV dose up to 14,000 J/m2 and a maximum contact time of 10 minutes. The main results show that metolachlor can be efficiently removed with ozone alone while for geosmin and MIB a complete removal can be obtained with the advanced oxidation of ozone (with concentration of 1.5-3 mg/L and contact time of 2-3 minutes) with UV radiation (with doses of 5,000-6,000 J/m2). As concerns the influence on the organic precursors, all the experimented processes show a medium removal of about 20-40% for UV absorbance and 15-30% for THMFP (trihalomethanes formation potential). As concerns bromate formation, the advanced oxidation of ozone/UV 254 nm shows a bromate formation that is about 40% lower with respect to conventional oxidation with ozone.     

Toxicity screening and evaluating in chlorination disinfection of wastewater reclamation processes.

Reclamation and re-use of wastewater is one of the most effective ways to alleviate the shortage of water resources, while the safety of reclaimed water becomes one of the critical problems for protecting human health and the ecosystem. While a toxicity test can vividly reflect biological effects of chemicals as a whole, in this study, the Microtox test was used to screen toxicity changes of wastewater during conventional reclamation processes. The results showed that toxicities of water samples decreased continuously along reclamation processes except chlorination/dechlorination in which the toxicity increased significantly. Furthermore, as for different forms of residual chlorine, toxicity of wastewater was quite different with increasing chlorine dosage. NH3-N had a trend to decrease toxicity of disinfected wastewater, while UV254 had a trend to increase toxicity. It was found that there was a good linear relationship between toxicity formation and UV254/NH3-N ratio for wastewater after disinfection with combined chlorine form before peak-point.     

Comparison of AOPs for the removal of natural organic matter: performance and economic assessment.

Control of disinfection by-products during water treatment is primarily achieved by reducing the levels of organic precursor species prior to chlorination. Many waters contain natural organic matter at levels up to 15 mg L(-1); therefore it is necessary to have a range of control methods to support conventional coagulation. Advanced oxidation processes are such processes and in this paper the Fenton and photo-Fenton processes along with photocatalysis are assessed for their NOM removal potential. The performance of each process is shown to be dependent on pH and chemical dose as well as the initial NOM concentration. Under optimum conditions the processes achieved greater than 90% removal of DOC and UV254 absorbance. This removal led to the THMFP of the source water being reduced from 140 to below 10 microg L(-1), well below UK and US standards. An economic assessment of the processes revealed that currently such processes are not economic. With advances in technology and tightening of water quality standards these processes should become economically feasible options.     

活性炭+陶粒复合滤料的再生水深度处理试验研究

针对济南某水厂出水,采用混凝沉淀+臭氧+复合滤料生物滤池组合工艺,对城市再生水进行深度处理。在臭氧消耗量和反应时间分别为5 mg/L和10 min,空床停留时间(EBCT)为15 min的条件下,臭氧/复合填料生物滤池对浊度、CODMn、UV254、NH3-N、NO2--N的平均去除率分别为75.1%、48%、54.6%、83.1%、76.6%,出水水质分别降为:0.56NTU、3.1 mg/L、0.052 cm-1、0.37 mg/L、0.04 mg/L。     

图们江布尔哈通河干流有机污染指标时空变化研究

根据布尔哈通河干流2000-2009年水质监测资料.研究其10年来的有机污染指标(CODMn)的时空变化情况及趋势,结果表明:2009年的有机污染物明显少于2006年,表明水污染治理工作取得了较大成绩,但是丰水期和枯水期水质差异明显,枯水期水质劣于丰水期;自2004年以来水质呈逐年变好趋势;布尔哈通河干流水质有所改善,...