An investigation into reservoir NOM reduction by UV photolysis and advanced oxidation processes

A comparison of four treatment technologies for reduction of natural organic matter (NOM) in a reservoir water was made. The work presented here is a laboratory based evaluation of NOM treatment by UV-C photolysis, UV/H(2)O(2), Fenton's reagent (FR) and photo-Fenton's reagent (PFR). The work investigated ways of reducing the organic load on water treatment works (WTWs) with a view to treating 'in-reservoir' or 'in-pipe' before the water reaches the WTW. The efficiency of each process in terms of NOM removal was determined by measuring UV absorbance at 254 nm (UV(254)) and dissolved organic carbon (DOC). In terms of DOC reduction PFR was the most effective (88% removal after 1 min) however there were interferences when measuring UV(254) which was reduced to a lesser extent (31% after 1 min). In the literature, pH 3 is reported to be the optimal pH for oxidation with FR but here the reduction of UV(254) and DOC was found to be insensitive to pH in the range 3-7. The treatment that was identified as the most effective in terms of NOM reduction and cost effectiveness was PFR.     

Minimization of the formation of disinfection by-products

The drinking water industry is required to minimize DBPs levels while ensuring adequate disinfection. In this study, efficient and appropriate treatment scheme for the reduction of disinfection by-product (DBPs) formation in drinking water containing natural organic matter has been established. This was carried out by the investigation of different treatment schemes consisting of enhanced coagulation, sedimentation, disinfection by using chlorine dioxide/ozone, filtration by sand filter, or granular activated carbon (GAC). Bench scale treatment schemes were applied on actual samples from different selected sites to identify the best conditions for the treatment of water. Samples were collected from effluent of each step in the treatment train in order to analyze pH, UV absorbance at 254 nm (UVA₂₅₄), specific UV absorbance at 254 nm (SUVA₂₅₄), dissolved organic carbon (DOC), haloacetic acids (HAAs) and trihalomethanes (THMs). The obtained results indicated that using pre-ozonation/enhanced coagulation/activated carbon filtration treatment train appears to be the most effective method for reducing DBPs precursors in drinking water treatment.     

用Nano-TiO2/O3和Nano-TiO2/UV/O3去除腐殖酸并控制臭氧副产物的生成

采用Nano-TiO2/O3和Nano-TiO2/UV/O3进行小试实验。通过对DOC、UV254、BrO3-和甲醛进行检测分析,研究了不同体系去除腐殖酸（HA）并控制臭氧副产物生成的效果。结果表明,当HA浓度为10 mg·L-1时,Nano-TiO2/O3体系对DOC的去除主要在反应进行20 min内完成,去除率仅达12.0%左右,对UV254的去除主要发生在2 min内,去除率仅达14.5%左右;而Nano-TiO2/UV/O3体系DOC和UV254的去除率分别达32.8%和53.3%。HA的存在显著减少了Nano-TiO2/O3体系BrO3-的生成量,出水BrO3-浓度为29.00 μg·L-1,而Nano-TiO2/UV/O3体系出水BrO3-浓度为5.00 μg·L-1。研究表明,相比Nano-TiO2/O3体系,Nano-TiO2/UV/O3体系能更好地控制BrO3-生成,同时能提高对HA的去除效果,且无甲醛生成的风险。     

基于微滤技术供水厂的臭氧预氧化前置工艺中臭氧投加量的优化

通过臭氧预氧化降解水体中溶解性有机物(DOM)对DOM的氧化效果以及微滤(MF)膜污染的缓和效应进行了研究,并分析了臭氧氧化过程中光谱参数变化的规律,进而提出一种通过多目标优化模型确定最佳臭氧投加量的方法。结果表明,臭氧预氧化技术能够将中等分子质量的芳香类DOM转化为低分子质量的有机化合物,对应的UV₂₅₄去除率最高可达90.34%,从而显著改变了MF进水的光谱特性。此外,臭氧预氧化还显著缓解了DOM造成的膜污染,膜污染指数(FI)最多可降低51.49%。根据上述结果可建立多目标优化模型,并用于确定臭氧预氧化-膜过滤工艺最佳臭氧投加量。根据层次分析法,对SUVA₂₅₄、FI和臭氧利用率3个客观指标分配不同的权重,以满足不同饮用水厂的需求。此外,模型分析中可用光谱斜率作为SUVA₂₅₄的替代参数,特别是S_275~295 (R²=0.979 7),用UV₂₅₄作为FI的替代参数(R²=0.879 9),进而简化模型系数的获取。以上研究结果可为水厂在实际应用中优化臭氧投加量、综合提高水处理效果、缓解膜污染并降低运行成本提供参考。     

Applicability of MIEX®DOC process for organics removal from NOM laden water

The aim of this study was to evaluate applicability of ion exchange process for organics removal from Douro River surface water at the intake of Lever water treatment plant using magnetized ion exchange resin MIEX®. Qualitative analysis of the natural organic matter present in the surface water and prediction of its amenability to removal in conventional coagulation process were assessed. Results obtained in MIEX®DOC process kinetic batch experiments allowed determination of ion exchange efficiency in dissolved organic carbon (DOC), UV absorbing organics, and true color removal. The data were compared with the efficiencies of the conventional unit processes for organics removal at Lever WTP. MIEX®DOC process revealed to be more efficient in DOC removal than conventional treatment achieving the efficiencies in the range of 61–91 %, lowering disinfection by-products formation potential of the water. DOC removal efficiency at Lever WTP depends largely on the raw water quality and ranges from 28 % for water of moderated quality to 89 % of significantly deteriorated quality. In this work, MIEX®DOC process was also used as a reference method for the determination of contribution of anionic fraction to dissolved organic matter and selectivity of the unit processes at Lever WTP for its removal.     

不同工艺对含高浓度腐殖酸地下水处理的可行性

针对内蒙古农村地区高腐殖酸地下水的处理问题,分别对（pH调节）-PAC强化混凝、高锰酸钾预氧化／混凝、活性炭吸附／混凝、Fenton氧化等技术处理的可行性进行了研究,同时利用三维荧光和高效体积排阻色谱分析处理前后水中有机物的组成变化特征。有机分析结果显示,水中的有机物为腐殖酸类物质,分子量分别为1600和3500,腐殖酸类物质为水中色度的主要贡献者。原水PAC强化混凝、高锰酸钾预氧化／PAC混凝对有机物的去除效果不佳,处理前后水样DOC浓度无明显变化,而pH调节．PAC强化混凝、微米活性炭吸附和Fenton氧化均能有效去除有机物。将原水pH调节至6．5,经300mg／LPAC混凝后出水DOC降至5．99mg／L。活性炭投加量为0．6g／L时,DOC降至7．6mg／L,然后采用60mg／LPAC混凝出去高度分散而不易沉降的小颗粒活性炭。此外,当反应初始pH值为3,过氧化氢投加量为0．5％（v／v）,亚铁和双氧水摩尔比为0．05时,出水DOC降至5．6mg／L,氧化后有小分子有机物生成。     

混凝-超滤工艺处理饮用水厂滤池反冲洗水和排泥水的效能

为探究饮用水厂滤池反冲洗水和排泥水的直接回用和处理后回用对水厂的影响及两类水处理过程中的差异,采用了污染负荷计算、实验室混凝小试和现场混凝-超滤中试装置对两类生产废水分别进行了研究。溶解性有机碳(dissolved organic carbon,DOC)、氨氮 (NH₄⁺-N)、Al³⁺和全氟类化合物(perfluorinated compounds,PFASs)的污染负荷计算结果表明生产废水直接回用会为水厂带来一定的额外负荷,其中排泥水和反冲洗水分别对PFASs和Al³⁺负荷贡献较大;通过对小试中浊度,UV₂₅₄以及5种荧光组分去除效果的对比,反冲洗水的混凝效果稍好于排泥水,同时10 mg·L⁻¹的聚合氯化铝为最佳混凝剂方案;在中试过程中,两类水中的浊度、有机物、Al³⁺和PFASs均可被有效去除,出水差异较小,但反冲洗水中的亲水性和小分子有机物使得其去除效果低于排泥水。总体来说,经过处理之后,两类生产废水均可回用,回用可有效减少废水排放量,提高水厂水资源利用率。     

Decolorizing of lignin wastewater using the photochemical UV/TiO2 process

Studies on applying the photochemical UV/TiO2 oxidation process to treat the lignin-containing wastewater for dissolved organic carbon (DOC), color and reducing A254 (the absorption at the wavelength of 254 nm) have been carried out. The data obtained in this study demonstrate that the UV/TiO2 process is effective in oxidizing the lignin thus reducing the color and DOC of the wastewater treated. The combined UV/TiO2 treatment can achieve better removal of DOC and color than the UV treatment alone. Color removal, based on American Dye Manufacture Index (ADMI) measurement, is greater than 99% if the pH is maintained at 3.0 with the addition of 1 g l(-1) TiO2. When 10 g l(-1) TiO2 is applied, the oxidation reduction potential (ORP) value is reached to result in an 88% removal of both DOC and color. A model was developed based on the variation of ORP during the photochemical reaction to simulate the decoloring process. The proposed model can be used to predict the color removal efficiency of the UV/TiO2 process.     

再生水臭氧氧化处理工艺对水质生物稳定性的影响

为了保障再生水水质生物稳定性,控制再生水在储存、输配和利用过程中微生物生长,对再生水臭氧氧化处理工艺水质生物稳定性进行了研究。研究发现,臭氧氧化对再生水厂二级出水的溶解性有机碳（DOC）去除效果有限,对UV254和荧光强度有较好的去除效果,但可导致水样AOC水平升高,水质生物稳定性降低。分析臭氧氧化后不同有机物组分的变化情况,发现臭氧氧化对分子量为0.5~20 kDa有机物有较好的去除效果,而分子量小于0.5 kDa有机物没有明显变化。     

土壤-纳滤系统处理再生水补充地下水的研究

为充分保障再生水回灌地下时的水质安全、提供高质量地下水资源,在土壤处理系统中嵌入纳滤技术强化对再生水的处理效果,并初步探讨土壤系统作为前处理对纳滤膜污染的控制机理.结果表明,未采用臭氧氧化预处理前,土壤处理对再生水DOC和UV254的平均去除率分别为22%和20%.臭氧氧化对UV254的平均去除率为51%,并将土壤对D...     

多相芬顿-活性炭工艺强化饮用水消毒效果

为了考察多相芬顿-活性炭工艺对饮用水中微生物消毒效果的影响,采用中试对活性炭工艺与多相芬顿-活性炭工艺进行了对比研究。该中试对水中溶解性有机物(DOC)、总细菌16S rRNA、三磷酸腺苷(ATP)及胞外多聚物(EPS)含量与性质进行了分析。结果表明,多相芬顿-活性炭工艺能够将出水DOC浓度控制在(0.90±0.11) mg·L-1,并使得EPS减少83.2%,降低EPS中蛋白质/多糖(PN/PS)比值,其凝聚性明显下降,在相同氯浓度投加情况下水中微生物16S rRNA基因拷贝数去除量提高了3.5个对数量级,ATP浓度降低为0.016 nmol·L-1。因此,多相芬顿-活性炭工艺明显提高了对有机物的去除能力,显著降低EPS中蛋白质的含量,使得微生物凝聚性变差,微生物更加容易被消毒剂灭活,该工艺强化了饮用水消毒效果。     

臭氧对再生水中指示病原微生物的灭活特性

以臭氧投加量(TOD)为臭氧消耗剂量评价指标,研究了北京市某实际再生水中臭氧对大肠杆菌及枯草芽孢的灭活特性,以及消毒过程中臭氧对溶解性有机碳(DOC)、色度、UV254、荧光强度的去除效果。在此基础之上,分析了色度与指示病原微生物灭活特性之间的相关性。结果表明,臭氧对大肠杆菌及枯草芽孢的灭活特性与余臭氧浓度有关。当水中无法检测到余臭氧时,随着TOD的增加,大肠杆菌灭活率增加的速率较慢,TOD增加 3 mg/L,灭活率增加了1.5 log。枯草芽孢则无显著灭活。当水中余臭氧浓度大于0时,大肠杆菌灭活率增加的速率快速提升,TOD增加 3 mg/L,灭活率增加了3 log。枯草芽孢灭活率也随TOD的增加而显著增加。消毒过程中,DOC无显著变化,而臭氧对色度、UV254、三维荧光强度的去除效果显著。当色度随TOD的增加而趋于稳定时,水中余臭氧浓度开始显著上升,预示着指示病原微生物开始进入高效灭活阶段。同时,进水色度越大,指示病原微生物进入高效灭活阶段所需的TOD越大。     

基于常规饮用水工艺羟基自由基处理高藻水

我国水体的富营养化日益严重,水源地出现季节性藻类爆发现象,严重威胁饮用水安全。以厦门市莲坂水厂各工艺段出水为研究对象,采用大气压强电离放电产生羟基自由基（·OH）,分别对水源水、混凝沉淀出水、砂滤出水进行处理,处理时间为4.5 s。当注入总氧化剂浓度为1.8 mg· L-1时,高藻浓度从25.3×104 cells · mL-1降到800 cells · mL-1;对混凝沉淀出水注入总氧化剂0.6 mg· L-1、砂滤出水注入0.2 mg· L-1时,藻细胞都未检出;·OH处理后CODMn、TOC及UV254均有明显降低,砂滤出水三卤甲烷小于8 μg·L-1;检测的各项指标均达到国家《生活饮用水卫生标准》（GB 5479-2006）。因此,·OH可快速有效安全地杀灭高藻,为我国高藻水源地饮用水卫生安全保障提供技术支撑。     

NOM characteristics and treatabilities of ozonation processes

The objectives of this study were intended to evaluate the effects of the characteristics of natural organic matter on the treatabilities of ozonation, coagulation, filtration, and granular activated carbon processes. The ultra-violet absorbance (UV254) was used as a surrogate parameter to assess each process in reducing the disinfection by-product formation potential (DBPFP). The results indicate that the DBPFP varies with the sources of water samples and treatment processes, but is closely related to the measurement of UV254/DOC. Coagulation/sedimentation can eliminate large molecular weight organic fractions. Both pre- and post-ozonation processes can reduce some of DBP precursors than the conventional treatment process, and are more reliable for reducing the overall DBPFP.     

土壤渗滤对有机微污染物去除性能研究

采用土壤柱试验研究了土壤渗滤对再生水中有机微污染物的去除性能。结果表明,土壤柱对再生水中的DOC、UV₂₅₄、总氮和总磷有较好的去除效果,并具有较高的抗冲击负荷的能力;土壤表层10 cm厚度对DOC的去除起主要作用;UV₂₅₄和AOX在土壤表层10 cm厚度降解效果不明显,随着深度增加去除率逐渐升高;液相色谱有机碳探测(LC-OCD)检测结果表明,土壤柱对溶解性有机物质的去除主要体现在对多糖物质的降解上,其次是有机酸类,对腐殖质也有一定的去除作用。     

Removal of NOM from drinking water: Fenton's and photo-Fenton's processes

The control of disinfection by-products during water treatment is primarily undertaken by reducing the levels of precursor species prior to chlorination. As many waters contain natural organic matter at levels of up to 15 mgl(-1) there is a need for a range of control methods to support conventional coagulation. Two such processes are the Fenton and photo-Fenton's processes and in this paper they are assessed for their potential to remove NOM from organic rich waters. The performance of both processes is shown to be depentent on pH, Fe: H2O2 ratio as well as Fe2+ dose. Under optimum conditions both processes achieved greater than 90% removal of DOC and UV254 absorbance. This removal lead to the trihalomethane formation potential of the water being reduced from 140 to below 10 microgl(-1), well below UK and US standards.     

Comparison of inclined plate sedimentation and dissolved air flotation for the minimisation of subsequent nitrogenous disinfection by-product formation

The formation of disinfection by-products (DBPs), including both nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products (C-DBPs), was investigated upon chlorination of water samples following two treatment processes: (i) coagulation-inclined plate sedimentation (IPS)-filtration and (ii) coagulation-dissolved air flotation (DAF)-filtration. The removal of algae, dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and UV₂₅₄ by coagulation-DAF-filtration was superior to coagulation-IPS-filtration. On average, 53%, 53% and 31% of DOC, DON and UV₂₅₄ were removed by coagulation-DAF-filtration process, which were higher than 47%, 31% and 27% of that by coagulation-IPS-filtration process. Additionally, coagulation-IPS-filtration performed less well at removing the low molecular weight organics than coagulation-DAF-filtration process. The concentrations of chloroform, dichloroacetamide (DCAcAm) and dichloroacetonitrile (DCAN) formed during chlorination after coagulation-DAF-filtration reached their maximum values of 13, 1.5 and 4.7 μg L⁻¹, respectively, and were lower than those after coagulation-IPS-filtration with the maximum detected levels of 17, 2.9 and 6.3 μg L⁻¹. However, the trichloronitromethane (TCNM) concentration after the two processes was similar, suggesting that DON may have less of a contribution to TCNM formation than DCAcAm and DCAN.     

义乌市分质供水系统水质变化分析

为探究义乌市分质供水系统中水质及有机物的变化特征,分季度调研了3个水厂沿程水质的变化,并采用光谱技术与高分辨率质谱分析了处理工艺对溶解性有机质的去除效果。水质调研结果表明,传统工艺(混凝沉淀-砂滤)对总磷和氨氮的去除率分别达到80%与50%以上,但对水体中的总氮与总溶解性有机碳的去除效果差。双膜法(超滤-反渗透)全面优于传统工艺,可以将营养盐和有机物的浓度降至极低的水平(去除率>90%)。三维荧光结合平行因子分析结果表明,混凝沉淀仅对地表水中陆源腐殖质组分有明显的去除,对类蛋白质组分的去除效果较差。高分辨率质谱的检测结果表明,混凝对木质素、单宁及稠环芳烃等物质有较好的去除效果。在混凝前增设曝气生物滤池并在混凝过程中添加粉末活性炭,能强化工艺对类蛋白质组分和腐殖质组分的去除效果。本研究结果可为水处理工艺优化提供理论依据。     

混凝剂中的铝形态对黄河水源水中出水余铝的影响

铝系混凝剂是应用最广泛的无机混凝剂,改善混凝剂中的铝形态可有效提高混凝效果,但其在净水过程中产生的余铝对人体健康及输水过程具有显著的影响。本文研究了氯化铝(AlCl₃)和高聚十三铝(Al₁₃) 2种混凝剂在处理黄河上游水源水时的混凝过程,结合出水中的溶解态及不同分子质量余铝含量、有机物紫外吸光度(UV₂₅₄)、pH、浊度、有机物种类及含量和絮体特性的变化趋势,探究混凝剂中的铝形态对混凝过程的影响。结果表明,在实验投加量范围内,当Al₁₃做混凝剂时,出水余铝质量浓度均低于0.2 mg·L⁻¹。Al₁₃具有较高的形态稳定性,在混凝过程中对出水pH影响较小。絮体粒度随混凝剂投加量的增加而增加,Al₁₃投加量达到0.08 mmol·L⁻¹时絮体粒度下降(强度因子由于静电排斥作用而下降)。在不同投加量下,使用AlCl₃做混凝剂时出水余铝均高于Al₁₃体系,且在不同投加量下AlCl₃体系出水余铝中小于1 000 Da的余铝占比最大。Al₁₃对富里酸和腐殖酸的去除效果优于AlCl₃,且AlCl₃在较高投加量下才能实现水中有机物的有效去除。     

硫酸亚铁协同过硫酸氢钾去除铜绿微囊藻

避免消毒副产物(DBPs)形成和胞内有机物(IOMs)的释放,是解决传统工艺治理蓝藻水华潜在风险的关键。为此,开展了FeSO₄协同过硫酸氢钾(PMS)高级氧化除藻研究,分别探讨了FeSO₄投加量、pH及无机离子对铜绿微囊藻细胞去除效果的影响。结果表明：当FeSO₄和PMS投加量均为0.1 mmol·L⁻¹时,藻细胞、DOC和UV₂₅₄的去除率分别为94.66%、58.92%和41.52%,藻细胞去除的氧化、絮凝的贡献率分别为30.50%和69.50%;当pH为6.0~10.0时,藻细胞去除率均保持较高水平,其中弱酸环境有利于提高藻细胞的去除;外加的HPO₄²⁻和${{\rm{NO}}_3^{-}} $对${{\rm{SO}}_4^{-}\cdot }$的竞争抑制,可导致藻细胞去除率降低;FeSO₄-PMS可以有效去除含有荧光特性的藻源性有机质(AOMs);当FeSO₄投加量低于0.1 mmol·L⁻¹时,藻细胞、叶绿素a去除率随着Zeta电位净值降低而升高。扫描电镜表征结果表明,协同氧化后大多数藻细胞形态结构完整,从而可有效避免IOMs释放。以上研究结果可为FeSO₄-PMS治理富营养化水体中蓝藻水华提供参考。