饮用水源腐殖酸高级氧化去除技术研究进展

自然水体中腐殖酸类天然有机物(NOM)在水厂氯化消毒过程中会生成卤代消毒副产物,因此腐殖酸的有效去除对于消减消毒副产物、提升饮用水水质具有重要的意义。高级氧化技术因其独特的除污染效能受到研究者们的广泛关注,本文综述了基于臭氧和紫外的两种高级氧化技术进展,介绍了高级氧化与其他水处理技术联用工艺,比较了各种工艺技术的优缺点,提出了该技术拟解决的主要技术问题及未来研究发展方向。     

高锰酸钾预氧化对混凝-超滤去除天然水体中腐殖酸的影响研究

采用高锰酸钾预氧化-混凝-超滤组合工艺去除天然水体中的腐殖酸,考察了水中腐殖酸的质量浓度分别为2.4、4.3、7.6 mg/L时,高锰酸钾投加量对各工艺出水水质和超滤膜污染的影响。结果表明,高锰酸钾预氧化可以有效提高组合工艺的出水水质。其中,预氧化、混凝和超滤过程分别对天然有机物、腐殖酸和大分子物质具有良好的去除效果。另外,控制高锰酸钾投加量在0.2~1 mg/L可显著减缓膜污染。即使当进水中腐殖酸的质量浓度达到7.6mg/L的条件下,膜比通量在1 h内始终维持在0.95~0.97。     

饮用水中天然有机物去除技术的研究进展

水中存在的天然有机物(NOM)在饮用水处理过程中不仅会增加消毒副产物(DBPs)的数量，影响后续工艺处理，还会和水中的其他物质结合生成毒性更强的物质(有机金属络合物),严重危害人类身体健康。因此，研究NOM的去除对水质安全意义重大。文中介绍了NOM的种类及其危害，根据国内外去除NOM技术的研究现状，综述了混凝、吸附、高级氧化、膜处理和离子交换等技术去除NOM的效果及机理，重点阐述了以混凝为核心单元的耦合工艺对NOM去除的研究进展，分析了各种耦合工艺的优势与局限性，并对今后混凝技术的研究方向进行了展望。     

紫外联用高级氧化技术处理饮用水应用进展

叙述了紫外-过氧化氢、紫外-芬顿、紫外-过氧化氢-臭氧、紫外-硫酸盐、紫外-氯、紫外-二氧化钛等紫外联用高级氧化技术在饮用水处理领域中的国内外科学研究及工程应用现状,比较了各组合技术的作用原理、处理特性及优缺点。为避免高级氧化工艺存在的缺陷,如氧化剂、催化剂消耗量大、易受水质影响、运行费用高、存在二次污染等,应针对价格低廉、稳定高效的新型氧化剂、催化剂及催化剂载体进行专项研发,降低该技术的应用成本;加强基于实际水体有机难降解污染物的降解动力学及传质机理研究,设计开发适于不同水质条件的紫外联用高级氧化一体化集成工艺的系统化光反应器,推进紫外联用的高级氧化技术实现实际工程化应用。     

臭氧氧化对饮用水原水中NOM的影响及改进处理方法

天然有机物(NOM)是普遍存在于自然水体中的一类复杂的有机混合物,不同处理方法对原水中NOM的去除情况不同,这对饮用水的安全性也有较大影响。臭氧氧化是近年来饮用水处理中常用的消毒方法,因此,研究臭氧氧化对饮用水原水中NOM的影响有着重要的意义。介绍了NOM的分类方法以及臭氧氧化对每种NOM组分的作用,分析了臭氧氧化NOM对饮用水消毒副产物生成的影响。同时,总结了一些以臭氧氧化为基础的改进处理方法,对比分析了它们的优缺点,并为以后的研究工作提出了建议和展望。     

不同预氧化剂强化直接过滤处理低温低浊微污染水的试验研究

低温低浊微污染水由于其水质的特殊性,一直是饮用水处理中面临的难题。以天津某水厂水源水为试验水质,在前期直接过滤试验研究基础上,采用高锰酸钾、臭氧为氧化剂进行预氧化以强化直接过滤处理低温低浊水的效果。结果表明,2种预氧化技术均能不同程度提高对水中有机污染物的去除效率,其中臭氧预氧化对水中有机微污染物去除效果提升较大,对UV254和CODMn的去除率均能达到57%,较单独直接过滤处理分别提高了42%和40%,比高锰酸钾预氧化工艺提高了32%和19%;臭氧预氧化-直接过滤工艺更适合于对该种水质的处理。     

预氧化强化混凝去除富营养化水体中藻类研究回顾

水体富营养化导致的水华威胁着饮用水安全和水生态平衡。近年来,如何高效地去除水中的藻类已成为国内外的研究热点。将预氧化和混凝法进行联用可以起到协同效果,从而有效去除水体中的藻类,而不同的预氧化方法在除藻机理、效果上均有很大差别。文中主要探讨了高锰酸钾、臭氧、二氧化氯、高铁酸盐、紫外预氧化强化混凝除藻时的不同特性、效果以及安全性,为水厂除藻工艺的选择提供参考。     

饮用水处理中常用预氧化剂的种类及特点

传统净水工艺主要处理水中悬浮物、胶体、大颗粒物质,对于溶解性有机物去除十分有限,由于饮用水标准的不断提高,对溶解性有机物的去除成为传统工艺提标改造的主要内容,预氧化技术是提高水源水中溶解性有机物去除率的有效技术手段之一,本文介绍了水处理工艺中常用的预氧化剂种类、优缺点及其适用的水质。     

不同氧化剂对水中微囊藻毒素-LR(MC-LR)释放及降解的效果

该文探讨了3种氧化剂(臭氧、高锰酸钾和次氯酸钠)对微囊藻毒素-LR(MC-LR)的降解效果,并研究了氧化剂处理铜绿微囊藻过程中对MC-LR的释放及其降解特性。结果表明3种氧化剂均可有效降解MC-LR。氧化处理铜绿微囊藻时,在臭氧投加速率为0.41 mg/L·min、氧化反应5 min和高锰酸钾投加量为2 mg/L、氧化反应5~8 min的条件下,均可将水中的MC-LR去除完全;此外,3种氧化剂处理含藻水的同时,可引起胞内藻毒素不同程度的释放,其中次氯酸钠处理含藻水将严重破坏藻细胞,致使产生大量的、常规水处理工艺无法有效去除的胞外溶解性MC-LR,导致饮用水水质存在安全隐患。     

超声联用技术处理有机污染物最新进展

超声技术能够产生空穴效应,然后生成·OH等活性物质,进而氧化分解难降解有机污染物,但是去除效率很低。为了提高超声技术的去除效能,可以采用与其他技术联用的方式。介绍了超声-臭氧法、超声-电化学氧化法、超声-光化学氧化法、超声-天然固体颗粒法等组合工艺,这些组合工业均表现出良好的去除效能;超声均相芬顿技术、超声非均相芬顿技术的应用更为广泛,其中超声非均相芬顿技术的优势明显。通过深入剖析超声联用技术的优势可以看出,超声联用技术在特种工业废水处理中效果显著。     

钙基脱硫工艺协同脱硝技术研究进展

采用钙基吸收剂的烟气脱硫技术拥有95%以上的市场份额,基于钙基烟气脱硫工艺协同乃至同时脱除NO_x是最现实可行的技术方向。本文阐明了钙基脱硫工艺协同脱硝的可行性,并根据硫氮协同脱除反应所处的温度区段,将钙基吸收剂硫氮协同脱除技术分为炉内联合脱除、中温同时脱除和低温段协同脱除三类,针对每类技术的基本原理、研究现状和存在的问题进行了分析和总结,指出将NO氧化为NO₂在低温段实现SO₂和NO_x协同乃至同时脱除是最现实可行的技术方向,并针对该技术存在的NO₂在低温脱硫工艺中吸收效率低和钙基吸收剂利用率低的问题提出了研究方向。最后,对钙基脱硫工艺协同脱硝技术的发展进行了展望,指出了实施超净排放后基于低温脱硫工艺协同脱硝技术应具有广阔的工业应用前景。     

Effect of potassium permanganate dosing position on the performance of coagulation/ultrafiltration combined process

The effects of potassium permanganate(KMnO_4)dosing position on the natural organic matter(NOM)removal as well as membrane fouling were investigated in the coagulation/ultrafiltration combined process.KMnO_4 oxidation altered the NOM characteristics in terms of hydrophobicity and molecular weight,and destroyed humic substances originated from terraneous organisms in raw water.The optimal KMnO_4 dosage was 0.5 mg·L~(-1) in the peroxidation enhanced coagulation process with respect to the dissolved organic carbon(DOC)removal.When KMnO_4 was dosed into both upstream and downstream of coagulation,namely in the proposed twoposition dosing mode,coagulation and KMnO_4 oxidation worked individually on the apparent DOC removal.However,compared to the KMnO_4 addition prior to or after coagulation,the two-position dosing mode dramatically alleviated membrane fouling and reduced fouling irreversibility.This was attributed to the change of NOM characteristics as a result of KMnO_4 addition prior to coagulation and the presence of MnO_2 on membrane surface as a result of KMnO_4 addition prior to ultrafiltration.This work may provide useful information for the application of KMnO_4 oxidation in the coagulation/ultrafiltration combined system.     

Contributions of electrochemical oxidation to waste‐water treatment: fundamentals and review of applications

OVERVIEW: This paper provides an overview of some fundamental aspects of electrochemical oxidation and gives updated information on the application of this technology to waste‐water treatment. In recent years, electrochemical oxidation has gained increasing interest due to its outstanding technical characteristics for eliminating a wide variety of pollutants normally present in waste‐waters such as refractory organic matter, nitrogen species and microorganisms. IMPACT: The strict disposal limits and health quality standards set by legislation may be met by applying electrochemical oxidation. However, treatment costs have to be cut down before full‐scale application of this technology. Deployment of electrochemical oxidation in combination with other technologies and the use of renewable sources to power this process are two steps in this direction. APPLICATIONS: Effluents from landfill and a wide diversity of industrial effluents including the agro‐industry, chemical, textile, tannery and food industry, have been effectively treated by this technology. Its high efficiency together with its disinfection capabilities makes electro‐oxidation a suitable technology for water reuse programs. Copyright © 2009 Society of Chemical Industry     

Effects of Ozonation on Natural Organic Matter Reactivity in Adsorption and Biodegradation Processes – A Case Study: The Úzquiza Reservoir Water

In this paper the influences of preozonation on the effectiveness of NOM adsorption and biodegradation processes are studied. Three different types of water have been used in this study: A natural water from the Úzquiza Reservoir (Burgos, Spain), synthetics waters prepared using natural humic substances (fulvic and humic acids extracted from the Úzquiza Reservoir) and a synthetic water prepared using a commercially supplied humic acid. The effect of preozonation on NOM adsorption by activated carbon is evaluated: adsorption of humic acids (hydrophobic, high molecular weight compounds) is improved following preozonation; however, for the fulvic acids (hydrophilic, low molecular weight compounds), no net appreciable effect of preozonation on adsorption was observed. Preozonation increases the biodegradability of NOM: biodegradable dissolved organic carbon (BDOC), which was determined using two different bioassays (Billen-Servais method and Joret-Lévi method), increases with increasing ozone dosage. A characterization of humic substances based on their adsorption and biodegradability properties is also reported, showing the effect of ozone.     

Effects of Ozonation on Molecular Weight Distribution of Humic Substances and Coagulation Processes – A Case Study: The Úzquiza Reservoir Water

In this article the influence of preozonation on the effectiveness of NOM removal via coagulation processes will be studied (focusing on the influence of the calcium hardness) as well as changes in MW (molecular weight) distribution of humic substances caused by ozonation. Additionally, THMFP removal in both ozonation and preozonation-coagulation processes is assessed. Three different types of water have been used in this study: a natural water from the Úzquiza Reservoir (Burgos, Spain), a synthetic water prepared using natural fulvic acids extracted from the Úzquiza Reservoir and a synthetic water prepared using a commercially supplied humic acid. Molecular weights of humic substances were determined using high-performance size exclusion chromatography (HPSEC); average molecular weights calculated for the unozonated humic substances are 4500 Da for the commercial humic acids and 1000 Da for the natural fulvic acids extracted from the Úzquiza Reservoir. Preozonation shifted the molecular weight distribution of humic substances (both humic and fulvic acids) towards lower average molecular weight values. For the natural water from the Úzquiza Reservoir (with low levels of calcium hardness and hydrophobic fraction (humic substances) being the main fraction of NOM), preozonation has a negative effect on the effectiveness of the coagulation process for NOM removal: the percentages of TOC removal via coagulation decrease with increasing ozone dosage; the maximum TOC removal (33%) is achieved for the unozonated water. Also for this water, ozonation reduced 5–25% of THMFP with ozone doses varying from 0.25 to 2.5 mg O₃/L. A preferential THMFP removal, that is to say, higher reduction in THMFP (43%) relative to TOC (28%) is achieved by the coagulation-flocculation process; this also occurs when preozonation is used, independently of ozone dosage.     

The Influence of the Removal of Specific NOM Compounds by Anion Exchange on Ozone Demand,Disinfection Capacity,and Bromate Formation

This research on a pilot scale focuses on the reaction of ozone with natural organic matter (NOM) for three water qualities with different dissolved organic carbon (DOC) concentrations and NOM compositions, obtained after several stages of an anion exchange process. It was shown that for the same ozone dosage per DOC, the ozone demand was higher, less bromate was formed and a lower disinfection capacity was reached for water containing mainly humic substances, than for water where the humic substances were partly removed. It can be concluded that NOM composition, specifically the humic substances, influences the ozone demand, disinfection capacity and bromate formation.     

Suppressing NOM access to controlled porous TiO2 particles enhances the decomposition of target water contaminants

Preferential oxidation of target chemicals of concern has been a challenging issue in TiO₂ photocatalysis, considering typical source water contains low concentrations of highly toxic substances along with high concentrations of less toxic naturally abundant organic matter (NOM). This study demonstrates simply controlling the porous structure of TiO₂ can suppress the access of large size NOM to the TiO₂ and thus improve the selective oxidation of small size target contaminants. Ibuprofen as a target contaminant was successfully decomposed even in the presence of humic acid as competing NOM. Selectivity enhancement mechanism was proposed, based on size exclusion principle.     

Mineralization of Ibuprofen and Humic Acid through Catalytic Ozonation

Advanced oxidation methods are used to remove traces of pharmaceuticals from aquatic environments. The application of a catalyst improves the total organic carbon removal during ozonation of pharmaceuticals in water. The aim of this study was to use MnO₂-CuO/ γ-Al₂O₃ catalyst for ozonation of ibuprofen (5 mgL^?1) and evaluate the effect of the presence of humic acid in the removal process. The presence of the catalyst increased the mineralization percentage of ibuprofen from 27% for noncatalytic ozonation to 55% in the presence of catalyst. The presence of humic acid increased noncatalytic mineralization by 10%. The reusability and stability of the catalyst, and its ability to adsorb reaction by-products were demonstrated.