Survey of Seawater Intrusion in the Pearl River Basin and Modeling Bromate Formation during Ozonation of the Raw Water

Bromate formation has been identified as a significant barrier in the application of ozone during water treatment the downstream region of the Pearl River Basin that contains high levels of bromide. Seawater intrusion will increase bromide concentration in the inshore surface water. In this study, seawater intrusion in the Pearl River Basin was surveyed and modeling bromate formation during ozonation of the raw water affected by seawater intrusion was studied. Bromate formation models were developed to simulate the effects of the characteristics of water quality and the operating parameters of treatment processes on bromate formation during preozonation process and postozonation process. The results show that the downstream of the Pearl River Basin is affected seriously by seawater intrusion and the bromide mainly comes from seawater. Some empirical models were developed to estimate the concentration of bromate in ozonated surface raw water affected by seawater intrusion during the treatment process.     

Ozonation at the 900 cfs Los Angeles Water Purification Plant

In 1979. the California Safe Drinking Water Act established a new turbidity limit of 0.5 turbidity unit for drinking waters. To meet this new standard at the Owens River Aqueductplantin Los Angelesi aprocessinvolvingpreozonation and direct filtration was tested and selected. In addition to providing water which meets the required turbidity standard, the ozone process reduces THM levels by about 50%, allowsfiltrationrates of 15 gpm/ft², reducescoagulation requirements, increases the removal of organics, thus reducing final chlorination requirements, and provides the most cost–effective reduction of levels of taste, odor, and color. The new Los Angeles water treatment plant will be on–line in 1986.     

Ozonation/Post-Chlorination of Humic Acid: A Model for Predicting Drinking Water Disinfection By-Products

Experiments were performed to evaluate disinfection by-products in model humic acid solutions which were ozonated at three different ozone to carbon levels and then chlorinated. These experiments were conducted in order to help understand whether the ozone/post-chlorination process alters the amount and type of mutagenic by-products formed, from those produced by chlorination of humic acid alone. Disinfection by-products were identified by gas chromatography/mass spectrometry (GC/MS). Samples of clarified and sand-filtered Mississippi River water at a pilotscale drinking water treatment plant in Jefferson Parish, Louisiana, that were ozonated and post-disinfected with chlorine, also were analyzed by GC/MS. A comparison of the by-products in the pilot plant study versus those in our laboratory study showed that similar compounds were produced. The effect of bromide ion in the pilot plant water on by-product formation also is discussed.     

臭氧对钼酸盐和聚磷酸盐阻垢效果的影响研究

结垢是工业循环冷却水运行中最常出现的问题,对正常的工业生产会造成一定的危害。本试验采用水处理剂阻垢性能的测定———CaCO3沉积法对Na2MoO4.2H2O、聚磷酸钠的阻垢效果进行试验研究。采用Na2MoO4.2H2O和聚磷酸钠作为单一的水处理阻垢药剂时,若要达到85%的阻垢效果,两种药剂的投加量分别至少要400mg.L-1和40mg.L-1,在使用两种药剂的同时通入O3,则Na2MoO4.2H2O和聚磷酸钠的药量分别在20mg.L-1和30mg.L-1左右即可达到国家标准。结果显示,在O3的协同作用下,减少了药剂的使用量,提高了阻垢效果。     

The use of Ozone to Control trihalomethanes in Drinking water Treatment

Trihalomethanes (THMs) are produced when certain organic materials are treated with chlorine. The U.S. EPA recently has promulgated a Maximum Contaminant Level for THMs in finished drinking water of 0.10 mg/L. Although ozone will not oxidize THMs at any significant rate once they have been formed, its use has been studied at many North American water treatment plants for oxidation of THM precursors before chlorine is added. In most cases ozonation prior to chlorination lowers THM formation potential (THMFP), but there have been many reports of increased THM formation when ozonation is followed by chlorination. The known chemistry of THM formation and of ozone oxidation of organic materials to both destroy and to form THM precursors is discussed to explain these results. In addition, recommendations are made for the use of ozone at various points in the standard drinking water treatment process, by which THM levels in the finished water can be decreased. These methods include ozonation at any point prior to chlorination and/or prior to a biological treatment process, such as adsorption of organics by means of granular activated carbon or by passage through slow sand filters. Pretreatment of raw waters to remove as much organic material as possible before adding any chemical oxidant, particularly chlorine, remains the best initial approach to controlling THMs, as well as other undesired by-products of oxidation processes.     

Ozonation at Wiggins Water Purification Works,Durban, South Africa

The post-ozone plant at Wiggins waterworks was commissioned during 1984. The main objective of the post–ozone plant was to ensure proper disinfection, including the elimination of viruses, whenever raw water for the works was pumped from the polluted lower Umgeni River. The main problems experienced with the post–ozone plant were poor ozone transfer efficiency in the contact tank and poisoning of the catalyst in the thermal-catalytic destructor.     

Advanced Water Treatment System of the Bureau of Waterworks,Tokyo Metropolitan Government

Since 1992, the Bureau of Waterworks, Tokyo Metropolitan Government (BWT) has introduced the advanced water treatment process, which is composed of ozonation and biological activated carbon treatment, within its service areas in a phased manner. The entire amount of water from the Tone River system has been treated by the advanced water treatment since 2014. The BWT currently has a capacity to treat approximately 5.5 million m³ per day using the advanced water treatment process. This report describes the progress of advanced water treatment facilities, the ozonation method, and the characteristic ozone diffusion devices used in Tokyo.     

臭氧活性炭联合工艺去除微污染水中有机物

采用臭氧活性炭联合工艺(O3+BAC)对以长江为水源的某水厂砂滤水进行深度处理。试验结果表明,该工艺对水中有机物有稳定的去除效果,在臭氧投加量为1mg/L,活性炭空床接触时间为8.6min时,对CODMn,UV254,DOC,THMEP(三氯甲烷生成势)和AOC(可同化有机碳)的平均去除率分别为32%,40%,22%,19%,7%。在DOC较低的情况下,三氯甲烷生成势与UV254有较好的正相关性。     

西江2000～2009年水环境质量及水质变化趋势分析

通过对西江干流中的封开江口、德庆、云浮六都水厂、肇庆三榕水厂、高要5个断面2000年至2009年的水质数据进行水质评价,探讨西江干流的水环境质量;用季节性Kendall检验法分析了西江水质10年内的变化趋势,为保护和利用西江水资源提出了建议。     

O_3预氧化—生物活性滤池直接过滤工艺处理黄河微污染原水

经过试验研究,O_3预氧化-生物活性滤池直接过滤工艺对黄河微污染原水有良好的处理效果。该组合工艺出水浊度小于1NTU,COD_(Mn)降低了50％,NH_4~ -N的去除率接近70％,有机物等污染物浓度大为减少,出水水质得以提高。     

臭氧-生物沸石处理湘江微污染原水试验研究

根据湘江水源水的特点,进行了臭氧一生物沸石的除污染组合工艺试验。试验结果表明,最优臭氧投加量为2．2mg／L左右,氧化接触时间为15min,水力负荷为2．3m／h左右。此时该工艺CODMn氨氮的去除率平均分别为53．6％和86．1％,从而为微污染源水处理提供了一种新的方法。     

Long Contact Time Ozanation For Swimming Pool Water Treatment

The elimination of contaminants in pool water through the “ozone – activated carbon process” is done stepwise. Sieving, flocculation and filtration steps are followed by ozonation. According to the German standards for the Treatment of Swimming Pool Water, the toxic ozone has to be removed from the water by filtration through an activated carbon layer before the water is brought back into the swimming pool. The treatment step is followed by chlorination for disinfection. In the ozone process described and in most of its modifications the time available for the reaction of the ozone is very short, usually 1.5 up to 3 min. First results with ozonation of model compounds, such as urea, creatinine, amino acids, etc., have shown–that the reaction rates are rather slow. Consequently, a longer reaction time leads to an improved decontamination of the swimming pool water. The efficiency of the ozonation process with longer reaction times followed by slower filtration has been proven in a research project, e.g. by experiments with the so–called “Ozone Combi Block^R – Process”. The potassium permanganate consumption and the combined chlorine as well as the formation potential of haloforms can be reduced effectively by elongated contact timeof ozone.     

Recent Development in the Role of Ozone in Water Purification and its Implications in Developing Countries

The recent discovery of chlorine-based halo–organic carcinogens in water supplies has highlighted the study of ozone as a suitable replacement to chlorine. Ozone is the most powerful oxidizing agent among water disinfectants. It has been used for water purification prior to chlorine and only its high cost has hampered its wider application. The recently discovered adverse effects of chlorine have buttresssed the use of ozone in water disinfection and today, over 1,100 water treatment plants around the world use ozone for disinfection. Large scale introduction of new disinfection systems in the developed countries will require suitable modifications in numerous existing water treatment plants. However, in the developing countries, the majority of the people do not yet have access to safe water supplies and the availability of plants which assure good quality water is ranked among the top priority targets in all national development programs in these countries.     

水污染问题与净水技术

阐述了21世纪饮用水面临的水质污染问题,包括无机化合物污染、合成有机化合物污染、微生物污染和环境激素污染.在此基础上分析讨论了新世纪的净水技术,重点介绍臭氧-活性炭联用技术、微生物处理技术、PoU(使用点)水处理技术以及膜分离技术等.建议加强对不同地区水质污染的调查,加强对环境激素污染等新污染问题的调研,加强净水技术的综合集成研究,重视膜分离技术在水处理中的应用研究等.     

基于BP神经网络的臭氧精确投加控制系统

自来水厂采用臭氧化工艺时臭氧投加量通常由生产经验判断确定,缺乏一定的准确性和时效性。根据浙江省T水厂150组实际运行样本数据,选用BP神经网络构建臭氧投加系统的前馈控制模型,能够在给定的工艺参数条件下较好地预测出水水质情况,也可根据进水水质情况和预期出水水质目标对所需的臭氧投加量进行预测。结果表明:基于BP神经网络的臭氧投加模型可以满足不同的水质变化,模拟精度较高,具有明显的优越性,对进一步提高供水安全性、节约制水成本具有重要的推动作用,也为臭氧-活性炭深度处理运行的自动化控制提出了新的理论思路。     

新臭氧技术及其应用

本文介绍了臭氧在净水处理中的作用和机理;新臭氧技术的特点;上海市周家渡水厂深度处理改造工程的工艺和进口臭氧设备性能测试结果,改造工程的水质测定结果。结果表明,臭氧活性炭工艺可降低色度到5度以下,降低耗氧量到2mg/L以下,并大幅度降低了水中的三致物质,使Ames试验结果由阳性转为阴性。     

水质控制对循环冷却水系统运行经济性影响分析

针对安徽省电厂敞开式循环冷却水系统的运行特点,从浓缩倍率的控制以及阻垢缓蚀剂配方体系的选择等几个方面,研究了水质控制对于循环冷却水系统运行经济性的影响,另外对淮河流域电厂循环冷却水系统的合理处理费用进行了评估。研究发现:安徽地区电厂循环冷却水系统浓缩倍率可适当提高到4～5,且不同区域应采用相应体系的阻垢缓蚀剂配方;另外,采用淮河水系为水源的电厂,其敞开式循环冷却水系统的阻垢缓蚀剂费用应在0.15元/t左右。     

A Comparison of Objectives,Level of Development and Energy Consumption of Two New Hungarian Ozonation Plants

Basedon the success of the first Hungarian large capacity drinking water treatment ozonation plant of Budapest that was put into operation in 1984, a similar second plant was put into operation in 1988 in Debrecen with 150,000 inhabitants. This recently built plant solves taste and odor problems and water quality development of a surface water treatment plant with a capacity of 50,000 m³/day that is operative for a longer period of time. The experiences gained at the Budapest ozonizing plant were utilized during both planning and construction. Thus, for example, the method of ozone absorption had been modified.

The in-situ repair of the Frings turbines for ozone contacting placed at the Rackeve plant of the Budapest Waterworks will be introduced, as well as a concept of a newer kind of ozone mixing.     

沉水植物及组合对城市缓滞水体水质的净化

针对北京市永定河莲石湖主要沉水植物菹草,由于夏季演替导致水质净化效果降低,选用伊乐藻(Elodea canadensis Michx)、轮叶黑藻(Hydrilla verticillata)、苦草(Vallisneria natans)、轮叶狐尾藻(Myriophyllum verticillatum L.)及其组合,研究对水中TN、TP、NH₃-N、叶绿素a、DO等水质指标净化效果,根据试验结果选出适宜莲石湖菹草演替的组合。试验结果表明,4种沉水植物及组合对TN、TP、NH₃-N均有较好的去除效果,对叶绿素a有明显的抑制作用。在试验周期内,对TP处理能力最好的是苦草+轮叶黑藻+轮叶狐尾藻的组合,平均每株的处理能力为11.11 mg;对TN处理能力最好的是伊乐藻+轮叶黑藻+轮叶狐尾藻的组合,平均每株的处理能力为141.36 mg;对NH₃-N处理能力最好的是苦草+轮叶黑藻+轮叶狐尾藻的组合,平均每株的处理能力为96.12 mg。结合每种植物的生长情况和特性,优选补种苦草+轮叶黑藻+轮叶狐尾藻的组合作为莲石湖夏季菹草演替的方案。     

Effects Of Ozone On The Production Of Biodegradable Dissolved Organic Carbon (BDOC) During Water Treatment

This article deals with the oxidation effect of ozone on the increasing fraction of biodegradable organic matter with the “ozotest” method, a laboratory technique which simulates the effect of ozonation and allows a complete oxidation assessment. Ozone treatment was performed on river water samples and sand filter effluent samples. Ozone consumption, reduction of UV absorbance and BDOC formation were monitored with applied ozone doses from 0 to 10 mg/L and with contact times from 0 to 60 min. The BDOC formation was optimum at an applied ozone dose of 0.25-0.5 mg O₃ per mg DOC (contact time = 5 min) corresponding to apparition of traces of residual ozone and maximum UV reduction. Maximum ozone consumption, UV reduction and BDOC formation occurred simultaneously during the first two minutes of treatment. Concerning BDOC formation, applied ozone dose showed a greater effectiveness than contact time. For the same quantity of consumed ozone, a short contact time associated with a high ozone dose was preferable to a long contact time and a low ozone dose.