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Chloramine demand estimation using surrogate chemical and microbiological parameters

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Journal of Environmental Sciences 2017年第7期29卷 1-7页

作者： Sina Moradi Sanly Liu Christopher W.K.Chow John van Leeuwen David Cook Mary Drikas Rose Amal School of Chemical Engineering The University of New South Wales australian water quality centre SA Water Corporation centre for water Management and Reuse School of Natural and Built EnvironmentsUniversity of South Australia

A model is developed to enable estimation of chloramine demand in full scale drinking water supplies based on chemical and microbiological factors that affect chloramine decay rate via nonlinear regression analysis *** model is based on organic character（specific ultraviolet absorbance（SUVA）） of the water samples and a laboratory measure of the microbiological（Fm） decay of *** applicability of the model for estimation of chloramine residual（and hence chloramine demand） was tested on several waters from different water treatment plants in Australia through statistical test analysis between the experimental and predicted *** showed that the model was able to simulate and estimate chloramine demand at various times in real drinking water *** elucidate the loss of chloramine over the wide variation of water quality used in this study,the model incorporates both the fast and slow chloramine decay *** significance of estimated fast and slow decay rate constants as the kinetic parameters of the model for three water sources in Australia was *** was found that with the same water source,the kinetic parameters remain the *** modelling approach has the potential to be used by water treatment operators as a decision support tool in order to manage chloramine disinfection.

关键词： Chloramine demand Drinking water treatment plants Modelling

Developing a chloramine decay index to understand nitrification:A case study of two chloraminated drinking water distribution systems

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Journal of Environmental Sciences 2017年第7期29卷 170-179页

The management of chloramine decay and the prevention of nitrification are some of the critical issues faced by water utilities that use chloramine as a *** this study,potential association between high performance size exclusion chromatography（HPSEC）data obtained with multiple wavelength Ultraviolet（UV） detection from two drinking water distribution systems in Australia and nitrification occurrence was *** increase in the absorbance signal of HPSEC profiles with UV detection at λ = 230 nm between apparent molecular weights of 200 to 1000 Da was observed at sampling sites that experienced rapid chloramine decay and nitrification while its absorbance signal at λ =254 nm decreased.A chloramine decay index（C.D.I） defined as the ratio of area beneath the HPSEC spectra at two different wavelengths of 230 and 254 nm,was used in assessing chloramine decay *** *** of waters at locations that experienced nitrification were consistently higher than locations not experiencing nitrification.A simulated laboratory study showed that the formation of nitrite/nitrate and/or soluble microbial products and/or the release of extracellular polymeric substances（EPS） during nitrification may contribute to the *** findings suggest that C.D.I derived from HPSEC with multiple wavelength UV detection could be an informative index to track the occurrence of rapid chloramine decay and nitrification.

关键词： HPSEC water distribution systems Nitrification Chloramine decay

High-performance size exclusion chromatography with a multi-wavelength absorbance detector study on dissolved organic matter characterisation along a water distribution system

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Journal of Environmental Sciences 2016年第6期28卷 235-243页

作者： Huiping Huang Emma Sawade David Cook Christopher W.K.Chow Mary Drikas Bo Jin School of Chemical Engineering The University of Adelaide australian water quality centre SA Water Corporation250 Victoria Square School of Earth and Environmental Sciences The University of Adelaide

This study examined the associations between dissolved organic matter（DOM） characteristics and potential nitrification occurrence in the presence of chloramine along a drinking water distribution system. High-performance size exclusion chromatography（HPSEC） coupled with a multiple wavelength detector（200–280 nm） was employed to characterise DOM by molecular weight distribution, bacterial activity was analysed using flow cytometry, and a package of simple analytical tools, such as dissolved organic carbon, absorbance at 254 nm, nitrate,nitrite, ammonia and total disinfectant residual were also applied and their applicability to indicate water quality changes in distribution systems were also evaluated. Results showed that multi-wavelength HPSEC analysis was useful to provide information about DOM character while changes in molecule weight profiles at wavelengths less than 230 nm were also able to be related to other water quality parameters. Correct selection of the UV wavelengths can be an important factor for providing appropriate indicators associated with different DOM compositions. DOM molecular weight in the range of 0.2–0.5 kDa measured at210 nm correlated positively with oxidised nitrogen concentration（r = 0.99）, and the concentrations of active bacterial cells in the distribution system（r = 0.85）. Our study also showed that the changes of DOM character and bacterial cells were significant in those sampling points that had decreases in total disinfectant residual. HPSEC-UV measured at210 nm and flow cytometry can detect the changes of low molecular weight of DOM and bacterial levels, respectively, when nitrification occurred within the chloraminated distribution system.

关键词： HPSEC-UV Distribution system DOM Sum of nitrate and nitrite concentration

Changes in the quality of river water before,during and after a major flood event associated with a La Nina cycle and treatment for drinking purposes

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Journal of Environmental Sciences 2014年第10期26卷 1985-1993页

作者： Mohamad Fared Murshed Zeeshan Aslam Rosmala Lewis Christopher Chow Dongsheng Wang Mary Drikas John van Leeuwen centre for water Management and Reuse Natural and Built Environments University of South Australia australian water quality centre South Australian Water Corporation State Key Laboratory for Environmental Aquatic Chemistry Research Centre for Eco-Environmental Sciences Barbara Hardy Institute Natural and Built EnvironmentsUniversity of South Australia

The treatment of organics present in the lower reaches of a major river system（the Murray–Darling Basin, Australia） before（March–July 2010）, during（December 2010–May 2011） and after（April–December 2012） a major flood period was investigated. The flood period（over 6 months）occurred during an intense La Nia cycle, leading to rapid and high increases in river flows and organic loads in the river water. Dissolved organic carbon（DOC） increased（2–3 times） to high concentrations（up to 16 mg/L） and was found to correlate with river flow rates. The treatability of organics was studied using conventional jar tests with alum and an enhanced coagulation model（mEnCo）. Predicted mean alum dose rates（per mg DOC） were higher before（9.1 mg alum/mg DOC） and after（8.5 mg alum/mg DOC） than during the flood event（8.0 mg alum/mg DOC）,indicating differences in the character of the organics in raw waters. To assess the character of natural organic matter present in raw and treated waters, high performance size exclusion chromatography with UV and fluorescence detectors were used. During the flood period, high molecular weight UV absorbing compounds（〉2 kDa） were mostly detected in waters collected,but were not evident in waters collected before and afterwards. The relative abundances of humic-like and protein-like compounds during and following the flood period were also investigated and found to be of a higher molecular weight during the flood period. The treatability of the organics was found to vary over the three climate conditions investigated.

关键词： Alum Coagulation Flood mEnCo prediction dose(EnCD) La Ni?a

Influence of coagulation mechanisms and floc formation on filterability

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Journal of Environmental Sciences 2017年第7期29卷 338-345页

作者： Ruyuan Jiao Rolando Fabris Christopher W.K.Chow Mary Drikas John van Leeuwen Dongsheng Wang Zhizhen Xu State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of Sciences australian water quality centre South Australian Water Corporation centre for water Management and Reuse School of Natural and Built EnvironmentsUniversity of South Australia Key Laboratory of Occupational Safety and Health Beijing Municipal Institute of Labor Protection

Minimizing particles in water is a key goal for improving drinking water quality and *** media filtration process,as the last step of the solid–liquid separation process,is largely influenced by the characteristics of flocs,which are formed and controlled within the coagulation *** a laboratory-based study,the impacts of the physical characteristics of flocs formed using aluminum sulfate on the filtration treatment of two comparative water samples were investigated using a photometric dispersion analyzer and a filterability *** general,the optimum dosage for maximizing filterability was higher than that for minimizing turbidity under neutral p H *** a monomeric aluminum-based coagulant,the charge neutralization mechanism produced better floc characteristics,including floc growth speed and size,than the sweep flocculation *** addition,the charge neutralization mechanism showed better performance compared to sweep flocculation in terms of DOC removal and floc filterability improvement for both waters,and showed superiority in turbidity removal only when the raw water had high *** the different mechanisms,the ways that floc characteristics impacted on floc filterability also *** low variation in floc size distribution obtained under the charge neutralization mechanism resulted in the flocs being amenable to removal by filtration *** the sweep flocculation mechanism,increasing the floc size improved the settling ability of flocs,resulting in higher filter efficiency.

关键词： Coagulation mechanisms Floc characteristics Filterability Turbidity

Prediction of DOM removal of low specific UV absorbance surface waters using HPSEC combined with peak fitting

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Journal of Environmental Sciences 2012年第7期24卷 1174-1180页

作者： Linan Xing Rolando Fabris W.K.Chow John van Leeuwen Mary Drikas Dongsheng Wang State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of ScinecesBeijing 100085China australian water quality centre South Australian Water Corporation256 Victoria SquareAdelaideSouth Australia 5000Australia SA water centre for water Management and Reuse University of South AustraliaMawson LakesSouth Australia 5095Australia

High performance size exclusion chromatography （HPSEC） is used in water quality research primarily to determine the molecular weight distribution of the dissolved organic matter （DOM）, but by applying peak fitting to the chromatogram, this technique can also be used as a tool to model and predict DOM removal. Six low specific UV absorbance （SUVA） source waters were treated using coagulation with alum and both the source and treated water samples were analysed using HPSEC. By comparing the molecular weight profiles of the source and treated waters, it was established that several DOM components were not effectively removed by alum coagulation even after high dosage alum treatment. A peak-fitting technique was applied based on the concept of linking the character （molecular weight profile） of the recalcitrant organics in the treated water with those of the source water. This was then applied to predict DOM treatability by determining the areas of the peaks which were assigned to removable organics from the source water molecular weight profile after peak fitting, and this technique quantified the removable and non-removable organics. The prediction was compared with the actual dissolved organic carbon （DOC） removal determined from jar testing and showed good agreement, with variance between 2% and 10%. This confirmed that this prediction approach, which was originally developed for high SUVA waters, can also be applied successfully to predict DOC removal in low SUVA waters.

关键词： DOM high performance size exclusion chromatography peak fitting water treatment

pH modeling for maximum dissolved organic matter removal by enhanced coagulation

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Journal of Environmental Sciences 2012年第2期24卷 276-283页

作者： Jiankun Xie Dongsheng Wang John van Leeuwen Yanmei Zhao Linan Xing Christopher W. K. Chow State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China SA water centre for water Management and Reuse NBE Universit of South Australia Australia australian water quality centre SA Water 250 Victoria Square Adelaide SA 5000 Australia

Correlations between raw water characteristics and pH after enhanced coagulation to maximize dissolved organic matter（DOM） removal using four typical coagulants（FeCl3,Al2（SO4）3,polyaluminum chloride（PACl） and high performance polyaluminum chloride（HPAC）） without pH control were *** correlations were analyzed on the basis of the raw water quality and the chemical and physical fractionations of DOM of thirteen Chinese source waters over three *** was found that the final pH after enhanced coagulation for each of the four coagulants was in？uenced by the content of removable DOM（*** and higher apparent molecular weight（AMW） DOM）,the alkalinity and the initial pH of raw water.A set of feed-forward semi-empirical models relating the final pH after enhanced coagulation for each of the four coagulants with the raw water characteristics were developed and optimized based on correlation *** established models were preliminarily validated for prediction purposes,and it was found that the deviation between the predicted data and actual data was *** result demonstrated the potential for the application of these models in practical operation of drinking water treatment plants.

关键词： enhanced coagulation modeling DOM fractionation pH control

Organic chloramines in chlorine-based disinfected water systems： A critical review

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Journal of Environmental Sciences 2017年第8期29卷 2-18页

作者： Zuo Tong How Ina Kristiana Francesco Busetti Kathryn L.Linge Cynthia A.Joll Curtin water quality Research centre Department of Chemistry Curtin University Perth Western Australia 6102 Australia

This paper is a critical review of current knowledge of organic chloramines in water systems,including their formation, stability, toxicity, analytical methods for detection, and their impact on drinking water treatment and quality. The term organic chloramines may refer to any halogenated organic compounds measured as part of combined chlorine（the difference between the measured free and total chlorine concentrations）, and may include N-chloramines,N-chloramino acids, N-chloraldimines and N-chloramides. Organic chloramines can form when dissolved organic nitrogen or dissolved organic carbon react with either free chlorine or inorganic chloramines. They are potentially harmful to humans and may exist as an intermediate for other disinfection by-products. However, little information is available on the formation or occurrence of organic chloramines in water due to a number of challenges. One of the biggest challenges for the identification and quantification of organic chloramines in water systems is the lack of appropriate analytical methods. In addition, many of the organic chloramines that form during disinfection are unstable, which results in difficulties in sampling and detection. To date research has focussed on the study of organic ***, given that breakpoint chlorination is commonly undertaken in water treatment systems, the formation of organic dichloramines should also be considered. Organic chloramines can be formed from many different precursors and pathways. Therefore, studying the occurrence of their precursors in water systems would enable better prediction and management of their formation.

关键词： Amino acids Disinfection by-products Organic chloramines N-chloramine Drinking water quality Organic bromamines Organic iodamines

Occurrence and formation of disinfection by-products in the swimming pool environment： A critical review

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Journal of Environmental Sciences 2017年第8期29卷 19-50页

作者： Rhys A.A.Carter Cynthia A.Joll Curtin water quality Research centre Department of Chemistry Curtin Uniuersity Perth Western Australia 6102 Australia

Disinfection of water for human use is essential to protect against microbial disease;however, disinfection also leads to formation of disinfection by-products（DBPs）, some of which are of health concern. From a chemical perspective, swimming pools are a complex matrix, with continual addition of a wide range of natural and anthropogenic chemicals via filling waters, disinfectant addition, pharmaceuticals and personal care products and human body excretions. Natural organic matter, trace amounts of DBPs and chlorine or chloramines may be introduced by the filling water, which is commonly disinfected distributed drinking water. Chlorine and/or bromine is continually introduced via the addition of chemical disinfectants to the pool. Human body excretions（sweat, urine and saliva） and pharmaceuticals and personal care products（sunscreens, cosmetics, hair products and lotions） are introduced by swimmers. High addition of disinfectant leads to a high formation of DBPs from reaction of some of the chemicals with the *** pool air is also of concern as volatile DBPs partition into the air above the *** presence of bromine leads to the formation of a wide range of bromo-and bromo/chloro-DBPs, and Br-DBPs are more toxic than their chlorinated analogues. This is particularly important for seawater-filled pools or pools using a bromine-based *** review summarises chemical contaminants and DBPs in swimming pool waters, as well as in the air above pools. Factors that have been found to affect DBP formation in pools are discussed. The impact of the swimming pool environment on human health is reviewed.

关键词： Disinfection by-products Disinfection Swimming pool Spa water quality Health effects