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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

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

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

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

A novel mathematical template for developing fDOM probe fluorescence signal correction models for freshwaters

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Journal of Environmental Sciences 2024年第12期146卷 103-117页

作者： Hiua Daraei Edoardo Bertone John Awad Rodney A.Stewart christopher w.k.chow Jinming Duan Amanda Mussared John Van Leeuwen Sustainable Infrastructure and Resource Management(SIRM) UniSA STEMUniversity of South AustraliaMawson LakesSA 5095Australia Griffith School of Engineering and Built Environment Griffith UniversityQueensland 4222Australia Cities Research Institute Griffith UniversityParklands DriveSouthportQueensland 4222Australia CSIRO Environment AdelaideSA 5000Australia Australian water Quality Centre SA Water250 Victoria SquareAdelaideSA 5000Australia Australian Rivers Institute Griffith University170 Kessels RoadNathanQueensland 4111Australia Environmental Health Research Centre Kurdistan University of Medical SciencesSanandajKurdistanIran

The reliable application of field deployable fluorescent dissolved organic matter(fDOM)probes is hindered by several influencing factors which need to be *** manuscript describes the corrections of temperature,pH,turbidity and inner filter effect on fluorescence signal of a commercial fDOM probe(fDOMs).For this,Australian waters with wide ranging qualities were selected,*** organic carbon(DOC)ranging from∼1 to∼30 mg/L,specific UV absorbance at 254 nm from∼1 to∼6 L/m/mg and turbidity from∼1 to∼350 ***-based model calibration experiments(MCEs)were performed.A model template was developed and used for the development of the correction *** each factor,data generated through MCEs were used to determine model coefficient(α)values by fitting the generated model to the experimental *** discrete factor models were generated by determination of a factor-specificα***αvalues derived for each water of the MCEs subset were consistent for each factor *** indicated generic nature of the fourαvalues across wide-ranging water *** correlation between fDOMs and DOC were achieved after applying the four-factor compensation models to new data(r,0.96,pween DOC predicted through fDOMs and actual DOC were decreased by applying the four-factor compensationmodel(from3.54(60.9%)to 1.28(16.7%)mg/L DOC).These correction models were incorporated into a Mi-crosoft EXCEL-based software termed EXOf-Correct for ready-to-use applications.

关键词： Surface waters Online monitoring fDOM probes Fluorescence signal Model-based corrections

Effects of carbonation on mechanical properties of CAC-GGBFS blended strain hardening cementitious composites

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Low-carbon Materials and Green Construction 2023年第1期1卷 3-20页

作者： wei Fan Yan Zhuge Xing Ma christopher w.k.chow Yue Liu Guangtong Huang d Nima Gorjian UniSA STEM University of South AustraliaAdelaideSA 5000Australia South Australian water Corporation AdelaideSA 5000Australia

Calcium aluminate cement(CAC)—based strain hardening cementitious composites(SHCC)has been developed and used for the rehabilitation of sewerage *** addition to well-known microbiologically induced corrosion,CO_(2)concentration in the sewerage environment is high,which may cause significant carbonation of ***,this paper aims to investigate the effects of carbonation on the mechanical performance of CAC-based *** types of CAC-based SHCC with different strength grades and a referenced OPC-based SHCC were *** accelerated carbonation test was conducted in a carbonation chamber with a 5%CO_(2)*** compressive and tensile behaviour of SHCC was tested first,and microstructure analysis,e.g.,X-ray diffraction and scanning electron microscopy,was then *** results showed that CAC-based SHCC specimens exhibited robust strain-hardening performance as well as large deformation capacity in tension due to the fiber-bridging ***,the compressive and tensile strength was significantly improved as well as achieving a higher tensile strain capacity after carbonation when compared with OPC-based *** analysis revealed that the metastable phases in carbonated CAC-based SHCC were converted into stable phases and calcium carbonate polymorphs,densifying the binder *** obtained results of this paper may provide new insight into utilizing carbonation to avoid the unstable conversion of hydrates in calcium aluminate cement.

关键词： Carbonation Calcium Aluminate Cement Strain Hardening Cementitious Composites Sewerage

Hydrolyzed Al(Ⅲ) clusters:Speciation stability of nano-Al_(13)

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Journal of Environmental Sciences 2011年第5期23卷 705-710页

作者： Shuifeng wang Chihpin Huang christopher w k. chow Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China. E-mail: wgds@*** Institute of Environmental Engineering National Chiao Tung University Hsinchu Taiwan China Australian water Quality Centre SA Water Corporation 250 Victoria Square Adelaide SA 5000 South Australia

Pure nano-All3 and aggregates at various concentrations were prepared to examine the particle size effect of coagulation with inorganic polymer flocculant. The property and stability of various species formed were characterized using Infrared, 27Al-NMR, photo correlation spectroscopy （PCS）, and Ferron assay. Results showed that concentration and temperature exhibited different roles on the stability of Al13. The quantity of Alb species analyzed by ferron assay in the initial aging period corresponded well with that of Al13, which has been confirmed in a dimension range of 1-2 nm by PCS. Al13 solutions at high concentrations （0.5-2.11 tool/L） were observed to undergo further aggregation with aging. The aggregates with a wide particle size distribution would contribute to the disappeared/decreased Al13 basis on the eTA1-NMR spectrum, whereas a part of Al13 would still remain as Alb. At low concentrations, All3 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90~C.

关键词： nano-All3 clusters inorganic polymer flocculant speciation stability

Emission properties of nanolasers during the transition to lasing

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Light(Science & Applications) 2014年第1期3卷 92-99页

作者： weng w chow Frank Jahnke christopher Gies Sandia National Laboratories AlbuquerqueNM 87185-1086USA Institute for Theoretical Physics University of Bremen28334 BremenGermany

This review addresses ongoing discussions involving nanolaser experiments,particularly those related to thresholdless lasing or few-emitter devices.A quantum-optical(quantum-mechanical active medium and radiation field)theory is used to examine the emission properties of nanolasers under different experimental *** active medium is treated as inhomogeneously broadened semiconductor quantum dots embedded in a quantum well,where carriers are introduced via current *** are made between a conventional laser and a nanolaser with a spontaneous emission factor of unity,as well as a laser with only a few quantum dots providing the *** is found that the combined exploration of intensity,coherence time,photon autocorrelation function and carrier spectral hole burning can provide a unique and consistent picture of nanolasers in the new regimes of laser operation during the transition from thermal to coherent ***,by reducing the number of quantum dots in the optical cavity,a clear indication of non-classical photon statistics is observed before the single-quantum-dot limit is reached.

关键词： nanolasers optoelectronics photon statistics quantum light sources quantum optics semiconductor quantum dots thresholdless lasing

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