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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： Jiank.n Xie Dongsheng wang John van Leeuwen Yanmei Zhao Linan Xing christopher w. k. chow State k.y 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 alk.linity 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 drink.ng water treatment plants.

关键词： enhanced coagulation modeling DOM fractionation pH control

Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography

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Journal of Environmental Sciences 2016年第4期28卷 236-245页

作者： Huiping Huang christopher w.k.chow Bo Jin School of Chemical Engineering The University of Adelaide School of Earth and Environmental Sciences The University of Adelaide Australian water Quality Centre SA Water Corporation

Understanding the complexity of dissolved organic matter（DOM）in stormwater has drawn a lot of interest,since DOM from stormwater causes not only environmental impacts,but also worsens downstream aquatic quality associated with water supply and *** study introduced and employed high-performance size exclusion chromatography（HPSEC）coupled with an ultraviolet–visible（UV–vis）diode array detector to assess changes in stormwater-associated DOM *** DOM was also analysed in relation to storm event characteristics,water quality and spectroscopic *** tools were used to determine the correlations within DOM and water quality *** showed that dissolved organic carbon（DOC）and UV absorbance at 254 nm（UV（254））as conventional DOM parameters were found to be correlated well to the changes in stormwater quality during each of the three storm events *** detector wavelengths（210and 254 nm）and their ratio（A（210）/A（254））were found to provide additional information on the physiochemical properties of stormwater-associated *** study indicated that A（210）/A（254） is an important parameter which could be used to estimate the DOM proportions of functional groups and conjugated carbon *** study provided also an understanding of stormwater quality constituents through assessing variability and sensitivity for various parameters,and the additional information of rainfall characteristics on runoff quality data for a better understanding of parameter correlations and influences.

关键词： Stormwater Dissolved organic matter HPSEC

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.Jahnk. 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

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 Drik.s 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 drink.ng 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 pack.ge 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 k.a 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 Drik.s 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 drink.ng 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 drink.ng 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 k.netic parameters of the model for three water sources in Australia was *** was found that with the same water source,the k.netic 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 Drink.ng 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 Drik.s John van Leeuwen Dongsheng wang Zhizhen Xu State k.y 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 k.y Laboratory of Occupational Safety and Health Beijing Municipal Institute of Labor Protection

Minimizing particles in water is a k.y goal for improving drink.ng 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 drink.ng 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 drink.ng 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

Intracellular signaling mechanisms regulating the activation of human eosinophils by the novel Th2 cytok.ne IL-33:implications for allergic inflammation

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Cellular & Molecular Immunology 2010年第1期7卷 26-34页

作者： Joyce YS chow Chun k.wong Phyllis FY Cheung christopher wk.Lam Department of Chemical Pathology The Chinese University of Hong KongPrince of Wales HospitalShatinNTHong KongChina Macao Institute for Applied Research in Medicine and Health Macao University of Science and Technology FoundationMacaoChina

The novel interleuk.n(IL)-1 family cytok.ne IL-33 has been shown to activate T helper 2(Th2)lymphocytes,mast cells and basophils to produce an array of proinflammatory cytok.nes,as well as to mediate blood eosinophilia,IgE secretion and hypertrophy of airway epithelium in *** the present study,we characterized the activation of human eosinophils by IL-33,and investigated the underlying intracellular signaling ***-33 mark.dly enhanced eosinophil survival and upregulated cell surface expression of the adhesion molecule intercellular adhesion molecule(ICAM)-1 on eosinophils,but it suppressed that of ICAM-3 and *** addition,IL-33 mediates significant release of the proinflammatory cytok.ne IL-6 and the chemok.nes CXCL8 and *** found that IL33-mediated enhancement of survival,induction of adhesion molecules,and release of cytok.nes and chemok.nes were differentially regulated by activation of the nuclear factor(NF)-k.,p38 mitogen-activated protein k.nase(MAPk.and extracellular signal-regulated k.nase(ERk.***,we compared the above IL-33 activities with two structurally and functionally related cytok.nes,IL-1 B and ***-1β,but not IL-18,mark.dly upregulated cell surface expression of ***-1βand IL-18 also significantly enhanced eosinophil survival,and induced the release of IL-6 and chemok.nes CXCL8 and CCL2 via the activation of the NF-κB,p38 MAPk.and ERk.*** efects on the release of IL-6 were also observed in combined treatment withIL-1B,IL-18 and *** together,our findings provide insight into IL-33-mediated activation of eosinophils via differential intracellular signaling cascades in the immunopathogenesis of allergic inflammation.

关键词： allergy cytok.nes eosinophils signal transduction