Igneous intrusion into coal-bearing strata can cause an abrupt increase of temperature-pressure and trigger hydrothermal circulation at the igneous rock-coal contact zone. The conductive heat of intruded lnagma and co...Igneous intrusion into coal-bearing strata can cause an abrupt increase of temperature-pressure and trigger hydrothermal circulation at the igneous rock-coal contact zone. The conductive heat of intruded lnagma and convective migration of secondary hydrothermal fluids have been observed to significantly alter the concentrations and modes of occurrence of mercury (Hg) in thermally-intruded coals.展开更多
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 ...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 Nia 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.展开更多
Objective: To evaluate the interactions between the crude extracts of Cocos nucifera(C.nucifera) and six front line antibiotics(ampicillin sodium salt, penicillin G sodium,amoxicillin, chloramphenicol, ciprofloxacin a...Objective: To evaluate the interactions between the crude extracts of Cocos nucifera(C.nucifera) and six front line antibiotics(ampicillin sodium salt, penicillin G sodium,amoxicillin, chloramphenicol, ciprofloxacin and tetracycline hydrochloride), against some bacterial pathogens linked with human infection.Methods: The pulverized husk of C.nucifera was dissolved in 95% n-hexane and extracted using Soxhlet extraction method and sterile distilled water(aqueous).The antibacterial susceptibility of the crude extracts of C.nucifera was tested against environmental and clinical strains(6) obtained from the South African Bureau of Standards(SABS), Vibrio(6) and Listeria pathogens(6).The agar-well diffusion method was used for screening the extracts for their antibacterial activity.The minimum inhibitory concentration and minimum bactericidal concentration of the extracts were determined.Time-kill assay was used to evaluate bactericidal and/or bacteriostatic activity.The synergistic effect of the crude extracts and antibiotics was assessed and evaluated by adopting the checkerboard methods.Results: With the time-kill assay, the highest bactericidal activity was observed on Vibrio fluvialis EL041 with a-5.6 ± 0.2 log_(10)CFU/mL decrease in cell density as a result of the combination of the extracts and chloramphenicol at two-fold minimum inhibitory concentrations.Synergisms using the time-kill assay constituted about 72%, while indifference constituted about 28%.The checkerboard method revealed synergistic interaction in 67% of the combinations, and indifference in 33%.There was no specificity in the observed synergy to a particular class of antibiotics.Conclusions: This investigation suggests the crude extracts of C.nucifera to be a potential broad spectrum antimicrobial compound.Therefore, further study is needed to isolate the pure compounds from these crude extracts.展开更多
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...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.展开更多
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 treatme...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 monochloramines.However, 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.展开更多
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-perfor...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.展开更多
We studied the formation of four nitrogenous DBPs(N-DBPs) classes(haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines), as well as trihalomethanes and total organic halogen(TOX), after chlori...We studied the formation of four nitrogenous DBPs(N-DBPs) classes(haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines), as well as trihalomethanes and total organic halogen(TOX), after chlorination or chloramination of source waters. We also evaluated the relative and additive toxicity of N-DBPs and water treatment options for minimisation of N-DBPs. The formation of halonitromethanes, haloacetamides, and N-nitrosamines was higher after chloramination and positively correlated with dissolved organic nitrogen or total nitrogen. N-DBPs were major contributors to the toxicity of both chlorinated and chloraminated waters. The strong correlation between bromide concentration and the overall calculated DBP additive toxicity for both chlorinated and chloraminated source waters demonstrated that formation of brominated haloacetonitriles was the main contributor to toxicity. Ozone–biological activated carbon treatment was not effective in removing N-DBP precursors. The occurrence and formation of N-DBPs should be investigated on a case-by-case basis, especially where advanced water treatment processes are being considered to minimise their formation in drinking waters, and where chloramination is used for final disinfection.展开更多
A freshwater microalga, Chlorella vulgaris, was grown in the presence of varying phosphate concentrations(〈 10–500 μg/L P) and environmentally realistic concentrations of arsenate(As(Ⅴ))(5–50 μg/L As). A...A freshwater microalga, Chlorella vulgaris, was grown in the presence of varying phosphate concentrations(〈 10–500 μg/L P) and environmentally realistic concentrations of arsenate(As(Ⅴ))(5–50 μg/L As). Arsenic speciation in the culture medium and total cellular arsenic were measured using AEC-ICP-MS and ICP-DRC-MS, respectively, to determine arsenic biotransformation and uptake in the various phosphorus scenarios. At high phosphate concentration in the culture medium, 〉 100 μg/L P, the uptake and biotransformation of As(Ⅴ) was minimal and dimethylarsonate(DMAs(Ⅴ)) was the dominant metabolite excreted by C. vulgaris, albeit at relatively low concentrations. At common environmental P concentrations, 0–50 μg/L P, the uptake and biotransformation of As(Ⅴ) increased. At these higher As-uptake levels, arsenite(As(Ⅲ)) was the predominant metabolite excreted from the cell. The concentrations of As(Ⅲ) in these low P conditions were much higher than the concentrations of methylated arsenicals observed at the various P concentrations studied. The switchover threshold between the(small) methylation and(large) reduction of As(Ⅴ) occurred around a cellular As concentration of 1 fg/cell. The observed nearly quantitative conversion of As(Ⅴ) to As(Ⅲ) under low phosphate conditions indicates the importance of As(Ⅴ) bio-reduction at common freshwater P concentrations. These findings on the influence of phosphorus on arsenic uptake, accumulation and excretion are discussed in relation to previously published research. The impact that the two scenarios of As(Ⅴ) metabolism, As(Ⅲ) excretion at high As(Ⅴ)-uptake and methylarsenical excretion at low As(Ⅴ)-uptake, have on freshwater arsenic speciation is discussed.展开更多
The reclamation and disinfection of waters impacted by human activities(e.g., wastewater effluent discharges) are of growing interest for various applications but has been associated with the formation of toxic nitr...The reclamation and disinfection of waters impacted by human activities(e.g., wastewater effluent discharges) are of growing interest for various applications but has been associated with the formation of toxic nitrogenous disinfection byproducts(N-DBPs). Monochloramine used as an alternative disinfectant to chlorine can be an additional source of nitrogen in the formation of N-DBPs. Individual toxicity assays have been performed on many DBPs, but few studies have been conducted with complex mixtures such as wastewater effluents. In this work, we compared the cytotoxicity and genotoxicity of wastewater effluent organic matter(Ef OM) before and after chloramination. The toxicity of chloraminated Ef OM was significantly higher than the toxicity of raw Ef OM, and the more hydrophobic fraction(HPO)isolated on XAD-8 resin was more toxic than the fraction isolated on XAD-4 resin.More DBPs were also isolated on the XAD-8 resin. N-DBPs(i.e., haloacetonitriles or haloacetamides) were responsible for the majority of the cytotoxicity estimated from DBP concentrations measured in the XAD-8 and XAD-4 fractions(99.4% and 78.5%, respectively).Measured DBPs accounted for minor proportions of total brominated and chlorinated products, which means that many unknown halogenated compounds were formed and can be responsible for a significant part of the toxicity. Other non-halogenated byproducts(e.g.,nitrosamines) may contribute to the toxicity of chloraminated effluents as well.展开更多
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 asso...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 treatability.This 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 characteristics.Stormwater DOM was also analysed in relation to storm event characteristics,water quality and spectroscopic analysis.Statistical tools were used to determine the correlations within DOM and water quality measurements.Results 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 studied.Both 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 DOM.This 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 species.This 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.展开更多
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 disinfectant.In this study,potential association between high pe...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 disinfectant.In 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 investigated.An 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 occurrences.The C.D.Is 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 C.D.I.increase.These 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.展开更多
Municipal wastewater consists of a downstream collection of flushed sewage(without solid waste),other household runoffs,industrial runoffs,hospital runoffs and agricultural runoffs through an underground pipe before t...Municipal wastewater consists of a downstream collection of flushed sewage(without solid waste),other household runoffs,industrial runoffs,hospital runoffs and agricultural runoffs through an underground pipe before treatment.A runoff collection system called the wastewater treatment plant(WWTPs)treats such wastewater before release into environment following specific regulatory standards.This years-long practice has been improved upon by adding end-to-end pipe technologies with a view to enhancing the quality of effluent released.However,effluents released into the environment from design/application of WWTPs appear to contain emerging contaminants of both biotic and abiotic nature.The observation of chemical contaminants,antibiotic resistant bacteria(ARB),antibiotic resistant genes(ARGs)and diverse pathogenic bacteria genera in wastewater works release further affirm the abundance of such emerging contaminants.As a result,the government and water regulatory organizations in various part of the world are considering the removal of water reuse act from recycling policy/process.Current global debate is focused on questions about sustenance of any improved additional treatment level;effect of energy consumption by added treatment stage and its impact on the environmental wellness as contaminants borne wastewater is consistently released.Technological advancement/research suggests implementation of newer innovative infrastructural systems(NIIS)such as Mobbing Bed Biofilm Rector(MBBR),for wastewater effluent management which involve addition of newer wastewater treatment stages.This review addressed current pitfalls including wastewater microbiota of high epidemiological/public health relevance and affirms the need for such improvement which requires modification of ongoing institutional framework with a view to encourage implementation of NIIS for an improved effluent release.Exploiting the advances of microbial biofilming and the potentials of microbial biofueling as discussed in various section promises a future of robust environmental system,stable operational standard,release of quality effluent and sustainable management of wastewater works.Application of the aforementioned would enhance qualityWWTPs release and in-defacto reduces spread of ARB/ARGs as well as impacts both the environment wellness and public health.展开更多
This study investigated the presence of pharmaceuticals in the water and sediment of Buffalo and Sundays River Estuary,South Africa.Extraction for water and sediment samples was achieved with solidphase extraction and...This study investigated the presence of pharmaceuticals in the water and sediment of Buffalo and Sundays River Estuary,South Africa.Extraction for water and sediment samples was achieved with solidphase extraction and ultrasonic extraction methods,respectively.Quantification of the target analytes was done with UPLC-QTOF-MS.The pH of surface water in all the sampling sites(8.18-10.1)were above the WHO guideline(6.5).A good correlation was observed between the concentrations of analytes with organic matter and organic carbon.Results showed that carbamazepine exhibited the highest concentration(8.75±1.45 mg/kg)of all the pharmaceuticals,while trimethoprim has the highest detection frequency with the highest concentration of 1.62±0.83 mg/kg in the sediment samples.Sulfamethoxazole was below the detection limit in both estuaries.Calculated risk quotients revealed that carbamazepine and trimethoprim could be of potential risk,while caffeine may pose a very low risk to the aquatic organisms investigated.Proper monitoring of the runoff entering Buffalo Estuary is required,being the point of discharge of Buffalo River to the Indian Ocean.Also,the domestic waste discharge from residences in the surroundings of Sundays Estuary should be monitored.展开更多
Maintaining soil fertility, while controlling pollution from excessive chemical fertilizer application is important for keeping soil productivity of sustainable agriculture. Variety of straws have been used and proven...Maintaining soil fertility, while controlling pollution from excessive chemical fertilizer application is important for keeping soil productivity of sustainable agriculture. Variety of straws have been used and proven to be good soil amendments for increasing soil organic matter (OM) and a range of additional soil nutrients. However, little is known about the utilization of cotton straw for soil amendment. To better understand the mechanism behind cotton straw soil amendments, investigations were performed upon cucumber seedlings, where changes to soil nutrients and microbial communities were investigated. The results revealed that the cotton straw application promoted the cucumber seedling growth by significantly increasing the soil OM, available nitrogen, available phosphorus, and available potassium. The concentration of cotton straw was positively correlated to both the number of the culturable microorganisms and also the total microbial biomass within soil. Furthermore, assessment of cotton straw application using Biolog metabolic profiling and phospholipid fatty acid analysis revealed that such application increased the microbial community metabolic activity, and markedly changed the structure of microbial community. 16S rRNA gene clone library construction and phylogenetic analysis of soil bacteria revealed 7- Proteobacteria sequences dominated the cotton straw amendment soil, comprising 27.8% of the total number of analyzed sequences, while they were less represented in control soil (13.4%). On the contrary, the Sphingobacteria (7.8%) and Verrucomicrobia (2.4%) in the cotton straw amendment soil decreased after application when compared to the control soil 15.2% and 15.2%.展开更多
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 h...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 investigated.These 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 seasons.It was found that the final pH after enhanced coagulation for each of the four coagulants was in?uenced by the content of removable DOM(i.e.hydrophobic 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 analysis.The established models were preliminarily validated for prediction purposes,and it was found that the deviation between the predicted data and actual data was low.This result demonstrated the potential for the application of these models in practical operation of drinking water treatment plants.展开更多
基金supported by the National Natural Science Foundation of China(grants No.41373108 and 41602167)
文摘Igneous intrusion into coal-bearing strata can cause an abrupt increase of temperature-pressure and trigger hydrothermal circulation at the igneous rock-coal contact zone. The conductive heat of intruded lnagma and convective migration of secondary hydrothermal fluids have been observed to significantly alter the concentrations and modes of occurrence of mercury (Hg) in thermally-intruded coals.
基金supported by a South Australian Premier's Science and Research Fund project‘Development of Materials Engineering Solutions for Treatment of Murray-Darling Basin Sourced Water Supplies’and the Australian Research Council through the ARC Linkage Project‘Materials Engineering Solutions for Tomorrow's Water Resources’,LP100100616
文摘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 Nia 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.
基金the South Africa Medical Research Councilthe National Research Foundation of South Africa for financial support
文摘Objective: To evaluate the interactions between the crude extracts of Cocos nucifera(C.nucifera) and six front line antibiotics(ampicillin sodium salt, penicillin G sodium,amoxicillin, chloramphenicol, ciprofloxacin and tetracycline hydrochloride), against some bacterial pathogens linked with human infection.Methods: The pulverized husk of C.nucifera was dissolved in 95% n-hexane and extracted using Soxhlet extraction method and sterile distilled water(aqueous).The antibacterial susceptibility of the crude extracts of C.nucifera was tested against environmental and clinical strains(6) obtained from the South African Bureau of Standards(SABS), Vibrio(6) and Listeria pathogens(6).The agar-well diffusion method was used for screening the extracts for their antibacterial activity.The minimum inhibitory concentration and minimum bactericidal concentration of the extracts were determined.Time-kill assay was used to evaluate bactericidal and/or bacteriostatic activity.The synergistic effect of the crude extracts and antibiotics was assessed and evaluated by adopting the checkerboard methods.Results: With the time-kill assay, the highest bactericidal activity was observed on Vibrio fluvialis EL041 with a-5.6 ± 0.2 log_(10)CFU/mL decrease in cell density as a result of the combination of the extracts and chloramphenicol at two-fold minimum inhibitory concentrations.Synergisms using the time-kill assay constituted about 72%, while indifference constituted about 28%.The checkerboard method revealed synergistic interaction in 67% of the combinations, and indifference in 33%.There was no specificity in the observed synergy to a particular class of antibiotics.Conclusions: This investigation suggests the crude extracts of C.nucifera to be a potential broad spectrum antimicrobial compound.Therefore, further study is needed to isolate the pure compounds from these crude extracts.
基金supported by the National Natural Science Foundation of China (No. 51025830)the National Basic Research Program of (973) China (No.2011CB933700)+1 种基金the South Australian Premier’s Science and Research Fund Project "Development of materials engineering solutions for treatment of Murray-Darling Basin sourced water supplies"supported by the special fund from the State Key Laboratory of Environmental Aquatic Chemistry, Project 08K08ESPCR
文摘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.
基金the Australian Research Council (LP110100548 and LP130100602)Water Corporation of Western Australia+3 种基金Water Research AustraliaCurtin University for supporting this studyCurtin University (Curtin International Postgraduate Research Scholarship)Water Research Australia (WaterRA PhD Scholarship)
文摘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 monochloramines.However, 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.
基金the Australian Research Council (ARC) for financial support of the Linkage Project 110100459 - Multi-scale Strategy to Manage Chloramine Decay and Nitrification in Water Distribution Systems
文摘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.
基金Funding from the Australian Research Council (LP100100548)Water Corporation of Western Australia+1 种基金Curtin UniversityWater Research Australia
文摘We studied the formation of four nitrogenous DBPs(N-DBPs) classes(haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines), as well as trihalomethanes and total organic halogen(TOX), after chlorination or chloramination of source waters. We also evaluated the relative and additive toxicity of N-DBPs and water treatment options for minimisation of N-DBPs. The formation of halonitromethanes, haloacetamides, and N-nitrosamines was higher after chloramination and positively correlated with dissolved organic nitrogen or total nitrogen. N-DBPs were major contributors to the toxicity of both chlorinated and chloraminated waters. The strong correlation between bromide concentration and the overall calculated DBP additive toxicity for both chlorinated and chloraminated source waters demonstrated that formation of brominated haloacetonitriles was the main contributor to toxicity. Ozone–biological activated carbon treatment was not effective in removing N-DBP precursors. The occurrence and formation of N-DBPs should be investigated on a case-by-case basis, especially where advanced water treatment processes are being considered to minimise their formation in drinking waters, and where chloramination is used for final disinfection.
基金provided by the Ontario Ministry of the Environment's ‘Best in Science’ program
文摘A freshwater microalga, Chlorella vulgaris, was grown in the presence of varying phosphate concentrations(〈 10–500 μg/L P) and environmentally realistic concentrations of arsenate(As(Ⅴ))(5–50 μg/L As). Arsenic speciation in the culture medium and total cellular arsenic were measured using AEC-ICP-MS and ICP-DRC-MS, respectively, to determine arsenic biotransformation and uptake in the various phosphorus scenarios. At high phosphate concentration in the culture medium, 〉 100 μg/L P, the uptake and biotransformation of As(Ⅴ) was minimal and dimethylarsonate(DMAs(Ⅴ)) was the dominant metabolite excreted by C. vulgaris, albeit at relatively low concentrations. At common environmental P concentrations, 0–50 μg/L P, the uptake and biotransformation of As(Ⅴ) increased. At these higher As-uptake levels, arsenite(As(Ⅲ)) was the predominant metabolite excreted from the cell. The concentrations of As(Ⅲ) in these low P conditions were much higher than the concentrations of methylated arsenicals observed at the various P concentrations studied. The switchover threshold between the(small) methylation and(large) reduction of As(Ⅴ) occurred around a cellular As concentration of 1 fg/cell. The observed nearly quantitative conversion of As(Ⅴ) to As(Ⅲ) under low phosphate conditions indicates the importance of As(Ⅴ) bio-reduction at common freshwater P concentrations. These findings on the influence of phosphorus on arsenic uptake, accumulation and excretion are discussed in relation to previously published research. The impact that the two scenarios of As(Ⅴ) metabolism, As(Ⅲ) excretion at high As(Ⅴ)-uptake and methylarsenical excretion at low As(Ⅴ)-uptake, have on freshwater arsenic speciation is discussed.
基金supported by the King Abdullah University of Science and Technology (KAUST) Office of Competitive Research Funds, entitled "Nitrogenous Disinfection By-Products in Reclaimed Wastewater Effluents: Chemistry, Toxicity and Control Strategies"
文摘The reclamation and disinfection of waters impacted by human activities(e.g., wastewater effluent discharges) are of growing interest for various applications but has been associated with the formation of toxic nitrogenous disinfection byproducts(N-DBPs). Monochloramine used as an alternative disinfectant to chlorine can be an additional source of nitrogen in the formation of N-DBPs. Individual toxicity assays have been performed on many DBPs, but few studies have been conducted with complex mixtures such as wastewater effluents. In this work, we compared the cytotoxicity and genotoxicity of wastewater effluent organic matter(Ef OM) before and after chloramination. The toxicity of chloraminated Ef OM was significantly higher than the toxicity of raw Ef OM, and the more hydrophobic fraction(HPO)isolated on XAD-8 resin was more toxic than the fraction isolated on XAD-4 resin.More DBPs were also isolated on the XAD-8 resin. N-DBPs(i.e., haloacetonitriles or haloacetamides) were responsible for the majority of the cytotoxicity estimated from DBP concentrations measured in the XAD-8 and XAD-4 fractions(99.4% and 78.5%, respectively).Measured DBPs accounted for minor proportions of total brominated and chlorinated products, which means that many unknown halogenated compounds were formed and can be responsible for a significant part of the toxicity. Other non-halogenated byproducts(e.g.,nitrosamines) may contribute to the toxicity of chloraminated effluents as well.
基金supported by Water Quality Research Australia(Project No.1020-09)a SA Water Capital Project to setup the monitoring system
文摘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 treatability.This 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 characteristics.Stormwater DOM was also analysed in relation to storm event characteristics,water quality and spectroscopic analysis.Statistical tools were used to determine the correlations within DOM and water quality measurements.Results 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 studied.Both 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 DOM.This 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 species.This 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.
基金supported under Australian Research Council's Linkage Projects funding scheme(LP110100459)the provision of in-kind and financial support from the Australian Water Quality Centre(SA Water),Water Corporation(Western Australia),and DCM Process Control
文摘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 disinfectant.In 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 investigated.An 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 occurrences.The C.D.Is 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 C.D.I.increase.These 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.
文摘Municipal wastewater consists of a downstream collection of flushed sewage(without solid waste),other household runoffs,industrial runoffs,hospital runoffs and agricultural runoffs through an underground pipe before treatment.A runoff collection system called the wastewater treatment plant(WWTPs)treats such wastewater before release into environment following specific regulatory standards.This years-long practice has been improved upon by adding end-to-end pipe technologies with a view to enhancing the quality of effluent released.However,effluents released into the environment from design/application of WWTPs appear to contain emerging contaminants of both biotic and abiotic nature.The observation of chemical contaminants,antibiotic resistant bacteria(ARB),antibiotic resistant genes(ARGs)and diverse pathogenic bacteria genera in wastewater works release further affirm the abundance of such emerging contaminants.As a result,the government and water regulatory organizations in various part of the world are considering the removal of water reuse act from recycling policy/process.Current global debate is focused on questions about sustenance of any improved additional treatment level;effect of energy consumption by added treatment stage and its impact on the environmental wellness as contaminants borne wastewater is consistently released.Technological advancement/research suggests implementation of newer innovative infrastructural systems(NIIS)such as Mobbing Bed Biofilm Rector(MBBR),for wastewater effluent management which involve addition of newer wastewater treatment stages.This review addressed current pitfalls including wastewater microbiota of high epidemiological/public health relevance and affirms the need for such improvement which requires modification of ongoing institutional framework with a view to encourage implementation of NIIS for an improved effluent release.Exploiting the advances of microbial biofilming and the potentials of microbial biofueling as discussed in various section promises a future of robust environmental system,stable operational standard,release of quality effluent and sustainable management of wastewater works.Application of the aforementioned would enhance qualityWWTPs release and in-defacto reduces spread of ARB/ARGs as well as impacts both the environment wellness and public health.
基金funded by the South African Medical Research Council(grant number UFH/SAMRC/P790).
文摘This study investigated the presence of pharmaceuticals in the water and sediment of Buffalo and Sundays River Estuary,South Africa.Extraction for water and sediment samples was achieved with solidphase extraction and ultrasonic extraction methods,respectively.Quantification of the target analytes was done with UPLC-QTOF-MS.The pH of surface water in all the sampling sites(8.18-10.1)were above the WHO guideline(6.5).A good correlation was observed between the concentrations of analytes with organic matter and organic carbon.Results showed that carbamazepine exhibited the highest concentration(8.75±1.45 mg/kg)of all the pharmaceuticals,while trimethoprim has the highest detection frequency with the highest concentration of 1.62±0.83 mg/kg in the sediment samples.Sulfamethoxazole was below the detection limit in both estuaries.Calculated risk quotients revealed that carbamazepine and trimethoprim could be of potential risk,while caffeine may pose a very low risk to the aquatic organisms investigated.Proper monitoring of the runoff entering Buffalo Estuary is required,being the point of discharge of Buffalo River to the Indian Ocean.Also,the domestic waste discharge from residences in the surroundings of Sundays Estuary should be monitored.
文摘Maintaining soil fertility, while controlling pollution from excessive chemical fertilizer application is important for keeping soil productivity of sustainable agriculture. Variety of straws have been used and proven to be good soil amendments for increasing soil organic matter (OM) and a range of additional soil nutrients. However, little is known about the utilization of cotton straw for soil amendment. To better understand the mechanism behind cotton straw soil amendments, investigations were performed upon cucumber seedlings, where changes to soil nutrients and microbial communities were investigated. The results revealed that the cotton straw application promoted the cucumber seedling growth by significantly increasing the soil OM, available nitrogen, available phosphorus, and available potassium. The concentration of cotton straw was positively correlated to both the number of the culturable microorganisms and also the total microbial biomass within soil. Furthermore, assessment of cotton straw application using Biolog metabolic profiling and phospholipid fatty acid analysis revealed that such application increased the microbial community metabolic activity, and markedly changed the structure of microbial community. 16S rRNA gene clone library construction and phylogenetic analysis of soil bacteria revealed 7- Proteobacteria sequences dominated the cotton straw amendment soil, comprising 27.8% of the total number of analyzed sequences, while they were less represented in control soil (13.4%). On the contrary, the Sphingobacteria (7.8%) and Verrucomicrobia (2.4%) in the cotton straw amendment soil decreased after application when compared to the control soil 15.2% and 15.2%.
基金supported by the National Natural Science Foundation of China (No. 50921064,51025830)the National Basic Research Program (973) of China(No. 2011CB933700)the Special Co-construction Project of Beijing Municipal Commission of Education
文摘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 investigated.These 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 seasons.It was found that the final pH after enhanced coagulation for each of the four coagulants was in?uenced by the content of removable DOM(i.e.hydrophobic 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 analysis.The established models were preliminarily validated for prediction purposes,and it was found that the deviation between the predicted data and actual data was low.This result demonstrated the potential for the application of these models in practical operation of drinking water treatment plants.