ORCID Profile
0000-0001-5829-8944
Current Organisation
University of South Australia
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Publisher: Informa UK Limited
Date: 12-2009
DOI: 10.5004/DWT.2009.972
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.WATRES.2007.12.006
Abstract: Conventional coagulation is not an effective treatment option to remove natural organic matter (NOM) in water with high alkalinity H. For this type of water, enhanced coagulation is currently proposed as one of the available treatment options and is implemented by acidifying the raw water and applying increased doses of hydrolyzing coagulants. Both of these methods have some disadvantages such as increasing the corrosive tendency of water and increasing cost of treatment. In this paper, an improved version of enhanced coagulation through coagulant optimization to treat this kind of water is demonstrated. A novel coagulant, a composite polyaluminum chloride (HPAC), was developed with both the advantages of polyaluminum chloride (PACl) and the additive coagulant aids: PACl contains significant amounts of highly charged and stable polynuclear aluminum hydrolysis products, which is less affected by the pH of the raw water than traditional coagulants (alum and ferric salts) the additives can enhance both the charge neutralization and bridging abilities of PACl. HPAC exhibited 30% more efficiency than alum and ferric salts in dissolved organic carbon (DOC) removal and was very effective in turbidity removal. This result was confirmed by pilot-scale testing, where particles and organic matter were removed synergistically with HPAC as coagulant by sequential water treatment steps including pre-ozonation, coagulation, flotation and sand filtration.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2EW00389A
Abstract: A continuous floc image analyser (C-FIA) was developed for tracking the dynamics of floc particle formation, growth and settling during conventional water treatment. This is based on a new RGB signal for flocculation index determination.
Publisher: Springer Science and Business Media LLC
Date: 07-01-2012
DOI: 10.1007/S11356-011-0714-Y
Abstract: The characteristics of organics in sulphite pulp mill effluent and in the receiving environment of effluent discharge were investigated to assess the basis for the persistence or attenuation of colour. Characterization of organics was conducted through determination of SUVA, specific colour, and molecular weight distribution of organics using high performance size exclusion chromatography and by solid-state (13) C cross polarization (CP) NMR. The characteristics of organics from mill wastewater before and after secondary aerobic treatment, followed by lime treatment and from the receiving environment, an enclosed brackish lake were compared. Changes in the character of organics in lake water over a period of 14 years were studied in the context of changes in mill processing and climate impacts. High colour in mill effluent and in receiving waters correlated with high SUVA and specific colour levels, high molecular weight range and aromatic content. Conversely, lake waters with low colour had UV absorbing compounds of much lower molecular weight range and low relative abundance of aromatic compounds. Attenuation of colour and changes in the character of organics in the receiving environment coincided with increased concentrations of metal cations. These increased concentrations appear to be due to the effects of climate change, lake management and their presence in mill effluent, with subsequent discharge to the lake. Attenuation of colour was found to be predominantly through removal of high molecular weight aromatic compounds where the removal processes could be through adsorption and co-precipitation with alent metals, as well as through dilution processes.
Publisher: IWA Publishing
Date: 03-2013
DOI: 10.2166/WS.2013.036
Abstract: Water quality from the Murray River, Australia, can vary considerably and is expected to become more challenging to treat due to recent drought followed by widespread flooding and future climate change impacts. Better tools are required to help plant operators maintain water quality. Morgan water treatment plant (WTP) operates overnight to take advantage of off-peak electricity, however the stop/start practices add an additional complication to accurate coagulant dosing. Online monitoring and feed forward prediction is ideal in these situations as it can provide information while there is still a chance to make adjustments, unlike the feedback (post-dosing) control achieved with many other methods. Using a multiport s ling arrangement, water quality was monitored at Morgan WTP for a 6 month period. Data were validated against other online parameters and laboratory measured s les. In a comparison of predicted versus actual plant dose, results showed that treatment was optimised when the plant dose was changed in response to product water quality deterioration and eventually matched the prediction, even though this was not known to the operators at the time. The software prediction demonstrated faster reaction to inlet water quality changes and can produce more stable treated water quality. The predicted dose was added to the operator's Supervisory Control and Data Acquisition (SCADA) system for several months as a real-time display to provide an additional tool to aid decision making and instill confidence in the resulting water quality.
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.JES.2015.12.011
Abstract: 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 (200-280nm) 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 254nm, 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 230nm 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 0.2-0.5kDa measured at 210nm 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 s ling points that had decreases in total disinfectant residual. HPSEC-UV measured at 210nm 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.
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CHEMOSPHERE.2008.01.061
Abstract: The photocatalytic removal of humic acid (HA) using TiO2 under UVA irradiation was examined by monitoring changes in the UV(254) absorbance, dissolved organic carbon (DOC) concentration, apparent molecular weight distribution, and trihalomethane formation potentials (THMFPs) over treatment time. A resin fractionation technique in which the s les were fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids, hydrophilic charged (CHA) and hydrophilic neutral (NEU) was also employed to elucidate the changes in the chemical nature of the HA components during treatment. The UVA/TiO2 process was found to be effective in removing more than 80% DOC and 90% UV(254) absorbance. The THMFPs of s les were decreased to below 20 microg l(-1) after treatments, which demonstrate the potential to meet increasingly stringent regulatory level of trihalomethanes in water. Resin fractionation analysis showed that the VHA fraction was decreased considerably as a result of photocatalytic treatments, forming CHA intermediates which were further degraded with increased irradiation time. The NEU fraction, which comprised of non-UV-absorbing low molecular weight compounds, was found to be the most persistent component.
Publisher: Royal Society of Chemistry (RSC)
Date: 20-06-2014
DOI: 10.1039/C4EM00227J
Abstract: The character of dissolved organic matter (DOM) in source water determines its treatability in drinking water treatment. In order to understand and improve drinking water treatment process operations, advanced characterization tools, three-dimensional excitation emission matrix technology (3D-EEM) and high-performance size exclusion chromatography (HPSEC), have been used. The DOM characteristics in both source and treated waters from 52 full-scale drinking water treatment plants of 23 cities in China were investigated. The dissolved organic carbon (DOC) concentration was similar as compared with other countries however, differences in the compositions of DOM between Chinese water sources and those of other countries were observed. The assessment confirmed that the origin of DOM is the key factor influencing its removal. Source water with the lowest anthropogenic source had the best DOC removal. According to the principal component analysis result of DOM characteristics, the source waters were found to be ided into two groups based on geographic location. Source waters in the east, north and center of China where there are larger populations tend to cluster together while those of the southwest, northwest and south of China tend to cluster together. These densely populated areas in China should face a bigger challenge of DOC removal during drinking water treatment. Moreover, it was concluded that more attention should be paid to advanced coagulation or hybrid treatment in the actual water treatment train because of the significant increase of the middle molecular weight fraction (1000-2000 Da) after coagulation treatment.
Publisher: Elsevier BV
Date: 03-2009
Publisher: Elsevier BV
Date: 05-2016
DOI: 10.1016/J.JHAZMAT.2016.01.030
Abstract: Dissolved organic matter (DOM) in surface waters used for drinking purposes can vary markedly in character dependent on their sources within catchments. The character of DOM further influences the formation of disinfection by products when precursor DOM present in drinking water reacts with chlorine during disinfection. Here we report the development of models that describe the formation potential of trihalomethanes (THMFP) dependent on the character of DOM in waters from discrete catchments with specific land-use and soil textures. DOM was characterized based on UV absorbance at 254 nm, apparent molecular weight and relative abundances of protein-like and humic-like compounds. DOM character and Br concentration (up to 0.5 mg/L) were used as variables in models (R(2)>0.93) of THMFP, which ranged from 19 to 649 μg/L. Chloroform concentration (12-594 μg/L) and relative abundance (27-99%) were first modeled (R(2)>0.85) and from these, the abundances of bromodichloromethane and chlorodibromomethane estimated using power and exponential functions, respectively (R(2)>0.98). From these, the abundance of bromoform is calculated. The proposed model may be used in risk assessment of catchment factors on formation of trihalomethanes in drinking water, in context of treatment efficiency for removal of organic matter.
Publisher: Informa UK Limited
Date: 05-2007
Publisher: Elsevier BV
Date: 11-2023
Publisher: American Society of Civil Engineers (ASCE)
Date: 10-2023
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.WATRES.2008.04.017
Abstract: The mechanism of natural organic matter (NOM) removal by AlCl(3) and polyaluminum chloride (PACl) was investigated through bench-scale tests. The fraction distributions of NOM and residual Al after coagulation in solution, colloid and sediment were analyzed as changes of coagulant dosage and pH. The influence of NOM, coagulant dose and pH on coagulation kinetics of AlCl(3) was investigated using photometric dispersion analyzer compared with PACl. Monomeric Al species (Al(a)) shows high ability to satisfy some unsaturated coordinate bonds of NOM to facilitate particle and NOM removal, while most of the flocs formed by Al(a) are small and difficult to settle. Medium polymerized Al species (Al(b)) can destabilize particle and NOM efficiently, while some flocs formed by Al(b) are not large and not easy to precipitate as compared to those formed by colloidal or solid Al species (Al(c)). Thus, Al(c) could adsorb and remove NOM efficiently. The removal of contaminant by species of Al(a), Al(b) and Al(c) follows mechanisms of complexation, neutralization and adsorption, respectively. Unlike preformed Al(b) in PACl, in-situ-formed Al(b) can remove NOM and particle more efficiently via the mechanism of further hydrolysis and transfer into Al(c) during coagulation. While the presence of NOM would reduce Al(b) formed in-situ due to the complexation of NOM and Al(a).
Publisher: Informa UK Limited
Date: 2009
DOI: 10.5004/DWT.2009.168
Publisher: Elsevier BV
Date: 05-2004
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.CHEMOSPHERE.2010.07.013
Abstract: China has a very complex water supply system which relies on many rivers and lakes. As the population and economic development increases, water quality is greatly impacted by anthropogenic processes. This seriously affects the character of the dissolved organic matter (DOM) and imposes operational challenges to the water treatment facilities in terms of process optimization. The aim of this investigation was to compare selected drinking water sources (raw) with different DOM character, and the respective treated waters after coagulation, using simple organic characterization techniques to obtain a better understanding of the impact of source water quality on water treatment. Results from the analyses of selected water s les showed that the dissolved organic carbon (DOC) of polluted waters is generally higher than that of un-polluted waters, but the specific UV absorbance value has the opposite trend. After resolving the high performance size exclusion chromatography (HPSEC) peak components of source waters using peak fitting, the twelve waters studied can be ided into two main groups (micro-polluted and un-polluted) by using cluster analysis. The DOM removal efficiency (treatability) of these waters has been compared using four coagulants. For water sources allocated to the un-polluted group, traditional coagulants (Al(2)(SO(4))(3) and FeCl(3)) achieved better removal. High performance poly aluminum chloride, a new type of composite coagulant, performed very well and more efficiently for polluted waters. After peak fitting the HPSEC chromatogram of each of the treated waters, average removal efficiency of the profiles can be calculated and these correspond well with DOC and UV removal. This provides a convenient tool to assess coagulation removal and coagulant selection.
Publisher: Elsevier BV
Date: 09-2009
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/S1001-0742(10)60493-7
Abstract: Eight typical drinking water supplies in China were selected in this study. Both source and tap water were used to investigate the occurrence of chlorinated disinfection byproducts (DBPs), and seasonal variation in the concentrations of trihalomethanes (THMs) of seven water sources was compared. The results showed that the pollution level for source water in China, as shown by DBP formation potential, was low. The most encountered DBPs were chloroform, dichloroacetic acid, trichloroacetic acid, and chlorodibromoacetic acid. The concentration of every THMs and haloacetic acid (HAA) compound was under the limit of standards for drinking water quality. The highest total THMs concentrations were detected in spring.
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.WATRES.2008.06.023
Abstract: Observations from many countries around the world during the past 10-20 years indicate increasing natural organic matter (NOM) concentration levels in water sources, due to issues such as global warming, changes in soil acidification, increased drought severity and more intensive rain events. In addition to the trend towards increasing NOM concentration, the character of NOM can vary with source and time (season). The great seasonal variability and the trend towards elevated NOM concentration levels impose challenges to the water industry and the water treatment facilities in terms of operational optimisation and proper process control. The aim of this investigation was to compare selected raw and conventionally treated drinking water sources from different hemispheres with regard to NOM character which may lead to better understanding of the impact of source water on water treatment. Results from the analyses of selected Norwegian and Australian water s les showed that Norwegian NOM exhibited greater humic nature, indicating a stronger bias of allochthonous versus autochthonous organic origin. Similarly, Norwegian source waters had higher average molecular weights than Australian waters. Following coagulation treatment, the organic character of the recalcitrant NOM in both countries was similar. Differences in organic character of these source waters after treatment were found to be related to treatment practice rather than origin of the source water. The characterisation techniques employed also enabled identification of the coagulation processes which were not necessarily optimised for dissolved organic carbon (DOC) removal. The reactivity with chlorine as well as trihalomethane formation potential (THMFP) of the treated waters showed differences in behaviour between Norwegian and Australian sources that appeared to be related to residual higher molecular weight organic material. By evaluation of changes in specific molecular weight regions and disinfection parameters before and after treatment, correlations were found that relate treatment strategy to chlorine demand and DBP formation.
Publisher: Elsevier BV
Date: 12-1995
Publisher: Elsevier BV
Date: 2022
Publisher: IWA Publishing
Date: 08-2013
Publisher: Elsevier BV
Date: 05-2016
DOI: 10.1016/J.CHEMOSPHERE.2016.02.030
Abstract: In full scale water treatment operation, the rapid filtration process, as the last step of solid-liquid separation, is largely influenced by floc characteristics. In this study, aluminium sulphate (alum) and nano-Al13 were investigated to understand the influence of coagulant species on the formation and filterability of flocs. At neutral pH, it was found that nano-Al13, a high MW polymer, showed better floc filterability than alum. This is because of the densely compacted and well-distributed size flocs from nano-Al13, even though floc sizes of alum were generally bigger. Al specie distributions of the two coagulants at different pH levels were compared by using electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) to further elucidate the reasons for the superiority of nano-Al13 in floc filterability. Depolymerisation/re-polymerisation of nano-Al13 occurred as pH changed, and Al species from nano-Al13were more abundant than that from alum, especially for the high molecular weight (MW) oligomers such as Al11, Al12, Al13 and Al14. Under the charge neutralisation mechanism, higher MW Al species was found to improve coagulation performance and floc filterability. In addition, breakage resistance and regrowth ability of nano-Al13 was better than alum, at weak acid condition. Flocs formed by the charge neutralisation mechanism readily regenerated after being thoroughly broken up. The floc regrowth ability of nano-Al13 at high shear rates (200 rpm and 300 rpm) was much better than at low shear and better than any shear applied to alum., and the flocs after breakage at 200 rpm and 300 rpm also showed better filterability than other conditions.
Publisher: Elsevier BV
Date: 2009
Publisher: Springer Science and Business Media LLC
Date: 20-10-2020
Publisher: Informa UK Limited
Date: 04-2013
Publisher: IWA Publishing
Date: 02-2009
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2EW00376G
Abstract: An optimized electrocoagulation process was investigated for enhanced removal of dissolved organic matter for eco-friendly drinking water production from surface water sources. A model-based control system was developed for electro-coagulant dosing.
Publisher: Elsevier BV
Date: 10-2010
DOI: 10.1016/J.WATRES.2010.06.033
Abstract: In this study, two of our recently developed laboratory scale wastewater treatment systems, fluidized-bed reactor (FBR) using formulated clay mixture absorbents (clay-FBR adsorption) and an annular slurry photoreactor (ASP) using TiO(2) impregnated kaolin catalysts (TiO(2)-K-ASP) were integrated as an adsorption-photocatalysis hybrid process to treat municipal wastewater as alternative secondary and tertiary treatment for wastewater reclamation. Primary effluent from sewage and secondary effluent from a membrane bioreactor treatment process were used to assess chemical removal capabilities of the FBR and ASP systems, and the hybrid process. The formulated clays-FBR system demonstrated the prevailing removal efficiency toward PO(4)(3-), NO(3)(-) and suspended solids. The TiO(2)-K-ASP showed superior degradation of dissolved organic content while the presence of inorganic ions caused a detrimental effect on its performance. The integration of the adsorption and degradation system as a hybrid treatment process resulted in a synergetic enhancement for the chemical removal efficiency. Complete elimination of PO(4)(3-) content was obtained in the adsorption stage while 30% and 65% NO(3)(-) removal were obtained from the hybrid treatment of the primary and secondary effluents, respectively. The corresponding COD reduction during the photodegradation was further investigated by the high-performance size exclusion chromatography technique, where it revealed the shift of apparent molecular weight of the dissolved organic contaminants toward the smaller region. This present study demonstrated that this adsorption-photocatalysis hybrid technology can be used as a feasible alternative treatment process for wastewater reclamation.
Publisher: IWA Publishing
Date: 04-2010
DOI: 10.2166/WST.2010.833
Abstract: Chitosan, a natural biopolymer, was evaluated for its ability to be used as a coagulant to treat water for potable use both in isolation and in combination with other water treatment technologies, specifically ion-exchange and activated carbon. Chitosan was found to be very effective for particle removal at doses far below those required for equivalent turbidity removal by inorganic coagulants. However in the water sources tested, chitosan was not particularly efficient for dissolved organic carbon (DOC) removal when applied as the sole treatment step. When applied as the final clarification stage of a multi-step treatment process, chitosan exhibited limited turbidity reduction due to specific flocculation requirements. This combination of treatment technologies was also unable to further reduce secondary water quality parameters, such as disinfectant demand and trihalomethane (THM) formation.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/S1001-0742(11)60717-1
Abstract: 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 influenced 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.
Publisher: Informa UK Limited
Date: 2005
DOI: 10.1081/AL-200043469
Publisher: Elsevier BV
Date: 12-1998
Publisher: Elsevier BV
Date: 08-2014
Publisher: Springer Science and Business Media LLC
Date: 10-10-2020
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.WATRES.2010.01.036
Abstract: The effect of TiO2 photocatalytic oxidation on the natural organic matter (NOM) properties of two Australian surface waters were quantified using UV-vis spectroscopy, high performance size exclusion chromatography (HPSEC) with a multi-wavelength UV detector, liquid chromatography with organic carbon detector (LC-OCD), and trihalomethane formation potential (THMFP) analyses. Both the UV absorbance at wavelengths greater than 250 nm and dissolved organic carbon (DOC) content decreased significantly with treatment, although complete mineralization of NOM could not be achieved. Multi-wavelength UV detection of HPSEC analysis was shown to be useful to display further changes to NOM composition and molecular weight profiles because the organic molecules was transformed into compounds that absorb weakly at the typical detection wavelength of 250-260 nm. The multi-wavelength HPSEC results also revealed that photocatalytic oxidation yields by-products with a low aromaticity and low molecular weight. The LC-OCD chromatograms indicated that low molecular acids and neutral compounds remained after photocatalytic oxidation. Those groups of compounds did not seem to contribute significantly to the formation of trihalomethanes.
Publisher: IWA Publishing
Date: 19-08-2021
Abstract: The bacterial regrowth potential (BRP) method was utilised to indirectly measure the assimilable organic carbon (AOC) as an indicator for the assessment of the microbial regrowth potential in drinking water distribution systems. A model using various microbial growth parameters was developed in order to standardise the experimental interpretation for BRP measurement. This study used 82 experimental BRP data sets of water s les collected from the water treatment plant to locations (customer taps) in the distribution system. The data were used to model the BRP process (growth curve) by a data fitting procedure and to obtain a best-fitted equation. Statistical assessment and validation of the model obtained equation by fitting these 82 sets of data were conducted, and the results show average R2 values were 0.987 for treated water s les (collected at the plant prior to chlorination) and 0.983 for tap water (collected at the customer taps). The F values obtained from the F-test are all exceeded their corresponding F critical values, and the results from the t-test also showed a good outcome. These results indicate this model would be successfully applied in modelling BRP in drinking water supply systems.
Publisher: Wiley
Date: 22-09-2023
Publisher: Elsevier BV
Date: 03-1998
Publisher: IWA Publishing
Date: 04-2011
DOI: 10.2166/WST.2011.318
Abstract: The use of integrated membrane systems (a train of treatment processes incorporating one or more membranes) is increasing globally as the technology is very effective for the production of high quality drinking water. In this investigation a laboratory scale integrated membrane system (IMS) featuring coagulation, powdered activated carbon (PAC) and ultrafiltration (UF) was investigated for the removal of an Australian strain of the cyanobacteria Anabaena circinalis and the cyanotoxin it produced. Three coagulants were compared, aluminium chlorohydrate (ACH), aluminium sulphate (alum) and an engineered aluminium coagulant referred to as high performance aluminium chlorohydrate (HPAC). PAC (Acticarb PS1000) was tested to determine adsorption of extracellular saxitoxin. Removal of A. circinalis cells was 100% by UF alone and the removal of cells prior to the membrane by coagulation reduced fouling attributed to algogenic organic material. Alum was the least efficient coagulant for removal of cells while ACH and HPAC were similar. Saxitoxin removal reached a maximum of 80% using ACH and PAC. The UF-IMS was challenged using a natural bloom of A. circinalis that occurred in the Myponga Reservoir in South Australia.
Publisher: MDPI AG
Date: 24-06-2022
DOI: 10.3390/W14132021
Abstract: The conventional drinking water treatment process involves disinfecting water at the final stage of treatment to ensure water is microbiologically safe at customer taps. Monochloramine is a popular disinfectant used in many water distribution systems (WDSs) worldwide. Understanding the factors that impact monochloramine decay in the WDS is critical for maintaining disinfection at the customer tap. While monochloramine residue moves through a WDS, it decays via several pathways including chemical, microbiological, and wall decay processes. The decay profile in these pathways is often site-specific and depends on various factors including treated water characteristics. In a water quality network model, the decay of a chemical species is often modelled using two parameters that represent bulk and wall decay kinetics. Typical bulk decay characteristics of monochloramine for a specific WDS can be easily established in the laboratory using grab s le tests, while in a real situation, wall decay is difficult to quantify. In this study, we compared two different approaches to model monochloramine decay in a WDS. In the first approach, the wall decay parameter was quantified using a parameter optimisation technique with monochloramine concentrations at different network locations simulated using a water quality network model. In the second approach, a data analytics model was developed using a machine learning algorithm. For both approaches, the model predicted monochloramine concentrations closely matched the observed data. Our study suggests that the data analytics model has a relatively higher accuracy in predicting monochloramine residual concentrations in a WDS.
Publisher: Elsevier BV
Date: 10-2009
Publisher: IWA Publishing
Date: 06-2012
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.CHEMOSPHERE.2015.09.066
Abstract: The treatability of NOM present in runoff and subsurface waters from discrete zero-order catchments (ZOCs) with three land management practices (Australian native vegetation, pine plantation, grasslands) on varying soil textures of a closed drinking water reservoir-catchment was investigated. Subsurface water s les were collected by lysimeters and shallow piezometers and surface waters by installation of barriers that erted waters to collection devices. For small s le volumes collected, a 'micro' jar testing procedure was developed to assess the treatability of organics by enhanced coagulation using alum, under standardised conditions. DOM present in water s les was quantified by measurement of DOC and UV absorbance (at 254 nm) and characterized using these and F-EEM. The mean alum dose rate (mg alum per mg DOC removed or Al/DOC) was found to be lower for DOM from sandy soil ZOCs (21.1 ± 11.0 Al/DOC) than from clayey soil ZOCs (38.6 ± 27.7 Al/DOC). ZOCs with Pinus radiata had prominent litter layers (6.3 ± 2.6 cm), and despite differences in soil textures showed similarity in DOM character in subsurface waters, and in alum dose rates (22.2 ± 5.5 Al/DOC). For sandy soil ZOCs, the lowest alum dose rates (16.5 ± 10.6 Al/DOC) were for waters from native vegetation catchment while, for clayey soil ZOCs, waters from pine vegetation had the lowest alum dose rates (23.0 ± 5.0 Al/DOC). Where ZOCs have a prominent O horizon, soil minerals had no apparent influence on the treatability of DOM.
Publisher: Elsevier BV
Date: 08-1996
Publisher: Royal Society of Chemistry (RSC)
Date: 1997
DOI: 10.1039/A703616G
Publisher: Elsevier BV
Date: 08-2014
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.JCIS.2007.08.036
Abstract: The relative importance of three different Al species, Al(a) (monomeric species, instantaneous reacted species), Al(b) (medium polymer species, reacted less than 120 min), and Al(c) (colloidal or solid species, no reaction), defined by timed complexation reaction rate measured by using ferron reagent in polyaluminum chloride (PACl) was investigated in terms of DOC (dissolved organic carbon), UV(254), and turbidity removal efficiencies. Micro-polluted, typical North China, source waters were used to conduct the experiments. The results show that DOC removal is correlated well to the content of Al(b). Removal of UV(254) is determined by the content of Al(b) and Al(c), particularly Al(c). Turbidity removal is primarily related to the content of Al(c) however, Al(b) could destabilize particles efficiently, and the flocs formed by Al(b) are not as large as those formed by Al(c), which affected the settling efficiency. Unlike the preformed Al(b), the in situ formed Al(b) could remove turbidity more efficiently since Al(c) is the dominant final species formed during coagulation. Al(a) shows a strong ability to react with some unsatisfied coordinate bonds of organic matter to facilitate particle and DOC removal. The distinct coagulation feature of Al(a), Al(b), and Al(c) can be applied to develop tailor-made PACl (with the correct distribution of Al species) to match the characteristics of raw water for optimized coagulation.
Publisher: Elsevier BV
Date: 06-2013
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.JHAZMAT.2009.12.049
Abstract: Our recent work reported that a mixed adsorbent with natural clay materials and lime demonstrated an enhanced capacity and efficiency to remove anionic Congo Red dye from wastewater. This study aims to investigate the removal kinetic and mechanisms of the mixed materials involved in the decolourisation of the dye to maximise their prospective applications for industrial wastewater treatment. The experimental results showed that dye removal was governed by combined physiochemical reactions of adsorption, ion-exchange, and precipitation. Ca-dye precipitation contributed over 70% total dye removal, followed by adsorption and ion-exchange. The dye removal kinetic followed the pseudo-second-order expression and was well described by the Freundlich isotherm model. This study indicated pH was a key parameter to govern the removal mechanisms, i.e. adsorption/coagulation at acidic pH and precipitation at basic condition. Yet, the overall removal efficiency was found to be independent to the operation conditions, resulting in more than 94% dye removal. This work revealed that the mixed clays and lime can be applied as alternative low-cost adsorbents for industrial wastewater treatment.
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.WATRES.2012.06.021
Abstract: In this study, the formulation of a novel polyaluminum chloride-chitosan composite coagulant that improves the coagulation process for natural organic matter (NOM) removal was investigated. The performance of the composite coagulant was tested using two water sources (synthetic and natural water) to develop a better understanding on the behaviour of the composite coagulant. Fourier Transform-Infra red (FT-IR) spectroscopy, ferron analysis and zeta potential studies were performed to characterise the composite coagulant. FT-IR analysis showed that there is an intermolecular interaction between Al species and chitosan molecules, while ferron analysis indicated that the distributions of Al(a), Al(b), and Al(c) in PACl-chitosan are different from those in PACl. At a low Al dosage (2.16 mg L⁻¹), a much higher removal of NOM from synthetic water, as evidenced from UV₂₅₄ and Dissolved Organic Carbon (DOC) measurements, was achieved by the composite coagulants in comparison to that removed by PACl or PACl and chitosan added separately. For natural water from the Myponga Reservoir, both polyaluminum chloride (PACl) and PACl-chitosan composite coagulants demonstrated similar dissolved organic carbon (DOC) percentage removal, whereas PACl-chitosan gave a slight improvement in removing the UV₂₅₄ absorbing components of NOM.
Publisher: Springer Science and Business Media LLC
Date: 09-07-2014
Publisher: Elsevier BV
Date: 11-2022
Publisher: Wiley
Date: 06-1999
Publisher: Elsevier BV
Date: 08-1996
Publisher: Elsevier BV
Date: 04-2010
Publisher: IWA Publishing
Date: 13-08-2016
Publisher: Elsevier BV
Date: 10-1999
Publisher: Elsevier BV
Date: 05-1995
Publisher: IEEE
Date: 12-2011
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.WATRES.2014.05.024
Abstract: This study investigated effects of pH, bromide and natural organic matter (NOM) level on yields and speciation of trihalomethanes (THMs) and haloacetic acids (HAAs) in chlorinated water. Experimental data were obtained using two water sources, one with a medium (DOC = 1.4 mg/L and SUVA = 2.60 L mg(-1) m(-1)) and the other with higher (DOC = 7.7 mg/L and SUVA = 4.26 L mg(-1) m(-1)) organic carbon level. The experiments employed the simulated distribution system (SDS) procedure at varying bromide concentrations and pH values of 7.0, 8.5 and 10. The speciation of THMs and dihalogenated HAAs (DHAAs) was interpreted based on the modelling of mixed halogenation yields via dimensionless ratios of bromination/chlorination reaction rates at each halogen incorporation node. The approach allowed precise modelling of the speciation of THMs and DHAAs at all examined pHs. In the case of DHAA, the dimensionless ratios of the bromination/chlorination reaction rates were not consistently affected by pH variations. For THMs, increase of pH caused the values of the dimensionless bromination/chlorination reaction rates to decrease in the case of halogenation of the initial reaction sites indicating a decreasing preference toward bromination at this reaction node. A similar trend was observed for the reactivity of dichlorinated reaction intermediate denoted as SCl2 whose formation precedes the release of CHCl3 and CHBrCl2. A similar but less consistent trend was observed for intermediate SBrCl whose halogenation yields both CHBrCl2 and CHBr2Cl. An opposite trend of increasing preference towards bromination at higher pHs was observed monobrominated intermediate SBr and in some extent dibrominated intermediate SBr2. These results help develop detailed DBP speciation models which needed to better understand the generation and potential health effects of THMs and HAAs at varying operating conditions and ultimately to adopt measure to minimize their levels in drinking water systems.
Publisher: Wiley
Date: 11-2006
Publisher: Elsevier BV
Date: 12-2016
Publisher: American Chemical Society
Date: 05-08-2008
Publisher: Elsevier BV
Date: 06-1995
Publisher: IWA Publishing
Date: 03-2009
DOI: 10.2166/WS.2009.015
Abstract: In this investigation, high-performance size exclusion chromatography (HPSEC) was used to characterise organic matter in treated drinking water at key s ling locations along two selected distribution systems (chlorinated and chloraminated). Other water quality parameters such as colour, UV254, dissolved organic carbon (DOC) and assimilable organic carbon (AOC) as measured by bacterial regrowth potential (BRP), were also determined. One of the aims of this work was to develop new tools to monitor organic character change along the distribution system in order to identify impacting factors and develop management strategies based on water quality change. This study used s les from two contrasting distribution systems with different disinfection regimes and organic characteristics together with s les generated from laboratory simulations. System 1 is a chlorinated distribution system and generally requires elevated chlorine dosage to meet the demand due to the high DOC level. System 2 is a chloraminated system with stable water quality, low DOC and low chloramine dose (mild oxidation). Molecular size distribution determination using HPSEC is a very informative technique in assessing treatment processes and in this study the appearance of a molecular peak at 1,700 Da that can be used as an indicator of biological activity in distribution systems was confirmed. The use of BRP values, for upstream and downstream s les in the distribution system, was found to be a good approach to assess biological impacts on water stability. The observed biological impact from the biofilms between the studied systems were particularly useful in confirming the organic characterisation results.
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.JHAZMAT.2011.01.111
Abstract: Cyanobacterial metabolites, both toxic and non-toxic, are a major problem for the water industry. Nanofiltration (NF) may be an effective treatment option for removing organic micropollutants, such as cyanobacterial metabolites, from drinking water due to its size exclusion properties. A rapid bench scale membrane test (RBSMT) unit was utilised to trial four NF membranes to remove the cyanobacterial metabolites, microcystin, cylindrospermopsin (CYN), 2-methylisoborneol (MIB) and geosmin (GSM) in two treated waters sourced from the Palmer and Myponga water treatment plants. Membrane fouling was observed for both treated waters however, only minor differences were observed between feed waters of differing natural organic matter (NOM) concentration. Low molecular weight cut-off (MWCO), or 'tight' NF, membranes afforded average removals above 90% for CYN, while removal by higher MWCO, or 'loose' NF membranes was lower. MIB and GSM were removed effectively (above 75%) by tight NF but less effectively by loose NF. Microcystin variants (MCRR, MCYR, MCLR, MCLA) were removed to above 90% by tight NF membranes however, removal using loose NF membranes depended on the hydrophobicity and charge of the variant. Different NOM concentration in the treated waters had no effect on the removal of cyanobacterial metabolites.
Publisher: SAGE Publications
Date: 07-1992
DOI: 10.1177/1045389X9200300303
Abstract: A neural network is applied to sensor signal processing in a novel ap proach to the determination of copper in reservoir water. The neural network performed well in determining the correct total of copper concentration in water when provided with only pH and copper(II) ion-selective electrode experimental data. This task followed an initial period of network exposure to a set of experimental data triplets, which were used as ex les of the required input/output data mapping.
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/S1001-0742(11)60923-6
Abstract: 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 s les 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.
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.SCITOTENV.2012.05.078
Abstract: For pollution monitoring, we developed a new combined fractionation technique (CFT) to characterize dissolved organic matter (DOM) in natural water by combining resin adsorption (RA) and ultrafiltration (UF) with 3D-fluorescence measurement. We tested the new technique on 4 polluted and 4 unpolluted s les. The 3D-fluorescence characteristics of size sub-components in the hydrophobic acid (HPOA) fraction could distinguish unpolluted from polluted DOM. The unpolluted HPOA fraction was composed of a single dominant size component-peak A (fulvic-like, around Ex240/Em410 nm) material with relatively large molecular weight (MW) (>10 kDa). In comparison, the HPOA in polluted DOM contained another predominant size component with lower MW (<5 kDa)-peak T material (tryptophan-like protein, around Ex230/Em340 nm). The fluorescence of peak T material with lower MW (<5 kDa) in HPOA would be a good indicator of pollution or deterioration of source water quality. The application of this new CFT could yield more detailed and scientific information on the size and chemical character of the fluorophores in DOM sub-fractions.
Publisher: Elsevier BV
Date: 04-2011
Publisher: Elsevier BV
Date: 11-2011
Publisher: IWA Publishing
Date: 30-09-2014
DOI: 10.2166/WS.2013.199
Abstract: In recent climatic events in Australia, the need for frequent jar testing to determine optimum coagulant and flocculant aid doses became apparent in order to determine optimum treatment efficiencies. The generally applied jar test procedure can be time consuming and this prompted investigations for capacity to test waters more rapidly, for a range of treatment conditions and raw water qualities. The aim of the study reported here was to develop a rapid procedure for determination of dissolved organic matter (DOM) removal, measured as dissolved organic carbon (DOC) and UV absorbance (254 nm/cm) for a range of treatment conditions (coagulant dose and pH). Using a previously established predictive model (mEnCo) for coagulant determination, several coagulant doses were then predicted for application in a modified jar test protocol. Best fitted and predicted data using the exponential decay function compared with data from a 6× jar test procedure were obtained using three doses, 0.5× EnCD, EnCD and a VHD (≥2× EnCD). It is proposed that this procedure may be used to more rapidly determine treatment efficiency based on the removal of organics compared with traditionally applied jar tests.
Publisher: IEEE
Date: 12-2011
Publisher: Elsevier BV
Date: 04-2009
DOI: 10.1016/J.WATRES.2008.12.041
Abstract: Absorbance spectra of fractions of natural organic matter (NOM) with varying apparent molecular weights (AMWs) were examined in this study. Size exclusion chromatography (SEC) was employed to obtain AMW distributions for three Australian water sources which represented low- and high-dissolved organic carbon (DOC) surface waters and a source with highly degraded NOM. These waters were coagulated with alum and other coagulants. Effects of coagulation on AMW distributions were quantified based on an absorbance slope index (ASI) calculated using NOM absorbance measured at 220, 230, 254 and 272 nm. This index can be calculated for any AMW fraction of NOM. Similarly to SUVA(254), ASI values decrease consistently in coagulated waters and are correlated with trihalomethane yields. Comparison of ASI indexes in different water sources indicates the presence of both common trends and differences indicative of NOM site-specificity.
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.JES.2017.01.006
Abstract: Minimizing particles in water is a key goal for improving drinking water quality and safety. The 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 process. In a laboratory-based study, the impacts of the physical characteristics of flocs formed using aluminum sulfate on the filtration treatment of two comparative water s les were investigated using a photometric dispersion analyzer and a filterability apparatus. In general, the optimum dosage for maximizing filterability was higher than that for minimizing turbidity under neutral pH conditions. For a monomeric aluminum-based coagulant, the charge neutralization mechanism produced better floc characteristics, including floc growth speed and size, than the sweep flocculation mechanism. In 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 turbidity. For the different mechanisms, the ways that floc characteristics impacted on floc filterability also differed. The low variation in floc size distribution obtained under the charge neutralization mechanism resulted in the flocs being amenable to removal by filtration processes. For the sweep flocculation mechanism, increasing the floc size improved the settling ability of flocs, resulting in higher filter efficiency.
Publisher: MDPI AG
Date: 13-04-2022
DOI: 10.3390/S22082987
Abstract: Water quality monitoring is an essential component of water quality management for water utilities for managing the drinking water supply. Online UV-Vis spectrophotometers are becoming popular choices for online water quality monitoring and process control, as they are reagent free, do not require s le pre-treatments and can provide continuous measurements. The advantages of the online UV-Vis sensors are that they can capture events and allow quicker responses to water quality changes compared to conventional water quality monitoring. This review summarizes the applications of online UV-Vis spectrophotometers for drinking water quality management in the last two decades. Water quality measurements can be performed directly using the built-in generic algorithms of the online UV-Vis instruments, including absorbance at 254 nm (UV254), colour, dissolved organic carbon (DOC), total organic carbon (TOC), turbidity and nitrate. To enhance the usability of this technique by providing a higher level of operations intelligence, the UV-Vis spectra combined with chemometrics approach offers simplicity, flexibility and applicability. The use of anomaly detection and an early warning was also discussed for drinking water quality monitoring at the source or in the distribution system. As most of the online UV-Vis instruments studies in the drinking water field were conducted at the laboratory- and pilot-scale, future work is needed for industrial-scale evaluation with ab appropriate validation methodology. Issues and potential solutions associated with online instruments for water quality monitoring have been provided. Current technique development outcomes indicate that future research and development work is needed for the integration of early warnings and real-time water treatment process control systems using the online UV-Vis spectrophotometers as part of the water quality management system.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.JHAZMAT.2012.02.039
Abstract: The adsorption of natural organic matter (NOM) from eight typical Chinese surface waters onto alumina was investigated using quartz crystal microbalance with dissipation monitoring (QCM-D). The adsorbed masses of NOM varied between 25ngcm(-2) and 64ngcm(-2), and these showed significant correlation with geographical location, and NOM character and concentrations. Adsorbed mass correlated with DOC concentration (slope k=0.0676, R(2)=0.61) and hydrophobic acid (HoA) and weakly hydrophobic acid (WHoA) (k=0.0342 and 0.0183 R(2)=0.49 and 0.52 for HoA and WHoA, respectively) constituents present in the water s les. The process of adsorbed layer formation was investigated from changes in the ΔD/Δf ratio and viscosity of adsorbed layer with injected time. The adsorbed layer viscosity increased exponentially with injected time (R(2)>0.99) for most s les. S les with low DOC concentration (k=-1091.8, R(2)=0.55) and low content of HoA and WHoA (k=-524.33 and -322.76 R(2)=0.41 and 0.64 for HoA and WHoA, respectively), the slope of logarithm viscosity value is steeper, the property of adsorbed layer and NOM is more inconsistent. The QCM-D technique provides a method to view the process of complexation between NOM and coagulant, and can provide useful information to establish a quantitative calculation model of the coagulation process.
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 30-03-2010
Publisher: Springer Science and Business Media LLC
Date: 13-05-2021
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.JHAZMAT.2013.10.036
Abstract: In this study, we investigated the relationship between water characteristics and removal of natural organic matter (NOM) using polyaluminium chloride (PACl) and a newly developed coagulant obtained by hybridising PACl with chitosan (PACl-chitosan) for two different types of water. Using UV-visible spectroscopy analysis, we showed that PACl-chitosan is more effective than PACl for treating water s les that contain higher levels of activated polyhydroxyaromatic moieties. As a result, a lower level of total trihalomethanes formation potential (THMFP) was detected for synthetic water treated with PACl-chitosan coagulant compared to water treated with PACl only. In contrast, no difference was observed for the total THMFP that were formed following coagulation with either coagulant, for water s le containing the same level of organic carbon concentration, but lower levels of polyhydroxyaromatic moieties. Our work shows how the complex characteristics and interactions of organic matter with coagulant component can affect the outcome of the treatment process, and in this case, enhance the treatment. The use of PACl-chitosan was also shown to produce larger floc for both water s les this again, can lead to better removal.
Publisher: Elsevier BV
Date: 12-2013
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.JHAZMAT.2010.12.049
Abstract: Cyanobacteria are a major problem for the world wide water industry as they can produce metabolites toxic to humans in addition to taste and odour compounds that make drinking water aesthetically displeasing. Removal of cyanobacterial toxins from drinking water is important to avoid serious illness in consumers. This objective can be confidently achieved through the application of the multiple barrier approach to drinking water quality and safety. In this study the use of a multiple barrier approach incorporating coagulation, powdered activated carbon (PAC) and ultrafiltration (UF) was investigated for the removal of intracellular and extracellular cyanobacterial toxins from two naturally occurring blooms in South Australia. Also investigated was the impact of these treatments on the UF flux. In this multibarrier approach, coagulation was used to remove the cells and thus the intracellular toxin while PAC was used for extracellular toxin adsorption and finally the UF was used for floc, PAC and cell removal. Cyanobacterial cells were completely removed using the UF membrane alone and when used in conjunction with coagulation. Extracellular toxins were removed to varying degrees by PAC addition. UF flux deteriorated dramatically during a trial with a very high cell concentration however, the flux was improved by coagulation and PAC addition.
Publisher: IWA Publishing
Date: 05-2009
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 02-2010
Publisher: World Scientific Pub Co Pte Ltd
Date: 22-11-2022
DOI: 10.1142/S0219622021500693
Abstract: A water utility requires myriads of data for effective decision-making. As the sources and ranges of data are becoming increasingly complex, the use of a metadata framework can play a significant role in effective data management. Using case study method, this research analyzed data needs of a water supply system in a small town in South Australia and designed a demo portal of a metadata framework. As part of the case study, the project team undertook a broad investigative approach using focus group (interviews), observation, exploration of potential data sources, identification of knowledge leaders and information technology systems. The metadata framework comprised two separate but interconnected metadata groups, (1) metadata elements to describe the metadata source and (2) metadata elements to describe the datasets held in each data source. The metadata framework was populated to describe data sources and data held in each of the sources. The data catalogue created by this process showed that it was accomplishable and appropriate to describe data sources and datasets via a metadata framework.
Publisher: Elsevier BV
Date: 07-2018
Publisher: IWA Publishing
Date: 03-2010
DOI: 10.2166/WST.2010.903
Abstract: Nanofiltration (NF) has been shown to be an effective way of removing organic micropollutants from drinking water due to its size exclusion properties. A rapid bench scale membrane test unit was utilised to trial six NF membranes to remove the algal metabolites, microcystin, cylindrospermopsin, 2-methylisoborneol (MIB) and geosmin (GSM). Membrane fouling due to the algal metabolites was observed for both charged and neutral metabolites. MIB and GSM were removed effectively by low molecular weight cut-off (MWCO) membranes but less effectively by a higher MWCO membrane. Removal of MIB and GSM by the higher MWCO membrane was improved as the membrane fouled. Microcystin was initially removed to above 90% by tight NF membranes but fouling of several membranes caused decreased percent removals over time. Tight NF membranes afforded removals of 90–100% for cylindrospermopsin, while removal by the higher MWCO membrane was lower but improved with time due to fouling.
Publisher: Informa UK Limited
Date: 10-2012
Publisher: Elsevier BV
Date: 06-2012
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.JES.2017.01.010
Abstract: 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 method. The model is based on organic character (specific ultraviolet absorbance (SUVA)) of the water s les and a laboratory measure of the microbiological (F
Publisher: Informa UK Limited
Date: 19-12-2020
Publisher: IWA Publishing
Date: 07-2011
DOI: 10.2166/WST.2011.432
Abstract: The character of dissolved organic matter (DOM) in source waters from two countries (Australia and China) was investigated using an extended fractionation technique by combining resin adsorption, ultrafiltration and high performance size exclusion chromatography. There are distinctive chemical characteristics associated with DOM origins. Australian sourced DOM had higher hydrophobic acid (HoA) content and exhibited a more pronounced humic character, indicating a higher influence from allochthonous organics (decayed plant bodies from vegetated catchments). The higher content of hydrophobic base and neutral components found in Chinese DOM, may be attributed to the effects of increasing pollution caused by the rapid urbanization in China. The molecular weights (MWs) of aquatic HoA are predominantly in the moderate (e.g. 1–10 kDa) or small (e.g. & kDa) ranges. This suggests that aquatic HoA should not be assumed as high MW organics without experimental validation. It is also found that some of the low MW compounds in our s les were hydrophobic, which could explain the observation of low MW organic compounds being able to be removed by conventional treatment processes.
Publisher: Oxford University Press (OUP)
Date: 22-08-2023
Abstract: Cardiac arrhythmia originating from the papillary muscle (PM) can trigger ventricular fibrillation (VF) and cause sudden cardiac death even in the absence of structural heart disease. Most premature ventricular contractions, however, are benign and hitherto difficult to distinguish from a potentially fatal arrhythmia. Altered repolarization characteristics are associated with electrical instability, but electrophysiological changes which precede degeneration into VF are still not fully understood. Ventricular arrhythmia (VA) was induced by aconitine injection into PMs of healthy sheep. To investigate mechanisms of degeneration of stable VA into VF in structurally healthy hearts, endocardial high-density and epicardial mapping was performed during sinus rhythm (SR) and VA. The electrical restitution curve, modelling the relation of diastolic interval and activation recovery interval (a surrogate parameter for action potential duration), is steeper in VA than in non-arrhythmia (ventricular pacing and SR). Steeper restitution curves reflect electrical instability and propensity to degenerate into VF. Importantly, we find the parameter repolarization time in relation to cycle length (RT/CL) to differentiate self-limiting from degenerating arrhythmia with high specificity and sensitivity. RT/CL may serve as a simple index to aid differentiation between self-limiting and electrically instable arrhythmia with the propensity to degenerate to VF. RT/CL is independent of cycle length and could easily be measured to identify electrical instability in patients.
Publisher: MDPI AG
Date: 12-11-2021
DOI: 10.3390/S21227525
Abstract: Nitrification is a common issue observed in chloraminated drinking water distribution systems, resulting in the undesirable loss of monochloramine (NH2Cl) residual. The decay of monochloramine releases ammonia (NH3), which is converted to nitrite (NO2−) and nitrate (NO3−) through a biological oxidation process. During the course of monochloramine decay and the production of nitrite and nitrate, the spectral fingerprint is observed to change within the wavelength region sensitive to these species. In addition, chloraminated drinking water will contain natural organic matter (NOM), which also has a spectral fingerprint. To assess the nitrification status, the combined nitrate and nitrite absorbance fingerprint was isolated from the total spectra. A novel method is proposed here to isolate their spectra and estimate their combined concentration. The spectral fingerprint of pure monochloramine solution at different concentrations indicated that the absorbance difference between two concentrations at a specific wavelength can be related to other wavelengths by a linear function. It is assumed that the absorbance reduction in drinking water spectra due to monochloramine decay will follow a similar pattern as in ultrapure water. Based on this criteria, combined nitrate and nitrite spectra were isolated from the total spectrum. A machine learning model was developed using the support vector regression (SVR) algorithm to relate the spectral features of pure nitrate and nitrite with their concentrations. The model was used to predict the combined nitrate and nitrite concentration for a number of test s les. Out of these s les, the nitrified s le showed an increasing trend of combined nitrate and nitrite productions. The predicted values were matched with the observed concentrations, and the level of precision by the method was ± 0.01 mg-N L−1. This method can be implemented in chloraminated distribution systems to monitor and manage nitrification.
Publisher: IWA Publishing
Date: 30-01-2015
DOI: 10.2166/WS.2015.010
Abstract: Understanding coagulation behaviour and treatability of waters impacted by algogenic organic matter (AOM) is important for waters with frequent algal blooms. Physico–chemical characteristics of AOM spiked into a water s le, before and after coagulation, were investigated using high-performance size exclusion chromatography (HPSEC) with UV and fluorescence detection, three dimensional-fluorescence excitation emission matrix (3D-FEEM) measurement and resin fractionation in which three fractions were determined including very hydrophobic acid (VHA), slightly hydrophobic acid (SHA) and hydrophilic fractions. Release of AOM from algal cells with consequential increases in dissolved organic carbon and UV absorbance led to changes in 3D-FEEM spectra indicative of increased aromatic protein presence. Changes in disinfection by-product formation potential after the AOM spiking indicated possible interactions between natural organic matter and AOM. A study of the treatability of the AOM spiked water using two coagulants, alum and a polyaluminum composite coagulant, was conducted with the relative percentages of UV absorbance values of both the SHA and hydrophilic fractions higher in the post coagulated AOM spiked water than in the coagulated water, with corresponding reductions in the VHA proportion. It was found that the increased SHA and hydrophilic components in the AOM spiked natural water were recalcitrant to removal by both coagulants.
Publisher: MDPI AG
Date: 11-04-2023
DOI: 10.3390/S23083893
Abstract: In the current practice, an essential element of safety management systems, Job Hazard Analysis (JHA), is performed manually, relying on the safety personnel’s experiential knowledge and observations. This research was conducted to create a new ontology that comprehensively represents the JHA knowledge domain, including the implicit knowledge. Specifically, 115 actual JHA documents and interviews with 18 JHA domain experts were analyzed and used as the source of knowledge for creating a new JHA knowledge base, namely the Job Hazard Analysis Knowledge Graph (JHAKG). To ensure the quality of the developed ontology, a systematic approach to ontology development called METHONTOLOGY was used in this process. The case study performed for validation purposes demonstrates that a JHAKG can operate as a knowledge base that answers queries regarding hazards, external factors, level of risks, and appropriate control measures to mitigate risks. As the JHAKG is a database of knowledge representing a large number of actual JHA cases previously developed and also implicit knowledge that has not been formalized in any explicit forms yet, the quality of JHA documents produced from queries to the database is expectedly higher than the ones produced by an in idual safety manager in terms of completeness and comprehensiveness.
Publisher: Elsevier BV
Date: 02-1997
Publisher: Elsevier BV
Date: 09-2008
Publisher: Elsevier BV
Date: 15-05-2009
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.JES.2016.11.007
Abstract: 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=230nm between apparent molecular weights of 200 to 1000Da was observed at s ling sites that experienced rapid chloramine decay and nitrification while its absorbance signal at λ=254nm 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 254nm, 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.
Publisher: Elsevier BV
Date: 06-2013
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/S1001-0742(10)60464-0
Abstract: Pure nano-Al13 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 mol/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 27Al-NMR spectrum, whereas a part of Al13 would still remain as Alb. At low concentrations, Al13 solution was quite stable at normal temperature, but lost its stability quickly when heating to 90 degrees C.
Publisher: Springer Science and Business Media LLC
Date: 20-07-2012
DOI: 10.1007/S10661-012-2786-7
Abstract: Conventionally, resin fractionation (RF) method has been widely used to characterize dissolved organic matter (DOM) found in different source waters based on general and broad DOM fractions grouping. In this study, a new refined method using multistep, microvolume resin fractionation combined with excitation emission matrix fluorescence spectroscopy (MSM-RF-EEMS) was developed for further isolation and characterization of subfractions within the primary DOM fractions separated from using the conventional RF method. Subsequently, its feasibility in indicating the occurrence of urban pollution in source waters was also assessed. Results from using the new MSM-RF-EEMS method strongly illustrated that several organic subfractions still exist within the regarded primary pure hydrophobic acid (HoA) fraction including the humic- and fulvic-like organic matters, tryptophan- and tyrosine-like proteins. It was found that by using the MSM-RF-EEMS method, the organic subfractions present within the primary DOM fraction could be easily identified and characterized. Further validation on the HoA fraction using the MSM-RF-EEMS method revealed that the constant association of EEM peak T1 (tryptophan) fraction could specifically be used to indicate the occurrence of urban pollution in source water. The correlation analysis on the presence of EEM peak T2 (tyrosine) fraction could be used as a supplementary proof to further verify the presence of urban pollution in source waters. These findings on using the presence of EEM peaks T1 and T2 within the primary HoA fraction would be significant and useful for developing a sensory device for online water quality monitoring.
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.JES.2015.07.003
Abstract: 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 (UV254) 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 (210 and 254 nm) and their ratio (A210/A254) were found to provide additional information on the physiochemical properties of stormwater-associated DOM. This study indicated that A210/A254 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.
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.WATRES.2010.02.039
Abstract: In recent years, semiconductor photocatalytic process has shown a great potential as a low-cost, environmental friendly and sustainable treatment technology to align with the "zero" waste scheme in the water/wastewater industry. The ability of this advanced oxidation technology has been widely demonstrated to remove persistent organic compounds and microorganisms in water. At present, the main technical barriers that impede its commercialisation remained on the post-recovery of the catalyst particles after water treatment. This paper reviews the recent R&D progresses of engineered-photocatalysts, photoreactor systems, and the process optimizations and modellings of the photooxidation processes for water treatment. A number of potential and commercial photocatalytic reactor configurations are discussed, in particular the photocatalytic membrane reactors. The effects of key photoreactor operation parameters and water quality on the photo-process performances in terms of the mineralization and disinfection are assessed. For the first time, we describe how to utilize a multi-variables optimization approach to determine the optimum operation parameters so as to enhance process performance and photooxidation efficiency. Both photomineralization and photo-disinfection kinetics and their modellings associated with the photocatalytic water treatment process are detailed. A brief discussion on the life cycle assessment for retrofitting the photocatalytic technology as an alternative waste treatment process is presented. This paper will deliver a scientific and technical overview and useful information to scientists and engineers who work in this field.
Publisher: Elsevier BV
Date: 10-2013
Publisher: Elsevier BV
Date: 08-2013
Publisher: Elsevier BV
Date: 10-2014
Publisher: Elsevier BV
Date: 12-2003
Publisher: IWA Publishing
Date: 07-12-2022
DOI: 10.2166/WS.2021.418
Abstract: There has been considerable research into prediction of water mains failure, however, those models are very complex and fail to convey the message of the health status of an asset to the relevant stakeholders. The study developed a ‘pipe health scorecard’ based on historical failure data which could be used for operation, maintenance, refurbishment, or replacement decisions by a water utility. This scorecard model was developed by using 160,413 pipe-condition data sets from the South Australian Water Corporation over ten years. Measures such as the Kolmogorov–Smirnov (KS) statistic, Area Under the ROC Curve (AUC), and Population Stability Index (PSI) showed the model is strong enough to predict the health status of water mains. The study found the factors influencing water mains failure to be in the order of importance: length, material, age, location (road vs verge), diameter, and operating parameters. The development of a simple but reliable model for the assessment of the health status of water mains will have major benefits to the water utility with the ability to identify and potentially replace water pipes prior to failure. Additional benefits of flexible scheduling of maintenance and replacement programs would contribute to cost savings.
Publisher: IWA Publishing
Date: 02-2011
DOI: 10.2166/WST.2011.248
Abstract: The use of coagulation and flocculation for tertiary treatment of pulp and paper mill effluent was investigated, where the evaluation was based on the removal of nitrogen (N), phosphorus (P) and BOD from post-coagulated wastewater. The study was undertaken on laboratory scale aerobic stabilisation basins (ASB). Two post coagulated (alum) wastewaters were studied, where the BOD:N:P ratios were 100:1.3:0.06 and 100:1.3:0.3. These wastewaters were treated in two identical concurrent simulations (A & B). The influent ratio for ‘A’ was selected representing the composition of actual coagulated Pinus radiata sulfite pulp effluent mixed with paper mill effluent. The input composition for ‘B’ represented a typical P concentration found in existing pulp and paper mill effluents. Unmodified sludge collected from a mill-pond was added at 4% v/v to each simulation replicating the treatment conditions at full-scale. Similar high percentage removals of BOD and COD occurred after 28 days (two HRTs) which were 94 and 67% respectively for ‘A’, and 98 and 70% respectively for ‘B’, where both remained at steady state during the third HRT. A statistical analysis of the data revealed that there was no significant difference in the s le variance of the BOD and COD results.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1EW00640A
Abstract: Major pathways of monochloramine disinfectant decay, kinetics involved, various influencing factors and the existing models to determine the chloramine decay in drinking water distribution systems are reviewed.
Publisher: Elsevier BV
Date: 06-2009
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.JHAZMAT.2009.06.094
Abstract: We explored a feasible approach to enhance removal capacity of three natural clays for removing anionic dye from aqueous solution. Optimal mixing proportions of the clay materials and temperature range for the calcination were investigated. We found that the removal efficiency can be improved significantly when the clay materials were mixed at certain ratio with the addition of lime and the mixed clay materials were calcined 100-300 degrees C. Batch experiments were conducted to study the effects of initial concentration, material dosage, contact time and pH on dye elimination. Kinetic study showed that more than 80% dye removal took place in 5 min. A high removal capacity (>575 mg g(-1)) of the mixed clay materials can be achieved at a low adsorbent dose. The mixed clay materials can be easily recovered by thermal treatment. The recovered mixtures demonstrated an enhanced removal capability after a few cycles of removal and regeneration. The results revealed that use of these clay materials could develop a low-cost treatment process for industrial wastewater.
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.JES.2014.08.001
Abstract: 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 6months) occurred during an intense La Niña 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 16mg/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 (9.1mg alum/mg DOC) and after (8.5mg alum/mg DOC) than during the flood event (8.0mg 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 (>2kDa) 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.
Publisher: Elsevier BV
Date: 02-2007
Publisher: MDPI AG
Date: 28-03-2022
Abstract: Nitrification is a major challenge in chloraminated drinking water systems, resulting in undesirable loss of disinfectant residual. Consequently, heterotrophic bacteria growth is increased, which adversely affects the water quality, causing taste, odour, and health issues. Regular monitoring of various water quality parameters at susceptible areas of the water distribution system (WDS) helps to detect nitrification at an earlier stage and allows sufficient time to take corrective actions to control it. Strategies to monitor nitrification in a WDS require conducting various microbiological tests or assessing surrogate parameters that are affected by microbiological activities. Additionally, microbial decay factor (Fm) is used by water utilities to monitor the status of nitrification. In contrast, approaches to manage nitrification in a WDS include controlling various factors that affect monochloramine decay rate and ammonium substrate availability, and that can inhibit nitrification. However, some of these control strategies may increase the regulated disinfection-by-products level, which may be a potential health concern. In this paper, various strategies to monitor and control nitrification in a WDS are critically examined. The key findings are: (i) the applicability of some methods require further validation using real WDS, as the original studies were conducted on laboratory or pilot systems (ii) there is no linkage/formula found to relate the surrogate parameters to the concentration of nitrifying bacteria, which possibly improve nitrification monitoring performance (iii) improved methods/monitoring tools are required to detect nitrification at an earlier stage (iv) further studies are required to understand the effect of soluble microbial products on the change of surrogate parameters. Based on the current review, we recommend that the successful outcome using many of these methods is often site-specific, hence, water utilities should decide based on their regular experiences when considering economic and sustainability aspects.
Publisher: IWA Publishing
Date: 02-2013
DOI: 10.2166/WS.2012.095
Abstract: The dissolved organic matter (DOM) plays significant role in water safety due to not only the natural occurrence but also man-induced pollution. To characterize and predict DOM treatability becomes therefore a very important and hot topic. In this paper, enhanced coagulation by four typical coagulants (FeCl3, Al2(SO4)3, polyaluminum chloride (PAC) and high performance polyaluminum chloride (HPAC)) without pH control was characterized using the chemical fractionation (resin adsorption, RA) and physical fractionation (high performance size exclusion chromatography (HPSEC) combined with peak fitting technique). The results show that the DOM removal can be separated into two stages, rapid removal and continual slow removal. The PAC exhibits efficient removal in the rapid part while the traditional salts are more efficient in the latter part. It is also very important for pH control to improve DOM removal by the traditional coagulants. DOM treatability per unit dosage (1 × 10−4 mol/l) for the four coagulants was then calculated in the order of HPAC (26.0%) & PAC (17.3%) & FeCl3 (14.3%) & Al2(SO4)3 (12.0%). Two sets of DOM treatability models, i.e. removal efficiency, for enhanced coagulation of the four coagulants were developed by combining the chemical and physical DOM fractions based on the quantitative analysis of the removal state of raw water. The two sets of models could be transformed to each other. The composition of the removable DOM by enhanced coagulation of the four coagulants was revealed and validated using 29 raw waters (in 13 source waters in three seasons), and as a result the low deviation indicated that the predicted data matched well with the actual data. It provided the possibility for the application in practical operation of water plant.
Publisher: Elsevier BV
Date: 04-2011
Publisher: IWA Publishing
Date: 09-2006
Publisher: Elsevier BV
Date: 06-1997
Publisher: Informa UK Limited
Date: 03-2013
Publisher: IWA Publishing
Date: 1999
Publisher: MDPI AG
Date: 15-10-2021
DOI: 10.3390/W13202890
Abstract: Calibration of a water distribution system (WDS) hydraulic model requires adjusting several parameters including hourly or sub-hourly demand multipliers, pipe roughness and settings of various hydraulic components. The water usage patterns or demand patterns in a 24-h cycle varies with the customer types and can be related to many factors including spatial and temporal factors. The demand patterns can also vary on a daily basis. For an extended period of hydraulic simulation, the modelling tools allows modelling of the variable demand patterns using daily multiplication factors. In this study, a linear modelling approach was used to handle the variable demand patterns. The parameters of the linear model allow modelling of the variable demand patterns with respect to the baseline values, and they were optimised to maximise the association with the observed data. This procedure was applied to calibrate the hydraulic model developed in EPANET of a large drinking water distribution system in regional South Australia. Local and global optimisation techniques were used to find the optimal values of the linear modelling parameters. The result suggests that the approach has the potential to model the variable demand patterns in a WDS hydraulic model and it improves the objective function of calibration.
Publisher: American Chemical Society (ACS)
Date: 02-08-2008
DOI: 10.1021/ES800794R
Abstract: This paper reports the use of high performance size exclusion chromatography (HPSEC) as a tool to assess NOM removal by coagulation. Quantitative information such as percentage removal can be determined after "peak-fitting" the HPSEC molecular weight profile of the source water. A peak-fitting approach was developed based on the molecular weight profile of dissolved organic matter from surface water. A sequential jar testing procedure with five treatment steps was used to characterize organics and to confirm that several NOM components were recalcitrant to coagulation with alum. Despite differences found in both the concentration and character of NOM in three surface waters studied, the final concentrations and characteristics (e.g., molecular weight profile) were very similar after five treatment stages. The molecular weight profiles of the recalcitrant organics were subsequently used to build a peak-fitting technique for NOM removal. The approach was validated by further jar test results of several other water sources, such as ground and river waters, including one found to be very difficult to treat in terms of NOM removal by alum treatment. Predictions of removable and nonremovable organic fractions by coagulation using this peak fitting technique were found to be within 10% of actual values.
Publisher: Elsevier BV
Date: 12-2012
Publisher: American Society of Civil Engineers (ASCE)
Date: 2013
Publisher: MDPI AG
Date: 12-01-2023
DOI: 10.3390/MA16020768
Abstract: Cement-based sensors include conductive fillers to achieve a sensing capability based on the piezoresistivity phenomenon, in which the electrical resistivity changes with strain. The microstructural characterisation of cement-based sensors can be obtained using a promising non-destructive technique, such as AC impedance spectroscopy (ACIS), which has been recently used by many researchers. This paper reviews the fundamental concepts of piezoresistivity and ACIS in addition to the comparison of equivalent circuit models of cement-based sensors found in the literature. These concepts include piezoresistivity theory, factors affecting piezoresistivity measurement, resistance measurement methodology, strain/damage sensing, causes of piezoresistivity, theories of conduction, AC impedance spectroscopy theory, and the equivalent circuit model. This review aims to provide a comprehensive guide for researchers and practitioners interested in exploring and applying different techniques to self-sensing concrete.
Publisher: Informa UK Limited
Date: 1994
Publisher: Elsevier BV
Date: 08-1999
Publisher: IWA Publishing
Date: 12-2012
DOI: 10.2166/WST.2012.448
Abstract: Resin fractionation is the most widely used technique to isolate and characterize natural organic matter (NOM) based on its hydrophobicity and hydrophilicity, however, it is also recognized as a time consuming technique. This paper describes the use of reverse phase high performance liquid chromatography (RPHPLC) as a rapid assessment technique to determine the hydrophobicity/hydrophilicity of NOM. The optimum column separation condition was achieved and without the need for concentrating the s le prior to analysis and with good reproducibility of the peak retention time and the peak area. The characterization results were further compared with the traditional resin fractionation technique using DAX-8 and XAD-4 resins. The results demonstrated that the polarities defined by the two methods were different but consistent and also that the fractions absorbed onto XAD-4 were less hydrophobic than those absorbed onto DAX-8. The difference in definition between resin fractionation and RPHPLC were further investigated.
Publisher: American Chemical Society (ACS)
Date: 11-07-2008
DOI: 10.1021/ES800887S
Abstract: In this study, changes in the physical and structural properties of natural organic matter (NOM) during titanium dioxide photocatalytic oxidation process were investigated using several complementary analytical techniques. Potential of the treated water to form trihalomethanes (THMs) and haloacetic acids (HAAs) was also studied. High-performance size exclusion chromatography analysis showed that NOM with apparent molecular weights of 1-4 kDa were preferentially degraded, leading to the formation of lower molecular weight organic compounds. Resin fractionation of the treated water demonstrated that the photocatalytic oxidation changed the affinity of the bulk organic character from predominantly hydrophobic to more hydrophilic. Short chain aldehydes and ketones were identified by mass spectroscopy as one of the key degradation products. The addition of hydrogen peroxide to photocatalysis was found to increase the degradation kinetics but did not affect the reaction pathway, thus producing similar degradation end products. The amount of THMs normalized per dissolved organic carbon (specific THM) formed upon chlorination of NOM treated with photocatalytic oxidation was reduced from 56 to 10 microg/mg. In contrast, the specific HAAs formation potential of the treated water remained relatively unchanged from the initial value of 38 microg/mg, which could be due to the presence of hydrophilic precursor compounds that were formed as a result of the photocatalytic oxidation process.
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Funder: Australian Research Council
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End Date: 2012
Funder: Australian Research Council
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End Date: 2016
Funder: Australian Research Council
View Funded ActivityStart Date: 2010
End Date: 2012
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 2016
Funder: Australian Research Council
View Funded ActivityStart Date: 2011
End Date: 2013
Funder: Australian Research Council
View Funded ActivityStart Date: 2005
End Date: 2008
Funder: Australian Research Council
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