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Refereed/Peer-reviewed Flocs produced during drinking water treatment play a key role in particle separation and removal. Floc characteristics affect both sedimentation and filtration efficiency, however, the methods used to optimise the coagulant dose during treatment do not usually take these into account. This study investigated the feasibility of using the Flocculation Index (FI), obtained from a photometric dispersion analyser (PDA) during flocculation, as a control parameter to optimise turbidity removal. Five waters, natural and synthetic, with different turbidity levels (from 6 to ⁓120 NTU) and low DOC (i.e.

Stormwater runoff contains a myriad of pollutants, including faecal microbes, and can pose a threat to urban water supplies, impacting both economic development and public health. Therefore, it is a necessity to implement a real-time hazard detection system that can collect a substantial amount of data, assisting water authorities to develop preventive strategies to ensure the control of hazards entering drinking water sources. An on-line UV-Vis spectrophotometer was applied in the field to collect real-time continuous data for various water quality parameters (nitrate, DOC, turbidity and total suspended solids) during three storm events in Mannum, Adelaide, Australia. This study demonstrated that the trends for on-line and comparative laboratory-analysed samples were complimentary through the events. Nitrate and DOC showed a negative correlation with water level, while turbidity and total suspended solids indicated a positive correlation with water level during the high rainfall intensity. The correlations among nitrate, DOC, turbidity, total suspended solids and water level are the opposite during low rainfall intensity. Nitrate, one of the main pollutants in stormwater, was investigated and used as a surrogate parameter for microbial detection. However, the microbiological data (Escherichia coli) from captured storm events showed poor correlations to nitrate and other typical on-line parameters in this study. This is possibly explained by the nature of the stormwater catchment outside of rain events, where the sources of bacteria and nutrients may be physically separated until mixed during surface runoff as a result of rainfall. In addition, the poor correlations among the microbiological data and on-line parameters could be due to the different sources of bacteria and nutrients that were transported to the stormwater drain where sampling and measurement were conducted Refereed/Peer-reviewed

There is an increasing need to use online instrumentation for continuous monitoring of water quality. However, industrial applications using online instruments, such as submersible UV-Vis spectrophotometers, may require the use of alternative techniques to remove particle effect rather than performing a physical filtration step. Some submersible UV-Vis spectrophotometers have built-in generic particle compensation algorithms to remove the filtration step. This work studied the influence of suspended particles on the measurements of a submersible UV-Vis spectrophotometer as well as the performance of the built-in particle compensation technique under laboratory-controlled conditions. Simulated water samples were used in the combinations of standard particles from laboratory chemical and natural particles extracted from water systems with ultrapure water and treated water from a drinking water treatment plant. Particle contributions to the UV absorbance at 254 nm (UV254) measurements of water samples varied differently when particle types or concentrations changed. The compensated UV254, measured by the submersible instrument using the built-in generic particle compensation algorithms, was compared with laboratory UV254, analysed by the bench-top instrument with the physical filtration method. The results indicated that the built-in generic compensation algorithms of the submersible UV-Vis spectrophotometer may generate undercompensated UV254 or overcompensated UV254 for various surface waters. These findings provide in-depth knowledge about the impact of suspended particles on the measurements of submersible UV-Vis spectrophotometers; source water dependence; and why site-specific calibration is often needed to get accurate measurements.

Insufficient dissolved organic matter removal results in higher residual organics (measured as dissolved organic carbon, DOC) in the treated water which can act as precursors for disinfection by-products (DBPs) and consequently increases the potential for health risk. This study aims to use drinking water treatment sludge (DWTS) as a coagulant-aid to improve the DOC removal efficiency. The effect of various DWTS doses (between 0.5 and 3 g/L) on the coagulation performance (by alum) to treat natural surface water that has relatively low turbidity and high DOC at optimum pH (~6) was examined using standard jar tests procedure. Although addition of DWTS at doses lower than 1.5 g/L improved the DOC removal efficiency (by 4% and 12% at DWTS dose of 0.5 and 1.0 g/L, respectively), the turbidity levels increased. In comparison to optimum dose of alum without DWTS, the addition of DWTS at 3 g/L led to reduce the alum dose to ~50% to achieve similar removal efficiency of organics (70% DOC removal). Further, addition of DWTS improved the floc’s characteristics (achieve larger flocs and rapid growth rate; measured by photometric dispersion analyser, PDA) and settling rate significantly, and the produced sludge volume decreased by ~50% compared to the figure with no DWTS addition. Trihalomethane formation potential (THMFP) was also reduced (up to ∼ 30%) when DWTS used. The results indicate that DWTS reuse as a coagulant-aid has the potential to reduce DOC and control DBPs formation when the organic loads require high coagulant dose exceeding the WTP design limits. Refereed/Peer-reviewed

Refereed/Peer-reviewed Traditionally, coagulant doses are determined by the operators for the coagulation process at water treatment plants which is a multi-factor approach based on raw and treated water quality and in some situations relies heavily on their decisions. It can be challenging to determine appropriate coagulant doses proactively for tight coagulation control with the traditional method. Therefore, this study looked for alternative approaches for coagulation control and maybe the first to build coagulant dose determination models using only online raw water quality data (UV–Vis spectra) combined with chemometrics to determine coagulant doses for a drinking water treatment plant (WTP). Online UV–Vis spectral data at the raw water intake and alum dose data from a drinking WTP were used for building coagulant dose determination models. Three modelling techniques, including multiple linear regression (MLR), partial least squares (PLS) and artificial neural networks (ANNs), were applied in this work. The results show that MLR and PLS models had almost identical performances with small root mean square errors (RMSE) and high correlation coefficients (R2). Both MLR and PLS had slightly better performance than the ANNs for alum dose predictions. This study shows that the combination of online UV–Vis spectra and a chemometric method (MLR or PLS) was able to mimic operators' decisions in the determination of coagulant doses with a pH target of 6 to achieve a target DOC level of less than 5 mg/L for treated water quality.

Stormwater runoff contains a myriad of pollutants, including faecal microbes, and can pose a threat to urban water supplies, impacting both economic development and public health. Therefore, it is a necessity to implement a real-time hazard detection system that can collect a substantial amount of data, assisting water authorities to develop preventive strategies to ensure the control of hazards entering drinking water sources. An on-line UV-Vis spectrophotometer was applied in the field to collect real-time continuous data for various water quality parameters (nitrate, DOC, turbidity and total suspended solids) during three storm events in Mannum, Adelaide, Australia. This study demonstrated that the trends for on-line and comparative laboratory analysed samples were complimentary through the events. Nitrate and DOC showed a negative correlation with water level while turbidity and total suspended solids indicated a positive correlation with water level during the high rainfall intensity. The correlations among nitrate, DOC, turbidity, total suspended solids, and water level are the opposite during the low rainfall intensity. Nitrate, one of the main pollutants in stormwater, was investigated and used as a surrogate parameter for microbial detection. However, the microbiological data (E.coli) from captured storm events showed poor correlations to nitrate and other typical on-line parameters in this study, possibly explained by the nature of the stormwater catchment outside of rain events, where the sources of bacteria and nutrients may be physically separate until mixed during surface runoff as a result of rainfall. In addition, the poor correlations among the microbiological data and on-line parameters can be due to the different sources of bacteria and nutrients that end up into the stormwater drain.

There is an increasing need to use online instrumentation for continuous monitoring of water quality. However, industrial applications using online instruments, such as submersible UV-Vis spectrophotometers, may require the use of alternative techniques to remove particle effect rather than performing a physical filtration step. Some submersible UV-Vis spectrophotometers have built-in generic particle compensation algorithms to remove the filtration step. This work studied the influence of suspended particles on the measurements of a submersible UV-Vis spectrophotometer as well as the performance of the built-in particle compensation technique under laboratory-controlled conditions. Simulated water samples were used in the combinations of standard particles from laboratory chemical and natural particles extracted from water systems with ultrapure water and treated water from a drinking water treatment plant. Particle contributions to the UV absorbance at 254 nm (UV

Sediment accumulates in distribution systems over time, and can potentially result in dirty water events. The primary origin of these particles in most networks has not been examined. Controlled sediment resuspension (flushing) events were performed at 10 sites in a drinking water distribution system and repeated six months later to observe redeposition. Different patterns of sediment deposition observed are suspected to be related to particle origin. A large proportion of pipe sediment resuspended during the first flushing event was composed of iron, most likely arising from corrosion of distribution system infrastructure. This sediment appears to play a role in sheltering microbial cells from secondary disinfection. In this study, a source of particles was identified that may provide an alternate explanation for the presence of iron deposits in systems not dominated by iron pipework.

Particles in the water can significantly affect UV–Vis absorption measurements. There is a need for the water industry to develop a reliable technique to eliminate particle impact on on-line water quality monitoring using UV–Vis spectroscopy. This study aims to develop and use digital techniques for particle compensation: single wavelength compensation, linear regression compensation and multiplicative scatter correction method for on-line UV–Vis spectrophotometers. Water quality data were collected from three selected water sources in water treatment plants which represent different water qualities in terms of particles and organic matters. UV254 measurements were determined with these three software compensation techniques in comparison with the proprietary instrument built-in compensation algorithm using Bland-Altman analysis. Linear correction methods were found to be able to adjust the three compensation techniques to achieve acceptable compensated UV254 results, particularly for raw waters. UV254 measurements using single wavelength compensation, linear regression compensation and multiplicative scatter correction techniques with the assistant of linear correction methods were confirmed to be comparable to the instrument built-in compensation method. Our results reveal that these particle compensation techniques can make the UV254 technology reliable for online water quality monitoring in water treatment network. This paper demonstrated the advantage of using software compensation method to establish local compensation and calibration models instead of relying on the predetermined global calibrations for online water quality monitoring. Refereed/Peer-reviewed

In a component of an extensive pilot distribution system (PDS) study, the effects of four different water qualities on biological stability in distributed water were investigated through identical (parallel) single-pass pipe arrangements. Through 24 months of monitoring, a number of key observations were made. Incorporation of a biological treatment step reduced the overall dissolved organic carbon (DOC) loss through the PDS by reducing biodegradable DOC (BDOC) within the water prior to distribution. In the absence of chlorine residuals, the proliferation of culturable organisms was favoured with considerably higher heterotrophic plate counts in samples at the outlet of the PDS. Despite different bacterial cell counts (measured by flow cytometry) entering each PDS from the four treatment streams, equivalent outlet cell numbers were achieved in all systems after 8 months' operation; however multi-step treatment streams took longer to reach equilibrium.

Monitoring and understanding water quality changes within the distribution system is essential to enable effective management to provide good quality water at the customer tap. A recent 2-year study utilised four parallel pilot distribution systems (PDS) and a range of simple tools to assess the impact improving treatment had on the water quality within the distribution system. Particle counting was more effective than turbidity to assess the impact of increasing treatment on sediment load entering the PDS while UV254 was as informative as dissolved organic carbon to assess organic load but has the additional potential benefit of on-line measurement. However, variability in water quality entering the PDS was often greater than measurable changes occurring within the PDS. It was critical to compare water quality entering the distribution system with the water quality at a defined point within the distribution system (at known hydraulic detention time) to enable effective assessment of water quality changes. Therefore, effective use of these simple tools requires monitoring of both inlet and distribution system locations, together with long term trending to monitor and compare changes within the system.

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) surface analysis was conducted to characterise deposits in polyethylene pipes used in a novel pilot water distribution system (PDS). The system consisted of four (4) parallel distribution systems receiving water from different treatment processes, ranging from conventional coagulation through to an advanced membrane filtration system. After two years of operation, the distribution system was shut down and samples of pipe were collected for autopsy analysis. Inlet and outlet samples from each PDS were collected for purpose of comparison. ToF-SIMS was used to assess chemical differences in surface biofilm accumulation and particulate deposition, which resulted as a consequence of the treatment method and operational mode of each system. These data supplemented previously collected bacteriological and chemical water quality data. Results from the inorganic analysis of the pipes were consistent with corrosion and contamination events that occurred upstream in the corresponding treatment systems. Principal component analysis of data on organic constituents showed oxygen and nitrogen containing fragments were associated with the treatment inlet and outlet samples. These types of signals can often be ascribed to biofilm polysaccharides and proteins. A trend was observed when comparing samples from the same PDS, showing an association of lower molecular weight (MW) organic fragments with the inlet and higher MW organic fragments with the outlet samples. Refereed/Peer-reviewed

A pilot-scale research investigation examining treatment technologies including coagulation, ion-exchange, activated carbon and membrane filtration and their impact on water quality coincided with a period of extensive variability in source water character. Distinct water quality periods as a result of extreme climatic conditions from drought to flood were observed and the natural organic matter (NOM) removal examined using a suite of organic characterisation techniques from simple ultraviolet (UV) absorbance to more advanced spectroscopic and chromatographic methods. The low specific UV absorbance (SUVA) and apparent molecular weight (AMW) distribution of the drought-impacted NOM was recalcitrant to coagulation with significant improvement in NOM removal resulting from the multi-step treatments. Among a number of discernible changes, floodwaters introduced high AMW, UV-absorbing NOM of terrestrial origin, which was shown to be more amenable to coagulation. Nevertheless the application of multi-step treatments resulted in further reduction in both the concentration and diversity of organic components. Filtration through granular activated carbon was observed to be the most variable treatment technology across the investigated period due to diminishing adsorption capacity. Conversely, the dual stage membrane filtration was shown to remove a broad range of organic matter, regardless of source water NOM concentration and character.

Four treatment processes; conventional coagulation, magnetic ion exchange (MIEX)/coagulation, with and without granular activated carbon (GAC), and membrane treatment combining microfiltration (MF) and nanofiltration (NF), were operated in parallel using the same source water from the Murray-Darling basin in South Australia. During the two year study, high levels of natural organic matter and turbidity arising from floods affecting the Murray-Darling basin in 2010-2012 challenged the four processes. The comparative study indicated that all four processes could effectively meet basic water quality guidelines of turbidity and colour despite challenging source water quality but that the more advanced treatments improved overall organic and bacterial removal. Interestingly, the high organics and turbidity arising from the floods resulted in improved treatment efficiency for all treatments incorporating coagulation to the extent that, despite flood conditions, treated water quality could remain comparatively constant provided that the process was operated and optimised effectively.

Jar testing and flow cytometry were used in conjunction with photometric dispersion analysis (PDA) to assess conventional alum coagulation with and without magnetic ion exchange (MIEX) pre-treatment for turbidity and bacterial removal capacity. Treatment assessment included powdered activated carbon (PAC) and pre-chlorination of the MIEX-treated raw water. Floc particles were subjected to shear forces after settling and re-suspended to gauge bacterial release potential, floc breakage and re-aggregation. MIEX in conjunction with alum coagulation achieved improved coagulation as measured by PDA but did not increase bacterial log removal value (LRV) in comparison with conventional coagulation. Pre-chlorination and PAC addition were seen to improve bacterial removal and coagulation, respectively, but were less effective for bacterial LRVs when they were used in conjunction during coagulation.

With increasing focus on the health implications from disinfection by-products (DBP) in drinking waters, appropriate monitoring parameters are required that can give rapid information on the potential of a treated water to form DBPs. Given that the most effective strategy for the reduction of concentrations of DBPs is the removal of their precursor, natural organic matter, parameters that relate to organic concentration and character are the most likely candidates. A project utilising four different treatment procedures applied to common source water was evaluated for DBP formation over three characteristic water quality periods and the link to key monitored parameters evaluated. Results showed that DBP formation was independent of the source water quality or treatment technology applied but was correlated to treated water dissolved organic carbon, and more strongly to the UV absorbance at 254 nm.

This work aimed to demonstrate the effect of optimised coagulation on minimise fouling for coagulation-ultrafiltration process. Coagulation as pretreatment has the potential to mitigate fouling and enhance flux. Operating parameters were tested by a matrix of experiments for various mixing conditions and coagulant doses. In coagulation experiments, varied shear forces were applied to generate different floc characteristics in order to assess the effect on membrane fouling. Floc properties were investigated with an optical monitoring technique to identify structure, size and growth of flocs. It was shown that stronger flocs are of advantage for fouling mitigation and that the coagulant dosage is crucial for the performance of filtration. The impact of water quality was assessed using general water quality parameters and organic characterisation techniques to investigate the performance of each treatment step. The treatment efficiency was further assessed based on comparing the molecular size fractions of the organic matter before and after coagulation using a size exclusion chromatography technique. The result confirmed the significance of organic character on treatment performance. Refereed/Peer-reviewed

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 samples 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. Refereed/Peer-reviewed

Research is increasingly indicating the potential chronic health effects of brominated disinfection by-products (DBPs). This is likely to increase with elevated bromide concentrations resulting from the impacts of climate change, projected to include extended periods of drought and the sudden onset of water quality changes. This will demand more rigorous monitoring throughout distribution systems and improved water quality management at water treatment plants (WTPs). In this work the impact of increased bromide concentration on formation of DBPs following conventional treatment and chlorination was assessed for two water sources. Bioanalytical tests were utilised to determine cytotoxicity of the water post disinfection. Coagulation was shown to significantly reduce the cytotoxicity of the water, indicating that removal of natural organic matter DBP precursors continues to be an important factor in drinking water treatment. Most toxic species appear to form within the first half hour following disinfectant addition. Increasing bromide concentration across the two waters was shown to increase the formation of trihalomethanes and shifted the haloacetic acid species distribution from chlorinated to those with greater bromine substitution. This correlated with increasing cytotoxicity. This work demonstrates the challenges faced by WTPs and the possible effects increasing levels of bromide in source waters could have on public health.

Four pilot-scale treatment process streams (Stream 1 - Conventional treatment (coagulation/flocculation/dual media filtration); Stream 2 - Magnetic ion exchange (MIEX)/Conventional treatment; Stream 3 - MIEX/Conventional treatment/granular activated carbon (GAC) filtration; Stream 4 - Microfiltration/nanofiltration) were commissioned to compare their effectiveness in producing high quality potable water prior to disinfection. Despite receiving highly variable source water quality throughout the investigation, each stream consistently reduced colour and turbidity to below Australian Drinking Water Guideline levels, with the exception of Stream 1 which was difficult to manage due to the reactive nature of coagulation control. Of particular interest was the bacteriological quality of the treated waters where flow cytometry was shown to be the superior monitoring tool in comparison to the traditional heterotrophic plate count method. Based on removal of total and active bacteria, the treatment process streams were ranked in the order: Stream 4 (average log removal of 2.7) > Stream 2 (average log removal of 2.3) > Stream 3 (average log removal of 1.5) > Stream 1 (average log removal of 1.0). The lower removals in Stream 3 were attributed to bacteria detaching from the GAC filter. Bacterial community analysis revealed that the treatments affected the bacteria present, with the communities in streams incorporating conventional treatment clustering with each other, while the community composition of Stream 4 was very different to those of Streams 1, 2 and 3. MIEX treatment was shown to enhance removal of bacteria due to more efficient flocculation which was validated through the novel application of the photometric dispersion analyser. Refereed/Peer-reviewed

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

Research has shown that in drinking water sources there is a portion of the natural organic matter (NOM) that is recalcitrant to coagulation, regardless of the treatment conditions applied. Advances in inorganic coagulants have resulted in the emergence of many pre-polymerized formulations which may demonstrate improved coagulation performance. The aim of this study was to determine the effects of several coagulant types on dissolved organic carbon (DOC) removal where the molar concentrations of the metal ions were comparable. In the second stage, this work also investigated selected coagulants to determine whether improvements in coagulation conditions or alternative coagulants will be sufficient to remove problematic components in the organic matter responsible for disinfection demand and disinfection by-product (DBP) formation in a high DOC water source. When compared at equimolar concentrations, advanced coagulants were found to perform equally for DOC removal as traditional inorganic coagulants. While they did not necessarily target or improve removal of recalcitrant NOM and DBP precursors, they successfully demonstrated broader conditions at which coagulation was effective, reducing the reliance on precise optimization strategies. Coagulation remains a well developed and cost effective means of water treatment, with continuing relevance into the foreseeable future. Refereed/Peer-reviewed

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.

Three South Australian source waters of low, mid and high dissolved organic carbon (DOC) levels were evaluated for coagulation efficiency in terms of natural organic matter (NOM) interaction and floc behaviour. Experiments were conducted using aluminium chlorohydrate (ACH) and aluminium sulphate (alum) at different mixing conditions with continuous monitoring of formation and breakage of flocs using a flow-through optical measurement device known as photometric dispersion analyser (PDA). A positive correlation of floc growth against coagulant dosage was found for ACH based on a limiting growth function. Floc structure was assessed by analysis of PDA derived parameters showing promise for more rapid coagulation condition optimisation than subjective visual criteria. Removal of NOM and growth of flocs are influenced more by the hydrophobicity of the NOM than the choice of coagulant. A higher hydrophobic fraction resulted in slower aggregation of flocs with both coagulants and better removal when using alum at controlled pH. Refereed/Peer-reviewed

Large tributary inflows into water supply reservoirs caused by heavy catchment rain may be of concern due to problems associated with high levels of natural organic matter (NOM) present in the inflows. The movement of these inflows within a reservoir is dependent on its relative density to the receiving waters. For example, if the inflow is denser (colder) than the recipient water it will travel along the base of the reservoir as an underflow and can penetrate as far as the dam wall water off-take to a water treatment plant (WTP). Field studies were conducted to track the passage of underflows through two South Australian reservoirs, Little Para and Myponga. Samples were collected before and during storm event inflows and analyses undertaken to determine NOM concentration, alum demand, disinfection by-product formation potential, and quality of the water. We demonstrate that by monitoring the movement of inflows into reservoirs, combined with changes in reservoir off-take levels, that the risk of NOM entering a water treatment plant can be reduced which in turn will lower water treatment costs by reducing alum dosing levels and lessen the risk to human health by reducing disinfection by-product formation.

Natural organic matter (NOM) is a heterogeneous mixture of organic compounds that is ubiquitous in surface waters. The character of NOM varies according to source, age and season. This variability can have an impact on the NOM reactivity during water treatment. In the present study, NOM removal efficiencies by TiO(2) photocatalysis from two Australian surface water samples were assessed by monitoring the concentration, absorbance in the ultraviolet range (200-350 nm), molecular weight distribution and the chemical polarity of the source and treated water. In addition, the potential of the treated waters to form trihalomethanes (THM) after chlorination were evaluated. From the two surface waters after photocatalysis, similar product distributions were observed, which indicates that the degradation process can be described in terms of a similar reaction pathway. The organics remaining in the treated water consist mostly of low molecular weight hydrophilic compounds with weak UV absorbance at wavelength of 254-260 nm, and little reactivity with chlorine to form THM. Most importantly, use of multiple complementary analytical approaches resulted in a better understanding of the photocatalytic degradation process and its products. Refereed/Peer-reviewed

The use of nanotechnologies in water treatment for the removal of natural organic matter (NOM) is a relatively new concept. Using simple self-assembled monolayer (SAM) techniques, a silica substrate was modified as an adsorbent and tested for its potential for reduction of water quality parameters such as UV absorbance, colour and dissolved organic carbon (DOC). Silica particles that were coated with an amino-siloxane SAM (NH2-SAM) were evaluated in both a high surface area powder form and also a more realistic granular sand form. Initial results using direct stirred contact with powdered NH2-SAM showed promising results with 60% reduction of UV254 after 1 h and up to 70% removal of DOC with higher doses and contact times. NH2-SAM powder removed NOM in a broader and less selective molecular weight (MW) range than coagulation treatment and this removal was enhanced by pH control at 6, especially for medium MW components. When NH2-SAM sand was applied, the significantly reduced effective surface area result...

Coagulation experiments at pH values ranging from 3 to 7 were conducted on raw water samples from four Australian reservoirs—Hope Valley, Myponga, Moorabool and Mt Zero—to assess the removal of natural organic matter (NOM) with alum. The aim was to characterise the NOM in these water sources that is highly recalcitrant to removal by alum coagulation. The selection of these water sources covered a range in raw water quality varying in inorganic and organic composition and character. NOM in both raw and treated waters was characterised by several techniques including specific UV absorbance (SUVA), high performance size exclusion chromatography (HPSEC) and pyrolysis–gas chromatography mass spectrometry (Py–GC–MS). The results can provide better understanding of the removal limitations of each treatment step and the knowledge will allow design engineers to select a suitable combined treatment process for optimum NOM removal. Despite the fact that the organic character of the four source waters were different, results showed that after optimised alum coagulation all four waters had a similar character. The molecular weight distribution analysis (HPSEC) indicated alum coagulation preferentially removed the higher molecular weight UV absorbing compounds whilst those remaining in the treated waters had the properties of lower apparent molecular weights (about 500–700 Daltons) and less UV absorbance. Py–GC–MS analyses of NOM in these waters before and after treatment indicated that polysaccharides and their derivatives are recalcitrant to removal with alum coagulation. Generally, the findings indicate that the character of the NOM is an important factor in determining its treatability.

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. Refereed/Peer-reviewed

A new approach of using free-ammonia measurements as the basis of a control strategy to optimise a chloraminated water distribution system was tested in a laboratory evaluation. A test rig with a newly developed low level on-line free-ammonia analyser was constructed to investigate two different control configurations, the currently used feedback and the proposed feedforward. The results of this trial showed that only using the free-ammonia analyser for feedback control is not ideal due to its inability to detect chlorine overdosing situations. Better results regarding the maximum yield of disinfectant residuals when using the feedforward configuration were observed, and free-ammonia concentrations below 0.065 mg/L were consistently achieved. Refereed/Peer-reviewed

Humic acid (HA) removal using advanced oxidation processes (AOPs) was investigated, particularly UVA/H2O2 and photo Fenton‐like process (UVA/Fe(III)/H2O2). Changes in the UV254 absorbance, dissolved organic carbon (DOC), apparent molecular weight (AMW) distribution, and the Trihalomethane formation potential (THMFP) of the organics were monitored. UVA/Fe(III)/H2O2 based process was found to be effective in removing more than 80% DOC and 90% UV254 absorbance. Differences in the reduction profiles of AMW distributions for UVA/Fe(III)/H2O2 based process and UVA/H2O2 process were observed, with the latter showing preferential removal of a certain molecular weight range. Selected samples were then fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids (SHA), hydrophilic charged (CHA), and hydrophilic neutral (NEU). The HA used is found to consist mostly of VHA fraction that is very susceptible to AOP treatments. The results illustrate that the degradation process o...

Despite the fact that natural organic matter (NOM) is significantly smaller than the pore size of microfiltration (MF) membranes, fouling due to organic compounds has emerged as a problematic issue for both potable water and wastewater membrane filtration. Pre-treatment of the feed water can be a useful strategy for reduction or mitigation of these fouling effects. The aim of this investigation was to evaluate various combined pre-treatment methods for reducing NOM fouling of laboratory scale micro-filtration (MF) membranes, including treatment with adsorbents such as MIEX® (MIEX® is a registered trademark of Orica Australia Pty. Ltd.) and powdered activated carbon (PAC) as well as coagulation with alum. High performance size-exclusion chromatography (HPSEC) was applied to determine molecular weight (MW) distribution and proved to be a simple analytical technique, capable of detecting the onset of fouling by observation of the >50,000 Da ‘colloidal’ peak in the water sources examined. Results obtained showed that treatments that reduce the majority of bulk water dissolved organic carbon (DOC) of all MW ranges, including ‘colloidal’ (very high MW) material successfully prevented short-term fouling of MF, where treatments that removed most of the DOC but did not remove the colloidal components, were unable to prevent fouling.

Three different powdered activated carbons were applied in combination with aluminium sulphate to treat a high dissolved organic carbon (DOC) source water with a focus on improving natural organic matter removal. Treated water quality was analysed using absorbance at 254 nm, DOC, trihalomethane formation potential (THM-FP), rapid fractionation, C13 NMR and molecular weight distribution by high performance size exclusion chromatography. Carbon C and B offered equivalent DOC removal but carbon C was considered superior as treated water THM-FP was reduced. It is postulated that an organic fraction around 1000 Daltons is responsible for differences in THM-FP shown in the treated waters.

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 sample, 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. Refereed/Peer-reviewed

To gain an improved understanding of the types of organic compounds that are recalcitrant to water treatment, natural organic matter (NOM) isolates from two drinking water sources (Mt. Zero and Moorabool reservoirs, Victoria, Australia) were separated into fractions of distinct chemical behaviour using resins. Four fractions were obtained from each water source and were organics absorbed to: (1) XAD-8 (very hydrophobic acids, VHA); (2) DAX-4 (slightly hydrophobic acids, SHA); (3) bound to an anion exchange resin (charged organics, CHAR); and (4) not absorbed or bound to resins (neutrals, NEUT). These fractions were then tested to determine the capacity of alum to remove them from water and to correlate this with the character of each isolate. The fractions were characterised by the application of high performance size exclusion chromatography (HPSEC), bacterial regrowth potential (BRP), trihalomethane formation potential (THMFP), pyrolysis gas-chromatography mass spectrometry (Py-GC-MS) and thermochemolysis. The highest removals of dissolved organic carbon (DOC) by alum treatment were in waters spiked with the CHAR fractions while the NEUT fractions were the most recalcitrant. The number average molecular weights (Mn) of DOC of the CHAR fractions before treatment were the highest, whilst those of the NEUT fractions were the lowest. After alum treatment, the Mn of the NEUT fractions were only slightly reduced. Results from Py-GC-MS and thermochemolysis indicate that the NEUT fractions had the highest relative proportion of saccharide derived organic material. Nonetheless, the BRP of waters spiked with the NEUT fractions differed markedly, indicating that organics recalcitrant to alum treatment can vary substantially in their chemical composition and capacity to support microbial growth.

Biofilm control in drinking water distribution systems (DWDSs) is crucial, as biofilms are known to reduce flow efficiency, impair taste and quality of drinking water and have been implicated in the transmission of harmful pathogens. Microorganisms within biofilm communities are more resistant to disinfection compared to planktonic microorganisms, making them difficult to manage in DWDSs. This study evaluates the impact of four unique drinking water treatments on biofilm community structure using metagenomic DNA sequencing. Four experimental DWDSs were subjected to the following treatments: (1) conventional coagulation, (2) magnetic ion exchange contact (MIEX) plus conventional coagulation, (3) MIEX plus conventional coagulation plus granular activated carbon, and (4) membrane filtration (MF). Bacterial biofilms located inside the pipes of each system were sampled under sterile conditions both (a) immediately after treatment application ('inlet') and (b) at a 1. km distance from the treatment application ('outlet'). Bacterial 16S rRNA gene sequencing revealed that the outlet biofilms were more diverse than those sampled at the inlet for all treatments. The lowest number of unique operational taxonomic units (OTUs) and lowest diversity was observed in the MF inlet. However, the MF system revealed the greatest increase in diversity and OTU count from inlet to outlet. Further, the biofilm communities at the outlet of each system were more similar to one another than to their respective inlet, suggesting that biofilm communities converge towards a common established equilibrium as distance from treatment application increases. Based on the results, MF treatment is most effective at inhibiting biofilm growth, but a highly efficient post-treatment disinfection regime is also critical in order to prevent the high rates of post-treatment regrowth. Refereed/Peer-reviewed

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 sampling arrangement, water quality was monitored at Morgan WTP for a 6 month period. Data were validated against other online parameters and laboratory measured samples. 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. Refereed/Peer-reviewed

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 sample 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. Refereed/Peer-reviewed

The application of a new combined fractionation technique (CFT) using high performance size exclusion chromatography (HPSEC) and rapid resin fractionation (RRF) for characterization of natural organic matter (NOM) in raw and post-coagulated water samples was assessed. Two natural water samples from Myponga and Hope Valley reservoirs, South Australia, respectively, were selected for this NOM removal by coagulation study. With the use of HPSEC and RRF individually, removal in the low molecular weight (LMW) organic region was observed by comparison of the HPSEC profiles of raw and treated waters and the removal of the hydrophobic organics was observed by comparing the RRF results. A new organic fractionation and characterization technique involving the sequential application of the two techniques, called RRF-HPSEC, was developed to provide additional analytical information particularly to determine the key control factor for the removal of LMW organics. The RRF-HPSEC results showed that good removal of LMW organics could be linked to the presence of high ratio of hydrophobic LMW organics compared with hydrophilic LMW organics. It was revealed, therefore, that the removal of LMW organics was achieved mainly through the reduction of hydrophobic fractions compared with hydrophilic fractions with the corresponding molecular weight. Refereed/Peer-reviewed

Purpose: 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. Conclusions: 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 divalent metals, as well as through dilution processes. Methods: 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 13C 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. Results: 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. Refereed/Peer-reviewed

In order to understand and improve drinking water treatment process operations, many techniques have been established to characterize natural organic matter (NOM). Resin fractionation is the most widely used technique to isolate NOM based on its hydrophobicity and hydrophilicity, these can be used to determine the treatability of NOM, 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 of the hydrophobicity/hydrophilicity of NOM. The reduction of total RPHPLC peak area correlated well with dissolved organic carbon (DOC) and UV absorbance at 254 nm (UV254) removal efficiency. After resolving the RPHPLC profile using a peak fitting technique, the ratio between hydrophobic and hydrophilic peak area can be used to quantify the treatability of NOM (particularly DOC removal). Further statistical analysis grouped the resolved peaks into three groups (two groups of hydrophilic and one group of hydrophobic) and established an expression to link peak area with UV254 and DOC removal. The characterization results were further compared by the traditional resin fractionation technique using DAX-8 and XAD-4 resins (combined). The results confirmed that despite the definition that hydrophobic and hydrophilic components measured by both methods could be different, both methods confirm that the hydrophilic fraction was recalcitrant after coagulation and is of small molecular weight. Refereed/Peer-reviewed

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. Refereed/Peer-reviewed

The effect of TiO(2) 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. Multiwavelength 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. Refereed/Peer-reviewed

In this investigation, high-performance size exclusion chromatography (HPSEC) was used to characterise organic matter in treated drinking water at key sampling locations along two selected distribution systems (chlorinated and chloraminated). Other water quality parameters such as colour, UV 254 , 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 samples from two contrasting distribution systems with different disinfection regimes and organic characteristics together with samples 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 samples 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. Refereed/Peer-reviewed

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.