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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.

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.

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.

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.

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.

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.

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

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...

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

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

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.

The objective of this study was to determine if the removal of NOM in reservoir waters in conventional treatment with alum is limited by the character of the NOM. A sequential jar test procedure, which included five treatment steps was employed to study the character of the NOM which could not be removed by flocculation/sedimentation. The NOM in the raw and treated waters was characterised by techniques including dissolved organic carbon (DOC), UV absorbance (UVA), high performance size exclusion chromatography (HPSEC), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFT). HPSEC analysis of the reservoir waters from three sources indicated that the organic fraction remaining after alum treatment was of lower molecular weight than that in the original raw waters. Pyrolysis of freeze dried material (FDM) from one raw water source (Hope Valley Reservoir) and following treatment with a high alum dose at pH 5 (coagulated and non coagulated material) gave by-products that indicated the presence of proteins, polyhydroxyaromatics and polysaccharides.