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

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 272nm. This index can be calculated for any AMW fraction of NOM. Similarly to SUVA254, 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. [Copyright &y& Elsevier]

Abstract: 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 >50,000Da ‘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. [Copyright &y& Elsevier]

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 Ala, Alb, and Alc 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. [Copyright &y& Elsevier]

Abstract: 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 254nm (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. [Copyright &y& Elsevier]

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 samples. 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 samples. Samples 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. [Copyright &y& Elsevier]

Abstract: Treatment of wastewater from a Pinus radiata sulfite pulp and paper mill with coagulation followed by aerated stabilization basins (ASBs) was investigated to determine a treatment process that minimizes the colour formation. Two post-coagulation wastewaters were investigated, one low in P (Simulation A; BOD:N:P=100:1.3:0.06) and the other higher in P but still moderately P-limited (Simulation B, BOD:N:P=100:1.3:0.3). Changes in the organics character of the wastewaters were investigated at several stages of treatment: untreated, after coagulation; during and after ASB treatment, using HPSEC and solid-state 13C CP NMR spectroscopy. Effective reductions in colour456nm, and UV254 and 280nm, (∼80%) were achieved by coagulation using alum (1860ppm). However, during ASB treatment, colour456nm increased (>100%) in both simulations. HPSEC analysis showed that removal of HMW (>3000Da) was achieved through coagulation with the simultaneous removal of LMW (<300Da) in the ASB simulations. Subsequent to the removal of HMW and LMW, an increase of intermediate-range compounds (300–3000Da) occurred. Solid-state 13C NMR analysis indicated some selective removal of aromatic and alkyl groups during the coagulation process and additional removal of aromatic C during ASB treatment. The slightly higher proportion of HMW (>1000Da) in ‘A’ than ‘B’ and the slightly higher proportion of aromatic C and alkyl groups remaining in the effluent of ‘A’ might be the basis for differences in the colour development in the two ASB simulators. The low nutrient loading (external) in the pre-treated wastewaters has been shown to be sufficient to sustain microbiological growth of organisms that contribute to colour formation with ASB treatment. This occurred in both simulations and it was concluded that the manipulation of the BOD:N:P ratio to optimise BOD removal had little effect on colour removal. This paper provides insight on the nature of recalcitrant organic compounds causing colour formation. [Copyright &y& Elsevier]

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 250nm 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 250–260nm. 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. [Copyright &y& Elsevier]

Abstract: The mechanism of natural organic matter (NOM) removal by AlCl3 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 AlCl3 was investigated using photometric dispersion analyzer compared with PACl. Monomeric Al species (Ala) shows high ability to satisfy some unsaturated coordinate bonds of NOM to facilitate particle and NOM removal, while most of the flocs formed by Ala are small and difficult to settle. Medium polymerized Al species (Alb) can destabilize particle and NOM efficiently, while some flocs formed by Alb are not large and not easy to precipitate as compared to those formed by colloidal or solid Al species (Alc). Thus, Alc could adsorb and remove NOM efficiently. The removal of contaminant by species of Ala, Alb and Alc follows mechanisms of complexation, neutralization and adsorption, respectively. Unlike preformed Alb in PACl, in-situ-formed Alb can remove NOM and particle more efficiently via the mechanism of further hydrolysis and transfer into Alc during coagulation. While the presence of NOM would reduce Alb formed in-situ due to the complexation of NOM and Ala. [Copyright &y& Elsevier]