Organophosphorus pesticides (OPPs) in source waters are a potential threat to drinking water safety. Although these chemicals could be removed upon chlorination in conventional water treatment, the formation of toxic decomposition products, i.e., oxons, can increase the toxicity of finished water. To address this problem, this study proposed a simple and practical treatment method for detoxifying OPPs by incorporating an alkaline hydrolysis procedure after pre-chlorination in the conventional treatment process. The experimental results showed that pre-chlorination with a chlorine dose of 1.5 mg/L could transform 87 %-92 % of OPPs with initial concentrations <50 & mu;g/L into oxons, resulting in a significant increase in toxicity. However, by adjusting solution pH to around 11 through addition of a base fostered hydrolysis reactions of the chlorinated by-products, reducing the toxicity of the treated solution to about 0 % after a 30-minute reaction. Furthermore, the present study demonstrated that, even at a higher OPPs concentration (e.g., 100 & mu;g/L for individual OPPs), a complete detoxification of the treated water could be achieved via adjusting pre-chlorination dose or reaction time, or hydrolysis reaction time. The presence of the common inorganic ions and organic matter in the source water matrix has negligible effects on the degradation and detoxication of OPPs. This study thus demonstrated that a combined pre-chlorination and alkaline hydrolysis process could be an effective and efficient treatment protocol for both degradation and detoxication of OPPs in water treatment.

Determination of coagulant dosage in drinking water treatment is related to the requirements for drinking water quality as well as the treatment costs. Selection of appropriate coagulant dosages has been an issue for water treatment utilities, though empirical approaches were normally considered or employed. Inspired by the theory of elasticity in microeconomics, this study explored a novel approach for the cost-effective optimum coagulant dosage. This could enable water utilities to achieve the maximum possible removal efficiency of precursors for disinfection byproducts (DBPs) while maintain an economical dosage without incurring an excessive cost. The relationships between DBP formation potential (DBPFP) and several relevant water quality parameters were first examined and evaluated. UV254 was found the most appropriate DBPFP indicator with the highest correlation coefficients. Based on the relationship of UV254 and DBPFP, an approach for determination of cost-effective optimum coagulant dosage was delineated. The results showed that use of the cost-effective optimum coagu-lant dosage, which account for approximately 33% of optimum coagulant dosage, could achieve 79% of maximum removal efficiencies of UV254 for the source waters tested, thereby substantially reducing the for-mation of DBPs. Further increase the coagulant dosage was believed uneconomical since the increase in UV254 removal was limited. Similar results were obtained with different coagulants and with raw water samples with diverse water qualities. The results suggest that the proposed approach could provide a mathematical tool for cost-effective optimum coagulant dosage control which could at the same time achieve sufficient removal of natural organic matter to reduce DBPs formation.

The removal of glyphosate and aminomethylphosphonic acid (AMPA) with synthetic water was carried out on a lab-scale nanofiltration unit using two membranes, NFX and NFW. The presence of humic acid and some inorganic matters (CaCl2 and NaCl) was tested in the experiment. The results demonstrate that NFX exhibits better separation performance than NFW. The herbicide filtration is found to have little effect on the permeate flux as compared to transmembrane pressure. Intermediate concentrations of NaCl act positively on foulant separation, and an increment of 3.3-5.4 percentage points in foulant rejection is obtained with the addition of 100mg/L of NaCl. In Contrast, CaCl2 has negative effect on foulant separation during nanofiltration. Humic acid alone shows little influence on the rejection performance, whereas it is slightly improved in the coexistence of humic acid and CaCl2. The nanofiltration technology proves to be a good approach to treat the problem of pesticide micropollution in a one-step process. This work clearly shows that the composition of the water matrices may influence the efficiency of the nanofiltration process in terms of the separation of the micropollutants.

The effects of recycling spent filter backwash water (SFBW) on the removal of 14 organic pesticides were examined in a simulated conventional drinking water treatment process.

In this study, a bench scale forward osmosis (FO) process was operated using two commonly available FO membranes in different orientations in order to examine the removal of foulants in the coal seam gas (CSG) associated water, the water flux and fouling behaviours of the process were also investigated. After 48 h of fouling simulation experiment, the water flux declined by approximately 55 and 35% of its initial level in the TFC-PRO and CTA-PRO modes (support layer facing the feed), respectively, while the flux decline in the TFC-FO and CTA-FO modes (active layer facing the feed) was insignificant. The flux decline in PRO modes was caused by the compounding effects of internal concentration polarisation and membrane fouling. However, the declined flux was completely recovered to its initial level following the hydraulic cleaning using deionised water. Dissolved organic carbon (DOC), adenosine tri-phosphate (ATP) and major inorganic scalants (Ca, Mg and silica) in the CSG feed were effectively removed by using the FO process. The results of this study suggest that the FO process shows promising potential to be employed as an effective pre-treatment for membrane purification of CSG associated water.

In this study, a laboratory pilot scale forward osmosis-reverse osmosis (FO-RO) hybrid system was used to desalinate both actual and spiked brackish surface water (BSW). An overall performance evaluation was conducted and the membrane foulings were characterised by comprehensive techniques. Severe flux decline was observed during the treatment of high scaling/fouling potential feed solutions. It was found that when the raw BSW was used as feed, the flux can be completely recovered by hydraulic cleaning. When the raw BSW was spiked with nutrients and/or scaling ions for accelerated scaling and biofouling, more severe flux decline was observed. Inorganic scaling caused by calcium and phosphate, and their interactions with organic constituents in the feed solutions were the dominant cause of the declined system performance. For the spiked feed water, the combined physical and chemical cleaning using two chemical agents was not able to restore reduced flux to its initial value. This study identified the need for implementing a sufficient cleaning strategy targeting different membrane foulants, particularly for inorganic sealants; as well as confirms the need of fouling-resistant membrane. (C) 2016 Elsevier B.V. All rights reserved.

This study examined the matrix effect of a typical surfactant on the detection of pesticides in water using ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry (UPLC–ESI–MS/MS). When direct sample injection is employed, surfactants in water samples tend to adsorb onto the chromatographic column, weakening its analyte separation capability and consequently lowering signal detection intensities and raising detection limits. A new sample preparation approach of a tailored solid-phase extraction (SPE) is proposed based on the difference in adsorption affinities between surfactant and pesticide for silylated surfaces. Using sodium dodecyl sulfate (SDS) as a representative surfactant, four types of silylated silica particles with different surface hydrophobicity and functionality were examined for selectively adsorbing and removing SDS from water samples with pesticide analytes to eliminate the matrix effect of the surfactant on liquid chromatographic (LC) separation. It was found that the tailored SPE sample preparation for cleanup of SDS could be effectively achieved based on this concept. Samples prepared with trimethylchlorosilane methylated silica particles in the tailored SPE produced a desirable LC separation and low detection limits for the pesticide analytes. The linear calibration range extended from 0.1 up to 40 μg L−1 (R 2 = 0.9906–0.9998, n = 6). Low limits of quantitation for the 11 pesticides were achieved (0.027–0.090 μg L−1). The precision of the proposed method for the 11 analytes was less than 10%.

The effect of silica nanoparticles (SNPs) deposition on the properties of a commercial forward osmosis (FO) membrane was investigated in this work.Deposition of SNPs on the FO membrane was performed by a conventional sol-gel hydrolysis of tetraethyl orthosilicate and a simple dip-coating procedure.Scanning electron microscopy, X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy confirmed the successful deposition of SNPs on the membrane surface.The coated membranes were used in a bench scale FO system and their performance was evaluated through measuring the permeate water flux and fouling resistance.Successful deposition of SNPs smoothed out the membrane surface and increased surface hydrophilicity.The effects of SNP enabled a higher water flux and fouling resistance than for the pristine FO membrane, possibly due to increased hydrophilicity and decreased membrane roughness.

Interest in forward osmosis (FO) research has rapidly increased in the last decade due to problems of water and energy scarcity. FO processes have been used in many applications, including wastewater reclamation, desalination, energy production, fertigation, and food and pharmaceutical processing. However, the inherent disadvantages of FO, such as lower permeate water flux compared to pressure driven membrane processes, concentration polarisation (CP), reverse salt diffusion, the energy consumption of draw solution recovery and issues of membrane fouling have restricted its industrial applications. This paper focuses on the fouling phenomena of FO processes in different areas, including organic, inorganic and biological categories, for better understanding of this long-standing issue in membrane processes. Furthermore, membrane fouling monitoring and mitigation strategies are reviewed.

The salinity of soil and water resources is one of the economically expensive challenges to achieve sustainable development across the world. Salinity, which is a major environmental issue for both arid and semi-arid regions, is highly stressful for vegetation and adds to other stresses including water scarcity, nutrient deficiencies and soil alkalinity. Remediation is a strategy to clean up pollutants from the plant root zone in order to reduce vegetation stress and enhance productivity. This strategy involves biological management of soil and water which often leads to increased soil infiltration and leaching of excess salts out of the root zone. Several methods of soil and water remediation have been proposed that can be classified into the two main groups of engineering-based remediation and green remediation. Green remediation is the use of vegetation to remove or contain environmental contaminants such as heavy metals, trace elements, organic compounds and radioactive compounds in soil or water. There has recently been increased interest in green remediation using halophytes, particularly in developing countries. This paper reviews the different methods of phytoremediation and their application in green remediation. It also describes how halophytes are an emerging means of desalination and how they can be used for phytoremediation of heavy metals.

Stock solutions of micropollutants with low water solubility are commonly prepared using organic solvents in laboratory studies on degradation of these organic compounds. Dilution of the stock solution unavoidably introduces a small amount of organic solvent into the experimental working solutions. This could possibly affect the estimation of the degradation rate constants of these organic micropollutants by UV-based advanced oxidation process such as UV/H2O2. To dertionstrate this problem, the effect of organic solvents on the reaction rate constant of malathion has been investigated in the UV/H2O2 process at the concentration levels that would likely be derived from stock solutions. Several organic solvents commonly used for stock-solution preparation were selected, including acetonitrile (ACN), acetone (Ac), methanol (MeOH), ethanol (EtOH), 1-propanol (PrOH), 1-butanol (BuOH) and 1-pentanol (PeOH). The results show that the reaction rate of malathion in the UV/H2O2 process could be affected by the presence of these organic solvents, even at a concentration well below that possibly introduced during the preparation of working solutions from the organic solvent stock solutions (e.g. 0.00005%, v/nu). The suppressive effect on the reaction rate constant depends on the type and concentration. With the increase of organic solvent concentration, the reaction rate constant of UV/H2O2 gradually decreases to the value for photolysis alone. The organic solvents having a stronger reaction activity with 'OH tend to impose a greater effect on the reaction rate constant. The findings here provide a plausible explanation for the discrepancies in the rate constants reported in the literature for some organic micropollutants during the UV-based advanced oxidation processes. (C) 2016 Elsevier B.V. All rights reserved.

Graphene (Gr)-based materials are a promising nanomaterial for the development of antibacterial surfaces owing to their biocidal activity. However, the effect of the physicochemical features of these materials on their antibacterial activity has yet to be clarified. Gr-based nanomaterials can interact with cellular components, e.g. membranes, proteins and DNA, and initiate a sequence of nanomaterials/bacterial interactions that rely on colloidal energies and active bio-physicochemical interfaces. Analyzing these different interfaces permits the development of anticipated relations between physical/chemical structure and bactericidal activity depending on Gr-based nanomaterial features such as shape, size, hydrophilicity, roughness and functionality. Realizing how nanomaterials are interacting with bacterial cell membranes is correlated to how they affect bactericidal activity and is thus critical for obtaining benign applications. This review analytically discusses specific Gr-based material features related to bacterial interactions, with special focus on the different modes of interaction between Gr-based materials and cell membranes, nucleic acids and lipid bilayers.

In this study, a laboratory pilot scale forward osmosis-reverse osmosis (FO-RO) hybrid system was used to desalinate both actual and spiked brackish surface water (BSW). An overall performance evaluation was conducted and the membrane foulings were characterised by comprehensive techniques. Severe flux decline was observed during the treatment of high scaling/fouling potential feed solutions. It was found that when the raw BSW was used as feed, the flux can be completely recovered by hydraulic cleaning. When the raw BSW was spiked with nutrients and/or scaling ions for accelerated scaling and biofouling, more severe flux decline was observed. Inorganic scaling caused by calcium and phosphate, and their interactions with organic constituents in the feed solutions were the dominant cause of the declined system performance. For the spiked feed water, the combined physical and chemical cleaning using two chemical agents was not able to restore reduced flux to its initial value. This study identified the need for implementing a sufficient cleaning strategy targeting different membrane foulants, particularly for inorganic scalants; as well as confirms the need of fouling-resistant membrane.

Removal of effluent organic matter (EfOM) from a wastewater secondary effluent by aluminum sulfate (alum) coagulation and its effects on haloacetic acid (HAA) formation were studied in the range of alum dose 0-120 mg/L and the pH range 4.0-9.0. Surrogate parameters, such as dissolved organic carbon (DOC), UV254, specific UV absorbance (SUVA), and fluorescence regional integration method were employed to evaluate organic removal efficiency. Results indicated that incomplete coagulation noticeably increased HAA formation in treated effluent and that enhanced coagulation significantly reduced disinfection byproducts (DBPs) precursors. pH control was more important for reducing DBP formation than coagulant dosage in terms of precursor removal from the EfOM. Under the same coagulation conditions, removal efficiencies of DOC, UV254, and SUVA were very different, but all reached their maximum values at pH 6. Removal efficiency of EfOM by coagulation was not as high as that reported for natural organic matter removal in water treatment. This is likely due to the unique nature of the EfOM characterized by the inclusion of soluble recalcitrant microbial products in the effluent. In contrast to what was observed in water treatment, UV254 was found to be a better indicator for the precursor of HAA formation for the wastewater effluent. Dichloroacetic acid and trichloroacetic acid were the major species generated following chlorination of both the raw and treated effluent. Presence of bromide and iodide ions in solution increased formation of fractions of bromo-or iodoacetic acids and also total haloacetic acids (THAA) following chlorination after alum coagulation at all pH values. Minimum THAA formation was observed at the optimum coagulation pH of 6 regardless of addition of bromide ions and iodide ions.

This study investigated the effect of membrane surface properties on membrane biofouling in a submerged membrane bioreactor treating synthetic wastewater, by employing qualitative membrane surface examination techniques and biofilm quantification. The investigation was carried out on three different types of fouled membrane samples obtained using different filtration methods. Lipid phosphate concentration, which represents viable biomass, was employed as a direct measure of biofouling. Contact angle and zeta potential measurements of clean and fouled ultrafiltration and hollow fibre membranes were conducted. Zeta potentials of membrane samples were measured at various electrolyte pHs. The surface energy of membrane samples was calculated and reported from the data obtained from contact angle of measurements. The outcomes from this study can be used as the basis of a technique to examine the potential of biofouling in membrane processes.

This study explored the efficacy and efficiency of a simultaneous UV-catalyzed oxidation-coagulation process of titanium sulfate (UV/Ti(SO4)2) for efficient removal of As(III) from water. It revealed that, As(III) could be oxidized to As(V) during the UV catalyzed coagulation of Ti(SO4)2 with highly efficient As(III) removal in the pH range 4-6. The UV catalyzed oxidation-coagulation showed surprisingly effective oxidation of As(III) to As(V) within a short time. XPS indicated that 84.7% of arsenic on the coagulated precipitate was in the oxidized form of As(V) after the UV/Ti(SO4)2 treatment of As(III) aqueous solutions at pH 5. Arsenic remaining in solution at high pH was in the oxidized form As(V). Removal efficiencies of As(III) were investigated as a function of pH, Ti(SO4)2 dosage, initial As(III) concentration and irradiation energy. As(III) could almost completely be removed (>99%) by the photocatalytic oxidation-coagulation process with a moderate dose of Ti(SO4)2 in the pH range 4-6 at an initial arsenic concentration of 200 μg/L. The mechanisms of the photocatalytic coagulation oxidation of Ti(SO4)2 are similar to those of UV/crystalline TiO2 particles, involving the formation and reactions of the hydroxyl radical OH and superoxide HO2/O2(-).

The aim of this study is to use a range of statistical tools to assess particulate matter less than 10 μm (PM10) in the atmosphere that has been measured daily at five locations in South Australia over a 7-year period. We consider a wind rose model to provide a graphical display of the frequency distribution of wind speed to explore the role of PM10 accumulation over time. A generalised least squares technique with a first-order autoregressive model was applied to the realisation of average changes in PM10, and these were assessed at the 5 % significance level. This study found the change in variability of PM10 concentration over time. The pre-whitened PM10 series were considered as realisations of white noise using correlogram plots. Furthermore, a robust regression technique involving wet (>0.5-mm rainfall) and dry properties (<0.5-mm rainfall) was used to assess the influence of rainfall on PM10 distributions for the city of Adelaide.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis coupled simply with water filtering before injection has proven to be a simple, economic and time-saving method for analyzing trace-level organic pollutants in aqueous environments. However, the linearity, precision and detection limits of such methods for late-eluting analytes were found to be much poorer than for early-eluting ones due to adsorption of the analytes in the operating system, such as sample vial, flow path and sample loop, creating problems in quantitative analysis. Addition of methanol (MeOH) into water samples as a modifier was shown to be effective in alleviating or even eliminating the negative effect on signal intensity for the late-eluting analytes and at the same time being able to reduce certain matrix effects for real water samples. Based on the maximum detection signal intensity obtained on desorption of the analytes with MeOH addition, the ratio of the detection signal intensity without addition of MeOH to the maximum intensity can be used to evaluate the effectiveness of methanol addition. Accordingly, the values of <50%, 50-80%, 80-120% could be used to indicate strong, medium and no effects, respectively. Based on this concept, an external matrix-matched calibration method with the addition of MeOH has been successfully established for analyzing fifteen pesticides with diverse physico-chemical properties in surface and groundwater with good linearity (r(2): 0.9929-0.9996), precision (intra-day relative standard deviation (RSD): 1.4-10.7%, inter-day RSD: 1.5-9.4%), accuracy (76.9-126.7%) and low limits of detection (0.003-0.028μg/L).