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Tests of microfiltration efficiency used for the pretreatment of backwash water from sand filters were conducted at two water treatment plants treating surface water and infiltration water. Microfiltration efficiency was evaluated for three membrane modules: two with polymeric membranes and one with a ceramic membrane. This study showed that the contaminants that limit the reuse of backwash water from both plants by returning them to the water treatment line are mostly microorganisms, including pathogenic species (Clostridium perfringens). Additionally, in the case of backwash water from infiltration water treatment, iron and manganese compounds also had to be removed before its recirculation to the water treatment system. Unexpectedly, organic carbon concentrations in both types of backwash water were similar to those present in intake waters. Microfiltration provided for the removal of organic matter, ranging from 19.9% to 44.5% and from 7.2% to 53.9% for backwash water from the treatments of surface water and infiltration water, respectively. Furthermore, the efficiency of the iron removal from backwash water from infiltration water treatment was sufficient to ensure good intake water quality. On the other hand, manganese concentrations in the backwash water, from infiltration water treatment, pretreated using the microfiltration process exceeded the levels found in the intake water and were, therefore, an additional limiting factor for the reuse of the backwash water. In both types of backwash water, the number of microorganisms, including Clostridium perfringens (a pathogenic one), was a limiting parameter for backwash water reuse without pretreatment. The results of the present study showed the possibility for using microfiltration for the pretreatment of backwash water, regardless of its origin but not as the sole process. More complex technological systems are needed before recirculating backwash water into the water treatment system. The polyvinylidene fluoride (PVDF) membrane proved to be the most effective for DOC and microorganism removal from backwash water. [ABSTRACT FROM AUTHOR]

Understanding the degradation kinetics and mechanisms of trace organic contaminants (TrOCs) by UV-based advanced oxidation processes (UV-AOPs) are pivotal in realizing their efficient application in water treatment. However, the relevant knowledge in practical flow-through reactors remains a void, compared with that of commonly used batch reactors. To fill the knowledge gaps, the current work investigated the degradation of atrazine (ATZ) in flow-through UV-AOP systems with different light sources and chlorine additions. The results showed that UV/Cl2 in the reactors (with a diameter of 50 mm) was not very efficient in ATZ degradation while the pseudo-first order degradation rate constant was elevated by over 2.7 times with vacuum UV (VUV)/UV. In contrast to observations in the batch reactors, the addition of chlorine to the flow-through VUV/UV system unexpectedly decreased the rate constant by about 39%. The analysis of the relative contributions of different degradation pathways revealed that the inhibitory effect of the chlorine addition arose from the transformation of HO• to reactive chlorine species (e.g., ClO•) which had low reaction rate constants with ATZ. The baffle implementation promoted the ATZ degradation by 12–58%, mainly due to an enhanced mixing that facilitated the radical oxidation. The energy costs of the UV-AOPs in ATZ removal ranged within 0.40–1.11 kWh m−3 order−1. The findings of this work are helpful in guiding efficient VUV/UV and VUV/UV/Cl2 processes in drinking water treatment. [ABSTRACT FROM AUTHOR]

This document provides information on various products related to groundwater monitoring and remediation. Geoprobe Systems and Vista Clara Inc. have developed the DP Nuclear Magnetic Resonance (NMR) Dart probe, which is effective in estimating aquifer properties such as porosity and permeability. AMS Inc.'s PowerProbes are versatile drilling rigs suitable for installing remedial injections and groundwater monitoring wells. Campbell Ultrafiltration+ offers a three-stage filtration system that reduces PFAS and other contaminants while maintaining flow rate. In-Situ Inc. has introduced VuSitu HydroVu Cloud Connection software, which makes it easier to view and manage data files and calibration reports for water quality monitoring. Calgon Carbon's FILTRASORB is a granular activated carbon product designed for the removal of organic compounds from drinking water. QED Environmental Systems Inc. has developed the single-use Combo Core soil sampler for analyzing VOC and PFAS. Van Essen Instruments' TD-Diver is a submersible datalogger for long-term water level monitoring. Robertson Geologging USA Inc.'s RGeo-eye is a borehole logging camera that provides a full 360° unwrapped image of the borehole. Protective Industrial Products Inc. offers bio-based ear plugs and seamless knit gloves with impact protection for increased comfort and performance. [Extracted from the article]

[Display omitted] • The fundamentals of SR-AOPs and membrane separation technology are summarized. • The limitations of SR-AOPs and membrane separation technology are analyzed. • The specific advantages of SR-AOPs and membrane technology complementing each other in wastewater treatment are provided. • Current challenges, issues and perspectives, future prospects and strategies for improvement are presented. Sulfate radical-based advanced oxidation processes (SR-AOPs) effectively eliminate trace organic pollutants from complex water matrices, making them appealing for wastewater purification. Membrane separation technology is a promising solution for environmental issues in various fields due to its efficiency, ease of operation, and space-saving design. In this review, a detailed summary of the different types of catalytic activation, catalyst characteristics, and catalytic mechanisms of SR-AOPs are provided. Also, the applications of membrane separation technology in different fields are summarized. Both technologies have their limitations, and exploring a new segmented or simultaneous catalytic-separation technology as a future development strategy is necessary. This new technology covers the advantages of the above processes; not only can synchronize the removal of organic matter, desalination, and sterilization, thus reducing membrane contamination, improving membrane life and water flux, and reducing secondary contamination, but also realizes convenient recovery of catalysts, which can play a non-negligible potential in complex wastewaters containing a large amount of difficult-to-degrade organic matter and salts, and is expected to solve the gradually developing needs of water treatment. It is expected to solve the developing progressively water treatment needs, showing a broad application prospect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanostructured SnO x -TiO 2 thin film photocatalyst by binder free method. • Structure and phase analysis confirmed defects induction and phase change. • Defects resulted in reduced bandgap and enhanced visible light absorption. • High rates of visible light degradation for cationic and anionic dyes. • Photoelectrochemical studies show efficient carrier generation and transport. Advanced oxidative removal of organic pollutants from water bodies using nanoparticles of metal oxide photocatalysts is a concurrent hot topic. In the present study, SnO x -TiO 2 heterogeneous nanocomposite thin film photocatalysts have been synthesized using SnO and TiO 2 precursors by binder-free doctor blade technique. X-ray diffraction was used to confirm the presence of anatase TiO 2 as a major phase at elevated temperatures. Raman spectra analysis confirmed phase transformation and defect induction. X-ray photoelectron spectroscopy was utilized to determine the purity and chemical condition of the synthesized thin films. The porous nature of the thin film surface was observed using field emission scanning electron microscopy. UV–Vis-NIR spectroscopy results showed a reduction of bandgap from 3 eV to 2.6 eV with enhanced light absorption. The superior oxygen evolution reaction, redox nature and charge carrier generation were demonstrated using photo-electrochemical techniques. Improved photoresponse of the photocatalysts was observed using chrono-amperometry technique. The superior visible light-driven photocatalytic activity of the samples was demonstrated utilizing cationic and anionic model pollutant dyes. The reusability of the catalyst is ensured through successive photodecomposition processes. These results show a facile fabrication of defects induced heterogenous nanocomposite photocatalyst thin films with improved visible light activity. [ABSTRACT FROM AUTHOR]

The study investigated the effects of pre-ozonation on the parameters such as turbidity, color, chlorophyll a and TOC on a pilot scale. The investigation results indicate that the amount of required ozone to remove TOC, color and turbidity depends on the quality of inlet water, and the efficiency of water ozonation depends on the process factors such as ozone dose, temperature, pH and ozone-water contact time. The study likewise shows that the lower amount of turbidity, TOC, temperature and higher alkaline pH of sample water boost the ozonation effect on removing the variables in question. The results also demonstrate a direct relationship between pH, ozone dosage and contact time, as well as an indirect relationship between temprerature and the removal of parameters. [ABSTRACT FROM AUTHOR]

Bimetallic nanoparticles comprised of iron (Fe) and nickel (Ni) were investigated for the removal of an azo dye contaminant in water. Morphology (core shell and alloy) and metal molar ratio (Ni2Fe10, Ni5Fe10, and Ni10Fe10) were tested as key nanoparticle properties. The shelf life of the nanoparticles was tested over a 3-week period, and the effect of initial nanoparticle concentration on dye removal was evaluated. The highest initial nanoparticle concentration (1000 mg/L) showed consistent Orange G removal and the greatest extent of dye removal, as compared to the other tested concentrations (i.e., 750 mg/L, 500 mg/L, and 250 mg/L) for the same nanoparticle morphology and metal molar ratio. The metal molar ratio significantly affected the performance of the core shell morphology, where overall dye removal was found to be 66%, 89%, and 98% with an increasing molar ratio (Ni2Fe10 → Ni5Fe10 → Ni10Fe10). In contrast, the overall removal of the dye for all molar ratios of the alloy nanoparticles only resulted in a variability of ±0.005%. When stored in water for 3 weeks, core shell nanoparticles lost reactivity with an average>17% loss in removal with each passing week. However, the alloy nanoparticles were able to continually remove Orange G from solution after 3 weeks of storage to ~97% when used at a starting nanoparticle concentration of 1000 mg/L. Overall, the Ni2Fe10, Ni5Fe10, and Ni10Fe10 alloy nanoparticles with a starting nanoparticle concentration of 1000 mg/L resulted in the greatest dye removal of 97%, 99%, and 98%, respectively. Kinetic rate models were used to analyze dye removal rate constants as a function of nanoparticle properties. Kinetic rate models were seen to differ from core shell (first-order kinetics) to alloy morphology (second-order kinetics). Alloy nanoparticles resulted in as high as X kinetic rate constant, and core shell nanoparticles resulted in as high as XX kinetic rate constant. Metal leaching from the nanoparticles was investigated; alloy nanoparticles resulted in leaching of 3% Fe and 5% Ni which is similar to core shell leaching of 3.2% Fe and 4.3% Ni from the Fe10Ni10 nanoparticles. [ABSTRACT FROM AUTHOR]

Fe/H2O2 and Co/PMS reactions were compared for L-proline degradation under different initial pH values, various transition metal salt and oxidant agent concentrations, as well with and without irradiation. The Fenton reaction took 60 min to degrade 90% of the L-proline, whereas the Fenton-like reaction achieved the same degradation after only 15 min. The best conditions for the Fenton-like reaction resulted from using 0.8 mM of cobalt salt with low PMS concentration (20 mM) at a neutral initial pH and without irradiation. Further experiments were performed using the Co/PMS system to estimate the effects of the other reaction conditions. The results of these experiments showed that pH, reagent concentration, and UV (λ = 365 nm) radiation had no significant effect on the degradation. Additionally, the Fenton-like reaction was made in heterogeneous phase, showing that the reaction proceed equally at same pH than homogeneous phase reaction with no significant effect of phase type used. Significant amount of cobalt was found being leached from the solid media to the water at acidic pH values during the heterogeneous process so the best process conditions were found at neutral pH where the amount of cobalt being leached was found negligible. The heterogeneous Fenton-like process was found feasible to be used for different contaminants degradation with no risk of increased toxicity related with cobalt leachate. The results of this work provide a good evaluation of heterogeneous and homogeneous Fenton-like reaction and suggest that high reagent concentrations are unnecessary for efficient contaminant removal in aqueous phase. [ABSTRACT FROM AUTHOR]

Abstract Intensive organic matter removal (OMR) associated with timber harvest has the potential to impart long-term alterations to soil biota and associated properties and processes; however, there is a lack of data to say if this trend persists at depth. This study investigated how OMR influences long-term stability of soil fungi to a depth of 1 m using a replicated experimental pine forest in the Gulf Coastal Plain, USA. Treatments included unharvested control stands as well as low- and high-OMR stands. Intensive OMR led to significant differences in community structure and the abundance of functional guilds in surficial soil. Saprophytic taxa increased while ectomycorrhizal (ECM) taxa decreased with intensive-OMR, which correlated strongly with increased surface temperature and reduced soil nitrogen. Ericoid mycorrhizae (ERM) also increased in intensive-OMR stands, which may indicate that following disturbance, ERM could outcompete ECM for colonization of subsequent seedlings. Overall, no differences were observed below 30 cm, except for alpha diversity, which was a function of high inter-replicate variability. Our results illustrate a distinct long-term structural and functional response of soil fungi to intensive-OMR in the upper portions of the soil profile, which could lead to altered stand productivity and ecosystem services. Highlights • Fungal community structure at 0–10 cm and 10–30 cm was altered by timber harvest. • Saprophytes increased and ectomycorrhizae decreased in intensively harvested stands. • Fungal communities at depth possessed high inter-replicate variability. [ABSTRACT FROM AUTHOR]

Graphical abstract ZIF-8(zinc-methylimidazolate framework-8) is reported for selective removal of oils from water surface, Experiment results show that the highly hydrophobic ZIF-8 particles could be reused in water-oil separation for 20 cycles. Highlights • The as-synthesized ZIF-8 exhibited highly hydrophobic and superoleophilic properties. • The highly hydrophobic ZIF-8 particles could be reused in water-oil separation for twenty cycles. • ZIF-8 particles could be regenerated by heating combined with reduced pressure treatment. Abstract ZIF-8(zinc-methylimidazolate framework-8), one of the zeolitic imidazolate frameworks (ZIFs), was put into a tea bag for selective removal of oils from water surface, and exhibits strong hydrophobicity with a water contact angle of 142°, ZIF-8 particles combined with highly hydrophobic and superoleophilic properties. Our Experiment results showed that the highly hydrophobic ZIF-8 particles and the ZIF-8/tea bag could be reused in oil-water separation for twenty cycles. More importantly, the oil could be readily removed from the surfaces of particles by heating combined with reduced pressure treatment whereas the particles still kept highly hydrophobic and superolephilic characteristics, which render its potential applications in the cleanup of oil spills and the removal of organic pollutants on water surface. [ABSTRACT FROM AUTHOR]

The aim of the present study was to compare the effectiveness of coagulation process carried out using non-prehydrolysed coagulants (iron (III) sulphate (VI) and aluminium sulphate (VI)) and prehydrolysed polyaluminium chlorides differing in basicity in the removal of natural organic matter (NOM) from groundwater. Volume coagulation was carried out in groundwater samples after aeration at natural pH or at pH adjusted to 6.0–8.5. The Al species (Ala-monomeric, Alb-polymerized, Alc-colloidal) distribution in the aluminium coagulants were analyzed by the Ferron complexation timed spectrophotometry. The fraction distributions of NOM and residual aluminium after coagulation were analyzed as changes of coagulant dose and pH. The efficiency of polyaluminium chlorides in the removal of NOM was found to increase with the polymerization of the products of aluminium prehydrolysis. Prehydrolysed coagulants were of greater utility than non-prehydrolysed coagulants in removing not only non-dissolved, but also dissolved fractions of NOM, and they were efficient over a wider range of pH. When the proportion of dissolved organic carbon in the total organic carbon load increased, the efficiency of total organic carbon removal decreased regardless of the type of coagulant tested. The worst results in the removal of NOM were produced by the iron coagulant. [ABSTRACT FROM AUTHOR]

This review summarizes the characterization and quantification of interactions between dissolved organic matter (DOM) and estrogens as well as the effects of DOM on aquatic estrogen removal. DOM interacts with estrogens via binding or sorption mechanisms like π-π interaction and hydrogen bonding. The binding affinity is evaluated in terms of organic-carbon-normalized sorption coefficient (Log K OC ) which varies with types and composition of DOM. DOM has been suggested to be a more efficient sorbent compared with other matrices, such as suspended particulate matter, sediment and soil; likely associated with its large surface area and concentrated carbon content. As a photosensitizer, DOM enhanced estrogen photodegradation when the concentration of DOM was below a threshold value, and when above, the acceleration effect was not observed. DOM played a dual role in affecting biodegradation of estrogens depending on the recalcitrance of the DOM and the nutrition status of the degraders. DOM also acted as an electron shuttle (redox mediator) mediating the degradation of estrogens. DOM hindered enzyme-catalyzed removal of estrogens while enhanced their transformation during the simultaneous photo-enzymatic process. Membrane rejection of estrogens was pronounced for hydrophobic DOM with high aromaticity and phenolic moiety content. Elimination of estrogens via photolysis, biodegradation, enzymolysis and membrane rejection in the presence of DOM is initiated by sorption, accentuating the role of DOM as a mediator in regulating aquatic estrogen removal. [ABSTRACT FROM AUTHOR]

In this work, poly(vinylidene fluoride) (PVDF) membranes of different graphite oxide (GO) dosage were prepared using phase inversion method. The results indicated that the hydrophilicity, rejection rate, anti-pollution capacities and pure water flux of membranes were efficiently enhanced with the introduction of GO, and the porosity of membrane was increased about 14.3%, which was attributed to the charge repulsion reaction between the negatively charged of dissolved organic matter and negative functional groups of GO. The raw water from Qinghe sweage treatment plant in Beijing had been utilized to evaluate the performance of PVDF-GO membranes, and permeate water was analyzed by the total organic carbon (TOC), UV–vis scanning spectrophotometer and three-dimensional fluorescence excitation-emission matrices (3D-EEM). Moreover, the membrane fouling mechanism was discussed and the membrane fouling was likely to be the result of the pore blocking by pollutants. In addition, the morphology properties of PVDF-GO membrane were investigated, and it was found when GO dosage was as high as 1.0 wt%, the anti-fouling of PVDF-GO membranes performed best. Therefore, the introduction of GO into the PVDF membranes was very effective to improve the performances of membranes varying adverse water conditions and it was also a good choice to the industrial applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A column bed was designed with pellets stacked in the column for removal of PAH from water. • Column bed showed remarkable efficiency for removal of Benzo(b) fluoranthene. • The pellets were recyclable for successive cycles of treatment. Abstract Performance of a novel prototype of a column-bed was evaluated for the removal of a potentially toxic Polycyclic Aromatic Hydrocarbon (PAH) - Benzo(b)fluoranthene (BbF) from the water. The column-bed was prepared using the pellets fabricated from a mixture of low-cost materials: Plaster of Paris (POP), Coconut coir and Zeolite. The pellets were coated with a unique combination of bioadsorbents (Chitosan and Alginic acid) for enhanced removal, greater stability, and reusability of pellets. The pellet based column- bed showed up to 91% removal efficiency during 120 min treatment time in graded concentrations ranging from 0.01 to 10.0 ppm. Evaluation of kinetic behavior of the column was performed through linear regression analysis by fitting the data into three well-known models: Thomas, Adams-Bohart, and Yoon-Nelson. The data showed good agreement between experimental and calculated values of adsorption capacity (qe) for all the models, however Adams-Bohart model fitted best to the data obtained. This report provides a novel design of a column bed-reactor for PAH removal from water. The pelleted form of packing material for column-bed is a unique approach to enhancing the column efficiency and reusability of the materials used for column-bed preparation. [ABSTRACT FROM AUTHOR]

Semi-volatile organic compounds (SVOCs) in drinking water have been considered a severe threat to public health worldwide. However, SVOC contamination and the associated human health risks of the drinking water from cities along tributaries of the Yangtze River and Huaihe River in China have been seldom reported. Here, we focused on the occurrence and distribution of a series of SVOCs, mainly including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and phthalate esters (PAEs), in drinking water of this region. In brief, a total of 31 SVOCs were detectable in all of the drinking water samples, and the total concentrations ranged from 0.92 ng/L to 266.16 ng/L in March and from 24.82 ng/L to 643.93 ng/L in August, with the highest concentrations in Dongtai (DT) and Xinghua (XH), respectively. Spatial and temporal differences of the SVOCs were also observed in drinking water samples, demonstrating the linkage between pollutant profiles and geographical locations, as well as exogenous wastewater discharge. Moreover, PAEs occupied 79.17–100.00% of the total concentrations of SVOCs in drinking water samples collected from the tributaries of the Yangtze River in March, while OCPs were the predominant SVOCs in most of drinking water samples from the tributaries of the Huaihe River. The human health assessment indicated that SVOCs posed negligible non-carcinogenic risks, but residents living in DT, Dafeng (DF), Chengdong (CD), Guanyun (GY) and Lianyungang (LY) may suffer carcinogenic health risks, which could be mainly induced by benzene hexachloride and heptachlor in August. [ABSTRACT FROM AUTHOR]

Rationale: Natural organic matter (NOM) is present in the environment and could influence the migration of heavy metals/radionuclides. The dissolved fraction of NOM (DOM) is usually quantified using total organic carbon analysis or UV–visible spectrometry. Nonetheless, analysis using pattern recognition cannot provide the full spectrum of organic molecules contained in waters, especially low‐molecular‐weight compounds. In the context of nuclear performance assessment studies, ground waters may contain DOM and a key aspect is to quantify different categories of NOM types in order to further evaluate the transport and fate of radionuclides in the environment. Methods: Thus, a method for the quantification of DOM at the molecular level was developed, based on electrospray ionization mass spectrometry (ESI‐MS). This method simultaneously gives structural information on DOM and the individual concentrations of these low‐molecular‐weight compounds without pretreatment and/or preconcentration of the samples. Results: Several methods of quantification (internal calibration, calibrated addition of external standard, sequential tandem mass spectrometry) have been optimized and successfully applied to real natural samples. They are discussed in this paper with a focus on acidic compounds, which are the compounds that most probably could influence the migration of heavy metals and radionuclides in the clay rock pore water from the French Callovo‐Oxfordian (COx) nuclear repository site. Conclusions: Quantification of in situ dissolved NOM from the COx has been performed using ESI‐MS. For the first time to our knowledge, it was possible to give a quite exhaustive and quantitative inventory of the small organic compounds present without proceeding to any chemical treatment or sample crushing and for naturally occurring concentrations. [ABSTRACT FROM AUTHOR]

A series of these novel CuO(x)/LaFeO 3 (x = 0–100%) nanocomposite photocatalysts were successfully fabricated by the sol-gel method. The obtained nanoparticles were characterized by several analysis techniques such as XRD, FT-IR, UV–Vis DRS, photoluminescence, TEM and EDS for identifying their structural, physical and optical characteristics. The photocatalytic activities of CuO(x)/LaFeO 3 nanoparticles were examined by photodegradation of Rhodamine B (RhB) under the visible light irradiation. The most improvement was achieved in the photocatalytic activity of the CuO(50%)/LaFeO 3 nanocomposite compared to those of the pure LaFeO 3 and other composites. It was interesting that addition of a low amount of H 2 O 2 (0.5 mL) greatly improved the photocatalytic performance so that a 6 ppm RhB was degraded only in dark (after 60 min without light illumination) and high concentration of RhB (30 ppm) was removed after 90 min. Furthermore, a 20 ppm phenol contaminant was destroyed after 150 min using the CuO(50%)/LaFeO 3 in presence of H 2 O 2 . These outstanding results could be ascribed to the simultaneous effects of the photocatalysis and Fenton-like mechanism that enhanced the photocatalytic efficiency. It was proposed that the non-toxic, inexpensive, highly active and stable CuO(50%)/LaFeO 3 nanocomposite photocatalyst have the potential to be used in practical industrial water treatment processes under the visible light illumination. [ABSTRACT FROM AUTHOR]

Abstract The presence of natural organic matter (NOM) in water can negatively affect water quality if NOM is present in excessive amounts during certain stages of water treatment. It is known that NOM constituents serve as precursors for DBPs (disinfection by-products) during the disinfection step of the water treatment process. Removal of natural organic matter (NOM) before disinfection is therefore essential to control DBP formation; however, owing to the heterogeneity and complexity of NOM, most water treatment processes are unable to attain complete removal of NOM from water sources. There is therefore a great need to develop methods that can effectively degrade NOM into smaller and relatively harmless compounds that are easily removed during water treatment processes. In this study, multi-walled carbon nanotubes/nitrogen, palladium co-doped titanium dioxide (MWCNT/N, Pd co-doped TiO 2) (0.5–5% MWCNTs) were fabricated for the enhancement of NOM degradation under visible-light illumination. Different MWCNT/N, Pd co-doped TiO 2 (also referred to as CT) nanocomposites were synthesised via a modified sol-gel method and characterised using ultraviolet visible (UV-Vis), X-ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) Spectroscopy and energy-dispersive X-ray spectroscopy (EDS) analysis. The UV-Vis results showed that introducing the MWCNTs on the nanocomposites was accompanied by a red shift, with CT (0.5% MWCNTs) occurring at a longer wavelength than the others. The efficiency and effectiveness of the synthesised nanocomposites was quantified through measuring the NOM degradation rate in raw water samples collected from two South African water treatment plants. These two drinking water treatment plants were selected as the raw water treated in these plants contains different NOM fractions: the raw water treated at Midvaal (MV) Water Company contains transphilic NOM fractions, while that treated at Plettenberg Bay (P) Water Treatment Plant contains high amounts of hydrophobic NOM. The changes in the amount of NOM in a sample were monitored by measuring the UV absorbance at 254 nm (UVA 254) as there is a strong correlation between absorbance at this wavelength and the aromatic content. The highest photocatalytic activity was observed with CT (0.5% MWCNTs) which attained 69.4% UVA 254 reduction for MV and 97.7% UVA 254 reduction for P raw waters. Compared to conventional methods applied by the two water treatment plants of interest, NOM removal efficiency (in terms of UVA 254 reduction) by CT (0.5% MWCNTs) increased by up to 9.4% and 11.5% for MV and P water treatment plants, respectively. The enhanced photocatalytic activity of this CT nanocomposite (0.5% MWCNTs) is attributable to the large surface area of the synthesised nanocomposites which allows huge amounts of NOM to be adsorbed onto the surface of the TiO 2 , thereby increasing their photodegradation. It is also due to the synergistic effect of N and Pd which enhanced the photoactivity of the TiO 2 in the MWCNT/N, Pd co-doped TiO 2 composite. Overall, it is clear that the use of the conventional processes is not effective in removing NOM from water. Findings obtained show that CT (0.5% MWCNTs) nanocomposite is a promising future NOM removal method that could complement the available water treatment processes in enhancing the removal of the aromatic component of NOM in water. Highlights • Natural organic matter (NOM) in water negatively affects water quality. • CNT anchored N, Pd co-doped TiO 2 nanocomposites were fabricated. • The nanocomposites showed enhanced NOM removal efficiency. • The activity was based on enhanced adsorption capacity of the nanocomposites. [ABSTRACT FROM AUTHOR]

Treatment of a persistent organic pollutant, carbamazepine (CBZ), in aqueous solution by a novel and sustainable method, Electro-activated carbon fiber-peroxydisulfate (E-ACF-PDS), was investigated and compared with ACF adsorption, Peroxydisulfate (PDS), ACF-peroxydisulfate (ACF-PDS), E-Pt (Pt-plating titanium as cathode in electrolysis), E-ACF (ACF as cathode in electrolysis), and Electro-Pt-peroxydisulfate (E-Pt-PDS) processes, respectively. The removal rate of CBZ by E-ACF-PDS was 98.78% in 30 min, which was much higher than that of the others. Besides, several tests were performed to investigate the role of operational conditions (pH, peroxydisulfate concentration, electrode potential, temperature, and water matrix) in E-ACF-PDS process. Moreover, it is worth noting that even after recycling ACF for 100 times, the removal rate of CBZ in 30 min decreased only slightly from 98.78% to 97.35% in E-ACF-PDS process. In addition, the surface functional groups, FTIR spectrum, Raman spectrum, BET surface area, micropore volume, and SEM images of ACF before and after long time service were investigated and the results revealed that the ACF could maintain the original features in E-ACF-PDS process even after 100 cycles, while the ACF alone was seriously damaged in ACF-PDS process after 50 cycles. These results suggested that the E-ACF-PDS process could remarkably enhance the removal of CBZ in aqueous solution due to the simultaneous adsorption of contaminants and the increase in the generation of active radicals on ACF. The electrons on cathode could inhibit the destruction of ACF caused by chemical oxidation such as sulfate radicals, hydroxyl radicals, and peroxydisulfate. Therefore, the E-ACF-PDS process may provide an effective and sustainable approach to water treatment for the elimination of contaminants of emerging concern in water. [ABSTRACT FROM AUTHOR]

Purification of water contaminated with organics, including pharmaceutical and personal care products (PPCPs), via adsorption, was carried out by using porous carbons obtained from the pyrolysis of metal azolate framework-6 (MAF-6, a subclass of metal-organic frameworks), especially in the presence of a KOH activator. The carbons showed high adsorption capacity for a wide range of PPCPs (the acidic ibuprofen; weakly acidic triclosan and oxybenzone; and basic diclofenac sodium and atenolol). The carbon prepared at 1000 °C showed record-high adsorption capacities for ibuprofen and diclofenac. A plausible adsorption mechanism for ibuprofen could also be suggested by adsorption under a wide range of pH conditions. Moreover, the used carbon could be recycled easily by solvent washing. Therefore, MAF-6-derived carbon (especially in the presence of a KOH activator) could be suggested as a potential adsorbent to purify water contaminated with organics such as PPCPs. [ABSTRACT FROM AUTHOR]

Organic micropollutants (OMPs), including both regulated and emerging contaminants, have been extensively detected in ground and surface waters, posing hazards to organisms and humans. Rapid and efficient removal of OMPs from environmental water by novel sorbents is still faced with severe challenges. Here we developed a magnetic nanoparticles-attached fluorographene-based (MNPs@FG) sorbent with high affinity to OMPs such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) compared to powdered activated carbon, the most widespread sorbent for OMPs removal. The removal efficiencies of PFOA and PFOS using the MNPs@FG sorbent were systematically examined at room temperature. The MNPs@FG sorbent showed 92–95% and 94–97% removal efficiencies of PFOA (180 μg/L) and PFOS (180 μg/L) in 2 min respectively, with relatively high sorption capacities for PFOA (50.4 mg/g) and PFOS (17.2 mg/g). The adsorption performance was stable even in the presence of natural organic matter. Moreover, the MNPs@FG sorbent could notably reduce PFOA and PFOS from ∼5 μg/L (an environmentally relevant concentration) to <50 ng/L in environmental water, lower than the U.S. Environmental Protection Agency health advisory level (70 ng/L). Besides PFOA and PFOS, the MNPs@FG sorbent also showed high removal efficiencies (97–99%) of difloxacin hydrochloride (DIF), acetochlor (ACE) and chlorantraniliprole (CHL) in short time (e.g. 10 min). The used MNPs@FG sorbent was facilely regenerated by methanol washing and reused five times without reduction in PFOA/PFOS removal and magnetic performance. Thus, this study provided a novel sorbent for rapid and effective removal of OMPs from environmental water. [ABSTRACT FROM AUTHOR]

Bio-MOF-1, Zn 8 (adenine) 4 (biphenyldicarboxylate) 6 O, was synthesized and used as a precursor for the first time in order to fabricate porous carbons by carbonization of the MOF. The characterization of Bio-MOF-1-derived carbons (BMDCs) revealed that the BMDCs are highly porous carbons (O- and N-doped, with a high degree of graphitization), which might be attractive materials for the study of adsorption. BMDCs, together with a commercial activated carbon (AC), were applied for the adsorption of bisphenol A (BPA), a typical endocrine-disrupting compound, from water. The BMDC-12h adsorbent showed an efficiency ∼5-times (in terms of q 12h, the adsorbed quantity at 12 h) of that of a commercial AC in BPA capture. More importantly, BMDC-12h exhibited the best performance for BPA uptake among the reported adsorbents so far. H-bonding is anticipated as the principal mechanism based on the functional groups present in BPA and those produced on BMDC-12h and the effect of solution pH on the BPA adsorption capacities. Moreover, BMDC-12h can be recycled by simple solvent washing and effectively used in subsequent cycles with negligible loss of performance. Therefore, BMDCs, particularly BMDC-12h, were suggested as remarkably efficient and easily recyclable adsorbents for water purification via BPA adsorption. [ABSTRACT FROM AUTHOR]

The photochemical removal of benzene was studied in air at atmospheric pressure using a side-on type 172 nm Xe2 excimer lamp with a wide irradiation area. After 1.5 min photoirradiation, C6H6 (1000 ppm) in air was completely converted to HCOOH, CO, and CO2 at a total flow rate of 1000 mL/min. The initial decomposition rate of C6H6 was determined to be 1.18 min−1. By using a flow system, C6H6 (200 ppm) was completely removed at a total flow rate of 250 mL/min. The conversion of C6H6 and the energy efficiency in the removal of C6H6 changed in the 31−100% and 0.48−1.2 g/kWh range, respectively, depending on the flow rate, the O2 concentration, and the chamber volume. On the basis of kinetic model simulation, dominant reaction pathways were discussed. Results show that the O(3P) + C6H6 reaction plays a significant role in the initial stage of the C6H6 decomposition. Important experimental parameters required for further improvement of the C6H6 removal apparatus using a 172 excimer lamp were discussed based on model calculations. [ABSTRACT FROM AUTHOR]

The security of recycled water quality in potable reuse can be enhanced by improving the credibility of reverse osmosis (RO) treatment for the removal of trace organic chemicals (TOrCs). This study evaluated the potential of online monitoring of N -nitrosodimethylamine (NDMA) before and after RO treatment as a surrogate indicator for TOrC removal by RO. This pilot-scale study monitored NDMA concentrations in RO feedwater (ultrafiltration-treated wastewater) and RO permeate every 22 min using novel online NDMA analyzers—high-performance liquid chromatography followed by photochemical reaction and chemiluminescence detection. NDMA rejection by RO varied considerably in response to changes in operating conditions (permeate flux and feedwater temperature). A high linear correlation between NDMA rejection and the rejection of six other TOrCs was observed. The linear correlation was also identified for an RO membrane damaged with chlorine. The correlation between another potential surrogate indicator (conductivity rejection) and TOrC rejection was relatively low. NDMA, which is the smallest compound among regulated TOrCs, revealed rejections lower than the other TOrCs, indicating that NDMA rejection can be a conservative surrogate indicator capable of predicting changes in TOrC removal. [ABSTRACT FROM AUTHOR]

Arsenic is a natural contaminant present in groundwater mantles which, in high concentrations, causes severe health and environmental problems such as the degradation of human health and the contamination of land used for agriculture during irrigation. Understanding the process of arsenic removal from water contributes to the sustainability of regions where this problem is present. This work presents an experimental study complemented with numerical predictions of the adsorption of arsenic (As(V)) in mini-columns using Granular Ferric Hydroxide (GFH) as adsorbent. The work focuses on the effects of the presence of organic matter, i.e., humic (HA) and fulvic (FA) acids, in a water inflow that is contaminated with As(V). The treatments contain the same concentration of organic matter, the same initial concentration of As(V) of 0.8 mg L −1 , and the same amount of GFH of 2 g for the filters. Results show that the samples containing organic matter (HA and FA) show a lower adsorption capacity, a lower breakthrough volume, a lower pH, and a non uniform saturation of the GFH filter. The results suggest the need to include the effects of organic matter in all subsequent analyses of arsenic removal from water because organic matter is always present in real life scenarios. Also, this work provides useful information to solve the problematic of the presence of high concentrations of As(V) (greater than 50 μg L −1 ) in the water mantles of the Bajio region of Mexico. [ABSTRACT FROM AUTHOR]

The corrosion of zero valent iron (ZVI) by hydrogen peroxide (H 2 O 2 ) generates hydroxyl (⋅OH) and other radical oxygen species (ROS) that degrade organic materials. To better understand the factors that govern the ROS formation during the H 2 O 2 -induced corrosion, we investigated the degradation of an organic probe compound (acesulfame (ACE)) in slurries of ZVI powder in unbuffered laboratory water at pH 6.5 ± 0.5. Chloride ions accelerated the corrosion of ZVI by H 2 O 2 and the formation ROS and, therefore, the degradation of organic materials. Conversely, slowing corrosion by phosphate buffer inhibited ROS formation and the degradation of organic compounds. The rate of H 2 O 2 decomposition was correlated with the liberation of Fe 2+ (aq) and the ACE degradation rate. The kinetics of H 2 O 2 decomposition was pseudo-first-order and zero-order at low (<0.04 mM/mg) and high [H 2 O 2 ]/[ZVI] initial ratios, respectively, and was consistent with Langmuir kinetics. The H 2 O 2 decomposition rate was proportional to the ZVI reactive surface area (SA) and nearly independent of the extent of ZVI oxidation, the presence of a Fe 2+ (aq) chelating agent, and ⋅OH quenchers (methanol and tert -butanol). Kinetic data suggest a mechanism involving rapid cathodic reduction of H 2 O 2 at the metallic ZVI surface which causes the liberation of Fe 2+ (aq) that generate ⋅OH via the homogeneous Fenton reaction. The stoichiometric efficiency (SE) of organics degradation ranged from 0.0008% to 0.014% and increased with decreasing H 2 O 2 decomposition rate. [ABSTRACT FROM AUTHOR]

The present study investigated the impact of different loading approaches and microbial activity on the Natural Organic Matter (NOM) removal efficiency and capacity of ion exchange resins. Gaining further knowledge on the impact of loading approaches is of relevance because laboratory-scale multiple loading tests (MLTs) have been introduced as a simpler and faster alternative to column tests for predicting the performance of IEX, but only anecdotal evidence exists to support their ability to forecast contaminant removal and runtime until breakthrough of IEX systems. The overall trends observed for the removal and the time to breakthrough of organic material estimated using MLTs differed from those estimated using column tests. The results nonetheless suggest that MLTs could best be used as an effective tool to screen different ion exchange resins in terms of their ability to remove various contaminants of interest from different raw waters. The microbial activity was also observed to impact the removal and time to breakthrough. In the absence of regeneration, a microbial community rapidly established itself in ion exchange columns and contributed to the removal of organic material. Biological ion exchange (BIEX) removed more organic material and enabled operation beyond the point when the resin capacity would have otherwise been exhausted using conventional (i.e. in the absence of a microbial community) ion exchange. Furthermore, significantly greater removal of organic matter could be achieved with BIEX than biological activated carbon (BAC) (i.e. 56 ± 7% vs. 15 ± 5%, respectively) when operated at similar loading rates. The results suggest that for some raw waters, BIEX could replace BAC as the technology of choice for the removal of organic material. [ABSTRACT FROM AUTHOR]

This study achieves a better operational simplicity for the phycoremediation of reverse osmosis (RO) concentrate using Scenedesmus quadricauda microalgae. Under continuous illumination with CO 2 supplementation, algal growth in the RO concentrate resulted in a conversion of polymeric organic matter (a mixture of humic substances and polysaccharides) to biodegradable fractions and their prompt removal along with inorganic nutrients (NO 3 − and PO 4 3− ). The algal-induced degradation of humic-like substances which are typically refractory to microbial decomposition was demonstrated in an indirect manner. In this study, we also investigated the effects of algal treatment on the growth of Escherichia coli and removal of trace organic compounds (TOrCs) from the RO concentrate. Our results indicate that algal treatment of the RO concentrate using aeration with 10% (v/v) CO 2 under continuous illumination is highly feasible as a safe and inexpensive technology to remove non- or slowly-biodegradable organic matter, reduce enteric bacteria, and attenuate TOrCs in wastewater. However, the results should not be generalized, but critically discussed, due to limitations of using the synthetic RO concentrate in evaluating the performance of wastewater remediation with microalgae. [ABSTRACT FROM AUTHOR]

In this study, magnetic nanoparticles of Fe 3 O 4 /SiO 2 /Pd-Mn were synthesized by wet deposition method for heterogeneous catalytic ozonation to remove the organic compounds in water. The as-synthesized Fe 3 O 4 /SiO 2 /Pd-Mn was characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) to clarify its chemical and physical properties. SEM images indicated that the particle size of Fe 3 O 4 /SiO 2 /Pd-Mn was about 50–100 nm. EDS results confirmed with the XRD findings, illustrating that Pd and Mn were successfully coated on the catalyst with the at% of 1.66 and 2.40%, respectively. The degradation efficiency of organics in water was examined by A 254 and dissolved organic compounds (DOC). Under heterogeneous catalytic ozonation treatment, the decomposition efficiency of A 254 and DOC of raw water, from Te-Chi reservoir, achieved 70 and 60%, respectively. The decomposition efficiency of A 254 and DOC increased to 80 and 90% when the pH was adjusted to 11. The calculated DOC degradation rate constant ( k d ) for was 6.5 × 10 −2  min −1 at pH 11 via heterogeneous catalytic ozonation method. Hydroxyl radicals were dominated for the removal of organic compounds in our heterogeneous catalytic ozonation system as an evidence of 7-hydroxycoumarin generation in radical scavenger experiments. In addition, the removal efficiency of THMFPs (Trihalomethane Formation Potentials) was 74 and 38% for Fe 3 O 4 /SiO 2 /Pd-Mn heterogeneous ozonation and sole ozonation, repectively, illustrating the enhanced oxidation ability. The endpoint of ozonation process can be controlled by the modeling results of Nernst simulating as ORP A 254  = 27240  −  14755.3 ln[ A 254 ]  −  2486.91 pH  + 2.64 ln[ THMFPs ]. [ABSTRACT FROM AUTHOR]

Abstract: Bacteria that degrade natural organic matter in groundwater contain oxygenase enzymes that can co‐oxidize trichloroethene (TCE). This degradation pathway is promising for large dilute plumes, but its evaluation is limited because the density of the bacteria with oxygenase enzymes has not been correlated to field scale rates of degradation. A 14C–TCE assay was developed to determine pseudo first‐order rate constants for the aerobic co‐oxidation of TCE in groundwater. The assay involved incubating 14C–TCE in samples of groundwater contained in 160 mL serum bottles, and monitoring the accumulation of radiolabel in degradation products. A first‐order rate constant for co‐oxidation was extracted from the rate of accumulation of 14C in products, accounting for volumetric changes in the serum bottles due to sampling and subsequent changes to the distribution of TCE between the aqueous and gaseous phases. Of the groundwater samples evaluated from 19 wells at five sites, eight samples at three sites had 14C product accumulation rates that exceeded the accumulation rate in filter‐sterilized groundwater controls. First‐order rate constants ranged from 2.65 to 0.0066 year−1, which is equivalent to half‐lives of 0.26 to 105 years. Groundwater samples from a few of the wells in which co‐oxidation occurred had volatile organic contaminants in addition to TCE; their presence may have induced the oxygenase enzymes that are needed for TCE co‐oxidation. 14CO2 represented ~37% to 97% of the 14C products that accumulated; the balance of the products was soluble and non‐volatile. [ABSTRACT FROM AUTHOR]

Simultaneous recovery of calcium phosphate granules (CaP granules) and methane from vacuum collected black water (BW), using an upflow anaerobic sludge blanket (UASB) reactor was previously investigated. It was calculated that only 2% of the total phosphorus (P) fed was present as CaP granules whereas 51% of the P accumulated dispersed in the reactor, limiting the applicability of this process for recovery of phosphate. This study proposes adding calcium to increase the P accumulation in the reactor and the production of CaP granules. Calcium was added in a lab-scale UASB reactor fed with BW. An identical UASB reactor was used as reference, to which no calcium was added. The treatment performance was evaluated by weekly monitoring of influent, effluent and produced biogas. Sludge bed development and CaP granulation were assessed through particle size analysis. The composition and structure of CaP granules were chemically and optically assessed. Calcium addition increased accumulation of P in the reactor and formation and growth of granules with size > 0.4 mm diameter (CaP granules). Moreover, with calcium addition, CaP granules contained 5.6 ± 1.5 wt% of P, while without calcium a lower P content was observed (3.7 ± 0.3 wt%). By adding Ca, 89% of the incoming P from BW accumulated in the reactor and 31% was sampled as CaP granules (> 0.4 mm diameter). Addition of 250 mgCa L −1 of BW was the optimum loading found in this study. Furthermore, no significant reduction in COD Total removal (> 80%) and CH 4 production (0.47 ± 0.10 gCOD-CH 4 g −1 COD Total -BW) was observed. Therefore, adding calcium can significantly increase the CaP granulation without inhibiting the simultaneous CH 4 recovery. This further indicates the potential of this process for phosphate recovery. [ABSTRACT FROM AUTHOR]

Pharmaceutical abatement in a groundwater (GW), surface water (SW), and secondary effluent (SE) by conventional ozonation, the conventional peroxone (O 3 /H 2 O 2 ), and the electro-peroxone (E-peroxone) processes was compared in batch tests. SE had significantly more fast-reacting dissolved organic matter (DOM) moieties than GW and SW. Therefore, O 3 decomposed much faster in SE than in GW and SW. At specific ozone doses of 0.5–1.5 mg O 3 /mg dissolved organic carbon (DOC), the application of O 3 /H 2 O 2 and E-peroxone process (by adding external H 2 O 2 stocks or in-situ generating H 2 O 2 from cathodic O 2 reduction during ozonation) similarly enhanced the OH yield from O 3 decomposition by ∼5–12% and 5–7% in GW and SW, respectively, compared to conventional ozonation. In contrast, due to the slower reaction kinetics of O 3 with H 2 O 2 than O 3 with fast-reacting DOM moieties, the addition or electro-generation of H 2 O 2 hardly increased the OH yield (<4% increases) in SE. Corresponding to the changes in the OH yields, the abatement efficiencies of ozone-resistant pharmaceuticals (ibuprofen and clofibric acid) increased evidently in GW (up to ∼14–18% at a specific ozone dose of 1.5 mg O 3 /mg DOC), moderately in SW (up to 6–10% at 0.5 mg O 3 /mg DOC), and negligibly in SE during the O 3 /H 2 O 2 and E-peroxone treatment compared to conventional ozonation. These results indicate that similar to the conventional O 3 /H 2 O 2 process, the E-peroxone process can more pronouncedly enhance O 3 transformation to OH, and thus increase the abatement efficiency of ozone-resistant pharmaceuticals in water matrices exerting relatively high ozone stability (e.g., groundwater and surface water with low DOM contents). Therefore, by installing electrodes in existing ozone reactors, the E-peroxone process may provide a convenient way to enhance pharmaceutical abatement in drinking water applications, where groundwater and surface water with low DOM contents are used as the source waters. [ABSTRACT FROM AUTHOR]

Previous work has demonstrated that pre-treatment of waste activated sludge (WAS) with free nitrous acid (FNA i.e. HNO 2 ) enhances the biodegradability of WAS, identified by a 20–50% increase in specific methane production in biochemical methane potential (BMP) tests. This suggests that FNA pre-treatment would enhance the destruction of volatile solids (VS) in an anaerobic sludge digester, and reduce overall sludge disposal costs, provided that the dewaterability of the digested sludge is not negatively affected. This study experimentally evaluates the impact of FNA pre-treatment on the VS destruction in anaerobic sludge digestion and on the dewaterability of digested sludge, using continuously operated bench-scale anaerobic digesters. Pre-treatment of full-scale WAS for 24 h at an FNA concentration of 1.8 mg NN/L enhanced VS destruction by 17 ± 1% (from 29.2 ± 0.9% to 34.2 ± 1.1%) and increased dewaterability (centrifuge test) from 12.4 ± 0.4% to 14.1 ± 0.4%. Supporting the VS destruction data, methane production increased by 16 ± 1%. Biochemical methane potential tests indicated that the final digestate stability was also improved with a lower potential from FNA treated digestate. Further, a 2.1 ± 0.2 log improvement in pathogen reduction was also achieved. With inorganic solids representing 15–22% of the full-scale WAS used, FNA pre-treatment resulted in a 16–17% reduction in the volume of dewatered sludge for final disposal. This results in significantly reduced costs as assessed by economic analysis. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysis with titanium dioxide (TiO2) has been shown to be a sustainable treatment technology to remove natural organic matter (NOM). This is of interest to the drinking water treatment industry. However, heterogeneous photocatalysis with TiO2 continues to suffer from several limitations such as the postrecovery of TiO2 particles, which impede its use in the drinking water treatment industry. In this study, the repeated use of the same photoactive TiO2 embedded into polyethylene pellets (PE-TiO2) made by the controlled-temperature embedding method was studied in the photocatalytic degradation of commercial humic acid (HA) to solve the postrecovery of TiO2 in slurry. Photocatalytic degradation percentage of dissolved organic carbon (DOC) removal with PE-TiO2 was stable after the second use of the same PE-TiO2 pellets, which was evaluated during five tests. PE-TiO2 removed 64.6% of the initial DOC during 270 min of photocatalytic degradation, and TiO2 in slurry removed 64.5% of the initial DOC during 180 min of photocatalytic degradation. Moreover, PE-TiO2 led to a considerable reduction in specific ultraviolet absorbances (SUVA = UV/DOC): SUVA254, SUVA280, SUVA365, and SCOA436 (specific color absorbance) and trihalomethane formation potential (THMFP). Therefore, PE-TiO2 is a promising material to remove NOM and solve the problem of postrecovery of TiO2 particles after water treatment. [ABSTRACT FROM AUTHOR]

A combination of processes was required for the proper treatment of old landfill leachate, as it contained a high concentration of pollutants. Humic substances comprised half of the total organic carbon in the raw leachate. Mobility of di(2-ethylhexyl) phthalate (DEHP) and metals could depend on the fate of these substances. Characterization of carbon in raw leachate and effluent of the membrane bioreactor, biofiltration, electro-oxidation, electrocoagulation, and nanofiltration showed complete removal of suspended solids and colloids. Physical processes could not remove the hydrophilic fraction due to its lower molecular weight. However, high removal of the hydrophilic fraction with a molecular weight <500 Da was expected in the biological process. In comparison with fulvic acid, larger sized humic acid resulted in complete removal by physicochemical processes. Because of DEHP partitioning on dissolved organic matter, especially on humic substances, its removal could be correlated with total organic carbon removal. Metals such as iron, aluminum, magnesium, and lead showed removal efficiency >80% in biological processes. Electro-deposition on the surface of an electrode and precipitation by hydroxide resulted in removal efficiencies >90 and >50% in electro-coagulation and electrooxidation, respectively. Rejection of metals by nanofiltration was >80% and depended on the size and charge of cation. All in all, a combination of membrane bioreactor and nanofiltration seems to be the optimal process configuration for efficient treatment of old landfill leachate. [ABSTRACT FROM AUTHOR]

Nonselective oxidation of organic chemicals during TiO2 photocatalytic water treatment significantly prohibits decomposition of toxic target contaminants, particularly in the presence of naturally abundant less toxic natural organic matter (NOM). To minimize the adverse effect of NOM, the authors have investigated physical size exclusion of large NOM onto mesoporous TiO2 photocatalysts, which allows small target contaminants to selectively access the porous structure for subsequent chemical reaction. Various treatment scenarios tested with different targets (ibuprofen, microcystin-LR) and competitors (humic acid, polyethylene glycol), and a series of mesoporous TiO2 materials proved the size exclusion mechanism. Discussion was made on the impact of the porous structure of TiO2 on selectivity and reactivity, considering size difference among targets < TiO2 pores < competitors as well as mass transfer limitation of even a target to small pores. This simple approach would greatly improve the photocatalytic treatment of toxic chemicals in water containing NOM. [ABSTRACT FROM AUTHOR]

Removal of natural organic matter (NOM) is increasingly important in production and distribution of drinking water complying with health and aesthetic guidelines. The impact of treatment is often investigated using the resulting dissolved organic carbon (DOC) concentration and trihalomethane formation potential. Water treatment processes of ferric and alum coagulation with and without pre-oxidation by ozone and permanganate were scanned for their ability to treat synthetic raw water from peat extract. To compare the efficiency of the treatment methods the dissolved organic carbon (DOC) concentration and chlorine decay and trihalomethane (THM) formation tests - the important parameters needed in practice were used. A high level of DOC removal (>80%) was achieved with all the treatments. A significant difference was observed in chlorine decay rates and THM production. Pre-oxidation with 2 mg/L of O3 and coagulation with 45 mg/L of ferric sulphate produced the most chlorine stable water followed by water treated with 80 mg/L of ferric sulphate. Chlorine decay test was found to be a more sensitive indicator of a successful treatment than DOC. The optimisation of the ozone dose is likely to identify the best water quality and chemical cost combination which is not likely achievable by the coagulation alone. [ABSTRACT FROM AUTHOR]

17α-ethynylestradiol (EE2) has become a growing concern due to its wide detection and high estrogenic potency. However, biodegradation of EE2 with individual microorganisms demonstrated poor degradation efficiency ranging from 10.3% to 45.8% in 120 h. Now, a system combining electrochemical with biological degradation was tested for its ability to remove EE2 from aqueous solution. EE2 removal is promoted at high dissolved oxygen concentrations and low pH when electrochemical methods alone are employed. Coupling electrochemical methods with anaerobic bacteria can improve the EE2 removal after 90 min to as much as 81.9% with a reaction rate constant of 0.0195 min −1 . An electric current of 100 mA at pH5.5 inhibits the growth of most microbial species, but Shewanella and Aeromonas survive well. They can enhance the efficiency of direct electron transfer efficiency between the bacteria and the electrodes, promoting EE2 degradation. This study provided a theoretical basis for the future applicability of bioelectrochemical technology to remove steroids from waste water. [ABSTRACT FROM AUTHOR]

Reclaimed water is usually stored in rivers or lakes before subsequent use. In storage ecosystems, the natural process of solar light irradiation plays a key role in water quality, altering disinfection byproduct formation potential in later use. This study investigated changes in haloacetamide formation potential (HAcAm FP) during subsequent chloramination when reclaimed water was exposed to solar light irradiation. Significant decreases in HAcAm FP were observed for the solar light irradiated reclaimed water, with reductions of 27%–69% for different haloacetamides. Moreover, transformation of dissolved organic nitrogen (DON) to inorganic nitrogen occurred during irradiation. The application of 15 N- labeled monochloramine indicated that the nitrogen source of the decreased HAcAms mainly originated from DON, rather than chloramine. Chloramination of the model compound l -asparagine after irradiation demonstrated that the decreased HAcAms could be attributed to the decrease in DON. After solar light irradiation, the brominated HAcAm FP in the presence of bromide was also reduced, while the bromine incorporation factor remained steady. Overall, this study revealed the contribution of natural processes in controlling HAcAm FP during subsequent chloramination, suggesting solar light irradiation is important to water purification during reclaimed water storage. [ABSTRACT FROM AUTHOR]

Organic micropollutants (OMPs) are becoming more common in drinking water supplies worldwide. Vacuum-UV (VUV) radiation is an incipient chemical-free oxidation process that offers a potentially cost-effective technology for the removal of OMPs. Utilizing a pilot system consisting of two annular VUV reactors, the authors investigated continuous-flow degradation of atrazine, a widely used herbicide, as a model OMP in synthetic and natural surface water. Nearly complete removal (i.e., 97%) of 100 ppb atrazine in an inlet stream was attained for both synthetic and raw surface water samples at a Reynolds number below 4,500. To provide a better understanding of the feasibility of this VUV process for the effective elimination of OMPs, a complete descriptive computational fluid dynamics (CFD) model was developed and validated using the data obtained from the pilot study. The proposed model closely predicted the impact of varying flow rates and water matrix (natural organic matter and alkalinity) on atrazine degradation, with less than 2.8% average absolute relative deviation (AARD%). A sensitivity analysis of the operational variables indicated the critical role of flow rate and background water com- position on degradation performance and energy efficiency of the VUV treatment systems. To assess cost-effectiveness of the pilot VUV system for remediation of atrazine-contaminated waters, an electrical energy-per-order (EEO) analysis was conducted, showing that a sequential installation of the two annular VUV reactors was up to 25% more energy efficient than a parallel configuration. [ABSTRACT FROM AUTHOR]

Cyclodextrins (CDs) are sugar-based cyclic oligosaccharides, which form inclusion complexes with small guest molecules through their hydrophobic cavity. Here we successfully synthesized highly porous poly-cyclodextrin (poly-CD) cryogels, which were produced under cryogenic conditions by the cross-linking of amine-functional CDs with PEG-based diepoxide cross-linker. The poly-CD cryogels showed aligned porous network structures owing to the directional freezing of the matrix, of which the pore size and architecture exposed variations depending on the composition of the reactants. The cryogels were employed for the removal of genotoxic polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. They reached PAH sorption capacities as high as 1.25 mg PAH per gram cryogel. This high sorption performance is due to interactions between PAHs and the complete swollen network, and thus, is not restricted by interfacial adsorption. Given that the hydrophilic nature of the components, the sorption performance could only be attributed to the inclusion complex formation of CDs with PAH molecules. The poly-CD cryogels could be recycled with an exposure to ethanol and reused without any significant loss in the sorption capacity of PAHs. [ABSTRACT FROM AUTHOR]

The azole fungicide fluconazole (FLC) is persistent in conventional wastewater treatment plants, thus posing potential threats to human and ecosystem health. This study investigated the oxidation of FLC in aqueous solution by thermally activated persulfate (TAP) under different operation conditions. Higher temperature greatly improved the removal rate of FLC (0.057 h −1 for 30 °C and 0.223 h −1 for 60 °C) and the relationship between pseudo-first-order rate constant ( k obs ) and temperature fit the Arrhenius equation, with a comparatively low activation energy of 37.8 kJ mol −1 . The degradation rate constants were enhanced with the increase of PS concentration during FLC oxidation (0.072 h −1 for 1.0 mM PS and 0.50 h −1 for 20 mM PS). Solution pH influenced the k obs of FLC degradation and the highest and lowest degradation rates were obtained at pH 3 (0.51 h −1 ) and pH 5 (0.23 h −1 ), respectively. Increasing the level of natural water constituents (HCO 3 − , Cl − , and humic acid) significantly inhibited FLC degradation. Geometry optimization of FLC was performed using density functional theory (DFT) and the data indicated that the C3 atom in the benzene ring was the most reactive site. SPE-HPLC/MS/MS analysis showed that intermediate products could form during FLC oxidation by PS and the total organic carbon (TOC) results indicated that FLC could be mineralized into CO 2 and H 2 O. Accordingly, a plausible pathway for the degradation of FLC by the thermally activated PS could be proposed. The results of this study suggested that TAP is an applicable approach for the removal of azole fungicides in water. [ABSTRACT FROM AUTHOR]

A kinetic model based on the Michaelis-Menten kinetic equations for simulating the complex reductive biodegradation kinetics of groundwater contaminants was developed that incorporates multiple levels of branching via the formation of multiple daughter products from a parent compound and/or a daughter product from multiple parent compounds. The model was tested using experimental data from two published laboratory studies involving the biodegradation of 2,4,6-trinitrotoluene (TNT) in the presence and absence of sorption. In each case, reasonable correlation was observed between the model-calculated and experimentally observed concentrations of TNT and its biodegradation products and the total mole balance with time. Model calibration-determined maximum specific rates of biodegradation were found to decrease with increasing substitution of nitro groups by amino groups from TNT to 2,4,6-triaminotoluene via aminodinitrotoluenes (ADNTs) and diaminonitrotoluenes (DANTs). Biodegradation of DANTs was also found to be strongly inhibited by the presence of parent intermediates ADNTs. The maximum specific rates of biodegradation for TNT and products were found to decrease in the presence of sorption. [ABSTRACT FROM AUTHOR]

Granular activated carbon (GAC) adsorbers for drinking water treatment were operated for approx. 14 months and the breakthrough of dissolved organic carbon (DOC) and trace organic chemicals (TOrCs) was monitored. Effluent concentration profiles of gabapentin and valsartan acid increase already at throughputs of <10,000 BV. The corresponding breakthrough curves flatten out without reaching the influent concentration level. This strongly indicates biological degradation of these substances in the GAC adsorbers under aerobic conditions, contributing to a more efficient use of GAC. The observed biodegradation in pilot GAC adsorbers also confirms recent reports of biodegradation of gabapentin and valsartan acid during managed aquifer recharge. Oxypurinol is comparatively well adsorbed and no breakthrough was observed during the experimental period. Adsorption capacity and breakthrough characteristics of oxypurinol appear very similar to carbamazepine. Breakthrough of GAC adsorbers operated with drinking water was compared to those of groundwater-fed adsorbers. The results show, that it is generally advisable to use previously aerated influents for GAC fixed-bed adsorbers because this can substantially improve biological removal of otherwise poorly adsorbable compounds and ensure full GAC accessibility for adsorbates by avoiding the undesirable formation of inorganic precipitates on adsorption sites. [ABSTRACT FROM AUTHOR]

Former studies have shown that enhanced-zero valent iron (ZVI) could effectively remove various contaminants. The present study evaluates for the first time the long-term performance of enhanced-ZVI to remove natural organic matter (NOM), an important water quality parameter in drinking water. Lab-scale flow-through experiments showed that averagely 7–14% dissolved organic carbon (DOC) and 6–15% ultraviolet absorbance at 254 nm (UV 254 ) reduction could be achieved by enhanced-ZVI in the first 10,000 bed volumes filtration when a 0.36 or 1.8 mins empty bed contact time (EBCT) was applied. After 10,000-bed volumes, the enhanced-ZVI bed became passivated. However, sulphuric acid was able to regenerate the passivated enhanced-ZVI bed, recover the capacity of enhanced-ZVI in removing NOM, and hence make the best use of the available ZVI. The acidic rinsing solution containing dissolved iron was suitable as a supplemental source of iron for coagulation. In addition, during the long-term experiments, the biofilters following enhanced-ZVI (1.8 min EBCT) removed more NOM than biofilters without any pre-treatment. This could be explained by the formation of biodegradable organic matter (BDOC) during the enhanced-ZVI process and the precipitation of iron in the biofilters. Based on these findings, a novel water treatment train, incorporating enhanced-ZVI with periodical regeneration, biofiltration, and coagulation, was proposed and evaluated. [ABSTRACT FROM AUTHOR]

A biocompatible and uniquely defined hydroxyapatite (HAP) adsorption membrane with a sandwich structure was developed for the removal of organic micropollutants for the first time. Both the adsorption and membrane technique were used for the removal of organic micropollutants. The hydrophilicity and hydrophobicity of the HAP adsorbent and membrane were tunable by controlling the surface structure of HAP. The adsorption of organic micropollutants on the HAP adsorbent was studied in batch experiments. The adsorption process was fit with the Freundlich model, while the adsorption kinetics followed the pseudo-second-order model. The HAP membrane could remove organic micropollutants effectively by dynamic adsorption in both aqueous and ethanol solutions. The removal efficiencies of organic micropollutants depended on the solution composition, membrane thickness and hydrophilicity, flow rate, and the initial concentration of organic micropollutants. The adsorption capacities of the HAP membrane with a sandwich structure (membrane thickness was 0.3 mm) were 6700, 6510, 6310, 5960, 5490, 5230, 4980 and 4360 L m −2 for 1-naphthyl amine, 2-naphthol, bisphenol S, propranolol hydrochloride, metolachlor, ethinyl oestradiol, 2,4-dichlorophenol and bisphenol A, respectively, when the initial concentration was 3.0 mg L −1 . The biocompatible HAP adsorption membrane can be easily regenerated by methanol and was thus demonstrated to be a novel concept for the removal of organic micropollutants from both aqueous and organic solutions. [ABSTRACT FROM AUTHOR]

An investigation of a sea water reverse osmosis desalination facility located in western Saudi Arabia has shown that aquifer treatment of the raw sea water provides a high degree of removal of natural organic matter (NOM) that causes membrane biofouling. The aquifer is a carbonate system that has a good hydraulic connection to the sea and 14 wells are used to induce sea water movement 400 to 450 m from the sea to the wells. During aquifer transport virtually all of the algae, over 90% of the bacteria, over 90% of the biopolymer fraction of NOM, and high percentages of the humic substance, building blocks, and some of the low molecular weight fractions of NOM are removed. Between 44 and over 90% of the transparent exopolymer particles ( TEP) are removed with a corresponding significant reduction in concentration of the colloidal fraction of TEP. The removal rate for TEP appears to be greater in carbonate aquifers compared to siliciclastic systems. Although the production wells range in age from 4 months to 14 years, no significant difference in the degree of water treatment provided by the aquifer was found. [ABSTRACT FROM AUTHOR]

We investigated a sequential photocatalysis-dark reaction, wherein organic pollutants were degraded on Ag/TiO2 under UV irradiation and the dark reduction of hexavalent chromium (Cr(VI)) was subsequently followed. The photocatalytic oxidation of 4-chlorophenol (4-CP), a test organic substrate, induced the generation of degradation intermediates and the storage of electrons in Ag/TiO2 which were then utilized for reducing Cr(VI) in the postirradiation period. The dark reduction efficiency of Cr(VI) was much higher with Ag/TiO2 (87%), compared with bare TiO2 (27%) and Pt/TiO2 (22%). The Cr(VI) removal by Ag/TiO2 (87%) was contributed by adsorption (31%), chemical reduction by intermediates of 4-CP degradation (26%), and reduction by electrons stored in Ag (30%). When formic acid, humic acid or ethanol was used as an alternative organic substrate, the electron storage effect was also observed. The postirradiation removal of Cr(VI) on Ag/TiO2 continued for hours, which is consistent with the observation that a residual potential persisted on the Ag/TiO2 electrode in the dark whereas little residual potential was observed on bare TiO2 and Pt/TiO2 electrodes. The stored electrons in Ag/TiO2 and their transfer to Cr(VI) were also indicated by the UV-visible absorption spectral change. Moreover, the electrons stored in the preirradiated Ag/TiO2 reacted with O2 with showing a sign of low-level OH radical generation in the dark period. [ABSTRACT FROM AUTHOR]