Search

Freshwater represents one of the most precious resources on the planet, so it is fundamental to preserve it. In this work, an innovative sunlight‐driven device composed of bismuth oxybromide (BiOBr) grown on a material derived from natural sources, i.e., Lightweight Expanded Clay Aggregates (LECA), is developed to clean surface waters under natural solar light irradiation. For this purpose, the photodegradation of two non‐steroidal anti‐inflammatory drugs, ibuprofen, and diclofenac, is investigated under varying operative conditions. Laboratory‐ and real‐scale experiments reveal that the fabricated floating BiOBr/LECA photocatalyst fully degrades diclofenac, whereas limited abatement of ibuprofen is observed. Based on the identification of specific transformation products (TPs) during the degradation, this behavior seems to be strongly related to the different structures of the two drugs. In fact, the main TP produced during diclofenac degradation derives from dechlorination and ring condensation: this type of photocatalytic degradation pathway is generally favored over the C─C bonds's cleavage, which is a unique possibility for IBU abatement. Moreover, the potential partial adsorption of these species on the photocatalyst's active sites can cause their deactivation. Finally, reusability tests demonstrate the high stability of the floating composite. [ABSTRACT FROM AUTHOR]

The requirements for water intended for domestic and economic purposes prompt the search for new solutions in surface water treatment technologies. In this study, the enhancement of coagulation processes by connections with adsorption and/or ozonation for surface water treatment was studied. The possibility of a reduction in natural organic matter (NOM) content in modified surface water was analysed regarding changes in colour, turbidity, oxidisability (OXI), total and dissolved organic carbon (TOC, DOC) and absorbance at 254 nm (UV254). Additionally, the changes in copper and zinc ion content during the modified surface water treatments studied were analysed for initial metal concentrations of 0.5 or 1.0 mg/L. Studies of modified surface water were carried out with doses of medium-basicity PAX coagulant (C2) 5 mg/L and PAC 100 mg/L. During the coagulation process, the colour decreased by 86–90%, turbidity by 85–90%, OXI by 65–77%, TOC by 65–76% and UV254 absorbance by 73–84%. The enhancement of coagulation with adsorption and/or ozonation resulted in an increased efficiency of colour and turbidity removal by 2 and 4%, respectively. The highest increase in efficiencies of OXI, TOC, DOC and UV254 removal, by 12, 12, 11 and 11%, was observed for the connection of ozonation with coagulation and adsorption. The efficiency of metal ion removal from modified water observed for the single coagulation process was 58 and 55% for copper and 46 and 43% for zinc, respectively, for initial concentrations of 0.5 and 1.0 mg/L. The intensification of coagulation with ozonation and adsorption resulted in metal removal on the level of 66 and 62% for copper and 62 and 54% for zinc. [ABSTRACT FROM AUTHOR]

This is the first study to describe a novel, patented process for the on-site synthesis and subsequent direct utilisation of Polyferric Chloride (PFC) at low Fe concentration dosing, which aims to facilitate the potential replacement of Polyaluminium Chloride (PAC) during surface water treatment (e.g., from reservoirs) for drinking water production. For this purpose, the PFC was synthesised and subsequently used as a coagulant in simulated surface water samples under different synthesis and coagulation/flocculation conditions, namely for different pre-hydrolysed Fe concentrations, pre-hydrolysis pH, coagulation pH, and flocculation times. The effectiveness of PFC was examined mainly in terms of total organic carbon (TOC) removal and the residual Fe concentration. The obtained results showed that the pre-hydrolysed Fe concentration at 0.5 ± 0.25%, pre-hydrolysis at pH 2.5 ± 0.25, coagulation at pH 5.5–7.0 and a flocculation time of 5 min could result in the highest TOC removal (i.e., residual values < 0.60 mg/L) and the lowest residual Fe concentration (<5 μg Fe/L), which is acceptable for a water quality assessment. These values are also substantially lower when compared to the respective TOC and residual metal concentrations using PAC (usually, the relevant obtained values are around TOC > 1 mg/L and Al > 50 μg/L). [ABSTRACT FROM AUTHOR]

An upflow sand filter operated in incremental filtration rates (0.072, 0.181, 0.481 m3 m-2 h-1) was studied for turbidity, total suspended solids (TSS), ammonia (NH4), and total coliform removal rates. Each cycle lasted for 45 days. The filter bed was made of sand with 0.10 mm D10 and supported by 0.49 mm and 2.10 mm gravel with a total bed depth of 0.50 m. Turbidity removal was recorded above 80% in all cycles with a maximum concentration of 7.29 NTU. TSS removal was maintained at over 90%, with an average discharge of 4.77 mg/L in all cycles. The NH4 removal increased steadily to 91% for 0.072 m3 m-2 h-1 and 93% for 0.181 m3 m-2 h-1 filtration rate. The algal bloom occurrence at 0.481 m3 m-2 h-1 filtration rate overloaded the system with NH4, declining the removal rate to 45%. Total coliform removal recorded an average of 99% in 0.072 m3 m-2 h-1, 89% in 0.181 m3 m-2 h-1, and 66% in 0.481 m3 m-2 h-1. A high filtration rate resulted in a shorter contact time between pollutants and microorganisms within the filter bed, which reduces the removal efficiency. The Shearing effect was also experienced where the attachments of particles and bacteria were minimised.

This paper reviews the research progress of micro-nano bubbles in enhanced wastewater treatment and surface water treatment, including their enhancement of ozonation technology, photocatalysis technology, air floatation technology as well as the enhancement of microbial activity and eutrophication mitigation in water bodies.We summarize the current applications of micro and nano bubbles technology in water treatment projects and provide an outlook on the future research prospects of micro and nano bubbles technology in water treatment, in order to provide a reference for the practical application of micro and nano bubbles in water treatment. [ABSTRACT FROM AUTHOR]

No Environmental Protection Agency (EPA) chemical treatments for preharvest agricultural water are currently labeled to reduce human health pathogens. The goal of this study was to examine the efficacy of peracetic acid- (PAA) and chlorine (Cl)-based sanitizers against Salmonella in Virginia irrigation water. Water samples (100 mL) were collected at three time points during the growing season (May, July, September) and inoculated with either the 7-strain EPA/FDA-prescribed cocktail or a 5-strain Salmonella produce-borne outbreak cocktail. Experiments were conducted in triplicate for 288 unique combinations of time point, residual sanitizer concentration (low: PAA, 6 ppm; Cl, 2-4 ppm or high: PAA, 10 ppm; Cl, 10-12 ppm), water type (pond, river), water temperature (12°C, 32°C), and contact time (1, 5, 10 min). Salmonella were enumerated after each treatment combination and reductions were calculated. A log-linear model was used to characterize how treatment combinations influenced Salmonella reductions. Salmonella reductions by PAA and Cl ranged from 0.0 ± 0.1 to 5.6 ± 1.3 log10 CFU/100 mL and 2.1 ± 0.2 to 7.1 ± 0.2 log10 CFU/100 mL, respectively. Physicochemical parameters significantly varied by untreated water type; however, Salmonella reductions did not (p = 0.14), likely due to adjusting the sanitizer amounts needed to achieve the target residual concentrations regardless of source water quality. Significant differences (p PAA) and contact time (10 > 5 > 1 min) having the greatest effects. The log-linear model also revealed that outbreak strains were more treatment-resistant. Results demonstrate that certain treatment combinations with PAA- and Cl-based sanitizers were effective at reducing Salmonella populations in preharvest agricultural water. Awareness and monitoring of water quality parameters are essential for ensuring adequate dosing for the effective treatment of preharvest agricultural water.

Here, multifunctional heterogeneous ion-exchange metal nanocomposite membranes were prepared for surface water desalination and bacterial inactivation under low-pressure (0.05 MPa) filtration conditions. Ultrafiltration (UF) heterogeneous ion exchange membranes (IEMs) were modified with different concentrations of AgNO3 and CuSO4 solutions using the intermatrix synthesis (IMS) technique to produce metal nanocomposite membranes. Scanning electron microscopy (SEM) images revealed that the metal nanoparticles (MNPs) (Ag and Cu) were uniformly distributed on the surface and the interior of the nanocomposite membranes. With increasing metal precursor solution concentration (0.01 to 0.05 mol·L−1), the metal content of Ag and Cu nanocomposite membranes increased from 0.020 to 0.084 mg·cm−2 and from 0.031 to 0.218 m·cm−2 respectively. Results showed that the hydrodynamic diameter diameters of Ag and Cu nanoparticles (NPs) increased from 62.42 to 121.10 nm and from 54.2 to 125.7 nm respectively, as the metal precursor concentration loaded increased. The leaching of metals from metal nanocomposite membranes was measured in a dead-end filtration system, and the highest leaching concentration levels were 8.72 ppb and 5.32 ppb for Ag and Cu, respectively. The salt rejection studies indicated that ionic selectivity was improved with increasing metal content. Bacterial filtration showed higher antibacterial activity for metal nanocomposite membranes, reaching 3.6 log bacterial inactivation. [ABSTRACT FROM AUTHOR]

The utilization of biochar holds promise as a viable method for the preservation of water resources and the remediation of wastewater. The objective of this study is to evaluate the advancements achieved in the field of biochar research pertaining to the remediation of surface water. The review was conducted by systematically collecting data from Scopus and doing bibliometric analysis. This study utilized the Scopus database to retrieve data pertaining to countries, institutions, highly cited articles, keywords, emerging subjects, and prospective research directions. Furthermore, the VOSviewer bibliometric software was utilized to assess the scholarly citations in this research paper. The results indicate that significant advancements have been achieved in this area of study during the year 2015. A total of 48 works has been indexed by Scopus, a renowned academic database, across 28 distinct international journals. A significant proportion of researchers primarily operate within the United States, often engaging in collaborative efforts with their counterparts from China. This article attempts to study the bibliography on the biochar for surface water treatment, identify popular topics, and discern the fields of future studies in this discussion. Furthermore, it investigates future research in the field of biochar will primarily concentrate on optimizing the synthesis of biochar and exploring its potential use in the treatment of heavy metals and organic chemicals. [ABSTRACT FROM AUTHOR]

Simulation is a modus operandi often used for imitating real-world processes. It involves a system and set of assumptions used for computing a numerical model, from which the outcome is an estimate of the true characteristics of how the system behaves. The intention of this research was to investigate the efficiency of fabric in two-stage cross-flow filtration using linen, crepe-backed satin, burlap and cotton fabric filter media. The results from previous pilot-scale experiments performed showed that linen fabric was the most effective medium at retaining particles. In continuation of this research, the aim of this paper was to utilize Hydrus-1D simulation software to simulate cross-flow filtration with fabric filter medium. This was done to further confirm the efficiency of cross-flow filtration, in particular with linen fabric filter media. Simulation entailed investigating fabric water content versus pressure head; bottom pressure head versus time; fabric water storage versus time; and cumulative infiltration versus time with both single and four layers of fabric filter media. Hydrus-1D simulation was productive since it confirmed that cross-flow filtration with linen fabric filter media has the potential of becoming a pre-filtration step in surface water treatment, further adding to the results obtained from previous pilot-scale experiments. HIGHLIGHTS Pre-filtration step in surface water treatment.; Removal of suspended particles from turbid river water using fabric filter media.; The use of linen fabric as an essential filter media in the removal of particles from turbid river water.; Increased efficiency of the removal of particles is enhanced by using four layers of fabric filter media.; Successful simulations of turbid water filtration by varying fabric filter media types.;

Organic matter present in natural water is a serious problem during water treatment in terms of the possibility of creating disinfection by-products (DBP). The new materials and processes are still analyzed in order to improve the efficient removal of organic matter as well as other pollutants from water intended for human consumption. The aim of the presented study was to evaluate the efficiency of using various combined processes: (a) coagulation and adsorption, (b) oxidation with ozone and coagulation, (c) oxidation with ozone, coagulation and adsorption, and (d) oxidation with ozone, UV irradiation, coagulation and adsorption for treatment of the modified surface water. In the presented study, the changes in pH, turbidity, color, organic matter content (evaluated as oxidizability, total and dissolved organic carbon content, UV 254 and 272 absorbances), and Ni2+, Cd2+, and Pb2+ ions content were determined during modified surface water purification. Supporting the coagulation process by adsorption with additional ozonation and UV irradiation of the water sample improved the treatment processes of modified surface water. Processes associated with coagulation increased the efficiency of removing color by 4–16% and reduced the value of UV254 and UV272 absorbance by 10–20%. Using ozonation did not significantly change the content of total organic matter. Heavy metal ions were mostly removed by coagulation and adsorption processes (40–60%). Including ozone, oxidation resulted in insignificant changes in the concentration of metal ions in the purified water (less than 5%). During the treatment of the tested, modified surface water, the best efficiency was observed after the use of coagulation and adsorption processes enhanced with ozone oxidation. The additional involvement of UV irradiation did not have a significant effect on the removal of the analyzed pollutants. [ABSTRACT FROM AUTHOR]

Steam system water inventory is mainly supplied by surface sources, such as lakes or rivers. The incoming surface water is highly contaminated with organic matter and mineral salts. Inadequate treatment of such water sources results in severe and widespread deposits and water-side corrosion. This paper studied the Fenton oxidation with coagulation as pretreatment of the surface water from Nile River (Ismailia Channel) used as makeup boiler water. The incoming water has been analyzed and characterized for one year; the examined characteristics in this work are pH, total dissolved solid (TDS), total hardness (TH), chlorides, total alkalinity (TA), and organic matter (OM). Additionally, the effect of two types of coagulants and Fenton oxidation process on the reduction of the above characteristics has been studied. Moreover, the effect of the combination of Fenton/coagulation process was investigated. The influence of Fe2+ concentration and coagulant dosages was studied. The experimental work was carried out by using Jar test. The results proved that coagulation with ferric chloride is more beneficial than alum at similar doses. It is also found that treatment by Fenton oxidation with coagulation is more effective than coagulation or Fenton oxidation, under operating conditions ([Fe2+] = 10 mg/L; Fe2+:H2O2 = 1.25:1; initial pH = 2.8; followed by coagulation at initial pH 8 with 5 mg/L ferric chloride). [ABSTRACT FROM AUTHOR]

According to the World Health Organization, antibiotic resistance is one of the main threats to global health. The excessive use of several antibiotics has led to the widespread distribution of antibiotic-resistant bacteria and antibiotic resistance genes in various environment matrices, including surface water. In this study, total coliforms, Escherichia coli and enterococci, as well as total coliforms and Escherichia coli resistant to ciprofloxacin, levofloxacin, ampicillin, streptomycin, and imipenem, were monitored in several surface water sampling events. A hybrid reactor was used to test the efficiency of membrane filtration, direct photolysis (using UV-C light emitting diodes that emit light at 265 nm and UV-C low pressure mercury lamps that emit light at 254 nm), and the combination of both processes to ensure the retention and inactivation of total coliforms and Escherichia coli as well as antibiotic-resistant bacteria (total coliforms and Escherichia coli) present in river water at occurrence levels. The membranes used (unmodified silicon carbide membranes and the same membrane modified with a photocatalytic layer) effectively retained the target bacteria. Direct photolysis using low-pressure mercury lamps and light-emitting diode panels (emitting at 265 nm) achieved extremely high levels of inactivation of the target bacteria. The combined treatment (unmodified and modified photocatalytic surfaces in combination with UV-C and UV-A light sources) successfully retained the bacteria and treated the feed after 1 h of treatment. The hybrid treatment proposed is a promising approach to use as point-of-use treatment by isolated populations or when conventional systems and electricity fail due to natural disasters or war. Furthermore, the effective treatment obtained when the combined system was used with UV-A light sources indicates that the process may be a promising approach to guarantee water disinfection using natural sunlight.

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.

Global surface waters are in a bad ecological and chemical state, which has detrimental effects on entire ecosystems. To prevent further deterioration of ecosystems and ecosystem services, it is vital to minimize environmental pollution and come up with ways to keep surface water healthy and clean. Recently, photogranules have emerged as a promising platform for wastewater treatment to remove organic matter and nutrients with reduced or eliminated mechanical aeration, while also facilitating CO 2 capture and production of various bioproducts. Photogranules are microbial aggregates of microalgae, cyanobacteria, and other non-phototrophic organisms that form dense spheroidic granules. Photogranules settle fast and can be easily retained in the treatment system, which allows increased amounts of water and wastewater to be treated. So far, photogranules have only been tested on various "high-strength" wastewaters but they might be an excellent choice for treatment of large volumes of polluted surface water as well. Here, we propose and tested for the first time photogranules on their effectiveness to remove nutrients from polluted surface water at unprecedented low concentrations (3.2 mg/L of nitrogen and 0.12 mg/L of phosphorous) and low hydraulic retention time (HRT = 1.5 h). Photogranules can successfully remove nitrogen (<0.6 mg/L, ∼80 % removal) and phosphorous (<0.01 mg/L, 90-95 % removal) to low levels in sequencing batch operation even without the need for pH control. Subjecting photogranules to surface water treatment conditions drastically changed their morphology. While, under "high-strength" conditions the photogranules were spherical, dense and defined, under polluted surface water conditions photogranules increased their surface area by forming fingers. However, this did not compromise their excellent settling properties. Finally, we discuss the future perspectives of photogranular technology for surface water treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

To investigate watershed remediation within a Total Maximum Daily Load program, this study examined the field-scale filtration performance of two specialty absorbents. The goal was to simultaneously remove nutrients and biological pollutants along Canal 23 (C-23) in the St. Lucie River Basin, Florida. The filtration system installed in the C-23 river corridor was equipped with either clay–perlite with sand sorption media (CPS) or zero-valent iron and perlite green environmental media (ZIPGEM). Both media were formulated with varying combinations of sand, clay, perlite, and/or recycled iron based on distinct recipes. In comparison with CPS, ZIPGEM exhibited higher average removal percentages for nutrients. Findings indicated that ZIPGEM could remove total nitrogen up to 49.3%, total Kjeldahl nitrogen up to 67.1%, dissolved organic nitrogen (DON) up to 72.9%, total phosphorus up to 79.6%, and orthophosphate up to 73.2%. Both ZIPGEM and CPS demonstrated similar efficiency in eliminating biological pollutants, such as E. coli (both media exhibiting an 80% removal percentage) and chlorophyll a (both media achieving approximately 95% removal). Seasonality effects were also evident in nutrient removal efficiencies, particularly in the case of ammonia nitrogen; the negative removal efficiency of ammonia nitrogen from the fifth sampling event could be attributed to processes such as photochemical ammonification, microbial transformation, and mineralization of DON in wet seasons. Overall, ZIPGEM demonstrated a more stable nutrient removal efficiency than CPS in the phase of seasonal changes. [Display omitted] • ZIPGEM perform better than CPS in removing nutrients. • Ammonification is a key process for removing nutrient. • Seasonal changes may affect the performance of filtration. [ABSTRACT FROM AUTHOR]

• Zwitterionic hydrogel nanolayer was synthesized by interfacial polymerization. • Zwitterionic monomer modulated the hydrogel layer structure and membrane characters. • Zwitterionic hydrogel hindered the adhesion of biomacromolecules and killed microbes. • The growth of biofilm on zwitterionic hydrogel nanolayer surface was inhibited. Ultralow-pressurized ultrafiltration membrane process with low energy consumption is promising in surface water purification. However, membrane fouling and low selectivity are significant barriers for the wide application of this process. Herein, an ultrathin zwitterionic hydrogel nanolayer was in-situ grown on polysulfone ultrafiltration membrane surface through interfacially-initiated free radical polymerization. The hydrogel-modified membrane possessed improved biological fouling resistance during the dynamic filtration process (bovine serum albumin, Escherichia coli and Staphylococcus aureus), comparing with commercial polysulfone membrane. The enhanced biofouling resistance ability of zwitterionic hydrogel nanolayer was derived from the foulant repulsion of hydration shell and the bactericidal effect of quaternary ammonium, according to the results of foulant-membrane interaction energy analyses and antibacterial performances. In surface water treatment, the zwitterionic hydrogel layer inhibited biofouling and resulted in the formation of a loose and thin biofilm. In addition, the hydrogel-modified membrane possessed 22% improvement in dissolved organic carbon (DOC) removal and 134% increasement in stable water flux, compared to commercial polysulfone membrane. The in-situ grown zwitterionic hydrogel nanolayer on membrane surface offers a prospectively alternative for biofouling control in ultralow-pressurized membrane process. [Display omitted] [ABSTRACT FROM AUTHOR]

The goal of the research was to determine the effects of artificial infiltration as an initial water treatment process at the river water intake. The effects were determined with respect to removal of chemical admixtures as well as lowering microbiological parameters. The impact of the seasons and operating conditions of the intake on the achievement of stabilized infiltration effects was investigated. The research was carried out on a water intake for a town with a population of 500,000 in Central Poland. The field research installation was used for the tests. The metering wells (piezometers) were drilled along the water flow path from the pond to the collecting well. The effects of infiltration were assessed in terms of the changes of the physical, chemical and microbiological parameters of infiltration water, compared to river water. The test results confirmed that the infiltration process improves the physicochemical and microbiological parameters of water. The water after the infiltration process exhibits similar characteristics to groundwater. The infiltration effects are affected by the phase of the pond operation cycle. This was visible in the case of organic compounds, the removal of which were the lowest at the beginning of pond operating cycle. [ABSTRACT FROM AUTHOR]

In the current study, aluminum formate was synthesized in various molar ratios (formic acid to aluminum) from 1 to 2.5 using aluminum hydroxide and formic acid. The coagulation ability of synthesized compounds was evaluated and compared with alum. All the aluminum formates synthesized with various molar ratios (i.e., 1-2.5) were performed similar to alum except molar ratio 1. The influence of coagulant dose, pH, and alkalinity-turbidity combinations on coagulation behavior of aluminum formates was determined using jar test. The optimum coagulant dose for aluminum formate was found as 80 mg/L. The optimum pH for lower residual turbidity was achieved at pH 6 using aluminum formate. The residual aluminum concentration of aluminum formate synthesized with molar ratio 2.5 was within the limits. In addition to that for higher OH-, CO3 2-, and HCO3 - alkalinity and turbidity combination relatively small quantity of coagulant was sufficient to remove turbidity effectively than with low OH-, CO3 2-, and HCO3 - alkalinity and turbidity combination. [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]

This study presents the preparation of a novel inorganic-biological composite flocculant, termed PAFC-CBF, which is composed of polymeric aluminum ferric chloride (PAFC) and compound bio-flocculant (CBF). It was investigated under different PAFC/CBF weight ratios. The turbidity and total organic carbon (TOC) removal efficiency were also investigated, when PAFC-CBF was added to the surface water. Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy were performed to characterize PAFC-CBF. Finally, floc properties including floc strength and recoverability were investigated using Mastersizer 2000. The results of the investigation indicated that CBF was successfully embedded into PAFC, forming a novel flocculant with the characteristic structure of PAFC and CBF. Considering the flocculation efficiency and economic cost, PAFC-CBF demonstrated a superior flocculation performance at the flocculant dosage of 25 mg/L, with an optimal turbidity removal efficiency of 90.28%, and a TOC removal efficiency of 26.75%. During the flocculation process, charge neutralization, adsorption bridging and sweep mechanisms served in the main role of colloidal destabilization and aggregation. [ABSTRACT FROM AUTHOR]

The impact of feed water quality on biofilm formation during membrane distillation (MD) was investigated in this study, particularly emphasizing the interrelationship between organics, salts, and microbes. Two types of typical natural surface waters in Nanjing, China, were chosen as feed solutions for long-term MD operation, including the Qinhuai River and Xuanwu Lake. The biofilms that developed under different feed water qualities exhibited distinct Foulant compositions and structures, causing different flux decline trends for the MD system. Accordingly, two typical patterns of biofilm formation were suggested for the MD operation of the two different kinds of surface waters in this study. Organics from a primal feed solution and dead bacteria were the key to the establishment of a biofilm on the membrane, and this needs to be effectively removed from the MD system through pre-treatment and process control strategies. Finally, a feasible strategy for MD biofouling control was suggested. [ABSTRACT FROM AUTHOR]

This work investigates the proanthocyanidin profile of willow bark crude extracts and these materials were cationized and preliminarily tested as biocoagulants for water treatment. The characteristics of crude extracts proanthocyanidin were investigated using size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). XPS analysis indicates that the crude extracts contain significant amounts of sugars. Furthermore, SEC and liquid-state NMR spectroscopy showed that crude extract contains roughly 3–4 flavan-3-ol units with procyanidin (PC)/ prodelphinidin (PD) ratio of roughly 3–5. Thus, the modified form of tannin (proanthocyanidin-enriched) coagulants obtained the higher cationic charge density. The coagulation experiments with kaolin-river water mixture suggested that all the selected willow hybrids' tannin coagulants were effective in settling the particles down. This study indicates that the value of willow bark can be significantly improved by the usage of crude extracts for water treatment. [Display omitted] • Crude extracts from eight willow hybrids are characterized and Mannich modified. • The extract contains roughly 3-4 flavan-3-ol units with PC/PD ratio of roughly 3-5. • Modified proanthocyanidin-enriched extracts have medium cationic charge densities. • The biocoagulants were effective in settling the particles down from river water. [ABSTRACT FROM AUTHOR]

Port Said Canal is one of the man-made Nile branches in Egypt that gain its water supply via the Ismailia Canal. The canal extended parallel to the Suez Canal navigation route providing the surrounding region the necessary drinking and irrigation waters. The water treatment plants along the canal use the surface water as a crude supply without preliminary pre-filtration process, and chlorination is applied in two phases, which may impose some health hazards. The study aims to ensure that the finished water is safe to drink and meet the international drinking water regulations. The public water purification systems in four treatment plants along Port Said Canal were tested for their efficiency and chlorination by-products. Raw and treated waters in these plants were analyzed for organic, toxic, trace, and heavy elements. Flow measurements were implemented at five sections along the main canal course during the summer and the winter seasons. Results indicated that the treated water suffers from low filtering effectiveness and exceeds the drinking water standards for the trihalomethane species. Furthermore, the change of canal flow from influent to effluent conditions during the winter season increases the contaminants' concentrations. Also, the heavy metal concentrations in the treated water samples from all treatment works were much higher than that of the raw water samples, especially for those higher in suspended particulate matter. The study proposed a better purification system including, sedimentation and gravel pre-filtration combined with slow sand filtration and underground water passage for the elimination of the existing pollution problems. [ABSTRACT FROM AUTHOR]

Environmental context: Contamination of surface water by micropollutants is a major environmental concern because of their high persistence and toxicity. Micropollutants are only partially removed in nanofiltration water treatment systems, encouraging the investigation of more complex systems involving partitioning with membrane materials, organic matter and ion exchange resins. This study elucidates the micropollutant partitioning mechanisms in this complex water treatment system. The accumulation of micropollutants, such as steroid hormones, in magnetic ion exchange resin-nanofiltration (MIEX-NF) poses a risk to the environmental contamination of surface water where the treated water is discharged. In this study, the partitioning of the steroid hormone estradiol (E2) with humic acid (HA), MIEX and the membrane is investigated at different feed water conditions (e.g. pH and presence of calcium). The transport and adsorption of E2 in NF is not affected significantly by the E2-HA interaction. Indeed, E2 partitions with HA between 8 % and 25 % at different pH. This is attributed to the presence of calcium ions, which reduces the number of HA molecules available to interact with E2 molecules. The calcium interference is evident especially at pH > 10, where calcite and HA precipitate to result in irreversible membrane fouling. In the hybrid MIEX-NF process, the E2-MIEX interaction occurs at all pH conditions. Approximately 40 % of the E2 total mass partitions with MIEX. This is significantly higher than E2 accumulation in NF. Since the partitioning is at least partially reversible, this poses a risk for accidental E2 release into the process streams. Environmental context. Contamination of surface water by micropollutants is a major environmental concern because of their high persistence and toxicity. Micropollutants are only partially removed in nanofiltration water treatment systems, encouraging the investigation of more complex systems involving partitioning with membrane materials, organic matter and ion exchange resins. This study elucidates the micropollutant partitioning mechanisms in this complex water treatment system. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Adding PACl/MPs first followed by PAM showed the optimal coagulation performance. • MCF process performed a wide working pH range than that of CF process. • Adsorption of organic matters on MPs and MPs-Al species facilitated UV 254 removal. • MPs increased collision frequency between particles in low turbidity water. • MPs served as particles, adsorbent and composited coagulant in MCF process. Abstract Magnetic seeding coagulation-flocculation (MCF) process was evaluated by jar tests compared to a reference coagulation-flocculation (CF) process. Steps were made toward elucidating the underlying roles of magnetic particles (MPs) in MCF process. The results indicated that MPs addition could significantly accelerate flocs sedimentation and enhance pollutants removal. With an optimal strategy of adding the composite PACl/MPs (MPACl, 15/30 mg/L) first followed by 0.4 mg/L PAM, turbidity, UV 254 and TP were removed up to 96.7%, 80.8% and 95.7% in 5 min under applied magnetic field (0.5 T). In addition, the multifunction of MPs reduced the negative impacts of pH changes, resulting in a wider working pH range. Humic acid-like components adsorbed on MPs and MPs-Al species improved the UV 254 removal in MCF process than that in CF process. For low turbidity water, MPs increased suspended particles concentration and served as nuclei to enhance the formation of settleable flocs, consistent with an increase in turbidity removal from 89.75% to 96.80%. The multiple roles of MPs (suspended particles, adsorbents and coagulants) in MCF process were thoroughly discussed. This study provides theoretical guidance for its application in real surface water treatment. [ABSTRACT FROM AUTHOR]

An iron–manganese co-oxide filter film (MeO x ) coated on filter sand has been shown be a good catalyst for the oxidation of ammonium in the treatment of groundwater. However, its catalytic activity decreases gradually when it is used to remove ammonium from surface water. In this study, phosphate was added to sustain the ammonium removal activity of MeO x in a pilot-scale filter system for surface water treatment. The results showed that the ammonium removal efficiency of the MeO x filter without phosphate dosing decreased gradually, and just 27.69% removal efficiency was obtained at 6.1 °C. After dosing with 30 μg/L phosphate, the ammonium removal efficiency remained high after continuous operation for 176 days and reached 85.74%, even at 6.1 °C. It was found that both the biological nitrification activity and the chemical catalytic activity of MeO x were markedly enhanced after phosphate dosing (compared with that without phosphate dosing). Through inactivation by ozone, the biological nitrification and chemical catalytic activity were distinguished. It was found that chemical catalytic activity accounted for around 67.59% of the total ammonium removal. Aluminum was found to accumulate on the surface of MeO x and combine competitively with its active sites. This may be the primary reason for the decrease in the catalytic activity of MeO x . With phosphate dosing, the accumulation of aluminum decreased by 60.53% and the chemical combination of aluminum and MeO x was suppressed, thus sustaining the catalytic activity of MeO x . [ABSTRACT FROM AUTHOR]

The present study highlights the effect of the periodical cleaning by backwashing and forward flushing, on fouling mitigation in a pressurized ultrafiltration (UF) membrane process treating high turbid surface water. The results showed that coupling backwashing and forward flushing has a better effect on membrane permeability recovery than applying only one cleaning technique. Moreover, during periodical cleaning, starting by backwashing followed by forward flushing would allow a better membrane recovery. A cake formation model was used to simulate the global trend of the relative membrane permeability. The modelling study enabled to quantify the effect of different cleaning strategy on fouling mitigation. [ABSTRACT FROM AUTHOR]

Surface flow constructed wetlands (SFCWs) can be effectively used to treat agricultural drainage waters, reducing N and P surface water pollution. In the Venice Lagoon drainage basin (northeastern Italy), an SFCW was monitored during 2007–2013 to assess its performance in reducing water, N, and P loads more than 10 years after its creation. Nitrogen concentrations showed peaks during winter due to intense leaching from surrounding fields. Phosphorus concentrations were higher after prolonged periods with no discharge, likely due to mobilization of P of the decomposing litter inside the basin. Over the entire period, N removal efficiency was 83% for NO3–N and 79% for total N; P removal efficiency was 48% for PO4–P and 67% for total P. Values were higher than in several other studies, likely due to the fluctuating hydroperiod that produced discontinuous and reduced outflows. Nitrogen outlet concentrations were reduced by the SFCW, and N removal ratios decreased with increasing hydraulic loading, while no strong correlations were found in the case of P. The SFCW was shown to be an effective long-term strategy to increase water storage and reduce N and P loads in the Venice Lagoon drainage basin.

Efficient water treatment design has progressively been growing in importance as the usage of water resources increases with population rise and industrial development. Their availability has been reduced with the more evident effects of climate change. Addressing this challenge necessitates more and efficient purification plants which can be realised by optimal design at conceptual stage. In this work, a mixed integer nonlinear programming (MINLP) model for the synthesis and optimisation of water treatment processes is proposed. Due to its numerous non-linearities and consequently, its non-stability, various linearisation, approximation and reformulation techniques have been implemented. Consequently, two improved formulations are derived, i.e. a partially linearised MINLP (plMINLP) and a mixed integer linear fractional programming (MILFP) models. The applicability of the mathematical formulations are investigated in case studies of seawater desalination and surface water treatment for the production of potable water. Finally, the models performance is analysed and compared against each other. [ABSTRACT FROM AUTHOR]

• The flocculant TRC, like proteins, has temperature-dependent hydrophobicity. • Residual TRC after flocculation hydrophilized UF membrane surface. • Inspired by protein folding, elevated cleaning temperature reduced membrane fouling. • An elevated temperature promotes the role of TRC in hydrophilization of membrane. • Structure of fouling layer containing TRC weakened at elevated temperature. Hydrophobic-modified flocculants have demonstrated considerable promise in the removal of emerging contaminants by flocculation. However, there is a lack of information about the impacts of dosing such flocculants on the performance of subsequent treatment unit(s) in the overall water treatment process. In this work, inspired by the ubiquitous protein folding phenomenon, an innovative approach using an elevated membrane cleaning temperature as the means to induce residual hydrophobic-modified chitosan flocculant (TRC), after flocculation-sedimentation, to reduce membrane fouling in a subsequent ultrafiltration was proposed; this was evaluated in a continuous flocculation-sedimentation-ultrafiltration (FSUF) process treating samples of the Yangtze River. The hydrophobic chains of TRC had similar temperature-dependent hydrophobicity to those of natural proteins. In the 40-day operation of the FSUF system with combined dosing of alum and TRC, a moderately elevated cleaning water temperature (45 °C) of both backwash with air-bubbling and soaking with sponge-scrubbing cleaning, significantly reduced reversible and irreversible fouling resistance by 49.8%∼61.3% and 73.9%∼83.3%, respectively, compared to the system using cleaning water at 25 °C. Material flow analysis, statistical analysis, instrumental characterizations, and computational simulations, showed that the enhanced fouling mitigation originated from three factors: the reduced contaminant accumulation onto membranes, the strengthened membrane-surface-modification role of TRC, and the weakened structure of the fouling material containing TRC, at the elevated cleaning temperature. Other measures of the performance, these being water purification, membrane stability and economic aspects, also confirmed the potential and feasibility of the proposed approach. This work has provided new insights into the role of hydrophobic-modified flocculants in membrane fouling control, in addition to emerging contaminant removal, in a FSUF surface water treatment process. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Asphalt and biochar-modified asphalt (BMA) absorbed Cu. • Biochar-modified asphalt enhanced the absorption. • Molecular simulations were employed to elucidate the absorption mechanisms. • More asphaltenes fractions appeared in the asphalt part of BMA. • Asphaltenes were the Cu adsorbing preference sites. Asphalt has been the primary material for pavements and other building components such as roof shingles and waterproofing systems, which can be the path for stormwater runoff pollutants such as heavy metals (HMs). In this study, the capability and mechanism of asphalt and biochar-modified asphalt (BMA) to remove Cu as the typical HM found in the road dust and surface runoff were fundamentally explored for the first time. Experiment and multiscale molecular simulations were performed. Molecular dynamics (MD) simulations showed the Cu absorption into the asphalts. Monte Carlo (MC) and density functional theory (DFT) revealed the detailed mechanism of Cu absorption. Biochar (BC) presence modified the spatial distribution of maltene and asphaltene fractions in asphalt and enhanced the absorption. Maltenes were absorbed into the porous structure of BC, leaving more asphaltenes in the asphalt part of BMA. Asphaltenes were the Cu adsorbing preference sites ascribed to the cation-π interaction between Cu and the aromatic plane. The DFT simulations also suggested favourable adsorption of other commonly found metals (e.g., Cr, Pb, Ni, Cd, and Zn) onto asphaltenes. The present study found the capability and mechanism of BMA and asphalt to remove HMs at the molecular scales, providing a path for designing asphalts with value-added functionality in minimizing environmental pollution. [ABSTRACT FROM AUTHOR]

The efficiency of persulfate-assisted advanced oxidation processes (PS-AOPs) in degrading organic pollutants is affected by the electron-donating capability of organic substances present in the water source. In this study, we systematically investigate the electron-donating capacity (EDC) difference between groundwater and surface water and demonstrate the dependence of removal efficiency on the EDC of target water by PS-AOPs with carbon nanotubes (CNTs) as a catalyst. Laboratory analyses and field experiments reveal that the CNT/PS system exhibits higher performance in organic pollutant removal in groundwater with a high concentration of phenols, compared to surface water, which is rich in quinones. We attribute this disparity to the selective electron transfer pathway induced by potential difference between PS-CNT and organic substance-CNT intermediates, which preferentially degrade organic substances with stronger electron-donating capability. This study provides valuable insights into the inherent selective removal mechanism and application scenarios of electron transfer process-dominated PS-AOPs for water treatment based on the electron-donating capacity of organic pollutants.

No Environmental Protection Agency (EPA) chemical treatments for preharvest agricultural water are currently labeled to reduce human health pathogens. The goal of this study was to examine the efficacy of peracetic acid- (PAA) and chlorine (Cl)-based sanitizers against Salmonella in Virginia irrigation water. Water samples (100 mL) were collected at three time points during the growing season (May, July, September) and inoculated with either the 7-strain EPA/FDA-prescribed cocktail or a 5-strain Salmonella produce-borne outbreak cocktail. Experiments were conducted in triplicate for 288 unique combinations of time point, residual sanitizer concentration (low: PAA, 6 ppm; Cl, 2-4 ppm or high: PAA, 10 ppm; Cl, 10-12 ppm), water type (pond, river), water temperature (12°C, 32°C), and contact time (1, 5, 10 min). Salmonella were enumerated after each treatment combination and reductions were calculated. A log-linear model was used to characterize how treatment combinations influenced Salmonella reductions. Salmonella reductions by PAA and Cl ranged from 0.0 ± 0.1 to 5.6 ± 1.3 log 10 CFU/100 mL and 2.1 ± 0.2 to 7.1 ± 0.2 log 10 CFU/100 mL, respectively. Physicochemical parameters significantly varied by untreated water type; however, Salmonella reductions did not (p = 0.14), likely due to adjusting the sanitizer amounts needed to achieve the target residual concentrations regardless of source water quality. Significant differences (p < 0.05) in Salmonella reductions were observed for treatment combinations, with sanitizer (Cl > PAA) and contact time (10 > 5 > 1 min) having the greatest effects. The log-linear model also revealed that outbreak strains were more treatment-resistant. Results demonstrate that certain treatment combinations with PAA- and Cl-based sanitizers were effective at reducing Salmonella populations in preharvest agricultural water. Awareness and monitoring of water quality parameters are essential for ensuring adequate dosing for the effective treatment of preharvest agricultural water., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)