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Abstract Increasing climate‐related extreme weather events and conflicts hinder safe water sanitation for vulnerable populations. In developing areas, centralized water systems are impractical due to high costs and poor infrastructure. Thus, technologies utilizing renewable energy like solar and mechanical energy for water treatment hold promise. It is critical to develop photocatalysts and piezoelectric/triboelectric catalysts that capture solar energy as well as mechanical energy to generate disinfectants to maximize energy utilization. The latest advancements in principles, materials, and processes utilizing solar and mechanical energy for water disinfection are highlighted in this review. First, we elucidate both direct and indirect mechanisms of sunlight‐mediated water disinfection, discuss the evolution of photocatalysts from simple UV absorption to visible‐light utilization, and even near‐infrared light exploitation to enhance solar spectrum utilization efficiency. Furthermore, we delve into the fundamental principles of piezoelectricity and triboelectricity relying on mechanical energy conversion as well as summarize the development of piezo/triboelectric catalysts from being driven by high‐frequency energy to utilizing low‐frequency mechanical energy from the environment. Finally, challenges and directions for efficient systems are outlined to inspire rational design strategies and accelerate the production of superior catalytic systems applicable across a broad range.

Alternative water disinfectants to chlorination need to be identified because its effectiveness is limited by water pH and potentially carcinogen by−products resulted from chlorination and organic compound reaction. The first study aimed to evaluate the effect of different drinking water chemical disinfection treatments on water quality, its potential hazard effects on animal health, water and feed consumption, and apparent total tract digestibility in dairy beef bulls fed high-concentrate diets. For 224 days, 24 Holstein bulls (176 ± 16.3 kg BW, and 149 ± 5.8 days of age) were individually assigned to one of four treatments with different drinking water chemical disinfectants: without disinfection (CTR); acidification and chlorination (ACCHL; 0.65 mL/L H3PO4 and 0.14 mL/L NaClO 15%); hydrogen peroxide (PER; 0.15 mL/L); and chlorine dioxide (DIO; 2.50 mL/L). Data were analysed with a mixed-effects model. Treatments affected the chemical characteristics of the water: in ACCHL, pH was 6.60 and free residual chlorine was 0.75 mg/L; in PER, H2O2 was 10.6 mg/L; and in DIO, ClO2 was 0.52 mg/L. Water physicochemical quality parameters in all treatments were below maximal thresholds established for safe water consumption by the Water Safety Royal Decree (RD 140/2003). In addition, the total coliform count of treated waters was reduced (P = 0.01) compared with CTR; moreover, ACCHL and DIO treatments were more effective in reducing total coliform count than PER. Dry matter intake tended (P = 0.07) to increase in DIO compared with CTR. Treatments did not affect blood parameters nor apparent total tract digestibility. The second study aimed to evaluate the potential benefit on animal performance of two drinking water disinfectants under commercial conditions in dairy beef crossbred Holstein bulls fed high-concentrate diets. Ninety-six animals (307 ± 4.4 kg BW, and 224 ± 1.8 days of age) were allocated to six pens for 140 days and assigned to one of two treatments: ACCHL, most common water disinfectant, and DIO. Data were analysed with a mixed-effects model. Water total coliform count and water consumption were similar between treatments. Concentrate intake was greater (P = 0.02) in ACCHL for the last 14 study days. Growth performance and carcass quality were similar between treatments. In summary, acidification and chlorination, H2O2, and ClO2 as drinking water disinfectants in dairy beef bulls had good disinfecting activity without detrimental effects on health and nutrient digestibility, and performance.

Clean and safe water is a fundamental requirement for human survival and well-being. The destruction of civilian infrastructure during wars or natural disasters can severely limit access to clean water for the local population, military, rescue workers and volunteers. The objective of the study was the evaluation of the efficiency of fresh water disinfection by electrolytic ozonation. The ozone concentration was measured photometrically by the intensity of the colour change in the reaction with N, N-diethyl-p-phenylenediamine sulfate. The water quality was assessed microbiologically by determining the total microbial count of the samples and by analysing the colour of the bottom of the flasks in which the water samples were stored. The efficiency of ozonation of artesian water in the field was evaluated. Electrolytic ozonation of 500 mL of spring water for two and five minutes produced an aqueous ozone solution with a concentration of 0.74 and 1.72 mg/L, respectively. Electrolytic ozone decomposed slowly and was detected in the samples three days after the water treatment. Ozonation of spring water for 5 and 10 minutes effectively inactivated all natural microorganisms (2.11 log CFU/mL), the water remained sterile and without any colour changes for a month. Water samples ozonated for 2 minutes did not demonstrate any visible changes after a month of storage, however the natural microflora partially recovered. Planktonic microorganisms in the amount of 2.33 log CFU/mL, as well as biofilms on the walls of the flasks, were detected in a month in the control water samples. The colour of the bottom of the control flasks changed to dirty yellow. In the field, ozonation of water for 10 minutes prevented its spoilage even when the recommended treatment volume was increased by 10 times. The obtained results indicate that electrolytic ozonation is an effective method of freshwater disinfection, and portable ozonators can play an important role in emergency water purification in areas of armed conflicts or natural disasters

Water treatment technology is advancing to extend the supply of pure drinking water to low-income societies. The application of biomass-based silver nanoparticles for the purification of water is among the outstanding innovations in this respect. Silver has less reactivity and excellent stability, which makes it preferable for biological applications such as drinking water. In this research review, the synthesis of silver nanoparticles (AgNPs) using different techniques of chemical synthesis, physical synthesis, photochemical synthesis, and biological synthesis was discussed. The synthesis of AgNPs supported by biomass-driven silica gel and its application for the treatment of water were found to be promising technologies. The use of biobased silica aerogel supported AgNPs for water disinfection has recently been the subject of promising research findings as an effective method for killing microorganisms from drinking water. The characteristics of bio-silica aerogel are unequalled, in large part because of its increased porosity, greater surface area, extraordinarily inadequate thermal conductivity density, and potent antibacterial action against both Escherichia coli (E. coli) and Staphylococcus aureas (S. aureus) at low concentrations. These features exhibited that the synthesis of bio-based silica aerogel-coated AgNPs for water disinfection is a promising research interest for the disinfection of drinking water. AgNPs also have anti-fouling properties that prevent the clogging of membrane filters, which enhances their potential for improving water quality and safety.

Nanotechnology has been rapidly developing in the past decade, and metal nanomaterials have shown promising improvement in microbial control. Metal nanoparticles have been applied in medical settings for adequate disease spread control and to overcome the challenges of multidrug-resistant microorganisms. Recently, the demand for safe water supply has increased, requiring higher sanitation of the water treatment technology as well as being environmentally sustainable. However, the employed water disinfection technologies cannot meet the elevated demand due to limitations including chemical byproducts, immobility, energy consumption, etc. Metal nanomaterials are considered to be an alternative disinfection technology considering their high efficiency, mobility, and stability. A significant amount of research has been carried out on enhancing the antimicrobial efficiency of metal nanomaterials and determining the underlying antimicrobial mechanisms. This paper provides an overview of emerging metal nanomaterials development, including the synthesis method, material characteristics, disinfection performance, environmental factors, potential mechanism, limitations, and future opportunities in the water disinfection process. HIGHLIGHTS Antimicrobial mechanisms are governed by microbe–metal nanoparticles interactions.; Synthesis methods and material characteristics impact microbial control performance.; Demonstrations via experimental study and simulation support its applicability.; Nanoscale metal materials have multi-tasking ability versus conventional treatments.; Limitations of possible toxicity, cost, and manufacturing call for further research.;

BackgroundConventional techniques for water disinfection are fraught with issues like personnel exposure to damaging radiation and formation of harmful and carcinogenic disinfection byproducts. There are difficulties related to transportation and handling, and expensive capital and working costs also are involved like costs associated with on-site generation of disinfectants. There is a dire need for newer disinfection technologies that are environment and health friendly.Scope and benefitsThis article reviews the use of natural disinfectants derived from plants to enhance the quality of water. Researchers have utilized herbal extracts, phytochemicals, and phytochemical-metal complexes for the disinfection of water. Various factors for these chemicals like efficacy, toxicity, cost, and water solubility have been discussed and some useful phytochemical disinfectants are also identified. These disinfection methods particularly when using only pure phytochemicals are generally thought to be free from the deleterious effects associated with chlorination and other conventional technologies. Inherently, chlorinated and other harmful disinfection byproducts are not formed.Key findings and conclusionsIn various studies eugenol, thymol and extracts of Ocimum sanctum and Azadirachta indica have been utilized with fairly effective disinfection capabilities. The significant antimicrobial effects of allicin, berteroin, sanguinarine, and thymol are reflected from their very low minimum inhibitory concentration values. Even so, presently the efficiency of phytochemicals is not comparable to conventional disinfectants. The use of phytochemical metal complexes is, however, a plausible option that might be investigated further. The metal complexes because of their greater water solubility than pure phytochemicals result in improved disinfection efficiency. Notable among those are flavonoid-metal complexes that should be considered further for use in water disinfection. It is also concluded that phytochemicals may be added to water that has also been disinfected with some other commonly-used technology. A way to do this may be to design a fixed bed tower of phyto-disinfectant through which water should pass.

This work deals with the synthesis, structural characterization and applications of N-halamine glycinate functionalized silica-mesoporous silica coated ZnO-NPs/AC composite for water disinfection. Several nanocomposite materials were obtained: ZnO-NPs/AC, ZnO-NPs/AC@SiO2, ZnO-NPs/AC@SiO2@mSiO2, ZnO-NPs@SiO2@mSiO2-Gly and ZnO-NPs@SiO2@mSiO2-N-halamine-Gly. These nanocomposite materials were fully characterized via different physiochemical techniques including: FTIR, TGA, XPS, XRD, SEM, TEM and BET. XRD indicated a predominance of crystalline pattern of ZnO-NPs impregnated into activated carbon (AC) and their silica and m-mesoporous silica coating precursors. The FTIR spectra confirmed an immense combination between ZnO-NPs and AC of ZnO-NPs/AC nanocomposite as well as its interactions with coated silica precursors. SEM, TEM images illustrated that the fabricated ZnO-NPs/AC nanocomposites are well coated with silica-mesoporous silica functionalized N-halamine. The distinctive surface area has decreased from 800 m2/g for pristine AC to 772 m2/g for ZnO-NPs/AC and to 282 m2/g for ZnO-NPs/AC@SiO2 and to 139 m2/g for ZnO-NPs/AC@SiO2@mSiO2 and to 15.4 m2/g for ZnO-NPs@SiO2@mSiO2-N-Gly. All those nanocomposites showed good efficacy against all four bacterial species, with higher inhibition zones for the 2 g-positive bacteria than that of the 2 g-negative ones. The ZnO@SiO2@mSiO2-N-halamine-Gly exhibited the high zone inhibition against all tested bacteria except for E. Coli.

The exploration of novel biomarkers to assess poultry health is of paramount importance, not only to enhance our understanding of the pathogenicity of zoonotic agents but also to evaluate the efficacy of novel treatments as alternatives to antibiotics. The present study aimed to investigate potential gut health biomarkers in broiler chicks challenged by Campylobacter jejuni and subjected to a continuous water disinfection program. A total of 144 one-day-old hatched broiler chicks were randomly allocated to four treatment groups with four replicates each, according to the following experimental design: Group A received untreated drinking water; Group B received drinking water treated with 0.01–0.05% v/v Cid 2000™ (hydrogen peroxide, acetic acid and paracetic acid); Group C was challenged by C. jejuni and received untreated drinking water; and Group D was challenged by C. jejuni and received drinking water treated with 0.01–0.05% v/v Cid 2000™. The use of Cid 2000™ started on day 1 and was applied in intervals until the end of the experiment at 36 days, while the C. jejuni challenge was applied on day 18. Potential biomarkers were investigated in serum, feces, intestinal tissue, intestinal content, and liver samples of broilers. Statistical analysis revealed significant increases (p < 0.001) in serum cortisol levels in C. jejuni-challenged broilers. Serum fluorescein isothiocyanate dextran (FITC-d) increased significantly (p = 0.004) in broilers challenged by C. jejuni and treated with drinking water disinfectant, while fecal ovotransferrin concentration also increased significantly (p < 0.001) in broilers that received the drinking water disinfectant alone. The gene expression levels of occludin (p = 0.003) and mucin-2 (p < 0.001) were significantly upregulated in broilers challenged by C. jejuni, while mucin-2 significantly increased in birds that were challenged and received the drinking water disinfectant (p < 0.001). TLR-4 expression levels were significantly (p = 0.013) decreased in both groups that received the drinking water disinfectant, compared to the negative control group. Finally, the C. jejuni challenge significantly increased (p = 0.032) the crypt depth and decreased (p = 0.021) the villus height-to-crypt-depth ratio in the ileum of birds, while the tested disinfectant product increased (p = 0.033) the villus height in the jejunum of birds. Furthermore, the counts of C. jejuni in the ceca of birds (p = 0.01), as well as its translocation rate to the liver of broilers (p = 0.001), were significantly reduced by the addition of the water disinfectant. This research contributes to novel insights into the intricate interplay of water disinfection and/or C. jejuni challenge with potential intestinal biomarkers. In addition, it emphasizes the need for continued research to unveil the underlying mechanisms, expands our understanding of broiler responses to these challenges and identifies breakpoints for further investigations.

Aeromonas hydrophila is a common emerging pathogenic bacterium in natural waters that affects the quality of drinking water. This becomes a challenge for the development and innovation of alternative technologies that provide safe water to families in rural communities. The present study evaluated the ability to inactivate natural A. hydrophila from surface waters using a drinking water treatment system at the point of use (POU). It is based on 2 thermofused polypropylene filters followed by a UV disinfection lamp, and it was installed in houses in two rural communities in Colombia. Experimental results showed that the POU systems removed A. hydrophila with a log reduction value (LRV) of 3.60 ± 0.02 in the synthetic waters, and removal values greater than 2 LRV in tests performed with natural surface waters with detected naturally occurring Aeromonas and quantified in these communities with LRV of 3.1 ± 0.6 and 2.2 ± 0.6, respectively, with a detection limit of 1 CFU/100mL. The concentrations of E. coli and total coliforms (TC) were also monitored in 54 homes all equipped with the above-described POU systems for 12 months. Given the efficacy found in this study and the availability, accessibility, and affordability of the elements used to design and manufacture the POU systems, it is feasible to propose their use to provide safe water to vulnerable families living in rural communities that lack water treatment systems.

Providing effective and sustainable water disinfection methods, without harmful by-products, is essential to protect public health and safety. It is hypothesized that the application of liquid-thin-film (LTF) technology can enhance the bactericidal activity of both ultraviolet (UV) irradiation and ozone (O3) treatments. Therefore, this study aimed to examine the bactericidal activity and synergistic effect of the combined UV + O3 + LTF treatment against Escherichia coli in water processing. The results showed that LTF technology significantly increased the disinfection efficiency of UV and O3 in potable water production. Thus, the combined UV + LTF, O3 + LTF, and UV + O3 + LTF treatments were more effective than the individual treatments under identical conditions. Particularly, the combined double-UV (41.7 mJ cm−2) + O3 (100% O3) + LTF (65 L min−1) treatment exhibited the highest bactericidal activity, resulting in a 5.8-log decrease in the E. coli load within 30 min. Pearson's correlation analysis demonstrated a significant correlation between the synergistic effects of the combined treatments and UV dosage (r = 0.88, p < 0.0001) and aqueous O3 concentrations (r = 0.84, p < 0.0001). These findings suggest that combined UV + O3 + LTF treatment could be a viable alternative method for water disinfection. HIGHLIGHTS Liquid-thin-film (LTF) enhances the bactericidal activity of UV rays and O3 disinfectant.; The combined UV radiation, ozone, and LTF had synergistic bactericidal effects.; UV + O3 + LTF combined treatment had the highest bactericidal activity against E. coli.; E. coli were susceptible to UV + O3 + LTF at a low chemical dosage and short exposure time.;

This study reports the synthesis of sunlight-active zinc oxide-tungstate-kaolinite photocatalytic composite prepared via a green process (solvent-free mechano-thermal process) at an optimum temperature of 500°C for 1 h in a furnace. Electron Paramagnetic Resonance (EPR) study suggests the presence of W5+ defect states in the prepared photocatalytic composite (ZnWK-5), which is responsible for its photoactivity in visible light. Results from further analysis show that hole (h+) and superoxide radical (.O2−) are the major contributors to the photocatalytic efficiency of ZnWK-5 photocatalytic composite. This photocatalytic composite was used to treat water containing an antibiotic chemical-ampicillin (AMP) under sunlight. Mass spectrometry analysis of the treated water suggests that the mechanism of photodegradation of AMP is via several bond and ring cleavages, including amide bond, phenyl ring, and β-lactam ring cleavages. These cleavage reactions were followed by subsequent mineralization of ca. 98% after 5 h without the formation of toxic products. The introduction of phosphate and carbonate anions had a serious negative impact on the photocatalytic activity of the composite. However, the photocatalytic composite completely disinfected water contaminated with gram-(−ve) and gram-(+ve) bacteria. Even after five re-use cycles, the photocatalytic composite maintained a 90% photodegradation efficiency of ampicillin in water.

Disinfection is key process in municipal water supply process. In this work, silver nanoparticles (AgNPs) were impregnated on activated carbon (AC) prepared from castor seed hull and used for disinfection of water. The AC and AgNPs-impregnated AC (AC-AgNPs) were characterized using Fourier transform infra-red (FT-IR), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectroscopy (SEM-EDX) to confirm the functional groups, morphology and the presence of silver nanoparticles on the activated carbon. A maximum 0.0427 wt% AgNPs loading was observed for AC treated with 100 mL AgNPs colloid solution and 32 h impregnation time. The maximum BET surface area of AC-AgNPs was 697.54 m2/g found for AC-AgNPs treated with 25 mL AgNPs colloid solution for 8 h. The disinfection performances of the AC-AgNPs on Escherichia coli (E. coli) were investigated through batch and continuous studies. In the batch study, the concentration of E. coli was reduced from 5.6 × 107 to 0.0 in 20 min for AC-AgNPs while no significant changes were observed for non-impregnated AC. Finally, the disinfected water was tested for AgNPs leaching with UV–vis and no AgNPs UV peak was observed.

The disinfection process is used in the treatment of water for human supply to promote sanitary safety and provide users with drinking water that meets potability standards. Thus, it is necessary to sustain a minimal concentration of free residual chlorine (FRC) throughout the entire distribution system. The present study investigated the decay process of FRC concentration in water destined for human supply. The decay was evaluated in bench-scale testing, using sodium hypochlorite, calcium hypochlorite, sodium dichloroisocyanurate (organic chlorine) as disinfectant agents, and also an alternative disinfectant solution (ADS) produced in loco, with oxidizing and disinfectant properties, which is being used in Brazilian sanitation industry. To evaluate the decay, four models were fitted: first-order, nth-order, limited first-order and parallel first-order, hence determining the corresponding parameters which describe the decay speed of the FRC concentration in water. Achieved results demonstrated that all models were statistically significant and predictive. However, the parallel first-order model produced the best fit. Regarding the evaluated disinfectants, there was preeminence of the ADS solution when compared to the others, since it imparted a higher FRC over time, a behavior indicated by lower values for reaction rate constant in all models and when compared to other disinfectants used in this study. HIGHLIGHTS Alternative disinfectant solution (ADS) tends to maintain a greater residual chlorine over time.; Chlorine decay over time is best described by the first-order parallel model.; The use of disinfectants that contain not only chlorine derivatives guarantees a greater residual-free chlorine over time.;

Drinking water disinfection is an essential process to assure public health all over the world. In this study, silver nanoparticles (AgNPs) on UiO-66 (Zr) Metal-Organic Frameworks (Ag@UiO-66) is proposed as a potential water disinfection strategy. AgNPs are synthesized using polyvinyl pyrrolidone (PVP) as stabilizing agent, and sodium borohydride as reducing agent are subsequently embedded on UiO-66, a high-stability organometallic framework. The effect of premixing time, reaction time and reactant concentration on the loading rate of AgNPs on UiO-66 was investigated. The maximum load rate of AgNPs on UiO-66 could reach 13% when the premixing time is 3 h, the reaction time is 45 min and the concentration of AgNO3 is 10 μg/mL. The formation of AgNPs loaded on UiO-66 was observed and confirmed with ultraviolet and visible spectrophotometry (UV-Vis), scanning electron microscopy (SEM), infrared emission spectroscopy (IES) and X-ray diffraction (XRD) analysis. Ag@UiO-66 exhibited strong antibacterial activity against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, with minimum inhibitory concentrations (MIC) of 64 and 128 μg/mL, respectively. The germicidal efficacy of Ag@UiO-66 enhanced significantly as the temperature rose from 4 °C to 37 °C. The results indicate that Ag@UiO-66 is potential candidate as a feasible water disinfection material.

Introduction: Accessibility to safe drinking water is an important human health issue, so water reuse and water resources management are critical in arid parts of developing regions. This study aimed to investigate the use of a combined simple designed solar geyser/photocell for drinking water disinfection. Materials and Methods: In this study, a solar geyser with a simple design was combined with a solar cell and its efficiency on the disinfection of contaminated water was investigated. This study was carried out with artificially polluted tap water by a solar geyser joined with a solar photovoltaic cell. The heated water (55°C) was kept for 2 hours using a solenoid valve. The pilot plant was operated and monitored for one year. The volume of the collected effluent was measured every 24 h. The most probably number (MPN) of total coliforms and fecal coliforms in 100 mL of 24-hour composed samples were measured. Results: The mean volume of disinfected water production was calculated as 2095.74 ± 270.28 mL/day. The strongest correlation was found between disinfected water and the maximum daily ambient air temperature with a linear model (R2 = 0.9937). The results showed that by increasing the sunny time, the volume of water outlet increased. Therefore, sunny time and UV radiation have direct effect on volume of disinfected water. Conclusion: The simple designed solar geyser for drinking water disinfection was efficient and recommended for tropical areas, emergency conditions, and farms for agricultural activities.

Drinking water disinfection or inactivation of pathogenic microorganisms is an essential step to minimize infection risks and decrease the incidence of waterborne diseases. Recently, chitosan nanoparticles (CNs) have been highlighted as an antimicrobial agent for a wide range of applications due to their natural antimicrobial properties, and low or no toxicity risk for human health. In this study, we generated CNs from three different molecular weight (MW) chitosan (low, medium, high) at various concentrations (0.25, 0.5 and 2% (w/v)). After the CNs preparation and quality assessment, the antimicrobial activity was evaluated by measuring the log reduction of Gram-negative bacteria E. coli as a model microorganism for faecal pollution. The results demonstrated that 0.25% of medium MW CNs are optimal for more than 99.99% reduction of cultivable E. coli and 97% inactivation of metabolically active E. coli. These results indicated that CNs were able to inhibit the growth of cultivable and metabolically active E. coli in tap water and demonstrated the potential use of CNs as an alternative antimicrobial agent in drinking water disinfection. HIGHLIGHTS CNs were synthesized by an ionic gelation method.; MMWC with a chitosan concentration of 0.25% is the the most suitable material for bacterial inactivation.; In drinking water, chitosan nanoparticles inhibit both cultivable and metabolically active E. coli.;

Extreme environmental changes caused by the cavitation bubble collapse, such as high pressure, high temperature and the microjet, will cause pyrolysis reaction at the gas and liquid interface inside the bubble. Self-excited pulsed cavitation jet has an instantaneous strong pulse pressure, which leads to local hot spots surrounding the cavitation bubbles. The generation of strong oxidizing free radicals promotes easy ozone conversion into oxygen. Numerical simulations were conducted for ozone decomposition by cavitation jet. Three groups of different collision angles were applied to compare and analyze the ozone degradation reaction. Results showed that the collision angle has a certain influence on the chemical reaction intensity, the degradation of ozone, and oxygen production. At the collision angle of 180°, the chemical reaction was the most violent, with ozone degradation and oxygen production at the highest level, followed by 120° and lowest at 90°.

The present study was conducted to assess the efficiency of solar energy in treating any potential pollution of drinking water in dam lakes caused by human activity in rural areas. The water quality parameters include temperature, pH, conductivity, total suspended solids, total nitrogen, total phosphorus, NH4-N, NO3-N, HCO3, Cl-, Na+, Mg2+, Ca2+, SAR, B, K+, SO42-, and E-coli were monitored. Samples was collected during the summer and winter (during the filling period). The results showed a rapid decrease in microbial counts upon exposure to solar radiation. More than 98% reductions were achieved after 8 hours for the bacterial communities tested under different conditions. The rate of inactivation, however, varied and was mainly affected by water turbidity and temperature during the experiments. The results indicated that turbidity affected the efficiency of water disinfection, and the efficiency improves with longer exposure duration, implying that in high turbidity and severe weather conditions, exposure time must be increased to compensate for the effects of these factors. The water in the system should be exposed to at least eight hours before leaving to the storage tanks. When scaled up, the proposed method could be a vital tool in solar water disinfection technologies, particularly in isolated and rural locations. Using solar energy to disinfect polluted water will certainly reduce the usage of chlorination and or filtration in water treatment, reducing treatment costs while also protecting the environment.

The first study aimed to evaluate the effect of drinking water disinfection (chlorination: NaClO 15%) and conditioning (acidification: H3PO4 diluted 1:5 in water) on water quality, water and feed consumption, apparent total tract digestibility, and its potential hazardous effects on Holstein bulls fed high-concentrate diets. Twenty-four animals (221 ± 20.9 kg of BW, and 184 ± 9.9 days of age) were individually assigned to one of four treatments according to a 2 × 2 factorial arrangement: conditioning (with or without acidification) and disinfection (with or without chlorination). The entire study lasted 210 days. Physicochemical and microbiological water quality, water and feed consumption, haematological and biochemical blood parameters, and apparent total tract digestibility were measured; data were analysed via a mixed-effects model. Chlorination and acidification increased (P = 0.02) free residual chlorine in water, and chlorination reduced (P = 0.01) total coliform and Clostridium perfringens counts in water. Treatment did not affect water consumption, total DM intake, or blood parameters. At the beginning of the study, NDF digestibility decreased (P = 0.04) with acidification, however, this was restored at the end of the study. The second study evaluated the potential benefit of drinking water chlorination and acidification on the performance of crossbred Holstein bulls fed high-concentrate diets under commercial conditions. Ninety-six animals (322 ± 35.0 kg of BW, and 220 ± 14.2 days of age) were allocated into six pens assigned to one of the two treatments: untreated drinking water or drinking water treated with chlorination and acidification for a total of 112 days. Physicochemical and microbiological water quality, water and concentrate consumption, eating behaviour, growth performance, and carcass quality were analysed via a mixed-effects model. Water conditioning and disinfection increased (P = 0.01) free residual chlorine concentration and reduced (P = 0.04) total coliform count in water. Although water consumption and eating behaviour were similar between treatments, water conditioning and disinfection increased average daily weight gain (P = 0.03), BW before slaughter (P = 0.01), and hot carcass weight (P = 0.01). In conclusion, drinking water chlorination and acidification in fattening dairy beef bulls is recommended as it improves growth performance without any detrimental side effects on health or nutrient digestibility.

This research was aimed at determining the efficacy of solar radiation as a good source of reducing microbial load in water and the determination of Bisphenol- A concentration in bottled water and sachet water. The parameters evaluated are: Total bacterial count, Total fungi count, Salmonella Shigella, Coliform, Bisphenol A, pH, Dissolve oxygen, Total dissolve solid, Turbidity, total hardness. The bacteria genera isolated are; Staphylococcus, Pseudomonas sp, Echerichia coli, Klebsiella sp, Salmonella sp, Bacillus sp. Micrococcus sp. Proteus sp. Corynebacterium sp. The fungi genera isolated are Penicillium sp, Aspergillus niger, Mucor sp. Cadida sp. Fusarium sp. These organisms reduce as the number of hours of exposure increases. The Bisphenol A concentration increases as the exposure time increases. The study revealed that solar radiation (sunlight) is a good source of water disinfection. The study however recommends the use of PET Polyethylene Terephthalate bottle in water purification using sunlight since PET bottles contains much less additives than bottles made from Poly Vinyl Chloride (PVC)

Abstract Shortages, deterioration in the quality of water sources and increased demand for water have been a problem for both developing and developed countries. In view of this scenario, the use of alternative sources such as the capture and use of rainwater proves to be a feasible solution. In remote places, without water and electricity supply, the use of a rainwater capture system, with ultraviolet disinfection and powered by an isolated photovoltaic panel can be the solution for the water and energy supply. Thus, this work evaluates the efficiency of the isolated photovoltaic system and the quality of rainwater after passing through the ultraviolet germicidal (UV) lamp. To measure water quality, laboratory analyzes were performed. Analyzes of water from the cistern were performed and after passing through the UV disinfection system using different flow rates to determine which would be more viable for the system. The rainfall and solar irradiation data are collected to determine whether the system powered by photovoltaic energy is viable in the city of Curitiba in the state of Paraná. The results for water analysis showed that the UV disinfection system is efficient, and in the medium and minimum flow rates, there were 100% improvements in the water quality for coliforms. The isolated photovoltaic system proved to be effective, as the irradiation rates were satisfactory even in the winter period, when solar irradiation is generally lower.

Photocatalysis disinfection has great potential for irrigation water disinfection to improve fresh produce safety. Titanium dioxide (TiO2) nanoparticle (NP)-embedded cellulose acetate (CA) film has shown effectiveness against Escherichia coli (E. coli) O157:H7 in water. The current study evaluated the effect of natural water compounds on the photo-disinfection efficacy of TiO2 NP-embedded CA film. Humic acid, calcium carbonate (CaCO3), and kaolin clay solutions were prepared at four concentrations, respectively. When concentration increased from 0 to 20 ml/L, inactivation of E. coli O157:H7 in humic acid, CaCO3, and kaolin clay solutions decreased from 6 log to 5, 4, and 2 log CFU/ml, respectively after 3 h treatment. Turbidity, UVT-254, water hardness, total suspended solids (TSS), and total organic carbon (TOC) of the solutions were measured. UVT-254 and turbidity had the highest correlation with the inhibition effect of water compounds on photo-disinfection efficacy. A prediction equation was developed with UVT-254 and water hardness as independent variables to predict photo-disinfection efficacy in natural water. E. coli O157:H7 decreased by 1 and 2.5 log CFU/ml in unfiltered and filtered natural creek water samples after treatment. The results from this study showed promise in the use of TiO2 NP-embedded CA film to inactivate pathogens in natural water. HIGHLIGHTS Natural water compounds affect TiO2 photo-disinfection efficacy in different degrees.; UV transmittance and water hardness are important water quality parameters that can affect TiO2 photo-disinfection efficacy.; Prediction equation was developed to predict TiO2 photo-disinfection efficacy in natural water.; Filtration is an effective pre-treatment method for improving TiO2 photo-disinfection in natural water.;

In the past, we could never imagine buying drinkable water. Who would buy to drink water? But now, bottled water are sold just about anywhere in the world, but there are still many countries with water supply shortages. When drinking water is contaminated with microorganisms, it can be exposed to various diseases such as hepatitis, cholera, diarrhea, and typhoid fever. We are not only interested in drinking water, but also the water used in bathrooms, gardens, and laundry of each household. We mention “water quality” because all of these kinds of water are enough to give us a direct stimulus such as odors and greens. When we use tap water in each household, the most direct irritation is the “smell”. In this case, we know that chlorine comes to mind first, and that chlorine is very useful in disinfection. Then, why are we sensitive to toxic odors in drinking water or swimming pools? The answer is simple. The effect of disinfecting with chlorine is only exerted in clear water, and we need to focus on the analysis of residual chlorine that is important for instrumental analysis. Therefore, what is introduced in this study is a “residual chlorine sensor” of a new constant voltage method that can be more accurate in measuring the amount of residual chlorine in water which is the most important factor when it comes to effectively disinfecting our drinking water.

Background: The main aspect of water purification to serve the human drinking purpose is the elimination of microbial agents and pathogens using the disinfectants. Although chemicals such as chlorine are the most common water disinfectants, the researchers have always sought to identify and introduce new disinfectants due to the formation of potentially carcinogenic byproducts. Owing to the high efficiency and lack of hazardous residues, nanoparticles have recently been used in many scientific activities. Objectives: In this study conducted in summer 2018, the copper and silver nanoparticles were used to remove Escherichia coli (E. coli) and Klebsiella from the synthetic and real samples. Methods: This experimental study was performed on Nano particles and by adding nanoparticles to samples (real and synthetic), the efficiency of removal of E. coli and Klebsiella was measured by MPN and pure plate methods. Results: By optimizing the conditions, in 200 ppm concentration as 2ml with pH=7, it has the highest removal rate of 99.25% for E. coli, and in 250ppm concentration as 1.5 ml with pH = 7, it has the removal rate of 81.25% for Klebsiella. Conclusions: In this case study, we found that using Nano particles led to high level of efficiency at a short time; moreover, they were cost-effective and environmentally friendly.

Photochemical processes for the treatment of water and wastewater have been receiving increasing attention as sustainable treatments involving a renewable, free and clean source of light, such as natural solar radiation. Different oxidative agents including hydrogen peroxide, peroxymonosulfate, persulfate, peracetic acid and free chlorine have been recently investigated as potential strategies to enhance the mere action of the solar photons for water disinfection.The aim of this study is to review the most recent advances reached in the scientific literature regarding these solar processess based on their promising capability to be further implemented in real field or industrial scale. The characterization of each oxidative agent, the efficiency of each solar photochemical process for disinfection of water and wastewater and the operating mechanism governing the microbial pathogens inactivation are discussed. Specific and complementary requirements of this type of applications such as the solar resource and the most promising solar reactors currently employed have been also described in detail. Finally, the main advantages, drawbacks, challenges and perspectives for their future implementation at full scale are also highlighted.

Identifying and monitoring the efficiency of alternative biocides that are presently used in livestock is gaining vast attention. The objective of this study was to determine, in vitro, the antibacterial activity of nine commercial water disinfectants, acidifiers, and glyceride blends against clinical isolates or reference strains of zoonotic pathogens belonging to the genera Escherichia spp., Salmonella spp., Campylobacter spp., Listeria spp., and Staphylococcus spp. For each product, the antibacterial activity was tested in concentrations ranging from 0.002 to 1.136% v/v and expressed as the minimum concentration of the product that inhibits bacterial growth (MIC). Water disinfectants Cid 2000™ and Aqua-clean® recorded MICs ranging from 0.002 to 0.142% v/v, while the lowest MICs were recorded at two strains of Campylobacter (0.002–0.004% v/v). Virkon® S displayed various MICs (0.013–0.409% w/v) and was highly effective at suppressing the growth of Gram-positive bacteria such as S. aureus (0.013–0.026% w/v). The MICs of water acidifiers (Agrocid Super™Oligo, Premium acid, and Ultimate acid) and glyceride blends (CFC Floramix, FRA®LAC34, and FRA®Gut Balance) ranged from 0.036 to 1.136% v/v, and for most of these products, MICs were closely correlated by their ability to modify the pH of the culture medium close to 5. In conclusion, most of the tested products showed promising antibacterial activity; as a result, they would be good candidates for pathogen control in poultry farms and for reducing the emergence of antimicrobial resistance. However, further in vivo studies are recommended to provide relevant information for the underlying mechanisms, as well as for the establishment of the optimal dosage scheme for each product and their possible synergies.

Increase water usage has led to its deterioration. Pollutants are easily found in the aquatic environment and treatment techniques must keep improving to meet the current needs and future demands. Membranes are attractive for water treatment, but limitations like fouling and the highly concentrate produced affect their performance. Combining membrane filtration with photocatalysis provides the opportunity to integrate a self-cleaning step during membrane filtration. In this work, we studied two simple and efficient approaches to combine membrane filtration with zinc oxide nanoparticles (using the catalyst in suspension and immobilized) activated by light emitting diodes (LED) emitting light at 365 nm. Both systems were used to test the disinfection efficiency in real surface water, compared in terms of catalyst concentration in the permeate stream (below the limit of detection) and its recovery after filtration (higher that 74%). The system’s capability to retain and inactivate target bacteria (total coliforms and E. coli) in the retentate stream was tested with samples of real surface water. The results obtained show that both configurations led to an improved performance in comparison to the membrane treatment alone with a higher retention of the bacteria (not detected in the permeate samples) and higher treatment of the retentate. For the modified membranes, different catalyst concentrations and thermal treatments were tested. The performance of all the processes was evaluated in terms of the level of treatment achieved and the permeate flux. All the modified membranes showed an efficient retention of the target bacteria from surface water, with higher performances than the unmodified membrane (96.2% for total coliforms and 94.9% for E. coli). Remarkable retention and treatment of the retentate was achieved using a membrane modified with a catalyst load of 125 mg subject during two hours to a thermal treatment of 300 °C. This modification has a performance comparable to the system with the same catalyst load in suspension. During operation, the permeate flux reduction is lower with the modified membranes which could lead to longer operation times without the need of further cleaning or replacement. The combined system, ceramic membranes modified with zinc oxide and UV-A LEDs proved to be effective to retain and disinfect water quality indicator bacteria present in real surface water matrices.

Herein, green and non-toxic bismuth sulphide@graphitic carbon nitride (Bi2S3@g-C3N4) nanosheets (NCs) were firstly synthesized by ultrasonicated-assisted method and characterized with different tool. Bi2S3@g-C3N4 NCs antimicrobial activity tested against three types of microbes. As well the heterostructured Bi2S3@g-C3N4 NCs was investigated for removing dye and hexavalent chromium under visible light and showed high efficiency of photocatalytic oxidation/reduction higher than g-C3N4 alone, attributing to lower recombination photogenerated electron-hole pairs. Bi2S3@g-C3N4 NCs showed high antimicrobial efficiencies against Staphylococcus aureus (S. aureus) as a Gram positive bacterium, Escherichia coli (E. Coli)as a Gram negative bacterium and Candida albicans (C. albicans) and that the disinfection rates are 99.97%, 99.98% and 99.92%, respectively. The core mechanism is that the bacterial membrane could be destroyed by reactive oxygen species. The Bi2S3@g-C3N4 NCs is promising for environmental disinfection including water and public facilities disinfection and solar photocatalytic depollution. Turnover number (TON) and Turnover frequency (TOF) are used as concise assessment indicator for photocatalytic efficiency.

Copper-based fungicides have a long history of usage in agriculture and aquaculture. With the rapid development of metal-based nanoparticles, copper-based nanoparticles have attracted attention as a potential material for prevention and control of Saprolegnia parasitica. The present study investigated the effectiveness of copper/carbon core/shell nanoparticles (CCCSNs) and a commercial CCCSNs filter product (COPPERWARE®) against S. parasitica in a recirculating system. Results showed that the growth of agar plugs with mycelium was significantly suppressed after exposure to both CCCSNs powder and COPPERWARE® filters. Even the lowest concentration of CCCSNs used in our study (i.e., 100 mg/mL) exhibited significant inhibitory effects on S. parasitica. The smallest quantity of the filter product COPPERWARE® (3.75 × 3.7 × 1.2 cm, 2.58 g) used in our aquarium study also demonstrated significant inhibition compared with the control group. However, we observed leaching of copper into the water especially when larger quantities of COPPERWARE® were used. Water turbidity issues were also observed in tanks with the filter material. Besides these issues, which should be further investigated if the product is to be used on aquatic species sensitive to copper, CCCSNs has promising potential for water disinfection.

The objects of the study were the Doy Chemical hollow-fiber ultrafiltration membranes which were use for preparation of make-up water for the Novocherkasskaya Regional Thermal Power Plant (RTPP).We tried out a possibility of applying the X-ray fluorescence spectrometry to study the condition of the spent non-recoverable ultrafiltration membranes in order to identify the causes of their irreversible destruction. The ARL Quant’X X-ray fluorescence energy dispersive spectrometer of Thermo Scientific (USA) was used in the study.Thin cuts of the Doy Chemical hollow-fiber ultrafiltration membranes were used in the experiments, which had worked for more than three years in the field conditions of the feed water of the Don River, Russia.The analysis of the obtained samples spectra allowed us to assume that the membranes were irreversibly contaminated by iron bacteria. Basing on the conclusions made during the analysis of X-ray fluorescence spectra we developed and tested in field conditions one of the optimization variants for technological pretreatment scheme. This scheme enables a significant increase in the service life of ultrafiltration membranes, even when the feed water is heavily contaminated by bacteria. Field tests of the modernized technology were carried out at Novocherkasskaya RTPP during 2016-2018 and showed a significant increase in the service life of the membrane modules. At the same time, the quality of the filtrate, productivity and pressure drops at the cascades of ultrafiltration units fully corresponded to the normative values even in conditions of deteriorated quality of the feed river water.It has been proved that aggressive regeneration of ultrafiltration membranes that have worked for a long time under the conditions of feed water having increased values of the total microbial number and high values of permanganate oxidation does not allow one to restore their initial state. In this case the main cause of ultrafiltration membranes contamination is iron, which is present in colloidal and bacterial forms in the pores and on the membranes surfaces. In the conditions of the Novocherkasskaya RTPP, in addition to timely flushing and chemical regeneration of ultrafiltration membranes, the necessity of organizing a preliminary treatment of the feed water with reagents having a prolonged bactericidal effect is accepted.

Hydrodynamic cavitation is a promising technique for water disinfection. In the present paper, the disinfection characteristics of an advanced hydrodynamic cavitation reactor (ARHCR) in pilot scale were studied. The effects of various flow rates (1.4–2.6 m3/h) and rotational speeds (2600–4200 rpm) on the removal of Escherichia coli (E. coli) were revealed and analyzed. The variation regularities of the log reduction and reaction rate constant at various cavitation numbers were established. A disinfection rate of 100% was achieved in only 4 min for 15 L of simulated effluent under 4200 rpm and 1.4 m3/h, with energy efficiency at 0.0499 kWh/L. A comprehensive comparison with previously introduced HCRs demonstrates the superior performance of the presented ARHCR system. The morphological changes in E. coli were studied by scanning electron microscopy. The results indicate that the ARHCR can lead to serious cleavage and surface damages to E. coli, which cannot be obtained by conventional HCRs. Finally, a possible damage mechanism of the ARHCR, including both the hydrodynamical and sonochemical effects, was proposed. The findings of the present study can provide strong support to the fundamental understanding and applications of ARHCRs for water disinfection.

Anolyte solution produced by membrane electrolysis of NaCl solution contains a high level of available chlorine content (ACC) and other oxidizing compounds, rendering this solution a strong disinfectant property. In this paper, some process parameters affecting the anolyte production efficiency, such as total inlet flow (240–320 L/h), saline solution concentration (1.65–3.50 g/L), and the type of membrane (cation exchange, anion exchange, and bipolar membranes) were investigated in an electrolysis cell. Changes in the quality of anolytes produced at three initial concentrations of very high (ACC1 = 816.5 mg/L), relatively high (ACC2 = 461.5 mg/L), and medium (ACC3 = 355.0 mg/L) during storage (from the production up to 20 weeks) were examined by adjusting the total inlet flow, saline concentrations, and membrane types. Changes in the ACC of the produced anolyte solution were generally affected by the type of membrane used in the electrolysis cell. The use of anion exchange membrane resulted in the lowest durability of anolyte quality (60–80% ACC reduction after 4 weeks of storage) and the cation exchange membrane had the highest durability (less than 40% decrease after 4 weeks of storage). In addition, changes in the pH and the oxidation–reduction potential of the anolyte were investigated during the storage period, which had a different trend depending on the type of applied membrane.

In this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial disinfection of lake water contaminated with Escherichia coli (E. coli). Characterization indicated the formation of a face-centered cubic structure of metallic silver nanoparticles with no insertion of Ag into the ZnO hexagonal wurtzite structure. Physicochemical and bacteriological analyses described in “Standard Methods for the Examination of Water and Wastewater” were used to evaluate the efficiency of the treatment. In comparison to pure ZnO, the synthesized Ag/ZnO nanoparticles showed high efficiencies against Escherichia coli (E. coli) and general coliforms present in the lake water. These pathogens were absent after treatment using Ag/ZnO nanoparticles. The results indicate that Ag/ZnO nanoparticles synthesized via green chemistry are a promising candidate for the treatment of wastewaters contaminated by bacteria, due to their facile preparation, low-cost synthesis, and disinfection efficiency.

Supply of clean drinking water is still a major problem in most developing countries especially in rural areas. Although many water purification methods exist, they are far beyond the reach of common people because of unaffordable cost or lack of technical how-how for operation. A new simple and cost-effective method for purification of river water for use by rural communities has been developed and tested. It involves use of moringa seed powder as a natural coagulant and flocculent to clarify turbid water and copper as an antibacterial agent to destroy pathogens like E. coli to produce clean drinking water. Raw water samples from nearby rivers were collected in glass beakers and moringa seed powder was prepared from locally obtained seeds. Seed powder was mixed with water and copper wire mesh was immersed in it. After about 4 h the supernatant was decanted through a closely woven cotton cloth and tested for turbidity and E. coli counts. Turbidity level was in the range 3 NTU–5 NTU and E. coli count was Non- Detected (N.D) in all treated samples, which were within the accepted levels for drinking water. The technique is reproducible, cost effective and capable of producing clean drinking water for domestic use, without any power source or technical assistance. It can be practiced with little effort in rural community households. Being a Point–of–Use (PoU) method, it is exceptionally useful in providing drinking water as an immediate solution in disaster areas affected by cyclone or floods.

Abstract Waterborne viruses frequently cause disease outbreaks and existing strategies to remove such viral pathogens often involve harsh or energy‐consuming water treatment processes. Here, a simple, efficient, and environmentally friendly approach is reported to achieve highly selective disinfection of specific viruses with living engineered biofilm materials. As a proof‐of‐concept, Escherichia coli biofilm matrix protein CsgA was initially genetically fused with the influenza‐virus‐binding peptide (C5). The resultant engineered living biofilms could correspondingly capture virus particles directly from aqueous solutions, disinfecting samples to a level below the limit‐of‐detection for a qPCR‐based detection assay. By exploiting the surface‐adherence properties of biofilms, it is further shown that polypropylene filler materials colonized by the CsgA‐C5 biofilms can be utilized to disinfect river water samples with influenza titers as high as 1 × 107 PFU L−1. Additionally, a suicide gene circuit is designed and applied in the engineered strain that strictly limits the growth of bacterial, therefore providing a viable route to reduce potential risks confronted with the use of genetically modified organisms. The study thus illustrates that engineered biofilms can be harvested for the disinfection of pathogens from environmental water samples in a controlled manner and highlights the unique biology‐only properties of living substances for material applications.

Natural water distillation can destroy and/or inactivate microorganisms that are sensitive to heat and ultraviolet radiation (UV). This method is currently used to provide fresh water in ships and in the desalination of brackish water. For the development of this research, a pilot-scale solar still was built and installed in the southern region of Brazil, in order to assess its efficiency in water disinfection, which was based on the most probable number (MPN) of total coliforms and Escherichia coli, in addition to the DNA copy number of human adenovirus type 5 (HAdV-5) in raw, undistilled samples and in treated distilled water. Results showed that the distillation process removed 100% of total coliform and Escherichia coli and 4.5 log (99.997%) of HAdV-5, which meets the microbiological standards for drinking water according to national Brazilian regulations, as well as USEPA and HEALTH CANADA requirements.

Abstract Background and aims: Drinking water pollution is a serious threat for public water supply. Water disinfection has a very important role in the reduction of pathogenic microorganism. Water electrodisinfection is an efficient and cost-effective method in water disinfection. The aim of this study was the survey of inactivation in two types bacteria (as index and resistant) by electrochemical process in the presence of supporting electrolytes. Materials and methods:Inactivation of E.Coli and Bacillus subtilis spore was studied at current intensity of 500mA, with each of the supporting electrolytes including CuI, NaBr and KCl. The type of electrodes was steel and the distance between electrodes was 2cm. Furthermore, the tests carried out in monopolar mode Fe-Fe, neutral pH and experimental temperature (21o c). The number of bacteria, amount of supporting electrolyte, voltage, and electrochemical action time were investigated. Results:Adding the supporting electrolytes to the electrochemical disinfection process decreased bacterial resistan Copper iodide (CuI) on 2 mg/l concentration showed more efficiency in bacterial inactivation. Conclusion:Supporting electrolyte CuI with concentration of 2 mg/l both enhances the electrochemical process performance due to an increase in ionic transmission rate and voltage current. Also, this decreases electrochemical inactivation time and increases bactericidal effect.

PVP (polyvinylpyrrolidone)-doped SnO2/TiO2 composite thin films and undoped films were prepared by sol-gel and dip-coating methods. The calcined films at 600 oC for 2 h were characterized by scanning electron microscopy, X-ray defractometer, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. Furthermore, the photocatalytic reaction on the degradation of methylene blue dye solution was also investigated in order to observe the correlation between the results of bacteria inactivation of the prepared films and that of photocatalytic activity on methylene blue degradation. The PVP-doped SnO2/TiO2 composite thin films and undoped films were preliminarily studied against gram negative Escherichia coli and gram positive Staphylococcus aureus bacteria. It revealed that PVP-doped SnO2/TiO2 composite films resulted in shifting the absorption wavelength towards narrowing the energy band gap, high crystallinity of anatase phase, and small crystallite size. Therefore, the 40PVP/SnO2/TiO2 composite thin film exhibited greater photocatalytic activity and water disinfection efficiency than those of undoped films.

The world faces a growing challenge for adequate clean water due to threats coming from increasing demand and decreasing supply. Although there are existing technologies for water disinfection, their limitations, particularly the formation of disinfection-by-products, have led to researches on alternative methods. Zinc oxide, an essential chemical in the rubber and pharmaceutical industries, has attracted interest as antimicrobial agent. In nanoscale, zinc oxide has shown antimicrobial properties which make its potential great for various applications. This review discusses the synthesis of zinc oxide with focus on precipitation method, its antimicrobial property and the factors affecting it, disinfection mechanisms, and the potential application to water disinfection.

A bifunctional magnetic Fe3O4@SiO2@TiO2 or MS-TiO2 antimicrobial nanocomposite was prepared based on simple sol-gel methods with common equipment and chemicals. Reaction pH was found to influence the TiO2 upload in the nanocomposite. The alkaline condition produced the greatest TiO2 upload, while the acidic condition the least. Annealing at 300 °C turned the as-synthesized amorphous TiO2 into one with high content of anatase, the most photoactive form of TiO2. Irradiated by 365 nm UV light, a sample of 30 mg/mL of annealed nanocomposite containing 12.6 wt.% Ti was shown to be able to completely eradicate 104 CFU/mL of the laboratory-grown E. coli within 25 min, 25 min faster than the control when the 365 nm UV light was employed alone. The nanocomposite demonstrated consistent antimicrobial performance over repeated uses and was easily recoverable magnetically due to its high magnetization value (33 emu/g). Additionally, it was shown to reduce the bacterial count in a real surface water sample containing 500–5000 CFU/mL of different microbes by 62 ± 3% within 30 min. The irradiating 365 nm UV light alone was found to have generated little biocidal effect on this surface water sample. The nanocomposite is promising to serve as an effective, safe, and eco-friendly antimicrobial agent, especially for surface water disinfection.

Computational fluid dynamics (CFD) analyses for the performance improvement of a closed-conduit ultraviolet (UV) reactor were performed by changing the lamp positions from symmetric to asymmetric. The asymmetric lamp positioning can be useful for UV reactor design and optimization. This goal was achieved by incorporating the two performance factors, namely reduction equivalent dose (RED) and system dose performance. Four cases were carried out for asymmetric lamp positioning within the UV reactor chamber and each case consisted of four UV lamps that were simulated once symmetrically and four times asymmetrically. The results of the four asymmetric cases were compared with the symmetric one. Moreover, these results were evaluated by using CFD simulations of a closed-conduit UV reactor. The fluence rate model, UVCalc3D was employed to validate the simulations results. The simulation results provide detailed information about the dose distribution, pathogen track modeling and RED. The RED value was increased by approximately 15% by using UVCalc3D fluence rate model. Additionally, the asymmetric lamp positioning of the UV lamps had more than 50% of the pathogens received a better and a higher UV dose than in the symmetric case. Consequently, the system dose performance was improved by asymmetric lamp positioning. It was concluded that the performance parameters (higher RED and system dose performance) were improved by using asymmetric lamp positioning.

Various reactive oxygen and nitrogen species are accompanied by electrons, ultra-violet (UV) radiation, ions, photons, and electric fields in non-thermal atmospheric pressure plasma. Plasma technology is already used in diverse fields, such as biomedicine, dentistry, agriculture, ozone generation, chemical synthesis, surface treatment, and coating. Non-thermal atmospheric pressure plasma is also considered a promising technology in environmental pollution control. The degradation of organic and inorganic pollutants will be massively advanced by plasma-generated reactive species. Various investigations on the use of non-thermal atmospheric pressure plasma technology for organic wastewater purification have already been performed, and advancements are continuing to be made in this area. This work provides a critical review of the ongoing improvements related to the use of non-thermal plasma in wastewater control and outlines the operational principle, standards, parameters, and boundaries with a special focus on the degradation of organic compounds in wastewater treatment.

A photocatalytic system for decolorization of double azo reactive black 5 (RB5) dye and water disinfection of E. coli was developed. Sol gel method was employed for the synthesis of Fe-TiO2 photocatalysts and were characterized using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and Brunauer–Emmett–Teller (BET) analysis. Results showed that photocatalytic efficiency was greatly influenced by 0.1 weight percent iron loading and 300 °C calcination temperature. The optimized reaction parameters were found to be the ambient temperature, working solution pH 6.2 and 1 mg g−1 dose to completely decolorize RB5. The isotherm studies showed that RB5 adsorption by Fe-TiO2 followed the Langmuir isotherm with maximum adsorption capacity of 42.7 mg g−1 and Kads 0.0079 L mg−1. Under illumination, the modified photocatalytic material had higher decolorization efficiency as compared to unmodified photocatalyst. Kinetic studies of the modified material under visible light irradiation indicated the reaction followed the pseudo-first-order kinetics. The illumination reaction followed the Langmuir-Hinshelwood (L-H) model as the rate of dye decolorization increased with an incremental increase in dye concentration. The L-H constant Kc was 1.5542 mg L–1∙h–1 while Kads was found 0.1317 L mg–1. The best photocatalyst showed prominent percent reduction of E. coli in 120 min. Finally, 0.1Fe-TiO2-300 could be an efficient photocatalyst and can provide a composite solution for RB5 decolorization and bacterial strain inhibition.

Abstract Background In resource-limited settings where laboratory capacity is limited and response strategy is non-specific, delayed or inappropriate intervention against outbreaks of Norovirus (NoV) are common. Here we report interventions of two norovirus outbreaks, which highlight the importance of evidence-based modeling and assessment to identify infection sources and formulate effective response strategies. Methods Spatiotemporal scanning, mathematical and random walk modeling predicted the modes of transmission in the two incidents, which were supported by laboratory results and intervention outcomes. Results Simulation results indicated that contaminated water was 14 to 500 fold more infectious than infected individuals. Asymptomatic individuals were not effective transmitters. School closure for up to a week still could not contain the outbreak unless the duration was extended to 10 or more days. The total attack rates (TARs) for waterborne NoV outbreaks reported in China (n = 3, median = 4.37) were significantly (p

Textile dyes and microbial contamination of surface water bodies have been recognized as emerging quality concerns around the globe. The simultaneous resolve of such impurities can pave the route for an amicable technological solution. This study reports the photocatalytic performance and the biocidal potential of nitrogen-doped TiO2 against reactive black 5 (RB5), a double azo dye and E. coli. Molecular docking was performed to identify and quantify the interactions of the TiO2 with β-lactamase enzyme and to predict the biocidal mechanism. The sol-gel technique was employed for the synthesis of different mol% nitrogen-doped TiO2. The synthesized photocatalysts were characterized using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) and diffuse reflectance spectroscopy (DRS). The effects of different synthesis and reaction parameters were studied. RB5 dye degradation was monitored by tracking shifts in the absorption spectrum and percent chemical oxygen demand (COD) removal. The best nanomaterial depicted 5.57 nm crystallite size, 49.54 m2 g−1 specific surface area, 11–40 nm particle size with spherical morphologies, and uniform distribution. The RB5 decolorization data fits well with the pseudo-first-order kinetic model, and the maximum monolayer coverage capacity for the Langmuir adsorption model was found to be 40 mg g−1 with Kads of 0.113 mg−1. The LH model yielded a higher coefficient KC (1.15 mg L−1 h−1) compared to the adsorption constant KLH (0.3084 L mg−1). 90% COD removal was achieved in 60 min of irradiation, confirmed by the disappearance of spectral peaks. The best-optimized photocatalysts showed a noticeable biocidal potential against human pathogenic strain E. coli in 150 min. The biocidal mechanism of best-optimized photocatalyst was predicted by molecular docking simulation against E. coli β-lactamase enzyme. The docking score (−7.6 kcal mol−1) and the binding interaction with the active site residues (Lys315, Thr316, and Glu272) of β-lactamase further confirmed that inhibition of β-lactamase could be a most probable mechanism of biocidal activity.

Today, there is an increasing interest in improving the physicochemical properties of polymeric membranes by merging the membranes with different inorganic materials. These so-called composite membranes have been implemented in different membrane-based technologies (e.g., microfiltration, ultrafiltration, nanofiltration, membrane bioreactors, among others) for water treatment and disinfection. This is because such inorganic materials (such as TiO2-, ZnO-, Ag-, and Cu-based nanoparticles, carbon-based materials, to mention just a few) can improve the separation performance of membranes and also some other properties, such as antifouling, mechanical, thermal, and physical and chemical stability. Moreover, such materials display specific biological activity towards viruses, bacteria, and protozoa, showing enhanced water disinfection properties. Therefore, the aim of this review is to collect the latest advances (in the last five years) in using composite membranes and new hybrid materials for water disinfection, paying particular emphasis on relevant results and new hydride composites together with their preparation protocols. Moreover, this review addresses the main mechanism of action of different conventional and novel inorganic materials toward biologically active matter.

Abstract A new method for creating nanopores in single‐layer molybdenum disulfide (MoS2) nanosheets (NSs) by the electrospray deposition of silver ions on a water suspension of the former is introduced. Electrospray‐deposited silver ions react with the MoS2 NSs at the liquid–air interface, resulting in Ag2S nanoparticles which enter the solution, leaving the NSs with holes of 3–5 nm diameter. Specific reaction with the S of MoS2 NSs leads to Mo‐rich edges. Such Mo‐rich defects are highly efficient for the generation of active oxygen species such as H2O2 under visible light which causes efficient disinfection of water. 105 times higher efficiency in disinfection for the holey MoS2 NSs in comparison to normal MoS2 NSs is shown. Experiments are performed with multiple bacterial strains and a virus strain, demonstrating the utility of the method for practical applications. A conceptual prototype is also presented.

Introduction & Purpose:Chlorine is the most important matter to water disinfection due to a residual effect. But by formation of by-products could be harmful to consumers’ health ,The researchers decided to use the method or other material. For this reason, in this study ozone used to water disinfection and its performance to disinfect of contaminated water with Escherichia coli was investigated. Methods: E. coli was utilized to contaminated water preparation. Culture and counting methods were performed according to the standard methods and recorded with CFU/ml. Normality of the data was analyzed by using Asmynrf-Kolmogrov test and T-test and ANOVA were used to statistical analysis, too. Results :Theresults showed that the destruction of E. coli increased by increasing of ozone concentration and decreasing of density. Removal of the concentration of 1 mg per liter, compared with a concentration of 5 mg per liter of ozone in the ozone density〖10〗^4و〖10〗^5 CFU / ml is significant(P_value0.05). Conclusion :Ozone due to its oxidizing effect on microorganisms is a good disinfectant properties. The results of this study, ozone can be highly contaminated with E. coli was significantly effective in disinfecting water.

In order to have drinking water, some countries have to use chlorine. It is use cause is effective and it’s cheap. An alternative to this process is the UV disinfection of drinking water. Most of the devices in the market use UV bulbs or mercury lamps. The UV LED, which is cheaper and smaller, allows creating new smaller devices. The main contribution of this paper is the use of Genetic Algorithms to help design a drinking water device with UV LEDs.

This paper investigated the application of advanced oxidative processes – Fenton’s reagent - in wastewater disinfection. The treatments included the variation of the hydrogen peroxide and ferrous ions concentrations (Fe2+/H2O2) and pH values. The sewage samples were collected at Ilha do Governador Wastewater Treatment Plant (ETIG) in Rio de Janeiro, Brazil, before the biological treatment with activated sludge. The average pH fluctuated from 6.5 to 7.2 and the most common value was 6.7. The reactions with the Fenton´s reagents, as well as the beginning of the analysis occurred within 24 hours after the sewage sample`s collection. The oxidative process, its behavior and the treatment effectiveness have been monitored by microorganism counting, COD, BOD, ammoniacal nitrogen and others. The results have shown a total elimination of the fecal coliforms in the wastewater samples when treated with H2O2 and Fe2+ in concentrations of 200 mg/L of 50 mg/L, respectively.