Natural Water Research Articles

Duplex Real-Time Fluorescent Quantitative PCR Assays for the Detection of Toxigenic Microcystis Genotypes Based on SNP/InDel Variation in mcy Gene Cluster.

In this study, the toxigenic characteristics of 14 strains of Microcystis were analyzed, and single nucleotide polymorphism (SNP) and insertion/deletion (InDel) loci in microcystinsynthetase (mcy)geneclusters were screened. Based on SNP and InDel loci associated with the toxigenic characteristics, primers andTaqMan or Cycling fluorescent probes were designed to develop duplex real-time fluorescent quantitative PCR (FQ-PCR) assays. After evaluating specificity and sensitivity, these assays were applied to detect the toxigenic Microcystis genotypes in a shrimp pond where Microcystis blooms occurred. The results showed a total of 2155 SNP loci and 66 InDel loci were obtained, of which 12 SNP loci and 5 InDel loci were associated with the toxigenic characteristics. Three duplex real-time FQ-PCR assays were developed, each of which could quantify two genotypes of toxigenic Microcystis. These FQ-PCR assays were highly specific, and two Cycling assays were more sensitive than TaqMan assay. In the shrimp pond, six genotypes of toxigenic Microcystis were detected using the developed FQ-PCR assays, indicating that above genotyping assays have the potential for quantitative analysis of the toxigenic Microcystis genotypes in natural water.

Effectiveness of balneotherapy in reducing pain, disability, and depression in patients with Fibromyalgia syndrome: a systematic review with meta-analysis.

Balneotherapy, using heated natural mineral waters at 36-38°C, presents a comprehensive treatment approach for Fibromyalgia Syndrome (FMS). This study aims to assess the effect of balneotherapy in reducing pain intensity, disability, and depression in patients with FMS. We want to assess this effect at just four time-points: immediately at the end of the therapy, and at 1, 3, and 6 months of follow-up. Following PRISMA guidelines, we conducted an aggregate data meta-analysis, registered in PROSPERO CRD42023478206, searching PubMed Medline, Science Direct, CINAHL Complete, Scopus, and Web of Science until August 2023 for relevant randomized controlled trials (RCTs) that assess the effect of balneotherapy on pain intensity, disability, and depression in FMS patients. Methodological quality was assessed using the Cochrane methodology, and the pooled effect was calculated using Cohen's standardized mean difference (SMD) and its 95% confidence interval (95% CI) in a random-effects model. Sixteen RCTs were included in the meta-analysis. Balneotherapy is effective in reducing pain intensity (SMD - 1.67; 95% CI -2.18 to -1.16), disability (SMD - 1.1; 95% CI -1.46 to -0.7), and depression (SMD - 0.51; 95% CI -0.93 to -0.9) at the end of the intervention. This effect was maintained at 1, 3, and 6 months for pain intensity and disability. Balneotherapy improves both pain intensity and disability in patients with FMS, providing evidence that its positive effects are sustained for up to 6 months of follow-up. Nevertheless, it is important to note that the improvement in depression varies across different temporal phases.

Study on the evolution of dissolved organic matter in the underground storage of mine water

ABSTRACT The water–rock interactions significantly affect the dissolution and release of dissolved organic matter (DOM) during the reinjection of mine water into the underground reservoir. In this study, the surface characteristics and chemical composition of the natural medium from the open-pit coal mine were characterized. The waste consists mainly of quartz-dominated sandstone (43.64%) and mudstone dominated by sanidine (76.36%). During the 35-day experiment, two protein-like, one humus-like, and one fulvic acid-like substances were identified by PARAFAC. It was observed that the type of aqueous medium significantly affected the variational trend of DOM. Compared to the artificial medium, the fluorescence intensity of waste materials in the waste dump increased significantly during the reinjection process. Therefore, a positive correlation was observed between the fraction of mudstone in the aqueous medium and the DOM composition, mainly due to the dissolution of polycyclic aromatic hydrocarbon substances from the mudstone. The results revealed that the natural water storage medium had a certain water storage feasibility when compared with the expensive artificial medium. However, the fraction of mudstone in the water storage medium should be controlled to minimize the release of organic matter into the environment.

Harnessing tidal energy efficiency: A comprehensive analysis of tandem flapping hydrofoils for maximizing power generation from low-level currents

Harnessing natural water currents for renewable energy generation holds significant promise. Flapping foil hydrokinetic turbines (FHTs), inspired by aquatic organisms' propulsion mechanisms, leverage undulating motion to extract energy from flowing water. This study investigates the impact of hydrofoil shape and mechanical parameters on oscillating tandem hydrofoil systems' performance for energy harvesting, focusing on Persian Gulf tidal currents. Computational Fluid Dynamics (CFD) in a 2D domain is employed for analysis. Parameters include hydrofoil profiles (IFS, NACA 0015, HSVA, and flat plate), damping coefficient, and initial pitch angle optimized for low-level currents around 1 m/s, derived from HYCOM data. Numerical simulations highlight the superior hydrodynamic efficiency of the IFS hydrofoil. Through RANS equations in unsteady conditions, an optimal configuration with a 75-degree initial angle and damping coefficient of 4 achieves a maximum power efficiency of approximately 66.77%. Efforts have been made to ensure data accuracy, including rounding reported efficiencies appropriately and conducting thorough uncertainty analyses.

A review on the enantioselective distribution and toxicity of chiral pesticides in aquatic environment.

Chiral pesticides account for about 40% of the total pesticides. In the process of using pesticides, it will inevitably flow into the surface water and even penetrate into the groundwater through surface runoff and other means, as a consequence, it affects the water environment. Although the enantiomers of chiral pesticides have the same physical and chemical properties, their distribution, ratio, metabolism, toxicity, etc. in the organism are often different, and sometimes even show completely opposite biological activities. In this article, the selective fate of different types of chiral pesticides such as organochlorine, organophosphorus, triazole, pyrethroid and other chiral pesticides in natural water bodies and sediments, acute toxicity to aquatic organisms, chronic toxicity and other aspects are summarized to further reflect the risks between the enantiomers of chiral pesticides to non-target organisms in the water environment. In this review, we hope to further explore its harm to human society through the study of the toxicity of chiral pesticide enantiomers, so as to provide data support and theoretical basis for the development and production of biochemical pesticides.

Investigations of nanomaterial-based membranes for efficient removal of contaminants from wastewater via membrane distillation: a critical review

The requirement for wastewater treatment is paramount in ensuring environmental sustainability and safeguarding public health. As industrialization and urbanization accelerate, the volume of wastewater generated continues to increase, containing a diverse range of pollutants and contaminants. Untreated wastewater poses serious threats to ecosystems, water bodies, and human communities, leading to pollution, waterborne diseases, and ecological imbalances. Effective wastewater treatment becomes essential to mitigate these adverse effects by removing or reducing pollutants before discharge into natural water sources. This process helps to preserve water quality, protect aquatic life, and maintain the overall health of ecosystems. Membrane distillation (MD) has emerged as a promising technology for wastewater treatment, offering an innovative approach to address the challenges associated with conventional treatment methods. In MD, a hydrophobic membrane serves as a selective barrier, allowing water vapor to pass through while preventing the passage of contaminants. This paper offers an extensive overview of the latest advancements in nanotechnology and membrane distillation applied in wastewater treatment. We will delve into different types of nanomaterials that have been used to enhance the properties of MD membranes, such as nanocomposites, nanoparticles, and nanofiber membranes. We also explore the mechanisms by which these nanomaterials improve the separation efficiency, anti-fouling properties, and durability of MD membranes. Additionally, we highlight the potential of hybrid membranes that combine different types of nanomaterials for further improving the performance of MD in wastewater treatment. We provide examples of recent studies that have investigated the use of hybrid membranes, including carbon nanotube-graphene oxide hybrid membranes, nanocomposite nanofiber membranes, and silver nanoparticle-embedded membranes. We also identify some areas for future research and development, such as the scale-up and commercialization of nanotechnology-based MD systems. In summary, this review paper highlights the potential of nanotechnology to enhance the performance of MD in wastewater treatment, leading to improved water quality and a cleaner environment.

Disparities in unintentional drowning fatalities in Texas, USA, 1999–2020

BackgroundDrowning is the third-leading cause of unintentional injury death worldwide. Although the USA as a whole bears a heavy burden, with approximately 4000 drowning fatalities annually, Texas stands out as...

Organic carbon, major and trace element release from and adsorption onto particulate suspended matter of the Ob River, western Siberia

Particulate suspended matter (PSM) of rivers is a significant factor for carbon, nutrient, and trace metal transfer from land to ocean. Towards better understanding the role that PSM exerts on major and trace elements in riverine systems, here we report the results of an experimental study which utilizes a two-fold approach to assess interaction between PSM and riverine solutes. First, we measured element leaching (via desorption and dissolution in distilled water, simulating snow melt) from PSM of the largest Siberian river, the Ob River. Second, we quantified the capacity of PSM to adsorb dissolved organic carbon (DOC), macro- and micronutrients and trace elements from organic-rich waters of the river floodplain. We documented sizable desorption of organic carbon, some major and trace metals, oxyanions and insoluble elements from PSM; the majority (>50 %) of elements were released over the first hour of reaction. In contrast, PSM of the Ob River was capable of removing 20 to 90 % of dissolved OC, nutrients (Si, P), and trace elements from the tributary and floodplain fen. Our experiments demonstrated preferential adsorption of aromatic compounds large molecular size colloids. Taken together, the adsorption of solutes by PSM can sizably decrease the concentration and modify the molecular size distribution, and therefore the potential bioavailability of major (DOC, P, Si) and trace micronutrients. Overall, the PSM of the Ob River exhibited high reactivity with respect to natural waters and was capable of modifying the elemental composition of the tributary and floodplain fen waters. This transfer of organic carbon and nutrients in the surface-adsorbed (particulate) form is especially important during spring flood and requires specific consideration in short-term biogeochemical cycles of elements in continental waters.

Enterobacter sp. HIT-SHJ4 isolated from wetland with carbon, nitrogen and sulfur co-metabolism and its implication for bioremediation

Both autotrophic and heterotrophic denitrification are known as important bioprocesses of microbe-mediated nitrogen cycle in natural ecosystems. Actually, mixotrophic denitrification co-driven by organic matter and reduced sulfur substances are also common, especially in hypoxic environments such as estuarine sediments. However, carbon, nitrogen and sulfur co-metabolism during mixotrophic denitrification in natural water ecosystems has rarely been reported in detail. Therefore, this study investigated the co-metabolism of carbon, nitrogen and sulfur using samples collected from four distinct natural water ecosystems. Results demonstrated that samples from various sources all exhibited the ability for co-metabolism of carbon, nitrogen and sulfur. Microbial community analysis showed that Pseudomonas and Paracoccus were dominant bacteria ranging from 65.6% to 75.5% in mixotrophic environment. Enterobacter sp. HIT-SHJ4, a mixotrophic denitrifying strain which owned the capacity for co-metabolism of carbon, nitrogen and sulfur, was isolated and reported here for the first time. The strain preferred methanol as its carbon source and demonstrated remarkable efficiency for removing sulfide and nitrate with below 100 mg/L sulfide. Under weak acid conditions (pH 6.5-7.0), it exhibited enhanced capability in converting sulfide to elemental sulfur. Its bioactivity was evident within a temperature from 25°C to 40°C and C/N ratios from 0.75 to 3. This study confirmed the widespread presence of microbial-mediated synergistic carbon, nitrogen and sulfur metabolism in natural aquatic ecosystems. HIT-SHJ4 emerges as a novel strain, shedding light on carbon, nitrogen and sulfur co-metabolism in natural water bodies. Furthermore, it also serves as a promising candidate microorganism for in-situ ecological remediation, particularly in dealing with contamination posed by nitrate, sulfide, and organic matter.

Ionic Composition of Different Types of Natural Water Sources in the River Basins of the Crimean Mountains

Ionic Composition of Different Types of Natural Water Sources in the River Basins of the Crimean Mountains

Epidemiological characteristics of fatal drowning and related factors in children in Zhejiang Province, 2022

Objective: To understand the epidemiological characteristics of fatal drowning in children in Zhejiang Province in 2022, analyze factors such as the swimming ability of children, the caregiver behavior at drowning site, types of first aid personnel and methods of first aid of unintentional fatal drowning and provide evidence for targeted intervention. Methods: Using the "Survey Form of Fatal Drowning Case in Children" designed by National Center for Chronic and Non-communicable Disease Control and Prevention of the China CDC, we collected case information of children aged 0-17 years who died due to drowning in Zhejiang in 2022 from medical history/death investigation records, telephone interviews, and home visits. Results: A total of 341 fatal drowning cases in children occurred in Zhejiang in 2022 and 330 cases were investigated (96.77%). The male to female of the cases was 2.33∶1, most cases were aged 15-17 years and 0-4 years, and 54.24% of fatal drowning cases occurred in children from other provinces. In the drowning cases, 83.33% were unintentional ones, and the proportion of intentional fatal drowning cases in children increased with age. Fatal drowning cases mainly occurred in open natural water bodies and public water storage facilities. More fatal drowning cases occurred in open natural water bodies in older children, while more fatal drowning cases occurred in public water storage facilities in younger children. In 275 children who died due to unintentional drowning, 73.09% could not swim, and only 1.09% were fully supervised by adults within an arm's length. First aid personnel, mainly medical staffs, bystanders and adult caregivers, were present for 47.63% fatal drowning cases. The proportion of the cases who had cardiopulmonary resuscitation as the first aid within 5 minutes was 2.18%. Conclusions: Drowning poses a serious threat to children's lives and there are differences in reasons and locations of fatal drowning in children in different age groups in Zhejiang Province in 2022. It is necessary to conduct to interventions to improve children's swimming skills, strengthen effective adult care and conduct health education about field first aid of drowning to reduce the incidence of drowning and related deaths in children.

Surface Microstructure Drives Biofilm Formation and Biofouling of Graphene Oxide Membranes in Practical Water Treatment.

Significant progress has been made previously in the research and development of graphene oxide (GO) membranes for water purification, but their biofouling behavior remains poorly understood. In this study, we investigated the biofilm formation and biofouling of GO membranes with different surface microstructures in the context of filtering natural surface water and for an extended operation period (110 days). The results showed that the relatively hydrophilic and smooth Fe(OH)3/GO membrane shaped a thin and spatially heterogeneous biofilm with high stable flux. However, the ability to simultaneously mitigate biofilm formation and reduce biofouling was not observed in the weakly hydrophilic and wrinkled Fe/GO and H-Fe(OH)3/GO membranes. Microbial analyses revealed that the hydrophilicity and roughness distinguished the bacterial communities and metabolic functions. The organic matter-degrading and predatory bacteria were more adapted to hydrophilic and smooth GO surfaces. These functional taxa were involved in the degradation of extracellular polymeric substances (EPS), and improved biofilm heterogeneity. In contrast, the weakly hydrophilic and wrinkled GO surfaces had reduced biodiversity, while unexpectedly boosting the proliferation of EPS-secreting bacteria, resulting in increased biofilm formation and aggravated biofouling. Moreover, all GO membranes achieved sustainable water purification during the entire operating period.

Effective Removal of Pb(II) from Multiple Cationic Heavy Metals—An Inexpensive Lignin-Modified Attapulgite

To develop cost-effective heavy metal adsorbents, we employed water-soluble lignin from black liquor to modify activated attapulgite, resulting in the creation of a novel adsorbent called Lignin-modified attapulgite (LATP). In this study, scanning electron microscopy and Fourier transform infrared spectrometer techniques were utilized to characterize the structural details of LATP. The results revealed that lignin occupies the micropores of attapulgite, while additional functional groups are present on the attapulgite surface. We conducted adsorption tests using LATP to remove five types of heavy metal ions (Cd2+, Pb2+, Zn2+, Mn2+, Cu2+), and it was found that LATP exhibited greater removal mass and binding strength for Pb(II) compared to the other ions. For further investigation, batch experiments were performed to evaluate the adsorptive kinetics, isotherms, and thermodynamics of Pb2+ removal from aqueous solutions using LATP. The results indicated that the adsorption capacity of Pb(II) on LATP decreased with decreasing pH, while the presence of Na+ had no effect on adsorption. The adsorption process reached equilibrium rapidly, and the Langmuir adsorption capacities increased with temperature, measuring 286.40 mg/g, 315.51 mg/g, and 349.70 mg/g at 298 K, 308 K, and 318 K, respectively. Thermodynamic analysis revealed positive values for ΔH0 and ΔS0, indicating an endothermic and spontaneous adsorption process. Furthermore, ΔG0 exhibited negative values, confirming the spontaneous nature of the adsorption. Consequently, LATP demonstrates great potential as an effective adsorbent for the removal of Pb(II). Therefore, LATP shows great potential as an effective adsorbent for the removal of Pb(II) from natural water environments, contributing to the sustainable development of man and nature.

Effective Removal of Pb(II) from Multiple Cationic Heavy Metals—An Inexpensive Lignin-Modified Attapulgite

To develop cost-effective heavy metal adsorbents, we employed water-soluble lignin from black liquor to modify activated attapulgite, resulting in the creation of a novel adsorbent called Lignin-modified attapulgite (LATP). In this study, scanning electron microscopy and Fourier transform infrared spectrometer techniques were utilized to characterize the structural details of LATP. The results revealed that lignin occupies the micropores of attapulgite, while additional functional groups are present on the attapulgite surface. We conducted adsorption tests using LATP to remove five types of heavy metal ions (Cd2+, Pb2+, Zn2+, Mn2+, Cu2+), and it was found that LATP exhibited greater removal mass and binding strength for Pb(II) compared to the other ions. For further investigation, batch experiments were performed to evaluate the adsorptive kinetics, isotherms, and thermodynamics of Pb2+ removal from aqueous solutions using LATP. The results indicated that the adsorption capacity of Pb(II) on LATP decreased with decreasing pH, while the presence of Na+ had no effect on adsorption. The adsorption process reached equilibrium rapidly, and the Langmuir adsorption capacities increased with temperature, measuring 286.40 mg/g, 315.51 mg/g, and 349.70 mg/g at 298 K, 308 K, and 318 K, respectively. Thermodynamic analysis revealed positive values for ΔH0 and ΔS0, indicating an endothermic and spontaneous adsorption process. Furthermore, ΔG0 exhibited negative values, confirming the spontaneous nature of the adsorption. Consequently, LATP demonstrates great potential as an effective adsorbent for the removal of Pb(II). Therefore, LATP shows great potential as an effective adsorbent for the removal of Pb(II) from natural water environments, contributing to the sustainable development of man and nature.

Exploring fine-scale urban landscapes using satellite data to predict the distribution of Aedes mosquito breeding sites

BackgroundThe spread of mosquito-transmitted diseases such as dengue is a major public health issue worldwide. The Aedes aegypti mosquito, a primary vector for dengue, thrives in urban environments and breeds mainly in artificial or natural water containers. While the relationship between urban landscapes and potential breeding sites remains poorly understood, such a knowledge could help mitigate the risks associated with these diseases. This study aimed to analyze the relationships between urban landscape characteristics and potential breeding site abundance and type in cities of French Guiana (South America), and to evaluate the potential of such variables to be used in predictive models.MethodsWe use Multifactorial Analysis to explore the relationship between urban landscape characteristics derived from very high resolution satellite imagery, and potential breeding sites recorded from in-situ surveys. We then applied Random Forest models with different sets of urban variables to predict the number of potential breeding sites where entomological data are not available.ResultsLandscape analyses applied to satellite images showed that urban types can be clearly identified using texture indices. The Multiple Factor Analysis helped identify variables related to the distribution of potential breeding sites, such as buildings class area, landscape shape index, building number, and the first component of texture indices. Models predicting the number of potential breeding sites using the entire dataset provided an R² of 0.90, possibly influenced by overfitting, but allowing the prediction over all the study sites. Predictions of potential breeding sites varied highly depending on their type, with better results on breeding sites types commonly found in urban landscapes, such as containers of less than 200 L, large volumes and barrels. The study also outlined the limitation offered by the entomological data, whose sampling was not specifically designed for this study. Model outputs could be used as input to a mosquito dynamics model when no accurate field data are available.ConclusionThis study offers a first use of routinely collected data on potential breeding sites in a research study. It highlights the potential benefits of including satellite-based characterizations of the urban environment to improve vector control strategies.

Photochemical fate of nonionic polyacrylamide induced by hydroxyl radicals in the natural water: Mineralization mechanism exploration and half-life time evaluation

Water-soluble polyacrylamide (PAM) compounds have been used extensively in various sectors. The abundance of PAM in the environment raises concerns about its environmental impact. However, the mineralization of PAM in water under natural light irradiation remains insufficiently explored. This study utilizes nonionic PAM (nPAM) as a representative model to investigate both the mechanism and efficiency of nPAM degradation in water when exposed to ultraviolet (UV) light with hydrogen peroxide (H2O2) as the hydroxyl radical source. In the dark or with only UVA irradiation, negligible mineralization of nPAM occurred. In contrast, the presence of hydroxyl radicals (produced by the UVA/H2O2 system) produced 50 % nPAM mineralization over 7 days under our experimental conditions. The corresponding molecular weight (MW) of the nPAM was swiftly reduced from 1.58 ×106 Da to 1.59 ×103 Da in 3 days. Moreover, five carboxylic acids and nitrate ions were identified as the photodegradation intermediates of nPAM. The efficiencies of nPAM photodegradation by the UVA/H2O2 system in different natural waters and environmental conditions were assessed. The rate constant for the reaction between the hydroxyl radical and nPAM was 2.17 ×109 M-unit−1 s−1. The half-lives of nPAM in the sea and continental surface waters were determined to be several years and dozens of days, respectively. The application of UVB obviously accelerated the mineralization of nPAM in ultrapure water (71 % degradation in 7 days). Moreover, mineralization of concentrated nPAM (200 mg/L) in sea water was more efficient when both UVA- and UVB-activated H2O2 were used. Additionally, toxic acrylamide was not generated during nPAM photodegradation. Moreover, the photodegradation intermediates from nPAM were found to be neither acutely nor chronically toxic to aquatic organisms. This comprehensive study sheds light on the photochemical fate of nPAM in natural waters and provides essential insight for practical treatment of PAM in water systems.

Three novel Enterobacter cloacae bacteriophages for therapeutic use from Ghanaian natural waters

Infections caused by multidrug-resistant (MDR) bacteria are a growing global concern. Enterobacter cloacae complex (ECC) species are particularly adept at developing antibiotic resistance. Phage therapy is proposed as an alternative treatment for pathogens that no longer respond to antibiotics. Unfortunately, ECC phages are understudied when compared to phages of many other bacterial species. In this Ghanaian-Finnish study, we isolated two ECC strains from ready-to-eat food samples and three novel phages from natural waters against these strains. We sequenced the genomic DNA of the novel Enterobacter phages, fGh-Ecl01, fGh-Ecl02, and fGh-Ecl04, and assessed their therapeutic potential. All of the phages were found to be lytic, easy to propagate, and lacking any toxic, integrase, or antibiotic resistance genes and were thus considered suitable for therapy purposes. They all were found to be related to T4-type viruses: fGh-Ecl01 and fGh-Ecl04 to karamviruses and fGh-Ecl02 to agtreviruses. Testing of Finnish clinical ECC strains showed promising susceptibility to these novel phages. As many as 61.1% of the strains were susceptible to fGh-Ecl01 and fGh-Ecl04, and 7.4% were susceptible to fGh-Ecl02. Finally, we investigated the susceptibility of the newly isolated ECC strains to three antibiotics – meropenem, ciprofloxacin, and cefepime – in combination with the novel phages. The use of phages and antibiotics together had synergistic effects. When using an antibiotic-phage combination, even low concentrations of antibiotics fully inhibited the growth of bacteria.

ФОРМИРОВАНИЕ СИСТЕМЫ ЭКОЛОГИЧЕСКОЙ БЕЗОПАСНОСТИ ПРОЦЕССОВ ВОДОПОДГОТОВКИ И ОЧИСТКИ СТОЧНЫХ ВОД НА ОСНОВЕ ПРИНЦИПОВ РЕСУРСОСБЕРЕЖЕНИЯ И ПРИРОДОПОДОБИЯ

Environmental safety refers to the state of protection of the natural environment and humans by ensuring an acceptable level of negative impact of natural and anthropogenic environmental hazards on the environment and humans. Based on the principles of nature similarity, resource substitution and conservation, modules and components of environmental safety of drinking water treatment and wastewater treatment processes have been formed. The functions of each module of the aquatic safety ecosystem are disclosed. Dangerous events and hazard factors in the processes of water treatment and water treatment are presented. The content of the system components of environmental safety of water treatment and wastewater treatment processes has been established: sanitary and epidemiological safety, consumer safety, technical safety, environmental safety of production and environmental and economic safety. An algorithm for the environmentally sustainable functioning of water management facilities, long-term and trouble-free operation of water treatment equipment, preservation of the health of water consumers and minimizing the impact on reservoirs, natural water sources (underground and surface) is proposed.

Effect of Escherichia coli on the photocatalytic behavior of TiO2 nanoparticles for H2 evolution from water

Various microorganisms are present in natural waters, and understanding their impact on the photocatalytic behavior of photocatalysts is crucial, especially in large-scale hydrogen production. In line with this, we conducted a systematic investigation into the influence of Escherichia coli on the photocatalytic performance of TiO2 nanoparticles for H2 evolution. The findings revealed a significant reduction in the photocatalytic activity of TiO2 nanoparticles in the presence of Escherichia coli. Specifically, the H2 evolution rate was observed to be 57% lower (8.3 mmol g−1 h−1) compared to when Escherichia coli was absent (19.1 mmol g−1 h−1). The primary reason for this phenomenon appears to be the rupture of Escherichia coli cells during the photocatalytic process. As a result, intracellular proteins are released and subsequently adsorbed onto the surface of TiO2 nanoparticles, impeding the photocatalytic hydrogen evolution reaction. These results provide valuable insights that can inform the design of future photocatalytic hydrogen production processes.

Выбор сорбента для элиминации ионов железа из сточных и природных вод

Natural waters and wastewaters often contain heavy metals, e.g., iron. Iron ore mining contaminates groundwater with iron up to 30 maximal permissible concentrations (MPC) as this element gets washed out from rock and soil. Adsorption is the most effective and economically feasible method of additional purification of natural and wastewater from iron. Its efficiency depends on the type of adsorbent. The research objective was to select the most efficient sorption material to eliminate water from iron, as well as to establish the adsorption patterns for different sorbents, thus creating sustainable and effective purification. The study featured carbonaceous sorbent of the SKD-515 grade, mineral sorption materials with aluminosilicate of the AC grade, and silicate-based sorbent of the ODM-2F grade. The porous structure was studied by porometry methods while the surface image was obtained using scanning electron microscopy. Other indicators included equilibrium, kinetics, and dynamics of iron adsorption by various sorbents. The Freundlich and Langmuir equations made it possible to calculate the key adsorption parameters. The Gibbs energy values were obtained from the Langmuir equation and equaled 11.93–20.66 kJ/mol, which indicated the physical nature of the adsorption process. Under static conditions, the sorbents demonstrated a high adsorption capacity with respect to iron, depending on the structure, and could be arranged as AC > SKD-515 > ODM-2F. In SKD-515, iron adsorption occurred in micropores; in AC and ODM-2F, it took place in mesopores. The kinetics of iron extraction showed that the adsorption process was limited by external mass transfer. The research provided a new understanding of iron adsorption by materials of various structures. The conclusions were supported by scanning electron microscopy images. Initial concentration, flow velocity, and loading layer height were studied in dynamics, i.e., during continuous operation of the adsorption column. The system proved extremely effective and reached 99.0% Fe3+ extraction under the following conditions: flow rate = 1 L/min, loading column height = 0.15 m, column diameter = 0.05 m, initial concentration = 0.5 mg/L (5 MPC). The column performance was tested at an initial concentration of iron ions of 50 MPC, which simulated the wastewater treatment at industrial enterprises. This comprehensive study of iron adsorption from wastewater proved the efficiency of the mineral sorption materials with aluminosilicate of AC grade.