Water Purification Effect Research Articles

Strategic Optimization of PFC Coagulation for Saline Water Pre-treatment: Enhancing RO Filtration Efficiency in the Mekong Delta

Abstract This study critically evaluates the application of Poly Ferric Chloride (PFC) as a pre-treatment coagulant in desalination, particularly for enhancing Reverse Osmosis (RO) filtration in the saline-affected Mekong Delta region. The research focuses on the optimization of PFC dosages and pH levels to maximize coagulation efficiency in varying salinity conditions. Through an extensive series of experiments, an optimal coagulation efficiency of 93.7% for Total Suspended Solids (TSS) removal was achieved with a PFC dosage of 0.7 ml at a pH of 11 in a 5 ppt saline solution. However, increasing salinity levels were found to complicate this relationship, revealing a nuanced interplay between PFC dosage, pH, and salinity. A particularly critical observation was the decreasing effectiveness of PFC as salinity levels rose, indicating a need for escalating PFC dosages in higher saline waters to sustain coagulation effectiveness. The study significantly contributes to the understanding of PFC pre-treatment in water desalination processes, highlighting the compound’s role in improving the input quality for RO systems and extending membrane longevity. These findings are pivotal for designing adaptive water treatment strategies, ensuring the sustainability and effectiveness of water purification in salinity-vulnerable contexts.

Assessment of Water-Related Ecosystem Services and Beneficiaries in the Hainan Tropical Rainforest National Park

Tropical rainforests are of vital importance to the environment, as they contribute to weather patterns, biodiversity and even human wellbeing. Hence, in the face of tropical deforestation, it becomes exigent to quantify and assess the contribution of ecosystem services associated with tropical rainforests to the environment and especially to the people. This study adopted a nuanced approach, different from traditional economic valuations, to estimate the water-related ecosystem services (WRESs) received by the people from 2010 to 2020 in the Hainan Tropical Rainforest National Park (HTRNP). The study focused on water yield, soil conservation, and water purification using InVEST, the SCS-CNGIS model, and spatial analysis. The results show (1) significant land cover changes within the HTRNP, as forest decreased by 4433 ha and water bodies increased by 4047 ha, indicating the active presence of human activities. However, land cover changes were more pronounced within the 5 km buffer area around the HTRNP, suggesting the effectiveness of the tropical rainforest conservation efforts in place. (2) The water yield of the HTRNP in the years studied decreased by 307.03 km3, based on the water yields in 2010 and 2020, which were 5625.7 km3 and 5318.7 km3, respectively. (3) Change detection showed that runoff mitigation in the rainforest has a negative mean (−0.21), indicating a slight overall decrease in soil conservation and runoff mitigation in the rainforest from 2010 to 2020; however, the higher curve number indicates areas susceptible to surface runoff. (4) The ecological effectiveness of water purification to absorb and reduce nitrogen load was better in 2020 (145,529 kg/year), as it was reduced from 506,739 kg/year in 2010, indicating improved water quality. (5) Population growth is more pronounced in areas with high water yields. Overall, the proposed framework has shown that the water yield potential of the HTRNP can meet the water consumption demands of people and industries situated within the buffer area. However, analysis of the study shows that it does not meet the crop water requirements. This study provides insights for decision makers in identifying potential beneficiaries and the essence of effective area-based conservation measures, and the proposed framework can be applied to any area of interest, offering a different approach in ecosystem services assessment.

Preparation of polymeric aluminum chloride from secondary aluminum dross and its water purification effect

ABSTRACT Aluminum dross is solid waste generated by the aluminum industry. Currently, a large amount of aluminum dross is produced annually year. Aluminum dross, a hazardous waste, contains harmful substances such as aluminum metal, aluminum nitride, fluoride and chlorine salts, which pose a serious threat to human health and also cause damage to the ecological environment. Thus, it is important to recycle secondary aluminum dross and realise its high-value utilisation. Polymeric aluminum chloride (PAC) is a polymer flocculant, at present, China's annual use of PAC in the field of water treatment is about 5 × 105 t, and with the continuous improvement of water purification requirements, the annual use of PAC increased year by year. Here secondary aluminum dross was used as a raw material to prepare PAC by hydrochloric acid (HCl) leaching, followed by the addition of sodium carbonate. The optimal conditions for the acid leaching of secondary aluminum dross for the preparation of PAC were as follows: HCl concentration, 18%; liquid-to-solid ratio, 4.5:1; stirring rate, 200 r/min; reaction temperature, 90 °C; and 60 min. An aluminum leaching rate of 85.5% was obtained under these conditions. The results showed that the acid leachate after adding sodium carbonate, under the conditions of polymerisation temperature of 70 °C, polymerisation time of 6 h, and polymerisation pH value of 3.0, the PAC prepared had an alumina content of 10.19%, salinity of 32.37%, density of 1.32 g/cm3, 1% aqueous solution pH 4.3. The water purification effect of the prepared PAC surpassed that of the commercially available PAC. The utilisation of secondary aluminum dross can reduce the environmental pollution caused by aluminum slag.

Combined extraction of manganese during water purification of technogenic solutions

A method for demanganization of technogenic aqueous solutions is presented. This method involves electrocoagulation purification of aqueous systems from high metal contents and extraction of manganese (II) ions by carbon sorbent adsorption. A coagulation technology based on electrogenerated aluminum hydroxide was used. According to diffraction analysis, such a hydroxide exhibits an amorphous porous hydrogel structure with a developed sorbing surface. The micellar structure of the as-generated aluminum hydroxide, which was attributed to a modification of gibbsite, is represented by the following colloidal particle: {[m Al(OH)3] nAl(OH)2+ (n-x) OH-}x+ xOH-. The associative process of sorption on gibbsite occurs by dispersion interaction, which is governed by the force of electrostatic attraction of instantaneous and induced dipoles of electrically neutral sorbent molecules and the [Mn (OH2)2(OH)2]0 manganese hydroxo-aquo complex. The adsorption limiting value of manganese ions amounted to 4.9 mmol/g at 298 K and pH 5.8, with the adsorption equilibrium constant reaching 1.36 . 104. The electricity consumption corresponded to 12.0 А.h at an optimal electrocoagulation duration of 15 min and a current density of 1.6 мА/сm2. The final purification of aqueous solutions using carbon sorbents was conducted in a slightly alkaline medium at pH 7.5. The manganese sorption value reached 1.68 mmol/g. Therefore, the resource-saving effect of processing of technogenic hydro-mineral solution is manifested in a significant reduction of heavy metal salts and in obtaining of demanded mixed coagulants of aluminum and iron sulfates from water purification wastes. Another positive effect of electrochemical water purification consist in water disinfection and its improved ogranoleptic parameters.

Research on hydrogen sulfide removal from water using a hydroejector

The war in Ukraine has significantly impacted the country's water resources, leading to deteriorated water quality, threats to drinking water supplies, and long-term environmental issues. Intensive pollution of surface water sources has necessitated increased use of groundwater for drinking purposes. The quality of groundwater in Ukraine varies greatly, often containing concentrations of iron, manganese, hardness salts, and hydrogen sulfide that exceed acceptable limits. Hydrogen sulfide concentrations in different regions range from 1 to over 20 mg/dm³, far exceeding the permissible limit of 0.05 mg/dm³ for drinking water. In the southern regions of Ukraine, such as Kherson, Mykolaiv, and Odesa oblasts, hydrogen sulfide levels exceed the norm by more than 100 times. Existing water purification methods for hydrogen sulfide require the construction of expensive aeration facilities with various loadings, biological reactors, and oxidation filters, which entail significant capital and operational costs. Moreover, these facilities do not always ensure the desired water quality. Therefore, developing new methods and technologies aimed at intensifying hydrogen sulfide removal from water, along with various devices and structures for their implementation, is a pressing issue related to supplying the population with quality water. Among the developed approaches, the use of aeration as an independent method for purification is notable; however, it is used for low hydrogen sulfide concentrations and is most effective at low water pH levels. This article presents the results of experimental studies on the purification of groundwater from hydrogen sulfide by aeration using a hydroejector. Optimal parameters for the hydrogen sulfide removal process, depending on its concentration and water pH, were determined. The effectiveness of water purification using the hydroejector was substantiated and investigated. The key operational parameters of the hydroejector were established.

Research on the Ecological Restoration Effects of a Vallisneria natans (Lour.) Hara-Dominated Multitrophic Level Ecosystem

This study aims to assess the ecological restoration effects of Vallisneria natans in a multitrophic level ecosystem. The water-purification effects of two hierarchical configuration modes of V. natans-Bellamya aeruginosa and V. natans-B. aeruginosa-Hyriopsis cumingii were studied. Results show that a V. natans and B. aeruginosa configuration ratio of 15:2 stabilizes water quality at Grade IV (TN ≤ 1.5 mg/L, TP ≤ 0.3 mg/L), and increasing B. aeruginosa density significantly reduces total phosphorus. The V. natans, B. aeruginosa, and H. cumingii configuration at 15:2:10 stabilizes water at Grade III (TN ≤ 1.0 mg/L, TP ≤ 0.2 mg/L), with a positive correlation between H. cumingii density and chlorophyll-a removal. Furthermore, the filtration and biocycling actions of B. aeruginosa (snails) and H. cumingii (mussels) significantly reduce levels of Total Nitrogen (TN), Total Phosphorus (TP), and Ammonium (NH4+-N) in water, thus enhancing the self-purification capacity of the water bodies. However, the bioturbation effect of H. cumingii can temporarily increase phosphorus release from sediments, leading to a short-term rise in TP concentration in the water. Overall, the study concludes that multitrophic level ecosystems are effective in purifying water quality and offer significant ecological restoration benefits. This research provides crucial data support for future construction and ecological restoration projects involving multitrophic level approaches in China’s rivers and lakes.

Experimental study on mine water purification mechanism for broken coal and rock masses in the underground reservoir of ecologically vulnerable mining area.

Water-rock interaction mechanism and water purification capacity of broken coal and rock masses are very important for the efficient operation of the underground reservoir. In this paper, a water purification simulation device for an underground mine reservoir was designed. The experimental study on the dynamic interaction between broken coal and rock masses and mine water was carried out. The water purification mechanism is analyzed from the changes in rock mineral composition and mine water quality before and after the test. The results show that after the broken coal and rock mass purification, the water turbidity and the concentration of chlorides and suspended solids decreased obviously. The water purification capacities of mudstone and sandstone are stronger than that of coal samples. After 60days of reaction between the working face sewage and the broken samples (mudstone, sandstone, and coal), the turbidity, chromaticity, and residual chlorine decreased by > 90%, 90%, and 60%, respectively; and COD decreased by 35.29%, 30.59%, and 28.99%, respectively. While the TDS and the total hardness increased by about 40%, 30%, and 10% for the mudstone, sandstone, and coal, respectively. It shows that coal also has the worst degradation performance. The water purification effect of broken coal and rock masses has a significant time effect. The early stage of water-rock interaction is dominated by mineral dissolution, and the middle stage is dominated by precipitation and adsorption. The pH value of the solution has a certain influence on the ion change. In the later stage, the water-rock interaction is weak in a dynamic equilibrium state, and the change in the mine water quality index is not obvious. Considering the influence of rock lithology on water quality and the law of water-rock interaction time, the construction site selection and water storage time optimization of underground reservoirs in Jinjie Coal Mine were carried out, respectively.

Electrospinning preparation and characterization testing analysis of nanofiber biofilms

In order to obtain a fibrous biofilm carrier material with a good water purification effect, the biofilm carrier of PAN and PAN-PEO (mass ratio 9:1) was prepared by the electrospinning process, and the performance differences between the fabric biofilm carriers of PAN, PAN-PEO (mass ratio 9:1), and blank non-woven fabric, including the structure of biofilm carriers (surface morphology, specific surface area, and porosity), surface wettability (water contact angle and water absorbance) and membrane hanging ratio, were tested through various characterization methods. The experimental results show that the nanofiber membrane of PAN and PAN-PEO (mass ratio 9:1) prepared by the electrospinning process has a diameter of 75–375 nm, a specific surface area of 19.2 m2/g, and a porosity of 80%. The fiber diameter of non-woven fabric is in the micrometer range, with a specific surface area of 0.3659 m2/g and a porosity of 60%. This indicates that the nanofiber biofilm of PAN and PAN-PEO (mass ratio 9:1) prepared by electrospinning belongs to the carrier with a small diameter, high specific surface area, and high porosity, which can provide more attachment sites and pores for micro-organisms and is more conducive to their attachment in wastewater treatment. At the same time, the water contact angles of PAN and PAN-PEO (mass ratio 9:1) are 27.97° and 18°, respectively, and the water absorption of both reached 300%. The water contact angle of non-woven fabric is 93.32°, and the water absorption rate is only 75%. This shows that the nanofiber biofilms of PAN and PAN-PEO (mass ratio 9:1) prepared by electrospinning effectively improve the infiltration of the carrier in sewage. Finally, under the same conditions, bacterial growth and biofilm growth experiments were conducted on the nanofiber biofilm carriers of PAN and PAN-PEO (mass ratio 9:1) and the biofilm carriers of non-woven fabric. It was found that the effectiveness of the PAN and PAN-PEO (mass ratio 9:1) nanofiber biofilm carrier was significantly higher than that of non-woven fabric in treating wastewater. After 3 days of bacterial cultivation, the membrane hanging ratio of the PAN nanofiber biofilm carrier was 90.36%, the membrane hanging ratio of the PAN-PEO (mass ratio 9:1) nanofiber biofilm carrier was 82.04%, and the membrane hanging ratio of the non-woven fabric biofilm carrier was only 27.32%. After 15 days of bacterial cultivation, the membrane hanging ratio of the PAN nanofiber biofilm carrier was 147.52%, the membrane hanging ratio of the PAN-PEO (mass ratio 9:1) nanofiber biofilm carrier was 147.52%, and the membrane hanging ratio of the non-woven fabric biofilm carrier was 110.53%.

Study on seasonal floating treatment wetland combination water purification based on numerical simulation

The North Canal Basin, Tianjin, section in Wuqing urban area is subject to multi-source pollution from its surroundings and exhibits characteristics of a stagnant water body. As an urban landscape water body, there is immense pressure to improve its water environment and quality. During the 13th Five-Year Plan, China's “Major Special Project for Water Pollution Control and Treatment Technology” conducted research and demonstration of remediation technologies for this river section. Three water quality indexes, ammonia nitrogen (NH3-N), total phosphorus (TP), and chemical oxygen demand (COD) were improved to some extent. In this study, based on the experimental results of the water special project and the achievements of the two-dimensional hydrodynamic water quality model of this river section, nine different Floating Treatment Wetland (FTW) combination schemes were designed for the summer, autumn, and winter without changing the original ratio of FTW in the demonstration project. The scenario simulation results indicate that the optimal FTW combination schemes for the three seasons are A3, B1, and C2, respectively; the water purification effects of each optimal FTW combination scheme are superior to those of the original demonstration project, with the removal rate performance of the optimal scenario simulations for the three seasons being B1 > C2 > A3. Further single-factor evaluation of water quality under the nine FTW combination schemes reveals that each scheme significantly improves the water quality of North Canal Basin in different seasons, with the best removal effect achieved in autumn, reaching Class IV water quality, followed by winter and summer, both achieving Class V water quality. The results of this study can provide guidance for devising aquatic plant arrangements that meet water quality standards in different regions and offer a theoretical basis for the sustainable development of water quality purification in different seasons for northern rivers, taking the example of North Canal Basin.

Investigation of the catalytic effect of defective Ni-MOF-74 on polymerization of dopamine and multi-pore polydopamine photothermal coating constructed with defective Ni-MOF-74 particles

Photothermal coating is an effective way to convert the seawater into fresh water, which is controlled by the light utilization capacity and micro-channel for the vaporation of water. In order to improve the effect of water evaporation and water purification driven by sunlight, polydopamine (PDA) coating with more micro-channel and high bonding was formed through the introduction of porous material and 3-Aminopropyltriethoxysilane (AMEO). Compared with Ni-MOF-74, defective Ni-MOF-74 could produce more coordination with dopamine and promote the polymerization of dopamine, resulting in the formation of sea cucumber structure, which is foundation for the micro-channel of the deposition coating of PDA. Also, depending on the sea cucumber structure, the as-prepared coating of PES/PDA/MOF-30 mg by the two-solvent strategy possesses the water evaporation rate of 1.85 kg/(m2·h), the photothermal conversion efficiency of 98.4%, the retention rate of alkali metal and heavy metal ions above 99% and good long-term stability. The coating with good comprehensive property is good choice for the water purification.

Effect and Mechanism of Applying Myriophyllum Verticillatum for Reclaimed Water Purification in Urban Rivers

Reclaimed water produced via the advanced treatment of domestic wastewater has broad application prospects for reuse in urban rivers, while the nutrients in reclaimed water, especially nitrogen and phosphorus, lead to eutrophication or ecological impacts. Submerged plants are preferred as an enhanced technology used at reclaimed water recharge sites for both water quality improvement purposes and ecological conservation functions. In this study, which adopted the typical submerged plant Myriophyllum verticillatum (M. verticillatum) as its experimental object, experiments were carried out in an illumination incubator without a substrate and under hydrostatic conditions to investigate the water purification effects and mechanisms of action of M. verticillatum at different planting densities. The analysis showed that the group with a wet weight of 2.5 g L−1 had the best growth status and the best overall performance with respect to improvements in water quality indicators, including COD, nitrogen, and phosphorus, as well as demonstrating excellent uptake and synergistic effects in the process of removing nitrogen and phosphorus. The contributions of natural effects, the uptake and enrichment by M. verticillatum itself, and the synergistic effects during the nitrogen and phosphorus removal process were quantified. Furthermore, 16S rRNA gene sequencing was used to determine the surface-attached bacterial colonies of M. verticillatum, to analyze their population diversity, and to identify environmental functional genera. In conclusion, an appropriate density of M. verticillatum can improve water quality and provide a suitable environment for the survival and growth of relevant environmentally functional microorganisms, effectively removing nitrogen and phosphorus through its own absorption and synergistic effects.

Bibliometric analysis of global research on bioretention from 2007 to 2021.

Bioretention is a typical low impact development (LID) practice that helps reduce peak urban stormwater runoff and runoff pollutant concentrations (e.g., heavy metals, suspended solids, organic pollutants), which has become an important part of urban stormwater management over the past 15years. To understand the research hotspots and frontiers in the field of bioretention facility research and provide a reference for research into bioretention facilities, we conduct a statistical analysis of global bioretention literature published during 2007-2021 using the Web of Science core database and the data visualization and analysis software VOSviewer and HistCite. The number of published articles related to bioretention facilities shows a rising trend over the study period, with research from China contributing greatly to global research on bioretention facilities. However, the influence of articles needs to be increased. Recent studies mainly focus on the hydrologic effect and water purification effect of bioretention facilities and on the removal of nitrogen and phosphorus nutrients from runoff rainwater. Further studies should focus on the interaction of fillers, microorganisms, and plants in bioretention facilities and its impact on the migration, transformation, and concentrations of nitrogen and phosphorus; the purification effect and mechanism of specific emerging contaminants in runoff; the selection and configuration optimization of filler materials and plant species; and the optimization of the design parameters of the model for bioretention systems.

Surpassing 2D Photoabsorbers with Palm Fiber Upcycling as Highly Hydrophilic and Low-Cost Photothermal Materials for Improved Water Transport Interfacial Solar Steam Generation

Solar steam generation (SSG) has been proposed in the recent years as one of the countermeasures for solving the increasing risk of water scarcity on a global scale. SSG outshines conventional water treatment technologies with solar energy being its primary driving energy as well as its relatively simple system design. Nevertheless, challenges have been addressed for SSG, particularly the low efficiency of steam generation and dubious economic feasibility. In this study, a solar evaporator consisting of low-temperature carbonized oil palm fibers with integration of polydopamine is used to construct a biomass-based solar evaporator. Owing to the synergistic effect of the wide solar absorption spectrum of the carbonized fiber and highly hydrophilic characteristics of polydopamine, a water evaporation rate of 1.637 kg m–2 h–1 is achieved under 1 sun irradiation. To demonstrate the ability of the as-designed system for water treatment applications, actual lake water and seawater are employed as water reservoirs, and the water purification effect is assessed in terms of total dissolved solids and salinity. This biomass-derived evaporator offers a design rationale for cost-effective steam generation via biomass waste upcycling of the oil palm industry, which is advantageous for the scalable setup of the system in water-scarce, impoverished area.

New insights into the microalgal culture using kitchen waste: Enzyme pretreatment and mixed microalgae self-flocculation

With the development of the catering industry, the output of kitchen waste increases significantly. To respond to the carbon neutral policy, this study proposed the technology of combining kitchen waste treatment and microalgae culture. The kitchen waste was pretreated by enzymatic hydrolysis, and the optimal composition and proportion of compound enzymes were investigated. The results showed that acid protease: α-amylase: glucoamylase: cellulase = 50:1:10:1 (enzyme activity ratio) was chosen as the most suitable compound enzymes according to the growth and water purification effect of Scenedesmus obliquus in the hydrolysate. To optimize the microalgae biomass accumulation especially high-value substances, microalgae harvesting, and water purification effects, mixed culture of microalgae was performed. Chlorella sp. HQ and Scenedesmus sp. LX1 were the best combination, in which the contents of lipid, polysaccharide, and protein were 8.78 ± 4.48%, 2.11 ± 0.14%, and 8.38 ± 0.12%, respectively. After combination, the flocculation rate reached up to 63.75 ± 1.08%, and the removal rates of chemical oxygen demand, total nitrogen, and total phosphorus were 88.54 ± 0.58%, 90.97 ± 4.73%, and 88.81 ± 4.75%, respectively. The above results indicated that the enzymatic hydrolysate of kitchen waste had a promising application prospect in microalgae culture, and self-flocculation of mixed microalgae had the potential to recover biomass.

Stormwater quantity and quality control performance of bioretention systems: A literature review.

Bioretention systems, as one of the most widely used modern stormwater management tools, have outstanding performance in capturing runoff, mitigating peak flow, delaying outflow occur time, and improving effluent quality. We reviewed the research of hydrologic and water quality performance of bioretention systems around the world from different perspectives, including the structure and classification of bioretention systems, the mechanisms of runoff and pollutants regulation of bioretention systems, the hydrologic and water quality performances of bioretention systems, the runoff control and water purification evaluation models of bioretention systems, as well as the influencing factors of runoff control and water purification efficiency. We proposed that future research should focus on hydrologic and water quality of bioretention systems, e.g., optimization of design configurations, revealing the mechanisms of plant action, revealing the mechanisms of microbial action, the effects of climate change on hydrologic and water quality performance, watershed/regional scale hydrologic and water quality performance, purification effect and mechanisms of emerging pollutants, maintenance methods, as well as life-cycle assessment and cost analysis. This review would provide theoretical and technical supports for research, design, construction, and maintenance of bioretention systems.

Environmental aspects of the use of pressure filters for water purification of reservoirs in drinking water supply systems

The experience of designing and operating water treatment facilities for natural surface sources for the needs of populated areas and industrial enterprises in countries with developed industry allows us to conclude that it is advisable to purify water with a suspended solids content of up to 100-150 g/m3 using filtration methods. Therefore, the introduction into the practice of designing water treatment methods that ensure the use of compact, high-performance, automatically controlled structures acquires national economic importance. Filter stations equipped with pressure filters operating in the ultra-high-speed filtration mode meet these requirements to the greatest extent. The object of this study is a vertical pressure filter with an upward flow of purified water and a clamped filter layer. The applied research methods include the analysis of literature sources on the topic under study, experimental studies performed in a laboratory installation that fully simulates the technological scheme being developed, etc. The purpose of the study is to determine the effectiveness of the use of pressure filters with an upward flow and a clamped load for the purification of natural waters containing up to 100-120 g/m3 of suspended solids, and to develop recommendations for their use in the conditions of the Uzbekistan Republic. Laboratory tests of ultra-high-speed pressure filtration with an ascending flow have proved the high retention capacity of loading from local granular materials when filtering the purified water in the direction of decreasing grain size. Thus, the effect of water purification to remove suspended solids during the inter-washing period of the filter, which reached 10-18 hours, was stable and amounted to 87-97 percent.

Comparative Characteristics of Quality Parameters of Waters of the Oka River in Places of Water Intake of Utility and Drinking Water System in Ryazan

INTRODUCTION: Surface water sources play an important role in supply of large cities with water. Their waters are subject to anthropogenic pollution with different chemical compounds which may be significant risk factors for the health of the population. The article presents the results of comparative sanitary-hygienic characteristics of the water quality of the Oka river in places of water intake of utility and drinking water supply system of Ryazan. Being the only surface source of water supply, the Oka river provides 53% of the total water consumption of the Ryazan population, therefore a rational choice of the place of water intake can have a considerable impact on the effectiveness of water conditioning and purification and on the final quality of drinking water.
 AIM: To give a comparative sanitary-hygienic characteristic of the water quality of the Oka river in places of the water intake of the utility and drinking water supply system of Ryazan.
 MATERIALS AND METHODS: A comparative evaluation of the water quality of the Oka river, as a surface source of water supply, was carried out based on the average long-term values of control parameters (organoleptic, microbiological, chemical) and the proportion of samples that do not meet hygienic standards in the sections of three water intakes in Ryazan in 20122019. The average parameters were compared by the method of variance analysis; for paired comparisons, Scheffe and Tamhein criteria were used, taking into account the results of Levene test. The statistical parameters were calculated in SPSS Statistics 19 program.
 RESULTS: The chemical composition of the Oka river water was characterized by the greatest pollution with iron (2+) and aluminum. The water of Oksky and Borkovskoy water intakes was characterized by higher average concentrations of iron (2+) and ammonia, as well as greater contamination with generalized and thermotolerant coliform bacteria, compared with the water of Sokolovsky water intake.
 CONCLUSION: A lower initial quality of the water in Oksky and Borkovskoy water intakes may be due to their location in the 'blind' river course characterized by the processes of eutrophication and slowed down water exchange. High concentrations of iron (2+) may be associated with supply of stream water from the underground sources or with anthropogenic pollution.

The effect of underwater supplemental light on the growth of V.spinulosa Yan and the restoration process of water

Submerged plants are often used in the ecological restoration of polluted water, and they have good water purifying effect. In the process of water restoration, submerged plants are faced with insufficient light due to high turbidity or water depth. Therefore, we proposed a new model of artificial light assisted submerged plants to purify water nutrients. In this paper, we investigated the effects of locations and light intensities on the growth of V.spinulosa Yan and its water purification effect. The results showed that the light location of the underwater supplemental light was more important than the light intensity. The top supplemental light may provide an excellent environment for algae on the water surface. Excessive algae or epiphytic microorganisms might prevent the V.spinulosa Yan from obtaining light. When the PAR= 109 μmol m−2 s−1, V.spinulosa Yan had a higher biomass (145.39 dw/m2) than before (65.2 dw/m2). When the PAR > 280 μmol m−2 s−1, the clonal reproduction of V.spinulosa Yan was reduced. The main effect of supplemental underwater light on the water restoration process was enhancing the photosynthesis of V.spinulosa Yan by changing ETRmax and Fv/Fm of V.spinulosa Yan leaves. It significantly increased V.spinulosa Yan biomass and improved dissolved oxygen. Improvement of the water environment possibly altered the microbial environment and promoted the removal of water nutrients.

Electroactive constructed wetland using Fe3C as an anodic exogenous electron donor: Performance and mechanisms

Constructed wetland microbial fuel cells (CW-MFCs) are promising for removing trace contaminants. We investigated using Fe3C as an anodic exogenous electron donor in a CW-MFC to remove bisphenol A (BPA). BPA removal and electricity production were used to evaluate the CW-MFC performance, and bacterial high-throughput sequencing was used to investigate the microbial response. The experimental system removed BPA (91.62 ± 0.85 %), chemical oxygen demand (76.44 ± 2.25 %), total phosphorus (98.40 ± 0.17 %), and ammonium nitrogen (91.62 ± 0.85 %). It also had a high voltage (352.13 ± 31.48 mV) and power density (3.88 mW/m2), and relatively high coulombic efficiency (3.31 %). Fe3C addition enhanced bacterial cooperation and community stability, and increased the abundance of electroactive and ferric ammonium oxidation bacteria (Desulfovibrio and Geobacter). These changes explained the improved water purification effect and electricity production. Fe3C as an anodic electron donor in CW-MFCs is promising for practical applications.

Water Purification Effect of Ecological Floating Bed Combination Based on the Numerical Simulation

The Wuqing urban section of the North Canal Basin, Tianjin, is a significant gathering place for multisource pollution, showing the characteristics of a stagnant water body supplied by unconventional water sources. With the development of the economy and society, the water quality of the Wuqing urban section of the North Canal Basin, Tianjin, has been seriously polluted due to the discharge of sewage outlets and the influx of nonpoint source pollution from farmland. In this study, based on the results of special water experiments, a two-dimensional hydrodynamic water quality model was constructed. The concentrations of ammonia nitrogen (NH3-N), total phosphorus (TP), and chemical oxygen demand (COD) in the study area were simulated, and the model parameters were calibrated and verified with the measured values. Based on the model verification, the water quality improvement scheme of the ecological floating bed with different plant ratios was set up to simulate the water quality. The research results showed that the average concentrations of NH3-N, TP, and COD decreased by 10.4%, 15.7%, and of d 26.3%, respectively, after the ecological floating bed was arranged. During model parameter calibration and validation, the RMSE ranges of NH3-N, TP, and COD were 0.09~0.22 mg/L, 0.00~0.02 mg/L, and 0.37~2.42 mg/L, respectively. Other statistical indicators are also within a reasonable range, and the model accuracy and reliability are high. The simulation results of different scenarios showed that the optimal ratio of ecological floating bed plants was 700 m2 of Scirpus validus Vahl and 700 m2 of Canna in zone 1 of the floating bed combination, 430 m2 of Scirpus validus Vahl, and 170 m2 of Iris in zone 2 of the floating bed combination, and 200 m2 of Iris and 200 m2 of Lythrum salicaria in zone 3 of the floating bed combination. This study can provide a theoretical basis for the sustainable development of water purification in the North Canal. It can also provide a model approach for the implementation of river water purification schemes, exemplified by the North Canal.