Purification Of Contaminated Water Research Articles

Features of using ozone for cleaning marine pollution

The subject of the research is issues related to the field of ship power plants and their elements, as well as the operation of water transport and its environmental safety. Studying the processes of ballast water purification and disinfection, as well as oil-containing water that are formed during the ships operation, shows the possibility of increasing the efficiency of these processes. It is proposed to consider these processes, starting from the stage of supplying the ozone-air mixture to the flow of treated water, without limiting ourselves to the study of the actual process of oxidation by ozone of a contaminated, including bacteriologically hazardous, substance. This approach makes it possible to establish the limiting stages of the contaminated water purification and disinfection process, which includes the stage of ozone dissolution in water during its transition from the ozone-air mixture, as well as the stage of subsequent diffusion of ozone dissolved in water into the reaction contact zone. It has been shown that the kinetic characteristics of the limiting stages depend on the conditions of their implementation, which can reduce the efficiency of ozone use due to the limited time of its existence. A technological proposal that makes it possible to increase the efficiency of ozone use and the reliability of ensuring the requirements for the quality of cleaning and disinfection of marine pollution has been developed. Technological proposals provide for the preliminary saturation with ozone of a specially allocated water stream for this purpose, the supply of this stream to the concentration zone of the oxidized and disinfected substance. A device in which the developed technological fragment, including a pump supplying a water flow to a contact column, an ozone generator, a device for supplying an ozone-saturated water flow to a filter, is implemented is also proposed.

Detailed Insight into Photocatalytic Inactivation of Pathogenic Bacteria in the Presence of Visible-Light-Active Multicomponent Photocatalysts.

The use of heterogeneous photocatalysis in biologically contaminated water purification processes still requires the development of materials active in visible light, preferably in the form of thin films. Herein, we report nanotube structures made of TiO2/Ag2O/Au0, TiO2/Ag2O/PtOx, TiO2/Cu2O/Au0, and TiO2/Cu2O/PtOx obtained via one-step anodic oxidation of the titanium-based alloys (Ti94Ag5Au1, Ti94Cu5Pt1, Ti94Cu5Au1, and Ti94Ag5Pt1) possessing high visible light activity in the inactivation process of methicillin-susceptible S. aureus and other pathogenic bacteria-E. coli, Clostridium sp., and K. oxytoca. In the samples made from Ti-based alloys, metal/metal oxide nanoparticles were formed, which were located on the surface and inside the walls of the NTs. The obtained results showed that oxygen species produced at the surface of irradiated photocatalysts and the presence of copper and silver species in the photoactive layers both contributed to the inactivation of bacteria. Photocatalytic inactivation of E. coli, S. aureus, and Clostridium sp. was confirmed via TEM imaging of bacterium cell destruction and the detection of CO2 as a result of bacteria cell mineralization for the most active sample. These results suggest that the membrane ruptures as a result of the attack of active oxygen species, and then, both the membrane and the contents are mineralized to CO2.

Removal of the Pigment Congo Red from Synthetic Wastewater with a Novel and Inexpensive Adsorbent Generated from Powdered Foeniculum Vulgare Seeds

In this research, powdered Foeniculum vulgare seed (FVSP) was treated separately with H2C2O4, ZnCl2, and a mixture of ZnCl2-CuS. The characteristics of the treated and untreated FVSP samples, as well as their abilities to eliminate Congo red (CR) from solutions, were investigated. The influences of the empirical circumstances on CR adsorption by the ideal adsorbent were studied. The thermodynamic, isothermal, and dynamic constants of this adsorption were also inspected. The ideal adsorbent was found to be the FVSP sample treated with a ZnCl2-CuS mixture, which eliminated 96.80% of the CR dye. The empirical outcomes proved that this adsorption was significantly affected by the empirical circumstances, and the second-order dynamic model as well as the Langmuir isotherm model fit the empirical data better than the first-order model and the Freundlich model. The values of Ea (15.3 kJ/mol) and ∆Ho (32.767 kJ/mol ≤ ∆Ho ≤ 35.495 kJ/mol) evidence that CR anions were endothermally adsorbed on Zn/Cu-FVSP via the ionic exchange mechanism. The superior Qmax values (434.78, 625.00, 833.33 mg/g), along with the cheapness and stability of the adsorbent used in this work, are evidence to confirm that this adsorbent will receive special interest in the field of contaminated water purification.

Plasmonic silicon nanowires for enhanced heat localization and interfacial solar steam generation

Solar-thermal energy conversion for passive steam generation is attracting a lot of attention as a next-generation eco-friendly and sustainable technology. Tremendous effort has been devoted to produce efficient light-absorbing materials such as metal nanoparticles, semiconductors, MXene, and carbon-based materials. Among the various candidates, silicon (Si) is an excellent light-absorber that has been widely used in solar power generation. However, Si barely absorbs photons that have energy below its bandgap (1.12 eV), which occupies 20% of the entire solar spectrum. Here, we propose a metal-Si hybrid nanowire (NW) structure (plasmonic Si NWs) suitable for overcoming the low absorption limit of Si. The bundle-shaped Si NWs involving plasmonic nanostructures exhibits strong light absorption properties (Aavg > 91%) over the entire solar spectrum (300–2500 nm). The low thermal conductivity of Si NWs enhance heat localization by suppressing the heat dissipation to the surrounding. Owing to the unique optical and thermal properties of the plasmonic Si NW structure, excellent evaporation rates and efficiencies of 1.12 kg m-2h−1 and 72.8 %, respectively, were obtained under 1-sun illumination (1 kW m−2). Thus, the plasmonic Si NWs have the potential to be used in various fields such as solar photothermal desalination, contaminated water purification, and solar thermoelectric power generation.

Hollow SiO2 microspheres in-situ doped poly(ionicliquid)s gels as efficient solar steam generators for desalination

AbstractSolar steam generation (SSG) is one of the promising technologies for seawater desalination and contaminated water purification. However, SSG devices are always restricted by poor insulation performance, insufficient solar spectrum absorption and serious salt-fouling. Here, a double-layered novel SSG system was fabricated by using poly(ionicliquid)s gels with hollow SiO2 microspheres in-situ doping to enhance the thermal insulation of lower layer, and co-modified the top surface by polypyrrole (PPy) and silver particles to strengthen the solar absorption capability. Benefiting from the low thermal conductivity (0.082 W m−1 k−1), strong light absorption (ca. 96%) and adequate water transport capability of poly(ionic liquid)s gels. As SSG device, a superb photothermal conversion efficiency of 90.5% is achieved under 1 sun illumination. Moreover, the poly(ionic liquid)s gels based SSG system also shows good desalination performance in artificial sea water and high concentration brine, and the purified water from artificial seawater can achieve the WHO's standard for drinking water. Therefore, this work combined attractive in-situ doping and co-modified strategies for fabricating high performance and thus shows significant potential for real applications.

Facile synthesis of a novel AgIO3/BiVO4 photocatalyst with two-step charge separation to enhance visible-light-driven photocatalytic performance for carbamazepine degradation

• A novel visible-light-driven AgIO 3 /BiVO 4 photocatalyst was fabricated. • The two-step charges separation in AgIO 3 /BiVO 4 enhanced the photocatalytic activity. • The different crystal facets in decahedral BiVO 4 facilitated the charges spatial pre-separation. Rapid recombination of photo-generated electron-hole in photocatalyst limits the improvement in photocatalytic activity. A novel visible-light-driven AgIO 3 /BiVO 4 photocatalyst with two-step charge separation enhancing photocatalytic activity was fabricated. The composite with optimum molar ratio of 40% AgIO 3 to BiVO 4 has a narrow band gap of 2.28 eV, which is smaller than that of BiVO 4 (2.41 eV). The composite presented 99.38% degradation efficiency of rhodamine B in 40 min under visible light irradiation, which is higher than 1% and 9% degradation efficiencies by BiVO 4 and AgIO 3 , respectively. In addition, a 97.86% degradation efficiency of carbamazepine was achieved in 60 min. Thus, the significant enhancement of photocatalytic activity depended on the two-step charge separation in AgIO 3 /BiVO 4 . The first step was the spatial pre-separation among different crystal facets in decahedral BiVO 4 . Photo-generated electrons accumulated on {0 1 0} facets. Moreover, photo-generated holes on {1 1 0} facets facilitated the production of •OH radicals. The second separation was achieved by the type Ⅱ heterojunction structure of AgIO 3 /BiVO 4 . Photo-generated electrons in conduction band were transferred from BiVO 4 {0 1 0} facets to AgIO 3 , and holes in valence band accumulated on BiVO 4 {1 1 0} facets. This work provides an effective method to further decrease electron-hole recombination in photocatalysts and promote their environmental application in contaminated water purification.

Bilayer rGO-Based Photothermal Evaporator for Efficient Solar-Driven Water Purification[ ] *.

Interfacial evaporation has emerged as a promising approach to produce freshwater. However, an urgent concern is that, due to the illegal discharge of industrial wastewater, most water bodies are polluted by trace volatile organic compounds (VOCs), which are easily volatilized and enriched in the collected water during the interfacial evaporation process. Herein, a bilayer photothermal evaporator was reasonably designed for contaminated water purification. The bottom hydrophilic rGO-sodium alginate (SA) sheets purposefully disintegrate water transport channels, thus quickly removing VOCs through physical adsorption. The rGO-SA-TiO2 upper layer sufficiently absorbs incident light and therefore persistently generates reactive oxidizing species to degrade upward VOCs. Notably, the oriented microchannels inside the evaporator allow sustained light reflections to improve the utilization of solar energy. The evaporation rate can reach 1.63 kg m-2 h-1 with a considerably high VOC removal efficiency of up to 96 %. Such an integrated bilayer evaporator provides an effective strategy to obtain clean water via solar distillation.

One-pot synthesis of silver nanoparticle deposited cellulose nanocrystals with high colloidal stability for bacterial contaminated water purification

Cellulose nanocrystals (CNCs) have been utilized as a scaffold to immobilize silver nanoparticles (AgNPs) for their potential application as an antibacterial agent and bactericidal filler. However, the present implemented strategies involve synthesis by multi-step and utilize environment non-friendly reducing agents for the deposition of AgNPs on CNCs. Furthermore, the long-time aqueous dispersion stability of prepared AgNPs hybrids is another issue of concern for their efficient utilization as an antibacterial filler. We have developed an environmentally benign one-pot method using a biocompatible polyvinyl+pyrolidone (PVP) as a reducing agent to deposit AgNPs on CNCs. The developed method exhibited the uniform in-situ deposition of AgNPs on CNCs. The formed (CNC-PVP-Ag) nanohybrid displayed excellent long time aqueous colloidal stability (8 months), antibacterial and anti-biofouling activities (12.5 µg/mL and 25 µg/mL for E. coli and S. aureus) which is 4 and 2 times lower than AgNPs (w/o CNCs) prepared by the identical process as of CNC-PVP-Ag. As water-borne microbial contaminations are a global water quality concern, the excellent antibacterial and anti-biofouling activity of CNC-PVP-Ag was applied for water purification. An efficient bacterial filtration performance (100% reduction of Escherichia coli viability) was achieved after two filtration cycles.

Hydrophilic 3D Interconnected Network of Bacterial Nanocellulose/Black Titania Photothermal Foams as an Efficient Interfacial Solar Evaporator.

The design and development of scalable, efficient photothermal evaporator systems that reduce microplastic pollution are highly desirable. Herein, a sustainable bacterial nanocellulose (BNC)-based self-floating bilayer photothermal foam (PTFb) is designed that eases the effective confinement of solar light for efficient freshwater production via interfacial heating. The sandwich nanoarchitectured porous bilayer solar evaporator consists of a top solar-harvesting blackbody layer composed of broad-spectrum active black titania (BT) nanoparticles embedded in the BNC matrix and a thick bottom layer of pristine BNC for agile thermal management, the efficient wicking of bulk water, and staying afloat. A decisive advantage of the BNC network is that it enables the fabrication of a lightweight photothermal foam with reduced thermal conductivity and high wet strength. Additionally, the hydrophilic three-dimensional (3D) interconnected porous network of BNC contributes to the fast evaporation of water under ambient solar conditions with reduced vaporization enthalpy by virtue of intermediated water generated via a BNC-water interaction. The fabricated PTFb is found to yield a water evaporation efficiency of 84.3% (under 1054 W m-2) with 4 wt % BT loading. Furthermore, scalable PTFb realized a water production rate of 1.26 L m-2 h-1 under real-time conditions. The developed eco-friendly BNC-supported BT foams could be used in applications such as solar desalination, contaminated water purification, extraction of water from moisture, etc., and thus could address one of the major present-day global concerns of drinking water scarcity.

Modeling and performance evaluation of a small solar parabolic trough collector (PTC) for possible purification of drained water

Small-scale solar thermal contaminated water purification is a promising green energy based decentralized process especially for rural area. The present work describes thermal performance estimation of a Parabolic Trough Collector (PTC) suitable for contaminated water purification. Contaminated drain water is pressurized through a slow sand filter and PTC with glass cover enclosing a copper tube. The diameter of the copper tube was estimated as 26 mm and that of the glass cover was 50 mm. The rim angle and width of the parabola were 60° and 1.2 m respectively. The PTC focal length, concentration ratio, overall heat loss coefficient was 493.4 mm, 13.93 and 7.39 W/m2K respectively. The maximum modeled and experimental thermal efficiency were about 60% and 55% respectively. Around water flow rate of 0.002 kg/s and solar radiation 750 W/m2, both water temperature and useful heat gain were maximum. The exergetic efficiency of the system increases with the increase of inlet temperature of water for different solar intensity. The solar purified water had all other parameters within acceptable limit except residual chlorine (0.24 mg/L).

Metal-phenolic network coated cellulose foams for solar-driven clean water production

Solar-driven water steam generation is a promising strategy for seawater desalination and wastewater purification. However, oil contaminants commonly exist in real water resources, which drives us to design and fabricate photothermal materials with high efficient water steam generation and outstanding anti-oil-fouling ability. Herein, we developed a metal-phenolic network-coated cellulose foam (Fe3+/TA@CF), which exhibits not only superb hydrophilicity and underwater lipophobicity, but also achieves high water evaporation rate of ∼1.3 kg m−2 h-1 even in oil-polluted seawater under one sun illumination. In addition, Fe3+/TA@CF is demonstrated to be both anti-oil-fouling and anti-salt-fouling, which benefits to long-term evaporation in practical utilizations. Metal ions and oil contaminants in the condensed water vapor are almost eliminated after purification. We believe that this low-cost, biodegradable Fe3+/TA@CF paves a way for rationally designing and fabricating high-performance evaporator for oil contaminated water purification.

Robust, functionalized reduced graphene-based nanofibrous membrane for contaminated water purification

This work proposes an anti-corrosive nanofibrous membrane by combining one-pot solvothermal reduction method and electrospinning technology as a solution to the ever-increasing water pollution issues. Such membrane is made of aromatic polymer-polyimide and further modified by reduced graphene oxide, which maintained the original performance under different external environment and multi-cycled test, and achieved high separation efficiency (99.19%) and flux (2040.04 L m-2h−1) at the same time. The purification process is suitable for various contaminants and different combinations. Additionally, the inherent purification mechanism was fully explored in this study. The practicability of the membrane can be tested for the contaminated water purification, the recycle of poisonous and harmful substances, pre-process of precision extraction and so on.

Critical point analysis and biocide treatment in a microbiologically contaminated water purification system of a power plant

Many industries use ultrapure water (UPW) for their operation. In spite of purification efforts, microbial contaminations are the major cause of manufacturing problems in these systems. In our experiments, the water purification system of a power plant was investigated: the microbiologically critical points of the ultrapure water purification system were located by checking the number and diversity of bacteria to determine the optimum operational unit for chemical intervention: the most contaminated site was the mixed-bed ion-exchange resin containing unit. Biocides were tested against bacteria previously isolated from the same system; effect of biocides was checked also in laboratory model systems, and based on the results, a biocide treatment was carried out in the mixed-bed ion-exchange resin columns of the working power plant. Kathon WT was the most effective from the studied chemicals, being effective already in low concentration against most studied microorganisms. In case of the handling of the mixed-bed ion-exchange resin, 8-h treatment with 25 ppm biocide concentration was effective. Following the treatment, the quality of the produced UPW met the standards (specific electric conductivity was < 1.0 × 10−3 µS cm−1 at 25 °C) and water production capacity increased; moreover, the run-down time of the mixed-bed ion-exchange resin significantly grew.

Obtaining of iron-containing silicate composites for contaminated water purification from arsenic compounds

The object of research is palygorskite – a natural clay mineral with a layered ribbon structure. It is characterized by high specific surface area, secondary porosity and sorption capacity for metal cations. However, due to the negative charge of the surface, palygorskite is inefficient when cleaning water from pollution that is in anionic form, in particular, from arsenic compounds. A significant drawback of the use of dispersed aluminosilicates as sorbents is the difficulty of their separation from the liquid phase after the process of sorption purification. Therefore, to increase the sorption properties of palygorskite by pollutants in the water in the form of anions, the authors used the method of modifying its surface with iron-containing compounds, including treating the prepared palygorskite with iron salts (III) in a weakly alkaline medium. Physical and chemical methods are used to study the structure of modified and initial samples of palygorskite, in particular, the method of infrared spectroscopy (IR spectroscopy) and the method of low-temperature nitrogen adsorption-desorption. The results indicate that the surface of the palygorskite is coated with iron compounds (III), which led to an increase in the specific surface area from 213 m 2 /g to 275 m 2 /g and a pore size from 1.9 nm to 2.25 nm. The obtained samples differ from the original mineral by increased sorption capacity with respect to arsenic compounds (V). The maximum sorption of arsenic by the modified sample is 7.8 mg / g, which is significantly higher than that for natural palygorskite – 0.2 mg/g. It has been shown that arsenic is removed by iron-containing silicate rather quickly and does not depend on the pH value of the aqueous medium in the range 3 – 8. This is due to the fact that when processing the surface of palygorskite by iron oxyhydroxides the latter acquires an increased reactivity by increasing the number of active sorption centers.

Preparation, characterization and performance of an electrospun carbon nanofiber mat applied in hexavalent chromium removal from aqueous solution.

Hexavalent chromium, Cr(VI), a highly toxic oxyanion known as a carcinogen and mutagen, is an issue of concern due to its adverse impact on human health. Therefore, development of effective technologies and/or materials for Cr(VI) removal from water has been of great interest for researchers. In this study, an electrospun carbon nanofiber (CNF) mat was prepared via electrospinning polyacrylonitrile (PAN), followed by thermal pre-oxidation and carbonization. Scanning electron microscopy (SEM) observation showed that the fiber diameter of the CNF with carbonization temperature of 950°C (CNF950) was about 266 nm. Potentiometric titration analysis demonstrated that the point of zero charge pH (pHpzc) of CNF950 was around 7.93. CNF950 demonstrated high adsorption capacity and fast adsorption kinetics for Cr(VI) at pH < 3. Langmuir isotherm calculations showed that the maximum adsorption capacity of Cr(VI) on CNF950 was 118.8 mg/g at pH 2. The adsorption isotherm of Cr(VI) on CNF950 was well described by the Redlich-Peterson model, revealing that Cr(VI) adsorption was the result of a combination of monolayer and multilayer adsorption, depending on the initial Cr(VI) concentration. Solution pH greatly affected Cr(VI) adsorption onto CNF950 due to the electrostatic interaction, and the adsorption capacity was relatively high when pH was below 3. X-ray photoelectron spectroscopy (XPS) analysis revealed that the removal of Cr(VI) might be the result of a combination of redox reaction and electrostatic adsorption. The adsorption-saturated CNF950 could be regenerated by NaOH solution. This study extends the potential applicability of electrospun CNF mats for Cr(VI)-contaminated water purification.

A comparative study of aeration, biostimulation and bioaugmentation in contaminated urban river purification

Abstract Microbe-based biological remediation has been widely adopted in treating contaminated soil and fresh water. The selection of various technologies is essential to reach an effective remediation. However, current application of bioremediation strategies are often just empirical in actual contaminated water purification. In this study, three bioremediation technologies, involving aeration, biostimulation and bioaugmentation, and their various combined processes are comparatively assessed for their potentials to treat the contaminated urban water. The technologies are all operated in industrial modes to simulate the bioremediation process in actual aquatic environments. Results indicated that the aeration and bioaugmentation significantly decreased COD concentration, but hardly reduced nitrogen level. The biostimulation performed significant denitrification potential, but led to the organics enrichment and the bacterial diversity decrease. The any two combinations of aeration, bioaugmentation and biostimulation could not reduce COD and nitrogen simultaneously. By comparison, the combination of aeration, bioaugmentation and biostimulation reduced both COD and nitrogen greatly, and preserved bacterial diversity abundant. In rivers polluted by both organics and nitrogen, an integrated process was more promising compared to the single process. The study would provide direct theoretical and experimental implications for the selection and optimization of bioremediation technologies.

Sorption Extraction of Heavy Metal Ions from Industrial Sewage

Contaminated water purification from products of anthropogenesis activity remains one of the main problems that chemists and ecologists are facing nowadays. The main mass of pollutants in the form of toxic compounds of heavy metals is made by insufficiently purified and untreated sewage from the mining and machine-building industries. Industrial sewage treatment has become one of the most common technological processes, thus the issues of its improvement and optimization are especially relevant.

Efficiency evaluation of arsenic(III) adsorption of novel graphene oxide@iron-aluminium oxide composite for the contaminated water purification

Abstract Prolong consumption of arsenic-rich drinking water causes serious health problem. Aiming to minimize the problem, it is attempted to develop cheap and advanced materials for arsenic extraction from the contaminated water. Thus, multifunctional graphene oxide (GO)-incorporated iron-aluminium mixed oxide (GIAMO) composite has been prepared with five different GO content, and evaluated by batch method for the arsenic(III) removal efficiency. Among the as-prepared GIAMO samples, three samples consisting 1.0, 2.0 and 3.0 g of GO show equally good (92–95%) arsenic(III) removal efficiency, which is 30–35% higher than pristine iron-aluminium oxide (IAMO) from an aqueous solution (5.0 mg AsIII·L−1) at pH 7.0 (± 0.2) and 303 K. Thus, 1.0 g GO-inserted GIAMO (GIAMO-1) sample was characterized as microcrystalline (10–15 nm) with BET surface area about 1.45 times higher than IAMO and investigated for the arsenic(III) adsorption. Optimized pH for arsenic(III) adsorption is 6.0–8.0. The kinetic data agree more closely with pseudo-first order equation (R2 = 0.98–0.99) than pseudo-second order equation (R2 = 0.92–0.93). The equilibrium data describe the Langmuir isotherm (R2 = 0.97–0.98) better than the Freundlich isotherm (R2 = 0.91–0.92), showing the Langmuir monolayer capacity 42.2836 mg·g−1 at 293 K which drops to 24.9170 mg·g−1 at 313 K. High negative enthalpy change (ΔH° ∼ −224 kJ. mol−1) is responsible for the spontaneous reaction (ΔG° = negative) despite unfavorable entropy change (ΔS° = −0.71 kJ. mol−1). The order of competitive effect of PO43−, SO42− and HCO3− on arsenic(III) removal efficiency is PO43− > SO42− > HCO3−. However, the high HCO3− (> 200 mg·L−1) enhances the arsenic(III) removal efficiency of this material. 2.0 M NaOH can regenerate arsenic adsorbed GIAMO-1 only up to 50–60%. 0.65 g. of composite per L of high arsenic (Astotal: 0.115 mg L−1) groundwater can upgrade to potable standard, encouraging possible safe use for high arsenic water treatment. Highly negative enthalpy change, poor regeneration, FTIR, XRD and CV analyses of arsenic-rich solid suggested that arsenic(III) is stabilized over the solid surface without oxidation by surface complex formation.

Removal of arsenic from water by porous charred granulated attapulgite-supported hydrated iron oxide in bath and column modes

Clays are increasingly used as hosting materials to develop cost-effective adsorbents for pollutant removal from water. This is especially urgent for arsenic purification in rural and undeveloped areas. However, the fine powder form of modified clay cannot be used directly in water treatment due to the separation difficulty. Herein, a simple and easy method was used to prepare a low-cost arsenic adsorbent through loading hydrated iron oxide into porous charred granulated attapulgite. The results show that iron impregnation can increase the Brunauer-Emmett-Teller surface area and micropore volume of charred granulated attapulgite, which was possibly caused by the nano-sized iron formed in the channel of charred granulated attapulgite. Batch studies indicate that As(Ⅲ) (arsenite) and As(Ⅴ) (arsenate) sorption on the prepared adsorbent fit well with the Langmuir equation as the maximum sorption capacities were 3.25 and 5.09 mg/g, respectively, which were higher than the reported low-cost arsenic adsorbent. The arsenic sorption rate on the iron impregnated sorbents varied with initial arsenic concentrations, but all can be described by a pseudo-second-order model. The iron modified charred granulated attapulgite performed well with a wider pH value (5–9). However, inhibition effects of arsenic sorption by coexisting ions SO42−, HCO3− and PO43− increased with the increase of their concentrations. Of these, PO43− exerted the largest effect. The arsenic adsorbed sorbent can be regenerated by 0.5 mol/L NaOH four times with an approximate 11.3% and 25.6% sorption capacity lost for As (Ⅴ) and As (Ⅲ), respectively. A fixed bed column experiment showed that iron-modified charred granulated attapulgite can treat 397 BV for As (V) and 175 BV for As (III) of arsenic contaminated water below 10 μg/L. These results indicated that the first reported low-cost iron modified charred granulated attapulgite is very promising for arsenic contaminated water purification in rural and developing area.

Biotechnological importance of sphagnum mosses

Abstract Since Belarus is rich in sphagnum bogs it is extremely important to develop ways to use the resources of sphagnum mosses with a number of useful properties. Sphagnum is the only genus in the class Sphagnopsida and includes 36 Bryophyta species in Belarus. Sphagnum mosses, which are widespread in Belarus, have great potential for possible use in contaminated water purification from various hydrophilic and hydrophobic solvents and salt solutions, in light industry and agriculture (considering the need of their renewal).