Natural Water Purification Research Articles

Exploring the properties of ultrafiltration membranes with a dynamic layer and bactericidal inoculation for the purification of natural waters

The authors established that with the creation at the surface and in the pore space of membrane of a dynamic layer, there occurs a sharp reduction in the performance efficiency of membranes due to the biological fouling. Biofilms block the outflow thus decreasing the productivity of membranes. In order to eliminate the blocking, it is proposed to introduce biocidal additives to the dynamic layer, which made it possible to decrease the influence of biofouling. The formation of a dynamic layer in the pore space and at the surface of membrane is substantiated with the help of simulation using the filtration equation of Poiseuille. To confirm theoretical positions under laboratory conditions, we developed a procedure for the modification of a flat filter. Next, at a semi-industrial installation we conducted a comparison of operation of membranes with a biocidal additive, without it and with a periodic washing by sodium hypochlorite. The membrane with a biocidal inoculation at the surface demonstrated a stable work at the highest efficiency. Testing at flat membranes may be used as an express method for evaluating the modifying properties of different compositions of additives. This makes it possible to rapidly estimate effectiveness of different compositions of reagents for the surface modification of any type of filters. Specific productivity of the membrane with a modified layer without a biocide treatment reached 58 l × m 2 /h, of the membrane with a periodic treatment – 97,5 l×m 2 /h, while the membrane with a modified layer and a bactericidal inoculation demonstrated a more stable performance and its productivity in seven days amounted to 89 l × m 2 /h. The proposed technology enables obtaining water with the required quality via one-stage treatment, which considerably simplifies the process of water preparation.

The use of adsorption-active additions of some natural minerals for raising the quality of coagulation purification of natural water

laboratory, pilot and production tests were carried out aimed at the use of powder clinoptilolite jointly with aluminum sulfate to improve the quality of purification of the Dnieper river water. The article showed the advantages of a combined use of these reagents: higher degree of purification, lower consumption of regents, and smaller volume of deposits. The research has begun to obtain composite coagulant by treating with hot sulfuric acid of clinoptilolite and aluminum hydroxide. First research has been conducted of water coagulation under laboratory conditions using composite coagulant and its efficiency was demonstrated.

Evaluación de lodos de coagulación de agua cruda tratada con Moringa oleífera para uso agrícola

Coagulation-flocculation is a physical-chemical process responsible for producing the largest amount of sludge in the purification of natural raw water. Conventionally, aluminum sulfate or alum has been used as a coagulant. However, disposal of the sludge produced has been problematic for the environment due to excess aluminum. Currently, the convenience of using natural coagulants such as seed extracts from Moringa oleifera (MO) is being studied, although, the properties of sewage sludge produced and its possible reuse are unknown. In this paper the physical-chemical, nutritional and dangerous characteristics from MO sludge were evaluated by using standard methods to verify its potential use in agricultural soils. Results indicated that pH, electrical conductivity, ion exchange capacity, organic matter and micronutrients from sludge were suitable for application to soils with agricultural potential; but deficiency of macronutrients and presence of fecal coliforms limits it to be used as soil improver and not as fertilizer. Sludge stabilization with hydrated lime at doses greater than or equal to 3 % was effective to ensure the elimination of pathogenic microorganisms and to obtain a Class A sludge, unrestricted for agricultural use and suitable for acid soils.

Adsorption Study on Moringa Oleifera Seeds and Musa Cavendish as Natural Water Purification Agents for Removal of Lead, Nickel and Cadmium from Drinking Water

The effectiveness of plant based materials Moringa oleifera (Moringa) seeds and Musa cavendish (banana peel) for removing heavy metals namely lead (Pb), nickel (Ni) and cadmium (Cd) from contaminated groundwater was studied. Tests were carried out with individual and combined biomass at neutral pH condition on synthetic groundwater samples. The optimum biomass doses were determined as 200 mg/L for single biomass and 400 mg/L (in the ratio of 200 mg/L: 200 mg/L) for combined biomasses and used for adsorption isotherm studies with contact time of 30 minutes. Results showed that combined biomasses was able to met the Pb, Ni and Cd WHO standards from higher Pb, Ni and Cd initial concentrations which were up to 40 µg/L, 50 µg/L 9 µg/L, respectively compared to individual biomass of Moringa seed and banana peel. Moringa seeds exhibited the highest removal of Pb (81%) while the combined biomasses was most effective in removing Ni (74%) and Cd (97%) over wider their initial concentration ranges. The experimental data were linearized with Langmuir and Freundlich adsorption isotherm models. Freundlich model described the Pb adsorption better than the Langmuir model for all the tested biomasses. However, the Langmuir model fit better with the experimental data of Ni adsorption by Moringa seeds. Both models showed negligible differences in the coefficient of determination (R2) when applied for Ni and Cd adsorption on banana peel and combined biomasses, suggesting that there were multiple layers on the biomass interacting with the metals. Chemisorption is suggested to be involved in Pb adsorption for all tested biomasses as the value of nF calculated was lower than one. This type of adsorption could explain the phenomenon of different behavior of Pb removal and the higher Pb adsorption capacity (represented by KF values) compared to Ni and Cd. The study demonstrates that Moringa seeds, banana peel and their combination have the potential to be used as a natural alternative to the other water treatment agents for removing the Pb, Ni and Cd from drinking water.

ORGANIC SORPTION-MEMBRANE TECHNOLOGY OF DON WATERS CLEAN

Within one year on the water of the river Don were conducted pilot tests of bio-sorptional-membrane installation, allowing to reduce the content of organic substances in drinking water. Thus, reducing the efficiency of COD concentration in the bio-sorptional-membrane reactor averaged 44.8%, the chroma - 59.1%, permanganate oxidation - 31.2%. The high degree of water purification has been obtained and turbidity was 95-96%. The results showed that the bio-sorptional membrane technology is a promising way to improve the process of natural water purification, in particular, to prevent the formation of chlorinated and brominated compounds in the chlorination of water.

ИССЛЕДОВАНИЕ ЭФФЕКТИВНОСТИ ПРИМЕНЕНИЯ МЕМБРАННЫХ ФИЛЬТРОВ ДЛЯ ОЧИСТКИ ПРИРОДНЫХ ВОД ОТ ВОДОЗАБОРНЫХ СООРУЖЕНИЙ ГУП «ПЕТРОПАВЛОВСКИЙ ВОДОКАНАЛ»

ИССЛЕДОВАНИЕ ЭФФЕКТИВНОСТИ ПРИМЕНЕНИЯ МЕМБРАННЫХ ФИЛЬТРОВ ДЛЯ ОЧИСТКИ ПРИРОДНЫХ ВОД ОТ ВОДОЗАБОРНЫХ СООРУЖЕНИЙ ГУП «ПЕТРОПАВЛОВСКИЙ ВОДОКАНАЛ»

Physiological responses of Cladophora glomerata to cyanotoxins: a potential new phytoremediation species for the Green Liver Systems

Due to increased pollution of potable water sources as a consequence of eutrophication and anthropogenic xenobiotics, sustainable water purification is an essential concern. Therefore, the Green Liver System, a natural, economic and sustainable water purification system employing the biotransformation capabilities of aquatic plants, was developed. To expand the capacities and applications of this system, new aquatic plants are continually evaluated for their potential to remediate various aquatic pollutants. In this study, the potential of Cladophora glomerata to internalize cyanotoxins, microcystins (MCs) and anatoxin-a, and consequently its ability to cope with the subsequent oxidative stress associated with toxin-uptake were investigated. C. glomerata was able to take up all three of the tested MC congeners as well as anatoxin-a, similarly to previous toxin internalizations reported for aquatic plants such as Ceratophyllum demersum, Myriophyllum spicatum and Hydrilla versiculata. The antioxidative stress defense of C. glomerata proved to efficiently endure the toxin-uptake with no adverse effects. Subsequently, the uptake potential of C. glomerata was investigated at lab-scale by exposure to the three MC congeners and anatoxin-a collectively. After a period of seven days, 95–97% of the MCs and 100% of anatoxin-a were removed from the exposure media. C. glomerata therefore, is a suitable candidate to be incorporated in future Green Liver Systems.

Pulsed Electric Discharge in Active Metallic Grains for Water Purification Processes

Chemical reactions in electric metal pulse dispersion in the aqueous solutions of inorganic substance (НSiO3–, Ni2+, Н2AsO4–, Mn2+, Cr2O72–) were determined through IR spectroscopy, X-ray phase, chemical, kinetic, and thermodynamic analyses. Under such conditions, both reduction and oxidation reactions occur, as well as, locally initiated by heating, hydrolysis and exchange reactions without changing the oxidation rate of the dissolved substance itself. Reduction and oxidation of dissolved substances is determined by the generation and activation of high dispersed Fe in an electric discharge. Physical and chemical processes which take place under the action of pulse electric discharges upon the layer of metallic grains in salt solution, containing НSiO3–, Ni2+, Н2AsO4–, Mn2+, Cr2O72– ions were determined on the basis of product composition, obtained experimentally and the thermodynamic data. It was shown, that PED discharge in heterogeneous mediums can be used for waste and natural water purification.

Research on self-purification capacity of Lake Taihu.

An effective measure to cope with eutrophication of lakes is to remove nutrients that can cause algal blooming by taking advantage of natural water purification processes. Here, the term "purification" is defined, in a wide sense, as the potential role of a water body to contribute to the reduction of pollutants and thus controlling eutrophication. Also regarded as a kind of ecological regulating services, biological purification involves various processes concerning seasonal nutrient fixation, such as uptake by aquatic macrophyte, biofouling onto foliage substrates, feeding by organisms in higher trophic level, and eternal loss or removal of substance from the water. In order to evaluate the water purification ability, a numerical lake ecosystem model (EcoTaihu) was developed and applied to Lakes Taihu. The model includes the biological interactions between pelagic compartments (phytoplankton and zooplankton, detritus, dissolved organic matter, fish, and nutrients). Under dynamic forcing of meteorological and hydrological parameters, the model was run over years to evaluate the annual nutrient cycles and purification functions. The reproducibility of the model was validated for water body by comparison with the field data from the water quality monitoring campaign. Numerical results revealed that self-purification capacity of nitrogen of Lake Taihu in years 2006, 2008, and 2010 is 4.00 × 10(4), 4.27 × 10(4), and 4.11 × 10(4)ton, respectively, whereas self-purification capacity of phosphorus of Lake Taihu in years 2006, 2008, and 2010 is 1.56 × 10(3), 1.80 × 10(3), and 1.71 × 10(3)ton, respectively.

The flow chart of purifying natural waters of nitrate ions using pressure-driven methods

The paper has proposed a complex flow chart of purifying natural waters of nitrate ions incorporating stages of reagent-enhanced nanofiltration (for removal of nitrates) and ultrafiltration (for rational use of the reagent). Using purification of natural water from a source with the concentration of nitrates 105 mg/dm3 as an example we showed the efficiency of using the given schematic for selective removal of nitrates under real conditions.

A Study and Analysis on the Physical Shading Effect of Water Quality Control in Constructed Wetlands

This study mainly utilized model basins to conduct relevant water quality analyses and tests to understand the influence of the shading effect of wetland plants in the natural water purification system on algae control and eutrophication of water bodies. The model basin tests are based on the physical shading effect in order to evaluate and further understand the influence of algae control and water quality parameters. The physical shading tests were conducted at different rates (100, 70, 50, 30, and 0%) and the research results indicate that the initial dissolved oxygen concentration of each group is between 5 - 7 mg/L. On Day 5, the average dissolved oxygen concentration of the 100 (aerobic) , 100 (anaerobic), 70, 50, 30 and 0% groups is respectively 9.22 ± 1.24, 8.54 ± 1.23, 18.8 ± 3.74, 21.71 ± 0.41, 22 ± 0, and 22 ± 0 mg/L while that of the 70, 50, 30, and 0% groups significantly increases. The initial concentration of Chlorophyll a of the 100 (aerobic) , 100 (anaerobic), 70, 50, 30 and 0% groups is, respectively, 5.27 ± 0.93, 5.92 ± 0.00, 7.9 ± 5.59, 5.92 ± 0.00, 7.9 ± 5.59 and 13.82 ± 2.79 μg/L. On Day 5, the average concentration of Chlorophyll a is, respectively, 57.27 ± 11.17, 9.87 ± 2.79, 244.86 ± 50.34, 280.4 ± 32.92, 329.77 ± 15.55 and 250.78 ± 32.21 μg/L. In general, the physical shading effect can prevent photosynthesis by algae in water by absorbing light and converting light into chemical energy for self growth and proliferation that cause a rapid increase in the number of algae. The physical shading effect, however, cannot reduce nutrients; this leads to a high nutrient level in water bodies during the latter stages of the tests. After the introduction of the Carlson Tropic State Index (CTSI), the completely shaded water bodies at the initial stage of tests are mesotrophic water bodies that contain neutral nutrients. The partially shaded water bodies are eutrophic. In the latter stages of the tests, the former turned eutrophic while the latter turned mesotrophic. The main cause lies in the relatively higher weight CTSI placed on total phosphorous content.

Waste Removal and Oxygen Condition in a Natural Water Purification System

Emergent incident of fish kill was occurred in the detention pond of natural water purification system. The objective of this study was revealed the cause of the incident.Novel measurements unprecedentedly employed in this study including SOD to measure sediment oxygen decay PCR to find out sediment microbial activity, SEM, EDX, and FTIR to view the macrophyte rhiyphere root surface to understand the pollutant adsorption. Algal bloom was the main reason to induce serious fish kill Particle size analysis demonstrated greater particles were setting in the upstream.Chlorophyll A, COD, SS, phosphorus, E coli was in descending of following the stream direction. The end of measuring point, detention pond, demonstrated the serious eutrophication which leads to diurnal pH and DO fluctuation to induce anoxic condition at night which induced fish kill. Sediment oxygen uptake (SOD) also measure to fine vertical oxygen profile. SEM, EDX, and FTIR results indicated the major functional groups of submergent macrophyte reed root were carboxyl, carbonyl, and phenol which could adsorp various pollutants.

Determination of selected nonsteroidal anti-inflammatory drugs in the aquatic environment

The presence of pharmaceutical compounds in the aquatic environment requires the development of an effective monitoring method. The paper presents the developed procedure of determination of pharmaceutical compounds selected from the group of nonsteroidal anti-inflammatory drugs – ibuprofen and diclofenac. To isolate selected compounds from the tested water the solid phase extraction (SPE) was employed. The quantitative and qualitative analysis was carried out by high performance liquid chromatography HPLC (UV) as well as gas chromatography coupled with mass spectrometry with electron ionization GC-MS (EI). Described analytical procedures allows to separate and quantificat pharmaceutical mixtures with a satisfactory reproducibility and accuracy. The values of the recovery degree confer the possibility of the complete quantitative control of tested pharmaceuticals in water samples. The described method can be used to control the analytical processes of natural water purification and wastewater treatment from pharmaceutical compounds.

Electrochemical behaviour of aluminium in electrocoagulation processes

Passivation of aluminium electrodes is a common problem in electrocoagulation reactors used for the purification of natural waters, leading to high cell voltages and compromising the viability of such industrial processes. In order to identify possible mitigation strategies, cyclic voltammetric, potentiostatic and galvanostatic measurements were made to investigate the effects of electrode surface topography and solution composition on the electrochemical behaviour of pure aluminium and Al 1050 in neutral electrolyte solutions. In addition, electrochemical impedance spectroscopy was used to estimate thicknesses of passive layers before and after dissolution. Chloride ions, well-known pitting promoters, were found to facilitate dissolution of passive surfaces, though attenuated by the presence of the naturally-occurring contaminant humic acid. Under galvanostatic conditions, a smooth aluminium electrode showed a constant rise in electrode potential due to passivation. However, even in the absence of pitting promoters electrodes with a ‘rough’ surface finish (Ra-values>1µm) exhibited an initial potential increase, followed by a dramatic decrease to relatively low steady state values due to ‘spontaneous de-passivation’. The precipitation of dissolved aluminium(III), releasing H+ ions, was identified as the probable cause of this effect, leading to acidic pH values, locally dissolving the passive layer and enhancing dissolution rates.

Possible applications of clinoptilolites for natural water purification

Possible applications of clinoptilolites for natural water purification

Physicochemical, crystalline and morphological characteristics of bricks used for ground waters purification in Bangui region (Central African Republic)

The development and improvement of natural water and wastewater purification technologies utilizing low-cost raw materials like bricks are necessary to make possible easy application in poor countries. The present work concerns the detailed studies on a soil which is commonly used to make bricks by craftsmen in Bangui region (Central African Republic). The chemical and mineralogical composition of this soil before and after thermal transformation, and its crystalline, morphological and surface properties were determined by combining several techniques: X-ray Diffraction (XRD), ThermoGravimetric Analyses (TGA), Differential Thermal (DTA) Analyses, TGA/Mass Spectrometry (MS), 27Al and 29Si NMR spectroscopy, and Environmental Scanning Electron Microscopy (ESEM; an apparatus equipped with an Energy Dispersive X-ray Spectrometer, EDS). The basic brick making led to an interesting mesoporous material that was found to be a good adsorbent for Fe(II) removal from contaminated natural waters. Column experiments further revealed significant improvement of the sorption capacity of this brick when its surface was coated with iron oxy-hydroxide. ESEM/EDS micro-analyses revealed that FeOOH was preferentially deposited onto brick clays (mainly disordered metakaolinite), thus showing the key role played by these minerals in the study water treatment when compared to the sorption performances obtained with raw sand and FeOOH-coated sand.

Using Ecosystem Valuation to Protect the Atlantic Rainforest: The Case of the Oasis Project

This article briefly explores the Oasis Project, an ecosystem payments scheme that protects parts of the remaining Atlantic Rainforest in Brazil in order to preserve drinking water and biodiversity. The Oasis Project pays landowners to protect their forested land in order to preserve some of the forests that provide drinking water for the metropolitan region of São Paulo, home to approximately 17 million people. Based on field research and research interviews, the article investigates the details, benefits, and challenges of the Oasis Project. It finds that to date the Oasis Project has protected about 700 ha of land and conserved parts of the forest that provide natural water treatment, purification, and pumping throughout the São Paulo metropolitan region, and that the program may offer useful lessons for those wishing to preserve forests elsewhere.

Removal of boron compounds in the course of pressure-driven demineralization

The paper has investigated the possibilities of ESPA-1 and OPMN-P membranes for born removal in the course of pressure-driven purification of natural waters. We have developed an effective method of processing regeneration solutions containing boron, which are formed in the course of selective removal of boron from permeates of reverse-osmosis units.

Nanosized Pt-, Ru-, and Pd-containing catalysts for organic synthesis and solution of environmental issues

Synthesis of Pt-, Ru-, and Pd-containing nanoparticles in the pores of polymeric matrix of hypercrosslinked polystyrene, their structure and catalytic properties are under consideration. Physicochemical studies have shown that metal nanoparticle formation depends on the properties of the polymeric matrix porous structure, the nature of metal precursors and the synthesis conditions. The study of catalytic properties of metal nanoparticles stabilized in mesoporous matrices showed promising applications of these systems in the reactions of selective oxidation and hydrogenation, which are intermediate stages in the synthesis of precursors of vitamins and medicines. In order to solve environmental problems, nanocatalysts were investigated in the processes of oxidative degradation of phenol and reductive denitrification of nitrates for purification of sewage and natural water.

THE USAGE OF CATALYSERS IN THE OXIDATION pROCESS OF NATURAL ANDWASTE WATER PURIFICATION

The authors give a short review on the usage of different catalysers in the process of natural and waste water purification with the help of oxidants.