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Preparation of sodium sulfate by isohydric crystallization during reverse osmotic treatment of mineralized wastewater and solution neutralization

I.A. Pochitalkina, A.V. Desyatov, T.A. Pavlishcheva, I.B. Sibiryakova, I.M. Kostanov, A.V. Kolesnikov

Section: Methodology and research methods. Models and forecasts

The article is devoted to the problem of neutralization of industrial wastewater containing highly toxic chlorides, sulfates, nitrates, ions of heavy and non-ferrous metals. Wastewater, as a rule, has an acidic reaction, and the first stage of its neutralization consists in the use of alkaline reagents (NaOH, Na2 CO3 , Ca(OH)2 ) to neutralize and form hybrid sediments of iron, aluminum and other metals. The total concentration of salt components in technological solutions ranges from 10 to 100 g/L, most often it is a mixture of Na2 SO4 , NaCl, NaNO3 , less often other salts. The technology of deep processing of mineralized water consists in softening, filtration on pressure filters and microfiltration of industrial waste. The peculiarity of the proposed scheme lies in the use of the reverse osmosis method of desalting, according to which it is concentrated by 3–5 times and evaporated to a salt content of 200–300 g/L. This scheme allows you to obtain concentrate and fresh water that meets environmental requirements. After water demineralization, the concentrate goes to isohydric crystallization with Na2 SO4 · 10H2 O by cooling to 0 о С. After centrifugation of the pulp, the mother liquor is mixed with the initial stream and sent to a reverse osmosis unit, and the crystalline hydrate is sent to drying to obtain anhydrous technical salt. On the example of a model technological solution that simulates liquid industrial waste from mining enterprises, with the help of computational and experimental studies, the fundamental possibility of obtaining anhydrous sodium sulfate by means of intracycle isohydric crystallization of a concentrate after a reverse osmosis plant has been shown. A schematic diagram of the neutralization of liquid inorganic waste of I and II hazard classes with the production of a secondary product, Na2 SO4 , is proposed; the possibility of isomorphic capture of impurities during its crystallization is estimated

Keywords: waste water, neutralization, industrial waste, crystallization, reverse osmosis membranes

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Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-043-049

“Green” fabrication of poly (vinylidene fluoride) membranes for microfiltration

E.S. Shirokova, P.A. Sozinov, V.A. Cherepanova, O.V. El’kin, S.V. Fomin, D.A. Kozulin, A.N. Bushuev, I.V. Tolstobrov, I.S. Kraeva

Section: Methodology and research methods. Models and forecasts

Membrane technology is a crucial tool toward technological process intensification in chemical industry. In addition to its undeniable contribution to desalination and reuse of water, the spread of separation applications in industry could save great part of the energy. Beyond the contribution to the environmental and economic improvement of separation processes, the membrane manufacturing industry itself needs to minimize environmental and occupational risks, that means meet principles of “green” chemistry. Membrane manufacturing should be developed with the reduction or elimination of hazardous compounds. The chemical processes of membrane production are linked with the use of a wide range of solvents. A lot of organic solvents required for membrane production are classified as toxic or hazardous substances and their use is strictly limited by law. One of the promising environmentally friendly methods of production of membranes is the applying of “green” solvents. As an alternative technology, it is proposed to use the freeze method, in which non-toxic dimethyl sulfoxide (DMSO) is used as a solvent. This technology requires less energy consumption, which also allows implementing the principles of “green” chemistry. Microporous membranes based on poly(vinylidene fluoride) (PVDF) with a thickness of 100 to 250 μm was carried out by freeze method. Dimethylsulfoxide (DMSO) was selected as the most environmentally friendly solvent for some fluoropolymers. Porosity, permeability, wettability, physical and mechanical characteristics for obtained membranes and their morphology were investigated. It has been found that the most optimal concentration of PVDF in the solution is 30 wt.%. In this case the best combination of technological and operational properties is provided. The efficiency of prepared membranes for microfiltration process was demonstrated by a suspension of the yeast Saccharomyces cerevisiae. Such technology in comparison with the existing ones, is devoid of some disadvantages like using of complex equipment and high operating temperature. Freeze method does not require high energy consumption and using of toxic solvents.

Keywords: “green” chemistry, microfiltration, membranes, poly(vinylidene fluoride), freeze method

Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-064-070

Flotation technologies for purification of filtration waters of solid waste landfills

V.P. Meshalkin, V.S. Kovalenko, G.A. Shcherbakova, A.V. Kolesnikov

Section: Methodology and research methods. Models and forecasts

Comparison of leachate water treatment methods for solid household waste (MSW) landfills is carried out. The experiments were carried out on model solutions and real filtrate from the MSW landfill of the Moscow region. It has been established that electroflotation treatment is an effective method due to high recovery rates, low energy consumption, as well as the possibility of automation and the absence of secondary water pollution. The effect of surfactants (surface-active substances, SAS), flocculants, Ca, Mg, Ba reagents on electroflotation extraction of UltraPAC coagulant in aqueous solutions of NaCl, Na2SO4 is described. It was found that the addition of an anionic surfactant to the system promotes the adsorption of the surfactant on its surface, which makes it more hydrophobic, increasing the degree of electroflotation extraction to 95–99% in some cases. The results of measurements of the particle size, surface charge of the dispersed phase of the UltraPAC co-he results of measurements of the particle size, surface charge of the dispersed phase of the UltraPAC coagulant are presented. It was found that the ζ-potential of Al(OH)2Cl in NaCl solutions in a wide range of pH 5–9 is positive, (+5–+33 mV). In Na2SO4 solutions at pH 7 surface recharge is observed, which is explained by the specific adsorption of SO4 2- anions on the surface of the dispersed phase of Al(OH)2Cl. The particle size varies from 38 μm (pH 5) to 12 μm (pH 9) – in Na2SO4 solutions and from 16 μm (pH 5) to 19 μm (pH 9) – in NaCl solutions. It was found that the addition of Ca2+, Mg2+ reagents to the solution for pH adjustment leads to suppression of the electroflotation process. The introduction of an anionic surfactant stabilizes the electroflotation process and increases the degree of extraction of the coagulant to 75% (MgCl2 – 0.1 g/L) and 99% (CaCl2 – 0.1 g/L).

Keywords: solid waste landfill filtrate, flotation, electroflotation, coagulant (Al), surfactant, flocculant

Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-020-027

Treatment of electroplating wastewater from metal ions with the use of sorption in static mode and electroflotation

A.M. Gaydukova, V.A. Kolesnikov, A.A. Pokhvalitova

Section: Ecologization of industry

Studies of the sorption process of extracting Fe3+ and Al3+ ions from aqueous solutions of sodium chloride, nitrate and sulfate salts in a static mode on an industrial powder sorbent of the OU-A brand have been carried out. The influence of Cl-, NO3- and SO42- anions on the value of sorption of metal cations was determined. By the nature of the adsorption isotherms of metal ions, an assumption about the mechanisms of the process was made. The values of the electrokinetic potential of coal particles in salt solutions were obtained, on the basis of which flocculants were selected and their effect on the efficiency of the electroflotation process for extracting spent carbon sorbent was evaluated. It was found that the spent sorbent with Fe3+ ions in an amount of up to 1 g/l, and the sorbent with Al3+ ions – up to 1.6 g/l within 10 minutes can be extracted from solutions of nitrate and sodium chloride salts by adding flocculants of cationic and nonionic types. The experimental studies have shown that the use of a combined method, including sorption treatment with subsequent extraction of the spent sorbent in the process of electroflotation, will not only reduce the duration of wastewater treatment, but also provide a high degree of their purification.

Keywords: sorption, powdered carbon sorbent, electroflotation, heavy metal, waste water, flocculants

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Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-160-166

Catalytic oxidative degradation of the azorubine dye in wastewater

T.V. Kon’kova, I.S. Belkina, A.D. Stoyanova, V.A. Kolesnikov

Section: Ecologization of industry

The production of high-quality phosphate fertilizers, in particular calcium acid phosphates, requires the use of ore rich in phosphates (above 28 wt.% P2O5 ) and containing a minimum amount of impurities, including harmful ones. The absence of such large natural deposits leads to the need to enrich the existing phosphate ore containing an average amount of phosphates (14–23% P2O5 ) and contaminated with various impurities. Enrichment of polymineral phosphate ores leads to the production of their concentrates and waste (sludge). Sludge is a mixture of clay impurities, iron compounds, phosphate substances contained in the original ore, as well as toxic surfactants used in its flotation enrichment. This prevents the use of sludge as a secondary source of raw materials in any industry and its return to waste deposits. The lack of methods for processing sludge leads to their accumulation and environmental pollution: the area of fertile land is shrinking, pollution of nearby natural water bodies increases. The proposed integrated physicochemical technology for processing phosphate ore dressing wastes using nitric acid is aimed at improving the environmental situation in the regions producing phosphate raw materials and obtaining a number of valuable products important for the national economy: glauconite sand, clay, hydrogen phosphate and calcium nitrate. The yield of sludge processing products was experimentally established, which amounted to: 68.6% glauconite, 6.91% clay, 12.9% technical calcium hydrogen phosphate, 18.2% technical calcium nitrate. Processing products – clay and glauconite sand are most widely used in the construction industry, in particular, in the production of bricks and concrete. Glauconite sand and clay are used in the production of sorbents, paints and primers. Hydrophosphate and calcium nitrate are used in agriculture as phosphorus and nitrogen fertilizers, respectively.

Keywords: phosphatic ore, slimes, the nitric-acid method of processing of a waste, glauconitic sand, clay, hydrophosphate of lime, nitrocalcite

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Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-154-159

Methodology for determining regional thresholds for the calculation of standards for the permissible discharge of liquid industrial waste into surface waters

Yu.A. Tunakova, S.V. Novikova, E.V. Baibakova, V.S. Valiev

Section: Methodology and research methods. Models and forecasts

Water quality standards are a key tool for regulating anthropogenic pressure on water bodies. A scientificallybased approach to the development of regional water quality standards is the use of modern mathematical methods for the analysis of experimental data and information technologies. We have developed a methodology for determining regional threshold standards for permissible discharge of liquid industrial waste for selected types of surface waters. The presented methodology uses a symbiosis of cluster analysis and expert evaluation methods, which allows to increase the validity of the results obtained. The typification of surface waters was carried out for water bodies of the territory of the Republic of Tatarstan on the basis of long-term systematic observations. Clustering was carried out according to the sets of all determined hydrochemical indicators using Kohonen neural self-organizing networks implemented in the author’s neural network filtering model. Experts in the relevant subject area acted as experts to assess the homogeneity of data groups in each of the selected clusters. Each heterogeneous group established by experts was divided into clusters using the Kohonen neural network until the required uniformity was achieved. Based on expert analysis, hydrochemical indicators, which had a uniform variability of values and did not allow water typing, were excluded from further evaluation. According to the values of other hydrochemical indicators, six types of waters are distinguished. Threshold values of hydrochemical indicators for clusters corresponding to the upper threshold of the variational series of values are determined. The obtained regional threshold concentrations for each type of water are proposed to be used to calculate the standards of permissible discharges during the disposal of liquid waste into water use facilities located in the Volga-Kama basin.

Keywords: liquid production waste, discharge, water bodies, neural network technologies, regional threshold concentrations, standards permissible discharges

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Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-028-033

Consequences of the impact of some industrial plants on the content of heavy metals in soils

A.R. Sukiasyan, S.Z. Kroyan, S.G. Skugoreva, A.A. Kirakosyan, H.Gh. Ghazaryan

Section: Monitoring of natural and anthropogenically disturbed areas

Studies have been carried out to assess the degree of soil pollution in Armenia with heavy metals (HM) near existing (Kajaran Copper-Molybdenum Plant and Hrazdan Cement Plant) and currently not operating (Alaverdi Mining and Metallurgical Plant and Vanadzor Chemical Plant) industrial enterprises. The selection of soil samples was carried out from the plots at a distance of 0.5, 1.5, 2.5, 5, 10, 15 and 25 km from the source of pollution. Analysis of the results of chemical analysis of soils showed that at a distance of up to 5 km from technogenic sources, soils are heavily contaminated with compounds of copper, zinc and lead. As the distance from the pollution source increases to 25 km, a significant decrease in the concentrations of all HMs occurs, and the comparative series is represented by the following sequence: Zn > Cu > Pb > Co > Mo. At a distance of 25 km, a significant decrease in anthropogenic load on the soil is noted. The greatest 50 times decrease in the total HM content was found for soils near the Alaverdi Mining and Metallurgical Combine, and the smallest in the case of the Hrazdan Cement Plant. For the rest of the considered enterprises, the decrease in the value of the coefficient of total pollution was 25 times on the average. The information obtained can be used to take into account the migration and storage capacity of HMs in the soil when organizing environmental measures, depending on the remoteness of the main source of pollution.

Keywords: soil, heavy metals, anthropogenic pollution, remoteness from the source of pollution, the total coefficient of soil pollution

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Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-090-097

Active carbons as an important factor in the sustainable development of the economy and the quality of life of the population

V.M. Mukhin, N.V. Korolev

Section: Social ecology

The article indicates the severity of the environmental threats and pollution of the biosphere. The main route of protection of the biosphere with the use of active carbons (AU) is justified. A modern definition of activated carbon is given as a material with a developed porous structure, having high absorption characteristics for impurities found in the media to be cleaned (air, gases, water and other liquids). A new approach to the evaluation of the adsorption properties of AU, justified by Academician M.M. Dubinin through the adsorption activity per unit volume of AU (mg/cm3 ), is proposed. The possibility of effective use of activated carbon in environmental technologies for the protection of the atmosphere, hydrosphere, lithosphere and man himself as the main object of the biosphere is shown. Special emphasis is placed on the coverage of the most important areas of application of AU that ensure the environmental safety of the Russian Federation, namely, detoxification of soils from pesticide residues, purification of drinking water and wastewater, treatment of waste gases from incinerators. It is shown that the introduction of AU in doses of 100–200 kg/ha into herbicide-contaminated soil allows not only to increase crop yields by 20–80%, but also to obtain environmentally friendly crop products. It is proved that active carbons of the DAS brand based on anthracite with a high volume microporosity (0.17 cm3 /cm3 ) significantly increase the efficiency of drinking water and wastewater treatment. Thus, the sorption capacity of DAS for phenol, as the most common pollutant of natural and waste water, is 2.5–3.5 times higher than that of the industrial sorbent KAD-I based on coal semi-coke. A number of problems of protection of the atmosphere with the use of AU are highlighted. The important role in the use of AU for detoxification of the human body is emphasized. New promising technologies of AU production are described. The need for AU for the Russian Federation in the amount of at least 70,000 tons/year is justified, which allows for the sustainable development of the economy and improving the quality of life of the population.

Keywords: environmental pollution, active carbons, sorbent, biosphere protection technologies, lithosphere, soil detoxification, hydrosphere, water treatment, atmosphere, incineration plants

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Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-210-217

Bioindication of oil-contaminated soils using invertebrates

E.N. Melekhina, A.A. Taskaeva

Section: Population ecology

The article discusses the possibility of using springtails (Collembola) as an indicator group of soil invertebrates in the case of oil pollution, as well as the rate of their recovery in soils reclaimed by different methods. Eight experimental sites were examined with the use of various biological preparations, agrochemical soil treatment and the background community in the Usinsk region of the Komi Republic. A decrease in the diversity and abundance of springtails, a depletion of the spectrum of their life forms, and a restructuring of the dominance structure on the experimental sites 12 years after reclamation are shown. The euedaphic and hemiedaphic species were found to be sensitive to oil pollution. Species characteristic of the initial stages of restoration of soil communities after oil pollution (Ceratophysella succinea, Proisotoma minima, Desoria hiemalis), as well as a species that may be sensitive to oil pollution (Protaphorura jacutica), have been identified. Analysis of the diversity of springtails can serve as an alternative to ecotoxicological tests in assessing the effectiveness of reclamation methods and the rate of restoration of disturbed soils.

Keywords: springtails, pollution of terrestrial ecosystems, bioremediation, European part of Russia

Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-181-186

Microbiological monitoring of technogenically polluted reservoirs of the Absheron industrial region

А.S. Gasimova, N.M. Ismailov, А.G. Talibly

Section: Monitoring of natural and anthropogenically disturbed areas

The presence of water bodies of anthropogenic origin on the territory of the Absheron industrial region is one of the acute problems. Many lakes have become receivers of wastewater and polluted water, they have a negative impact on adjacent environments – soil cover, groundwater and the atmosphere of the entire Absheron Peninsula, including the capital of the country, Baku, with its three million population. The object of research in 2016–2017 was the largest and most polluted lakes of the Absheron Peninsula – Boyuk-Shor (the surface of this reservoir is 1300 hectares) and Zykh (20 hectares). The research is devoted to the study of the structure of the microbiocenosis of reservoirs contaminated with oil and oil products, biogenicity and their self-cleaning ability. In the self-purification of these reservoirs, oil-oxidizing microorganisms play an important role, the abundance of which in the water of reservoirs ranges from 103 to 105 cells/dm3 . The most active decomposition of organic substances in water occurs in the summer and autumn. This is favored, first, by the temperature factor. The difference in the degree of biogenicity in different zones of water bodies is associated with high levels of hydrocarbon pollutants, namely: in the areas of pollutant intake, self-cleaning ability does not compensate for the rate of their destruction.

Keywords: Absheron Peninsula, water bodies, pollution, self-purification, microorganisms, microbiocenosis structure

Article published in number 4 for 2021
DOI: 10.25750/1995-4301-2021-4-083-089

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