scholarly journals Treatment of waste water containing chromium (VI)

Author(s):  
Kundyz Sovetova ◽  
Akmaral Ismailova

In the production of chromium and in the process of transportation of chromiumcontaining materials, contamination of natural waters and soils with chromium compounds inevitably occurs. In this paper, the sorption of chromium (VI) ions with carbon sorbents is studied as a method for treating waste and natural water contaminated with chromiumcontaining compounds. Sorption method of extraction and concentration of elements is one of the most effective and simple technological method of chromium extraction. For extraction of chromium (VI), carbon sorbents obtained from recycling of wheat grains waste (RWGW) (wheat husk or bran) modified with ammonium nitrate were used. RWGW (recycling of wheat grains waste) + NH4NO3 (3%), RWGW (recycling of wheat grains waste) + NH4NO3 (5%), RWGW (recycling of wheat grains waste) + NH4NO3 (7%) were used. Chromium sorption was investigated depending on various factors. It has been established that the most effective sorbent is RWGW (recycling of wheat grains waste) + NH4NO3 (3%), with which it is possible to extract chromium by 98% from solutions at pH=1 in 30 min. This sorbent has been tested for industrial wastewater treatment containing up to 36 mg/L of chromium (VI) ions. The metal recovery rate was 95.2%. The obtained results indicate the prospects of application of RWGW (recycling of wheat grains waste) + NH4NO3 (3%) for wastewater treatment from chromium (VI).

Author(s):  
E. N. Kipriyаnova ◽  
◽  
K. E. Smirnov ◽  

Sorption method for wastewater treatment from bichromate ions using AV-17-8chs anionite is considered. The conditions of effective cleaning are investigated. Determined, the working exchange capacity of the anion exchanger.


Author(s):  
Sоfiia Haidash ◽  
◽  
Viktor Kostenko ◽  

Introduction. In the process of coal mining and beneficiation, a large amount of wastewater is formed at enterprises. Sewage has a variety of origins, which can be classified into: natural (mine, quarry, drainage); technological (water for carrying out technological process, water for cooling of cars and devices); surface (water from rain, snow and maintenance of the enterprise); household (water is formed from showers, bathrooms, dining rooms). Wastewater from mines and factories is highly polluted and can have toxic effects on the environment. Problem Statement. Natural waters have a high rate of mineralization, salts of heavy metals, iron. Waters are polluted with organic matter, large and small particles of coal and rock. Surface and process effluents are contaminated with coal dust and petroleum products. Domestic waters are contaminated with surfactants, fats, animal and plant food residues, alkali, cadmium, nickel. Purpose. The aim is to study in detail the sources of pollution of mine effluents, to determine their composition and properties. Identify the seasonality of sources. Describe the method of water treatment and suggest possible improvements to existing technology. Materials and methods. The water must undergo some purification before it enters the environment. One of the main processes of wastewater treatment is filtration. This process is the most common and effective, so it should be part of the cleaning technology. The filter element can be a thin partition with pores or three-dimensional elements with a porous filler. This paper presents a technology with a granular filter, also called fast. The fast filter works on the principle of volume filtration, impurities are retained in the entire volume of the filter medium, in the pores and on the surface of the grains. Before filtration, the water is treated with coagulants. Types of granular materials: quartz sand, anthracite, expanded clay, expanded polystyrene, ceramic sand, mesoporous coal. Mesoporous coal is a promising material for filtration. Results. In the result of consideration of the composition and properties of wastewater, the appropriate technological scheme of mine wastewater treatment is selected and described. The technology provides purification from large impurities in open hydrocyclones, water treatment with flocculant, provides a filter and clarifier, enhanced purification from petroleum products in the oil trap and carbon filter. Filling the filter is sent to the coal warehouse, which is a cost-effective solution. Conclusions. The effluents of mining enterprises are saturated with pollutants and have a very aggressive composition, so it is unacceptable to release them into the environment without prior lighting. Should attention be paid to the purification of petroleum products that fall into the water as a result of the operation of machines and devices. As one of the possible methods, the technological scheme, improved by the department with oil trap and filter, is presented. Filter backfill is mesoporous coal, which is a very promising sorbent. Water treated with this technology can be used for recirculating water supply. This is justified not only by the economic aspect, but also by the environmental one. Keywords: mine drains, mining, pollution, petroleum products, filtration, technological scheme.


RSC Advances ◽  
2019 ◽  
Vol 9 (62) ◽  
pp. 36144-36153 ◽  
Author(s):  
Bin Zheng ◽  
Yizi Ye ◽  
Baowei Hu ◽  
Chunhui Luo ◽  
Yuling Zhu

To effectively destroy the structure of the passive oxidation film covering zero-valent iron (ZVI), an Fe(iii)-reducing strain, Morganella sp., was isolated from anaerobic activated sludge and coated on the ZVI.


2019 ◽  
Vol 26 (20) ◽  
pp. 20386-20399 ◽  
Author(s):  
Norfadhilatuladha Abdullah ◽  
Norhaniza Yusof ◽  
Muhammad Hafiz Abu Shah ◽  
Syarifah Nazirah Wan Ikhsan ◽  
Zhi-Chien Ng ◽  
...  

Author(s):  
Elis de Oliveira Lopes ◽  
Ithiara Dalponte Dallabona ◽  
Regina Weinschutz ◽  
Regina Maria Matos Jorge

2005 ◽  
Vol 59 (2) ◽  
pp. 252-257 ◽  
Author(s):  
Christopher R. Dockery ◽  
Jack E. Pender ◽  
Scott R. Goode

A new method for the speciation of ng/mL concentrations of Cr(III) and Cr(VI) solutions with analysis by laser-induced breakdown spectroscopy (LIBS) is reported. Speciation is achieved by pre-concentration of the chromium onto commercially available cation exchange polymer membranes. Chromium(III) is removed directly by cation exchange; chromium(VI) in the filtrate is reduced to Cr(III) and concentrated onto a second cation exchange membrane, affording independent measurement of both species. Large volumes of waters containing Cr(III) and Cr(VI) can be concentrated onto the membranes and directly analyzed by laser-induced breakdown spectroscopy. The estimated limit of detection corresponds to 500 ng of Cr on the membrane: if a solution volume of 1 L is used, then the detection limit corresponds to a solution concentration of 0.5 ng/mL. Excellent separation of the chromium species is attained. Results show that overall method efficiencies range from 94–116% and are independent of the matrix. The influence of pH has been measured, and although Cr(VI) converts to Cr(III) in acidic solutions, the total Cr recoveries are not appreciably influenced by pH over the range of natural waters (4 to 9). In addition, speciation was performed in the presence of a number of different cations and showed that the method is robust in many different and complex matrices.


Author(s):  
Dmitry Pakhomov ◽  
Gennadii Kochetov ◽  
Dmitry Samchenko

Issues related to the prospects of implementing the latest technologies aimed at achieving energy efficiency in the field of water supply, resource conservation in material-intensive processes at industrial enterprises and prevention of environmental pollution are considered. A study of ferritative wastewater treatment from chromium compounds, which belong to the first class of danger. The efficiency of thermal and electromagnetic pulse activation of the process is compared. Appropriate experimental setups were developed and the main parameters of the purification process were studied and determined: the ratio of iron (II) and chromium (VI) ions, magnetic field strength, frequency of electromagnetic pulses, ferritization process duration, temperature and pH of the reaction mixture. The expediency of using electromagnetic pulse activation of the reaction mixture by passing electromagnetic pulses through the reaction mixture has been studied and scientifically substantiated. Rational values ​​of the strength and frequency of the electromagnetic field when using this method of activation, which are 0.01 - 0.14 Tl and 1 Hz, respectively, as well as the ratio of concentrations of heavy metal ions Fe2 + / Cr6 + = 10/1 for washing water chrome plating line . It is shown that purified water meets the requirements of category 1 when reused in production. The results of X-ray diffraction analysis of ferritization sediments showed that stable crystalline phases, such as chromium ferrites and magnetite, are formed with increasing magnetic field strength. The chemical resistance of sludge allows them to be safely disposed of. It is established that this method of electromagnetic pulse activation is not inferior to thermal, and the technical and economic calculations confirmed a significant reduction in industrial costs in its application


Antioxidants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1365 ◽  
Author(s):  
Sara C. Pereira ◽  
Pedro F. Oliveira ◽  
Sónia Rodrigues Oliveira ◽  
Maria de Lourdes Pereira ◽  
Marco G. Alves

Male reproductive tissues are strongly susceptible to several environmental and lifestyle stressors. In general, male reproductive health is highly sensitive to oxidative stress, which results in reversible and/or irreversible changes in testosterone-producing cells, spermatogenesis, and sperm quality. Chromium compounds are widely used in the +3 and +6 valence states, as food supplements, and in the industrial field, respectively. Chromium (III) compounds, i.e., Cr(III)-tris-picolinate, [Cr(pic)3], known as chromium picolinate, are used as nutritional supplements for the control of diabetes, body weight, and muscular growth. However, previous studies showed that animal models exposed to chromium picolinate experienced degenerative changes in spermatogenesis. Contradictory results are documented in the literature and deserve discussion. Furthermore, the long-term effects of chromium picolinate on the antioxidant system of treated subjects have not been properly studied. Comprehensive studies on the role of this compound will help to establish the safe and useful use of chromium supplementation. On the other hand, chromium (VI) compounds are widely used in several industries, despite being well-known environmental pollutants (i.e., welding fumes). Chromium (VI) is known for its deleterious effects on male reproductive health as toxic, carcinogenic, and mutagenic. Previous studies have demonstrated severe lesions to mouse spermatogenesis after exposure to chromium (VI). However, workers worldwide are still exposed to hexavalent chromium, particularly in electronics and military industries. Data from the literature pinpoints mechanisms of oxidative stress induced by chromium compounds in somatic and germ cells that lead to apoptosis, thus underlining the impairment of fertility potential. In this review, we analyze the benefits and risks of chromium compounds on male fertility, as well as the mechanisms underlying (in)fertility outcomes. Although supplements with antioxidant properties may maximize male fertility, adverse effects need to be investigated and discussed.


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