hexavalent chromium reduction

Hexavalent chromium reduction by chromate-resistant ...

Hexavalent chromium reduction by whole cells and cell free extract of the moderate halophilic bacterial strain Halomonas sp. TA-04. Int J Biodeterioration Biodegradation. 2012; 66:63–70. [Google Scholar] Zhang K, Li F. Isolation and characterization of a chromium-resistant bacterium Serratia sp. Cr-10 from a chromate-contaminated site.

Reduction of Hexavalent Chromium and Detection of …

Hexavalent chromium reduction was mainly associated with the soluble fraction of the cell evaluated with crude cell-free extracts. A protein of molecular weight around 25 kDa was detected on SDS-PAGE gel depending on the concentration of hexavalent chromium in the medium (0, 100 and 500 mg/L).

How Do You Remediate Hexavalent Chromium Cr(VI)?

A full implementation design plan was prepared for the reduction of hexavalent chromium and stabilization in both soil and groundwater. Case Study: Remediating Cr(VI) at a Former Wire Plating Site. At a wire manufacturing company, hexavalent chromium plating operations were performed from 1963 to …

Enhanced reduction and adsorption of hexavalent chromium ...

The formation of FeCr 2 O 4 can be attributed to the reduction of Cr(VI) by the nZVI and coprecipitation of chromium oxide with iron on the RS700 surface. Therefore, nZVI-RS700-Pd is a potential remediation reagent that can be used to effectively treat Cr(VI)-contaminated groundwater.

Hexavalent Chromium Solubility and Reduction in Alkaline ...

Hexavalent Chromium Solubility and Reduction in Alkaline Soils Enriched with Chromite Ore Processing Residue Bruce R. James, Soil Chemistry Laboratory, Agronomy Dep., Univ. of Maryland, College Park, MD, 20742

Electrochemical Reduction of Hexavalent Chromium in ...

electrochemical reduction of hexavalent chromium without interference from H + or H. 3. O + equivalents. To reduce hexavalent chromium in non-aqueous media, a suitable procedure must be developed, the mechanism of the reduction process must be understood and ways to make the reduction more efficient must be explored. The focus of this research

A study on the reduction of hexavalent chromium in …

Hexavalent chromium introduced to the water ecosystem is an important issue due to the toxic effect it poses. The first step of conventional treatment of wastewaters containing hexavalent chromium is its reduction to chromium (III) which is less toxic. The use of industrial waste material for the re …

Biological reduction of hexavalent chromium - A field ...

A leachate that contains hexavalent chromium (Cr6+) is formed when rainwater percolates through the dust deposit. In this study, Cr6+ in the leachate was reduced to trivalent chromium (Cr3+) by biological treatment in a biofilm process operated under anaerobic conditions. The reactor volume was 26 m (3) and it was filled with 16 m (3) plastic ...

The reduction of hexavalent chromium by sulphite in …

The reduction of hexavalent chromium, Cr(VI), in unbuffered aqueous solution by sulphite was investigated as a function of pH, possible dosage and contact time required to reach equilibrium. Dissolved Na 2 Cr 2 O 7.2H 2 O served as the aqueous source of Cr(VI).

Reduction Monitoring in the Chromium Wastewater Treatment ...

The hexavalent chromium in this wastewater must be reduced before the water can be discharged. This requires a two-step process: hexavalent chromium (CR 6) is reduced to trivalent chromium (CR 3 ); and CR 3 is precipitated as chromium hydroxide. As the oxidation reduction potential (ORP) and the speed of the reduction reaction are closely tied ...

(PDF) The reduction of hexavalent chromium by sulphite in ...

The reduction of hexavalent chromium, Cr(VI), in unbuffered aqueous solution by sulphite was investigated as a function of pH, possible dosage and contact time required to reach equilibrium.

Hexavalent chromium reduction kinetics in rodent stomach ...

1. Introduction. Extracellular reduction of hexavalent (Cr(VI)) to trivalent chromium (Cr(III)) in gastric fluid is a well-recognized detoxification process (De Flora and Boido, 1980, De Flora, 2000) thought to protect against systemic toxicity of ingested Cr(VI) at doses that do not overwhelm reductive capacity.Recently, chronic exposure to Cr(VI), in the form of sodium dichromate dihydrate ...

Full-scale Demonstration Testing of Hexavalent Chromium ...

Reduction/Coagulation/Filtration for Hexavalent …

Hexavalent Chromium Removal from Drinking Water Nicole Blute, PhD, PE Ying Wu, DEnv, PE Ramon Abueg, PE. Agenda •Introduction ... Cr 6 Reduction by Ferrous Iron at Various Reduction Times with Chlorination (Bench-Scale Testing Results) Cr(VI) in Reduced Water Cr(VI) in Chlorinated Water

Efficient adsorption/reduction of aqueous hexavalent ...

Efficient adsorption/reduction of aqueous hexavalent chromium using oligoaniline hollow microspheres fabricated by a template-free method. Chongzhuo Bao, School of Materials Science and Engineering, Yunnan University, Kunming, PR China. Search for more papers by this author.

Bioprocess development for hexavalent chromium reduction ...

Hexavalent chromium, Cr (6 {sup +}), is a common and toxic pollutant in soils and waters. Reduction of the mobile Cr (6 {sup +}) to the less mobile and less toxic trivalent chromium, Cr (3 {sup +}), can be achieved with conventional chemical reduction technologies. Alternatively, Cr (6 {sup +}) can be biochemically reduced to Cr (3 {sup +}) by ...

(PDF) Biological Reduction of Hexavalent Chromium—A Field ...

Ishibashi Y., Cervantes C., and Silver S. (1990). Chromium reduction in Pseudomonas putida. Applied and Environmental Microbiology, 56, 2268-2270. Megharaj M., Avudainayagam S., and Naidu R. (2003). Toxicity of Hexavalent Chromium and its reduction by bacteria isolated from soil contaminated with tannery waste. Current Microbilogy, 47, 51-54.

Hexavalent chromium analysis, reduction and stabilization ...

Hexavalent chromium is one of the toxic contaminants unavoidably widespread in the environment that exists in cement and concrete. Cement producers need to determine and control the content of hexavalent chromium, hence this study investigated the effect of environmental parameters on the leachability, stability and reduction of Cr(VI) in

Hexavalent Chromium Reduction under Fermentative ...

Microbial reduction of toxic hexavalent chromium (Cr(VI)) in-situ is a plausible bioremediation strategy in electron-acceptor limited environments. However, higher [Cr(VI)] may impose stress on syntrophic communities and impact community structure and function. The study objectives were to understand the impacts of Cr(VI) concentrations on community structure and on the Cr(VI)-reduction ...

Modeling hexavalent chromium reduction in Escherichia coli ...

A model based on te analysis of the mechanism of enzymatic reactions was developed to characterize the rate and extent of microbial reduction of hexavalent chromium in Escherichia coli 33456. A finite reduction capacity (R c) was proposed and incorporated into the enzymatic model to regulate the toxicity effect on cells due to the oxidizing power of Cr(VI).

Department of Defense Cadmium and Hexavalent Chromium ...

Hexavalent chromium (Cr 6+) • Known carcinogen • Attacks the respiratory tract, liver, kidneys, skin, and eyes • Exposures occur during welding, coating processes, and surface finishing processes • Documented 75,219 pounds of Cr 6+ used in CY 2015 (5 depots); 67,173 pounds of Cr 6+ used in CY2017 (14 depots) Cadmium (Cd) • Known ...

Reduction of hexavalent chromium in wastewater using ...

The toxic hexavalent chromium is highly mobile whereas its trivalent counterpart, Cr (III) is less mobile and less toxic. Hence treatment of hexavalent chromium requires a reduction process. Most of the chemical reduction processes with subsequent precipitation using zerovalent iron or ferrous sulphate generates a huge quantity of sludge that ...

Reduction of Hexavalent Chromium and Detection of Chromate ...

Effects of citrate on hexavalent chromium reduction by ...

1. Introduction. Hexavalent Chromium (Cr(VI)) is a widespread pollutant in the environment, largely due to its use in industries such as steel manufacturing and leather tanning .Chromium has several oxidation states, but the most common and stable forms are Cr(III) and Cr(VI).

PHOTOCATALYTIC REDUCTION OF HEXAVALENT …

Thus, reduction of chromium from its hexavalent to trivalent states simplifies its removal from effluent and also reduces its toxicity and mobility. 2 Chemical precipitation has traditionally been the most used method for the treatment of Cr(VI) following its reduction. The most widely-used industrial reducing

Technical Notebook HEXAVALENT CHROMIUM REDUCING …

HEXAVALENT CHROMIUM REDUCTION - CHEMICAL BACKGROUND While Cr (VI) is a strong oxidising agent in acid solution, in an alkaline media (such as the cement gauge water) the situation is different and it is impossible to reduce the Cr (VI) using most of the reducing agents which

Factors affecting the reduction and absorption of ...

Factors affecting the reduction and absorption of hexavalent chromium in the gastrointestinal (GI) tract: Potential impact on evaluating the carcinogenic ity of ingested hexavalent chromium. Hexavalent chromium is a known human carcinogen via inhalation (IARC, 2012; OSHA, 2006; U.S.

Reduction of hexavalent chromium by Ochrobactrum ...

Hexavalent chromium-resistant Ochrobactrum intermedium BCR400 was isolated from chromium contaminated soil collected from Vadodara, Gujarat. It reduced 100 mg Cr(VI)/L completely in 52 h with initial Cr(VI) reduction rate of 1.98 mg/L/h. The Cr(VI) reduction rate decreased with increase in Cr(VI) concentration from 100 to 500 mg/L.

US3679557A - Hexavalent chromium reduction - Google Patents

disclosed is an electrochemical process of reducing cr(vi) oto cr(iii) in aqueous solution. the ph of the solution is adjusted to about 1.5-3 and subjected to the action of an electrolytic cell by passing the solution through the cell and hece the cathode thereof. the cathode of the cell is made of an electrolytically conductive material, for instance carbon, having a high surface area per ...

Chrome Reduction | Products Finishing

That being said, our experience has been that, for the vast majority of chrome reduction applications, the use of sodium metabisulfite (MBS) is best. Sodium metabisulfite (Na 2 S 2 O 5 ), when added to water, forms sodium bisulfite (NaHSO 3 ), which reacts with the hexavalent chromium (Cr +6 ) to form trivalent chromium (Cr +3 ) according to ...

(PDF) Hexavalent chromium reduction by Providencia sp ...

Hexavalent chromium reductase in bacteria rate, maximum chromium reduction by unit dry weight of the is mainly associated with the soluble fraction of the enzyme. biomass and maximal chromium reduction with varying initial The chromate reductase purified from P. putida MK1 is also chromium …

Hexavalent chromium removal by reduction with ferrous ...

DOI: 10.1021/ES050486P Corpus ID: 39057480. Hexavalent chromium removal by reduction with ferrous sulfate, coagulation, and filtration: a pilot-scale study. @article{Qin2005HexavalentCR, title={Hexavalent chromium removal by reduction with ferrous sulfate, coagulation, and filtration: a pilot-scale study.}, author={Gang Qin and M. McGuire and N. Blute and C. Seidel and L. Fong}, journal ...

Evoqua removes hexavalent chromium from groundwater using ...

Chromium is a naturally occurring element found in rocks, animals, plants, and soil. Chromium has several different forms. The most common forms are chromium metal (or chromium (0)), trivalent (or chromium (Ill)), and hexavalent (or chromium (VI)). Chromium (0) and chromium (VI) are generally produced by industrial processes.