Removal of hexavalent Chromium-Industry treated water and Wastewater: A review

Heavy metals present in industrial effluents enter the biological cycle through aquatic organisms. Heavy metals undergo bioconcentration and prove to be toxic even in trace quantities. Chromium is necessary for carbohydrate metabolism, but in higher concentrations, it tends to be harmful. Hexavalent chromium Cr (VI) ions are prevalent, and its toxicity causes environmental and public health concerns. Chromium (IV) based industrial effluents have become a worldwide menace. This collection of toxic metals ions from effluent streams affects both humans and the environment. The non-depleting heavy metal ions cause severe damage to the environment. Environmental pollution affects both human life and eco-system. Water pollution from municipal sources and industries are matter of concern. The solution to the fast-depleting natural water bodies and acquifiers is to reuse treated effluent. Several remediation technologies are available, for reclaiming effluent after treatment for heavy metals like Cd, Cr, Cu, Hg, Ni, Pb, and Zn. This paper attempts to assimilate concise information on removing hexavalent chromium through laboratory experiments to implement cost-effective, plausible industrial treatments practically. The importance of efficient industrial effluent treatment lies in the recovery of heavy metals and usage of the treated effluent. A list of techniques is thought of for the treatment of heavy metals removal that has minimal impact on the environment in liquid / solid phases, cost of treatment, and scaling up to industrial levels. Adsorption is one of the prominent techniques used for heavy metals treatment. The adsorption kinetics and isotherms help understand the reduction of Cr (VI) from effluent streams. The wastewater treatment techniques currently employed treat hexavalent chromium-containing effluent streams with low-cost industrial byproducts. Emphasis is on novel techniques of wastewater treatment electrochemical techniques for Cr (VI), contributing to various environmental problems based on their toxicity. (C) 2020 Elsevier Ltd. All rights reserved.