![]() Again, advanced treatment techniques, such as ion exchange, reverse osmosis, electrocoagulation, membrane filtration, and electrodialysis are effective for removing Cr(VI), but these are expensive and produce concentrated wastes that require subsequent treatment and disposal (Komori et al. Parameters or factors that are affecting the precipitation including the type of precipitation agent, pH, speed or agitation, sludge volume, time of mixing, and complexing agents (Abdulla et al. Commonly used chemical precipitators are sodium hydroxide, calcium hydroxide, magnesium oxide, or calcium magnesium carbonate. 2005).Among these, chemical precipitation is the common way for the removal. Several treatment procedures such as adsorption, chemical precipitation, electrocoagulation, ion exchange, electrodialysis, and membrane separation are available for removal of Cr from wastewater (Fathima et al. For this reason, hard and fast environmental regulations exist in many countries for controlling the discharge concentration limit of chromium to the environment. Apart from surface water pollution, groundwaters are also contaminated by Cr-related industrial activities (Belay 2010 Swathanthra and Rao 2014 Kowalski 1994 Dokken 1999). The trivalent chromium is more stable and sometimes is essential for mammals in trace amount and comparatively immobile in the aquatic system owing to its low water solubility. Its toxicity may damage human organs including kidney and liver as well as can cause dermatitis and gastrointestinal ulcers. This Cr(VI) is a carcinogenic agent which can cause health risks for humans. Chromium exists in oxidation states of Cr(II), Cr(III) and Cr(VI) where hexavalent form of Cr is 500 times more toxic than the trivalent one. In addition, water contamination by chromium (Cr) has drawn greater attention in the present context of global ecology as this metal has found its extensive use in textile industries, electroplating, leather processing, metal finishing, and chromium preparation. Among them, chromium is one of the familiar contaminants which gains importance owing to its highly toxic character even at a very low concentration. ![]() Treatment of wastewater for removing toxic metal pollutant contents is of great concern as these metals create a great threat to people’s and animal’s health. Wastewaters from industries generally include processing waste from the manufacturing unit, sanitary waste of employees, water discharged from washing factory floor and relatively uncontaminated heating and cooling water (Emongor et al. Various industrial processing are the main sources of water pollution, and it may vary extensively with the nature of industry. In the name of urbanization and industrialization, people on Earth are polluting the Earth’s blood that is water. Without water, Earth may be considered as an another planet, a sterile, desolate, grey hunk of orbiting rock (Spellman 2017). ![]() ![]() Water in the Earth is analogous to blood in the human body. This paper represents the review of various available techniques as well as represents a case study of chromium removal from tannery effluent by a low-cost absorbent. Recently, various applications of advanced technologies such as membrane technology, electrocoagulation, ion exchange, and electrodialysis for tannery wastewater have been growing due to their relative advantages over other technologies in terms of sustainability. Conventional physico-chemical and biological processes can remove this heavy metal in considerable amounts. The heavy metal chromium (Cr), one of the pollutants found in tannery effluent, is very much detrimental to human health, animals, and plants. ![]() Tannery industry releases more toxic effluent than most industries, which directly and indirectly exerts stress on various ecosystems. Industrial activities that consume water generate wastewater as a by-product of processing which introduces various contaminants such as heavy metals into the neighbouring water bodies that creates adverse effects on the surrounding environment. ![]()
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