Chromium (VI) Reduction from Tannery Wastewater and Aqueous Solutions by Adsorption and Biosorption

Toxic and harmful metals found in wastewaters are released to the environment, and this affects the living (flora and fauna including beneficial microbes) systems. An efficient and low-cost process facilitating their treatment needs to be established. Bioremediation (metallic biodegradations) is an optimistic scheme due to its low expenditure, high proficiency, and eco-friendly nature. The ability of microbes can be used as a lucrative option for eliminating/reducing chromium from the effluent by bioremediation methods. Recently, much works have been done facilitating the understanding of the interaction between the metal and the microbial communities. Such interaction is further utilized for the detoxification of different metals. Effluent is one of the hazardous pollutants of tannery industry. Higher amounts of chrome powder and chrome liquor are used during the process of tanning. Chromium an important pollutant is famous for mutagenicity, carcinogenicity, and teratogenicity in humans, experimental animals, and plants. The removal of Cr (VI) either by reduction or biosorption can significantly reduce the dangers to human body. Bio-adsorption refers to an uptake mechanism of the constituents in the wastewater by employing the living organisms. The findings of the present study demonstrated that the bacterial strain could efficiently reduce the toxic and chromium form aerobically. Strain 1 has shown a maximum capacity (98.77%) to biosorb the chromium from 100 ppm chromium aqueous solution. As the isolated bacterial strain is an excellent reduction potential of chromium, it can be exploited at the commercial level for bioremediation of chromium-contaminated environments. The tannery wastewater was analyzed and physicochemical parameters such as alkalinity, total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), chloride, dissolved solids(DO), biological oxygen demand (BOD), chemical oxygen demand (COD), phosphate, sulfate, silicate, nitrite, nitrate, hardness, calcium, magnesium, iron, and chromium (Cr). The values are when compared with Indian standard. In this work, focus was made on the removal of cations and anions by using low-cost adsorbent, namely coir pith activated carbon. This treatment has resulted in the reduction of COD, Chloride, TS, TDS, TSS, Calcium, and chromium in 1, 10, 50, and 100% diluted tannery effluent. The results indicate that the bacterial strains have exhibited the capacity for the detoxification mechanism of chromium at low at the same time, higher adsorption capacity under a wide range of environmental circumstances. The possibility of the use of these bacterial strains for the reduction of the toxic metal in the industrial wastewater has been assessed. The identified organisms can be further employed for eco-friendly cleanup processes.