Removal of Cr(III) and other pollutants from tannery wastewater by Moringa stenopetela seed

Abstract

The tanneries release a substantial amount of trivalent chromium with wastewater that bring about serious environmental pollution problem and health hazards without proper treatment. Therefore, the chromium concentration should be kept permissible in tannery effluent. In this study, the dried Moringa stenopetela seed was used as bio-adsorbent for the removal of Cr(III) from tannery effluent. Different adsorption parameters viz. pH, adsorbent dosage, initial chrome concentration, etc. were studied for optimizing the adsorption process. The sorption mechanism was described by various isotherm models and physicochemical parameters like turbidity, conductivity and TDS were also tested after treatment. The analyses showed that the percentage of Cr(III) removal (82.93%) was obtained at pH 3, adsorbent dosage 20g(mg/l), initial concentration 1123.3mg/l, for contact time 12hours at ambient temperature. The adsorption process followed Langmuir isotherm model. Additionally, the reduction in physicochemical parameters e.g. turbidity (67.68%-72.70%), conductivity (72.88%-80.99%) and TDS (71.96%-83.33%) was found satisfactory and the values were closed to the permissible limit set by DoE. Therefore, dry Moringa stenopetela seeds can be successfully used as a low-cost tannery effluent treatment agent to reduce the environmental threats caused by harmful tannery effluents.