Investigating the effectiveness of using natural zeolite as an adsorbent for removing chromium from tannery wastewater :

Abstract

During the tanning step, 30–40% of trivalent chromium remains in the solid and liquid wastes, generating highly polluted sewage. Chromium is a toxic heavy metals and once it is mobilized in the aquatic ecosystem greatly endangers the life of aquatic organisms that use water for survival and also to people who consume fish causing several irreversible damages such as genetic defects, impairment of pulmonary and kidney function. In this study, zeolite was used as a low-cost adsorbent to remove trivalent chromium from tanning effluent. Batch adsorption experiments on zeolite was performed. After samples were filtered, and the uptake of chromium was determined. A 3-level Box-Behnken Design was used to study the combined effect of contact time, pH values and adsorbent dose on the removal of trivalent chromium.

The study was done in skyfat tannery located in Jinja, Uganda. The effects of pH (3–8), contact time (5–60 mins), and adsorbent dose (0.1-1g) and their interactions were investigated using response surface methodology following a box Behnken design. Optimum adsorption capacity (92.21%) was obtained at pH 4.41, contact time 31.667 minutes and adsorbent dose 0.6545g by response surface plots and response optimizer in Minitab 20.0 software