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
