Removal of Heavy Metals from Industrial Wastewater Using Rice Husks

Abstract

Heavy metals are widely used in textile industries and significant losses occur during the manufacture and processing of textiles, and these lost heavy metals are discharged in the effluent. Adsorption of heavy metals is a new technology for treatment of wastewater containing different types of selected heavy metals. In this study, adsorbents Carbonized Rice Husk (CRH) and Activated Rice Husk (ARH) made out of rice husks, available as agriculture waste, are investigated as viable materials for treatment of Pb, Cd, Cu, and Zn containing industrial wastewater at controlled pH. The results obtained from the batch experiments revealed a relative ability of the rice husk in removing some heavy metals at pH 7. One hand one, the CRH adsorption capacity decreases in the order of Cu > Pb > Zn > Cd in batch adsorption whereas during Rapid Small Scale Column Tests the adsorption capacity decrease as follow Cu> Zn> Pb> Cd. On the other hand, ARH adsorption capacity performance is similar to CRH. However, during Rapid Small Scale Column Tests the adsorption capacity decreases in the order Zn>Cu>Pb>Cd. The kinetic removal in batch experiment shows that the net uptake of Pb, Cd, Cu, Zn was 54.3%, 8.24%, 51.4% and 56.7%, respectively whereas using CRH, while it varied as 74.04%, 43.4%, 70.08% and 77.2% for the same dosages of ARH. Therefore, it is concluded that as regards to CRH, ARH demonstrated higher potential to remove relatively all selected heavy metals.