Removal of heavy metals using kaolinite and Bentonite filter media

Abstract

Heavy metals are among the most lethal pollutants of surface water. The main sources of heavy metals are industrial wastes from processes such as mining operations and ore processing, smelter, textile, leather dyeing, coating, metal finishing, chemical manufacturing, refineries, power generation and nuclear fuel processing. The concentration of heavy metals should be reduced to the acceptable levels before discharged into the environment because these are non degradable into nontoxic metals end products and the well known damaging effects of heavy metals on human being and other habitants. Sets of experiments were carried out to examine the ability of (kaolinite and bentonite) to reduce the concentration of chromium and cadmium ions in raw synthetic wastewater using upflow filter respectively. The main parameters were solution pH 2-6, retention time 12-72 hrs, the initial concentration of pollutants 100–500 ppm and filter media height 10.5-42 cm. All data were analyzed by regression analysis model to correlate the different boundary conditions. The highest achieved % removal efficiency of Cr and Cd were 96% and 91% through kaolinite and bentonite clay filter media at pH 6.0 and 5.0 respectively, retention time 24 hr, initial concentration 100 ppm and filter media height 42 cm. The results of regression models indicate that the most influential independent variables in the % removal efficiency of Cr and Cd ions from aqueous solutions using kaolinite and bentonite clay upflow filter pH, retention time and height media filter, which affects positively. Results of the experimental data show that the best empirical correlation achieved the highest fitting of predicted % removal of Cr and Cd using kaolinite and bentonite clay separately that gives the highest value of (R2 = 0.995 and 0.988)respectively.