Removal of pesticide in agricultural runoff using granular-activated carbon: a simulation study using a fixed-bed column approach

The use of pesticide and its subsequent release to the environment is a major concern for modern society as concerns over environmental pollution associated with toxic emission are recognized due to contaminants present in pesticide (particularly malathion). Adsorption process using activated carbon is among the most effective techniques for the removal of pesticides in the treatment of various waste streams. The adsorption of pesticide containing malathion in agricultural runoff was investigated using granular-activated carbon (GAC) as the adsorbent; GAC made of coconut, and palm shells were used and their effectiveness in retaining the pesticide is discussed. A fixed-bed column test was performed to simulate the actual condition of adsorption in a continuous manner in a filtration process. Different flow rates were used to evaluate their effects on the column performance, where different breakthrough curves were obtained. The Adam-Bohart breakthrough curve equation was used to predict the breakthrough curve and to obtain the adsorption capacity of pesticide on GAC. The results showed that the Adam-Bohart equation fitted the experimental data well, and the use of a bed of GAC as the adsorbent in the set up showed high capacity in retaining the pesticide present in the aqueous solution, achieving removal efficiency at the rate of 71.4 and 82.9% for palm shell activated carbon and coconut shell activated carbon, respectively. Our results indicate that the use of GAC through adsorption process shows exceptional promise as a means for treating problematic pesticide in agricultural runoff.