REMEDIATION OF PETROLEUM CONTAMINATED GROUNDWATER USING SAWDUST AS AN ADSORBENT

Among the various adsorbents used, sawdust appears to be the most attractive material in terms of cost, versatility and abundance. In the present research, synthetic contaminated water with gasoline was used. Adsorption of petroleum compounds on four types of sawdust (Walnut, Poplar, Beech and Pine) was studied by using batch adsorption techniques. It was found that walnut sawdust has higher adsorption capacity than other types of sawdust. It was also observed that equilibrium adsorption capacity was a function of pH, temperature, and H_2O_2 concentration in solution. Maximum adsorption of petroleum compounds was obtained at pH 8. The adsorption of petroleum compounds was increased by decreasing the temperature and H_2O_2 concentration in the solution. The maximum equilibrium capacity of walnut sawdust was 84.03 (mg COD)/(gr sawdust)nd 606.37 (mg TPH) (gr sawdust) obtained at pH 8 and+ a temperature of 10˚C. The experimental adsorption data were fitted to a Freundlich and Langmuier adsorption model. Calculated correlation coefficients indicated that the Freundlich model was best suited, indicating that the nature of walnut sawdust is heterogeneous. In this study, to illustrate the relation between q_e, C_e, pH and temperature, regression analysis was taken into consideration. The obtained model (with R^2=0.985) improved the correlation coefficient at least 1.13% compared to the Freundlich model. The maximum and minimum error of the predicted values of q_e to the experimental data was obtained as 14.29% and 0.034% for regression model, while these errors for the Freundlich model were 52.15% and 1.63%.