In recent years, numerous low cost adsorbent materials have been evaluated for their capacity to remove phenol from aqueous solution. This book provides a study of the potential use of sewage sludge ash (SSA) as an adsorbent in removing phenol from aqueous solutions. Parameters which contributed to affect phenol removal were initial phenol concentration, contact time, adsorbent dosage, pH and particle size of adsorbent. Results showed that the adsorption capacities of adsorbent (Kf) for phenol decreased as initial phenol concentration, contact time and adsorbent dosage increased however, increased as particle size increased and pH decreased. Results also revealed that solution with higher initial phenol concentration required longer time to reach equilibrium state. Adsorption isotherm analysis showed that the experimental data fit Freundlich model in most conditions. The results from this study provide an important insight for engineers, scientists, environmentalists and researchers in this area.