Powdered activated carbon (PAC) produced from thermal gasification of cotton gin trash was characterized. It had an average iodine number of 242 and weak adsorptive properties. The raw carbon was thoroughly washed with acid and water, and mild chemical and steam activation was performed. Upon impregnation of the carbon with ZnCl₂ in the ratio 0.8 g ZnCl₂./g carbon, the average iodine number was increased to 432. Activation with superheated steam at 150 C increased the average iodine number to 396. This activated carbon was used to treat wastewater from the Texas A&M treatment plant and was observed to follow the Freundlich isotherm. Performance characteristics were compared to commercially available activated carbons. High percentages of metal adsorption can be achieve for some specific metals in solution. More than 90% removal efficiencies were observed for adsorption of manganese and iron.