Primary sewage sludge-derived activated carbon: characterisation and application in wastewater treatment

The present study deals with the characterization of primary sewage sludge-derived activated carbons which were used for phenol adsorption from the synthetic wastewater. The waste-derived adsorbents were prepared by a two-step process: chemical activation (with ZnCl2 and KOH) followed by pyrolysis. The mesoporous adsorbents were found to have BET surface area comparable to commercial activated carbon (surface area = 495-515 m(2)/g). The adsorption runs were performed in orbital shaker with synthetic phenolic wastewater (phenol concentration = 50-250 mg/L) to investigate the effect of various reaction parameters. The equilibrium phenol adsorption data could be described by Redlich-Peterson isotherm model and the pseudo first-order kinetic model exhibited the best fit to time-based adsorption data. The phenol adsorption was endothermic for all adsorbents. The performance of the thermally regenerated waste-derived adsorbents in the wastewater treatment was found to reduce significantly.