Utilization of sludge based adsorbents for the removal of various pollutants: A review

Sludge based adsorbents are widely used for the removal of various pollutants from water and wastewater systems and the available data is much diversified. The purpose of this review is to organize and critically review the scattered available information on the potential of use of sludge based adsorbents for the removal of various pollutants. It was observed that performance of the sludge based adsorbents varies depending on the type of pollutants, type of precursor sludge, carbonization time-temperature profile and the type of activation conditions used. The variation in pyrolysis and activation conditions found to directly affect the adsorbent properties, adsorption capacity and the mechanism of pollutant removal by sludge based adsorbents. The interaction mechanisms of pollutants with adsorbent surface found to have a detrimental effect on desorption and regeneration of the adsorbents and its recycling potential. Therefore, desorption and regeneration technique used for recycle of the adsorbents is also discussed in detail. Moreover, life cycle and cost analysis of sludge based adsorbents is assessed to ensure the cost effectiveness of their application in water treatment operations.