Dried activated sludge has been explored for the sorption of phenol, o-chlorophenol and p-chlorophenol from aqueous solutions. The maximum sorption capacity of dried activated sludge was found to be 86.1 mg/g for phenol, 102.4 mg/g for o-chlorophenol and 116.3 mg/g for p-chlorophenol at 100 mg/L initial pollutant concentration. Selvaraj et al. investigated the potential of distillery sludge for Cr(VI) removal and reported the Langmuir adsorption capacity of 5.7 mg/g for Cr(VI). Li et al. utilized wine processing waste sludge as an effective adsorbent for Cr(III) removal. Adsorption dynamics had been successfully described by the Lagergren model and intraparticle diffusion model.
Biological sludge after physical activation with steam was studied for industrial effluent treatment. It was shown that after activation, there was an improvement of pore and adsorption characteristics of the adsorbent, with specific surface area reaching 230 m2/g and equilibrium adsorption capacities of 50 mg/g for phenol.