Effect of type of activating agent on properties of activated carbon prepared from digested solid waste

Anaerobic digestion has been proved to be a widely used and effective technology. The main challenge for the sustainable biogas industry is to find ways to efficiently recycle and utilize the anaerobic digestate. The conversion of digestion products into activated carbon seems to be an attractive way. Therefore, the present study focused on assessing the potential of digested solids as a promising source of activated carbon using a range of activators including KOH, ZnCl₂ and H₃PO₄. The activated carbon prepared from digested solids was subjected to an activation process to investigate the physicochemical and surface properties of the resulting activated carbon. The results showed that KOH appeared to be the best activator for producing activated carbon from high silica precursors such as digested solids. The effectiveness of KOH activation can be attributed to the ability of K to readily form poorly layered compounds with carbon, as well as a significant increase in the number of porosities during KOH activation due to the violent reaction of KOH with C and the volatilization of the inorganic minerals in the digested char. The KOH activated sample had the lowest L_a and L_c, which means it had the theoretically largest specific surface area. This study provides experimental basis and theoretical guidance for the conversion of digested solids into high value-added activated carbon.