The production of attrition resistant, sewage–sludge derived, granular activated carbon

Granular activated carbon (GAC) production from waste materials is of considerable interest. However, waste-derived GACs may exhibit an inferior attrition resistance, inhibiting their use in pressure swing adsorption (PSA) processes or adsorption beds. This study investigated the use of pelletisation to improve the attrition resistance of a sewage sludge-derived GAC. Both extrusion and hydraulic compaction were investigated as pellet production techniques. A range of binders were evaluated, as follows: Ammonium LignoSulphonAte (ALSA); PolyVinyl Alcohol (PVA); phenolic resin; araldite resin; LignoSulphonic Acid, Calcium salt (LSAC); CarboxyMethyl Cellulose sodium salt (CMC). Hydraulic compaction (typically >500 kg/cm2) was found to be more effective than extrusion. Both low (40–110 °C) and high (500–800 °C) curing temperatures were assessed, as was the sequencing of the steam activation and pelletisation steps. The most effective pellet production method comprised coupling a lignosulphonate binder with post-pelletisation activation.

► Granular Activated Carbons (GACs) prepared from sewage sludge and attrition resistance assessed. ► Range of binders employed to enhance GACs’ attrition resistance by pelletisation. ► Pelletisation by both extrusion and mechanical (hydraulic) compaction evaluated. ► Robust GACs produced using lignosulphonate binder with post pelletisation, steam activation. ► Lignosulphonate and phenolic resin binders raised surface area of GACs activated after pelletising.