Adsorptive removal of Pb2+ and Cu2+ from stormwater by using water treatment residuals

The removal of heavy metal ions from stormwater runoff is a global issue. One of the critical solutions is the selection of innovative adsorbent used in stormwater bioretention systems. The potential use of water treatment residuals (WTRs) containing polyaluminium chloride and anionic polyacrylamide to remove divalent lead ions (Pb2+) and divalent copper ions (Cu2+) from stormwater was investigated by batch adsorption experiments with respect to varying adsorption conditions. The maximum adsorption capacity was determined as 224.4 mg Pb2+/g WTRs and 89.0 mg Cu2+/g WTRs under acidic conditions. The adsorption process might be simultaneously controlled by surface adsorption and intraparticle diffusion. WTRs can be considered as an effective and promising media in stormwater bioretention systems to remove both ions due to its advantage of low cost, wide availability, and relatively large adsorption capacity. Further studies should be performed by using fixed bed columns at a pilot scale before field trials.