Metal Adsorption Methods in Treated Sewage Using Bioadsorbents and Nanoadsorbents

Metals are persistent pollutants in aquatic ecosystems that pose significant environmental and public health risks. This study evaluated seasonal variations in metal concentrations in real treated sanitary sewage (TSS) from a wastewater treatment plant (WWTP) and assessed the efficiency of two adsorbents for metal removal. Treated sewage samples were monitored over a one-year period, revealing that aluminum (Al3+) and iron (Fe2+) frequently exceeded the regulatory limits established for Class II receiving waters. Adsorption experiments were performed under optimized conditions (pH 6, 25 mg of the adsorbent, 25 mL of solution, 10 min contact time) using banana peel flour (BPF) as a bioadsorbent and Fe3O4@chitosan nanoparticles (MEC) as a nanoadsorbent. The results showed that MEC achieved higher removal efficiency for Fe2+ (76.8%), while BPF presented slightly higher removal efficiency for Al3+ (53.5%). However, adsorption efficiencies in TSS were lower than those previously observed in simulated wastewater systems, highlighting the influence of complex wastewater matrices on adsorption processes. These findings indicate that adsorption using BPF and MEC may serve as a complementary polishing step for reducing residual metal concentrations in wastewater treatment systems.