Optimizing biochar-based column filtration systems for enhanced pollutant removal in wastewater treatment: A preliminary study

: This study aims to test the efficiency of biochar-based substrates in removing chemical and bacteriological pollutants from wastewater and to determine the optimal percentage of biochar (BC) to implement for large-scale filters (e.g., constructed wetlands). So, a preliminary test was conducted on a lab column scale for wastewater treatment of decanted wastewater using column filtration systems (CFS) integrated with BC (BC-based CFSs) at different concentrations (0%, 10%, 25%, and 50%). The BC used here was produced from exhausted olive pomace (pyrolised at T 590 °C, residence time of 2 h and a heating rate of 10 °C min-1). The results revealed that the BC incorporated into the CFS improved the efficiency of nitrogen species removal (total nitrogen (TN) 64-65%, total kjeldahl nitrogen (TKN) 75%-77%, organic nitrogen (ON) 78%-87%, and NH4+-N 57%-69%); phosphorus species (total phosphorus (TP) 39%-44%, PO43- 38%-42%); total and soluble chemical oxygen demand (TCOD (44%-56%), and SCOD (33%-51%) respectively); and total suspended solids (TSS) 87%-92%, compared to the control filter (CFS0). Bacteriological analysis focused on faecal bacteria indicators, including total coliforms (TC), faecal coliforms (FC), faecal streptococci (FS), as well as the pathogen Staphylococcus (SP) and total aerobic mesophilic flora (TAMF). The highest removal efficiencies were observed for CFS10. Based on this preliminary study, the efficiency of CFS in removing pollutants from wastewater is optimal with a small amount of BC (10%) from both water quality and economic points of view.