<p>Disinfection byproducts (DBPs) are generated via the interaction between natural organic matter (NOM) and disinfectants, such as chlorine, and have been linked to many health issues, such as liver, kidney, and central nervous system problems; reproductive effects; and some forms of cancer. One method to address the DBP issue is to remove NOM so that precursors are unavailable at the time of chlorination to form DBPs. Two common treatment options for NOM removal include adsorption using activated carbon and membrane separation. Here, the ability of biochar to adsorb NOM from water when incorporated into polysulfone (PSf)-based membranes was investigated to develop multifunctional adsorbing membranes. This was carried out by comparing PSf ultrafiltration membranes immobilized with biochar, lab-activated biochar, carbon black, and activated carbon. For biochar activation, parameters such as the activating agent, activation time, and activation agent exposure time were investigated. The results showed that the addition of biochar to the PSf membrane matrix not only improved the permeability of the membranes but also improved the rejection of humic acid from water. Furthermore, membranes with biochar activated with 1% hydrogen peroxide (H₂O₂) exhibited the highest humic acid rejection (92.4 ± 0.5%) as compared to 71.1 ± 2.0%, 65.7 ± 3.5%, 70.9 ± 3.7, and 25.9 ± 3.6% of the inactivated biochar, activated carbon, black carbon, and pristine PSf-NMP membranes respectively. These findings showed that biochar could act as an alternative to activated carbon and black carbon for the removal of humic acid and that membranes made with biochar rejected humic acid via both sieving and adsorption mechanisms.</p>