Performance of garden-waste-based activated carbon to remove natural organic matter from reservoir water: transition from GAC to BAC

Graphical abstract showing activated carbon from municipal garden waste used in long-term column filtration of reservoir water, promoting biofilm formation and enhancing NOM removal, resulting in improved effluent quality across different carbon media. This is the first research to investigate the conversion potential of garden-waste-based activated carbon (SAC) into biological activated carbon (BAC) for water treatment. Five identical columns containing different carbon media were operated with reservoir water for eight months to compare the performance of natural organic matter (NOM) removal. Effluent chemistry was monitored regularly, and three distinct phases were observed across the operational period for all carbon media. From days 1 to ∼65, ∼65 to 146, and 146 onwards, phases can be defined as the development phase, the breakthrough phase, and the equilibrium phase, respectively. Conversion of activated carbon (AC) into BAC was demonstrated by the steady removal of dissolved organic carbon (DOC) during the equilibrium phase, biofilm formation on the AC media, and was visualized. Seeding with pre-established BAC did not enhance column stabilization time. Despite having lower initial DOC removal, SAC ultimately showed a similar removal efficiency (37.5%) to commercial AC by the end of the experiment, particularly for NOM with a molecular weight below 3,000 Da. Therefore, the results suggest SAC as an effective medium for biological filtration and this finding may open up a promising approach for water utilities to provide affordable services through the re-use of municipal garden waste.