Enhanced pollutant removal in multi-pollutants contaminated water by bioaugmented slow filtration

Slow filtration is a low-cost and low-carbon water treatment approach, yet its broad application is limited by long start-up times and insufficient understanding of multi-pollutant removal. Here, we evaluate whether bioaugmentation with manganese-oxidizing bacteria enhances pollutant removal in water contaminated with NH₄⁺ -N, Mn²⁺, readily biodegradable emerging contaminants (ECs, atenolol and trimethoprim), and relatively non-biodegradable ECs (carbamazepine and sulfamethoxazole). Bioaugmented filtration increased the removal rates of NH₄⁺-N and Mn²⁺ by 32.2% and 33.9%, respectively, during the first 10 days of the experiment. The proposed approach also demonstrated superior average removal rates (30.1%-99.6%) of four ECs compared to the filter column without QJX-1 inoculation (16.7%-99.3%). Furthermore, bioaugmented filtration effectively reduced the relative abundances of antibiotic resistance genes (ARGs) subtypes such as macB, tetA(58), and bcrA in the influent. The composition of ARGs on the filter media in both process groups is highly similar, with the relative abundance of ARGs at the top and middle of the filter column slightly higher than at the bottom. The mechanism study revealed that Mn²⁺ was effectively oxidized to biological manganese oxides, which was conducive to the adsorption and oxidation of Mn²⁺ and ECs. The metagenomic results confirmed the pmoC-amoC gene in Nitrospira promoted the removal of NH₄⁺-N. Toxicity prediction indicated that the toxicity of most ECs intermediates was significantly lower than that of their parent compounds. The findings of this study verify the viability of employing cost-effective and few-chemical water treatment technologies to treat muti-pollutant contaminated water and guarantee the quality of drinking water.