| Summary: | The enhanced effects of formaldehyde biodegradation in a biofilm packing tower are investigated in this study. Three experimental groups were established: a blank control group, a biochar addition group, and a lanthanum addition group. The inlet gas flow rate, the inlet gas concentration, and the structural succession characteristics of the microbial community in the tower were investigated by regular sampling. The intracellular metabolites and key enzymes of the dominant functional bacteria, Pseudomonas P1 and Methylobacterium Q1, in the tower were analyzed. The results indicated that with the biochar addition, the formaldehyde purification efficiency increased significantly from 91.67–94.67 % to 94.12 96.85 %, and the bio-elimination capacity increased with an increase in the inlet gas flow rate from 2.314 to 13.988 mg L−1h−1 to 2.697–15.051 mg L−1h−1. With the addition of lanthanum, the purification efficiency increased significantly from 90.80–93.98 % to 94.36–96.78 %, and the bio-elimination capacity increased with an increase in the inlet gas concentration from 1.099–11.284 mg L−1h−1 to 1.266–11.961 mg L−1h−1. The microbial community structure in the tower changed with system operation, and the formaldehyde degrading functional bacteria formed the dominant bacteria. It was verified that P1 and Q1 metabolized high concentrations of formaldehyde by the serine cycle and the ribulose monophosphate (RuMP) cycle.
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