Study of the Performance of a Composite Bioreactor on Removal of High Concentrations of Formaldehyde

Controlling high concentrations of industrial formaldehyde pollution has become a hot issue in recent years. This problem needs to be solved, where formaldehyde, which is highly soluble in water, in biofilm packed towers led to the reduction of removal performance of the packed towers. This paper presented a new method which is based on the biofilm packed tower, a liquid-phase treatment device consisting of an aeration tank and a sedimentation tank that was added to construct a composite bioreactor system. Moreover, this study investigated the effects of the composite bioreactor on the removal of formaldehyde under different operation conditions and the structural succession characteristics of the dominant bacterial communities in the composite biological system. The results indicated that even if the operating conditions including meteorological formaldehyde concentrations at the inlet, gas flow, and circulating liquid flow were changed, the B (amount of biochemically degraded formaldehyde in waste gas per unit time in a unit volume) in the composite bioreactor was also higher than that of the blank biofilm packed tower. Also, at the genus level, the microbial community structures of the two systems were not the same, where the dominant genera of the biofilm packed tower (blank group) included Pseudomonas, Methyloversatilis, Cupriavidus, and Hyphomicrobium. After the addition of the liquid-phase treatment device, the composite bioreactor promoted three aerobic bacteria including Ensife, Acidimicrobiales_norank, and Anaerolineaceae_norank to become the dominant genera. In the two systems, the relative abundances of the formaldehyde-degrading bacteria including Pseudomonas, Methyloversatilis, Methylophilus, and Methylobacterium increased with time and gradually became stabilized.