Formaldehyde biodegradation by immobilized Methylobacterium sp XJLW cells in a three-phase fluidized bed reactor

In the present study, the ability of a newly isolated strain, Methylobacterium sp. XJLW to degrade formaldehyde was investigated in shake flasks and in a bioreactor. The resting cells of Methylobacterium sp. XJLW showed high formaldehyde tolerance (60 g L-1) and high degradation rate (1,687.5 mg L-1 h(-1)) in shake flasks. This biodegradation was initiated by a dismutation reaction since formic acid was formed and caused significant dropping of pH in the media. The addition of CaCO3 to the media was found as an effective strategy to control the pH and keep the cells in high degradation bioactivity. A three-phase fluidized bed reactor (TPFBR) was designed to test the formaldehyde-biodegrading ability of immobilized Methylobacterium sp. XJLW. Using a repeated-batch degradation mode, the immobilized cells were able to degrade 5 g L-1 formaldehyde (with a maximal degradation rate of 464.5 mg L-1 h(-1) under the optimum conditions) and showed stable bioactivity after 20 batches of reuse in the TPFBR.