METHANOTROPHIC BIODEGRADATION OF TRICHLOROETHYLENE IN A HOLLOW-FIBER MEMBRANE BIOREACTOR

Biodegradation of trichloroethlyene (TCE) in a hollow fiber membrane b ioreactor was investigated using a mutant of the methanotrophic bacter ia, Methylosinus trichosporium OB3b. Contaminated water flowed through the lumen (i.e., fiber interior), and the bacteria circulated through the shell side of the membrane module and an external growth reactor. In mass transfer studies with a radial cross-flow membrane module, 78 .3-99.9% of the TCE was removed from the lumen at hydraulic residence times of 3-15 min in the lumen and the shell. In biodegradation experi ments, 80-95% of the TCE was removed from the lumen at hydraulic resid ence times of 5-9 min in the lumen. The TCE transferred to the shell w as rapidly biodegraded, with rate constants ranging from 0.16 to 0.9 L (mg of TSS)(-1) day(-1). Radiochemical data showed that over 75% of t he transferred TCE was biodegraded in the shell, with the byproducts b eing approximately equally divided between carbon dioxide and nonvolat iles. This study shows that a hollow fiber membrane bioreactor system coupled with the mutant strain PP358 of nn. trichosporium OB3b is a ve ry promising technology for chlorinated solvent biodegradation.