Demonstration of efficient trichloroethylene biodegradation in a hollow-fiber membrane bioreactor.

Rapid cometabolism of trichloroethylene (TCE) by pure cultures of Methylosinus trichosporium OB3b PP358 was demonstrated in a two-stage hollow-fiber membrane bioreactor over the course of 3 weeks. PP358 was grown in a continuous-flow chemostat and circulated through the shell of a hollow-fiber membrane module (HFMM), while TCE contaminated water (160 to 1450 micrograms/L) was pumped through the fiber lumen (fiber interior). In parallel-flow HFMM biological experiments, 82% to 89% of the influent TCE was removed from the lumen (5.1-min residence time) with 99% of the transferred TCE undergoing biodegradation. Biological experiments in a larger capacity baffled radial-flow HFMM resulted in 66% to 99% TCE transferred and 93% to 96% TCE biodegradation at lumen residence times of between 1.5 and 3.7 min. Biodegradation was maintained throughout the experiments at pseudo-first-order biodegradation rate constants of 0.41 to 2.8 L/mg TSS/day. Best-fit computer modeling of the baffled radial-flow biological process estimated mass transfer coefficients as large as 2.7 x 10(-2) cm/min. The computer model was also shown to simulate the experimental results quite well.