Hybrid-Hollow-Fiber Membrane Bioreactor for Cometabolic Transformation of 4-Chlorophenol in the Presence of Phenol

摘要

Hybrid-hollow-fiber membrane bioreactors were developed for the enhanced cometabolic biotransformation of phenol and 4-chlorophenol (4-cp) by Pseudomonas putida ATCC49451. Bioreactor performance was investigated, compared, and analyzed under batch and continuous operating modes. The spinning solutions contained polysulfone (PS), N-methyl-2-pyrrolidone, and various weight ratios of granular activated carbon (GAC) (GAC: PS of 0, 1:4, and 1:2). The bioreactor fabricated with 1:2 GAC hybrid-hollow-fiber membranes demonstrated the best performance for the removal of phenol and 4-cp, both under batch and continuous operations. Under batch operation, 500 mg L-1 phenol and 4-cp were completely removed within 23 h in the bioreactor, compared with 26 and 30 h for the 1:4 GAC and GAC free bioreactors. Sorption, biotransformation, desorption, and bioregeneration were identified as the four steps for substrate removal during batch operation. The 1:2 GAC hollow-fiber membrane bioreactor also manifested superiority over the other two during continuous operation for start up and the transient phase after shock loadings of the feed. 300 mg L-1 phenol and 4-cp were completely removed in the 1:2 GAC hybrid-hollow-fiber membrane bioreactor whereas 4-cp was not completely removed in the other two bioreactors at a feed rate of 30 mL h?1. From the experimental results, it was inferred that at steady state, biotransformation was achieved through the dynamic equilibrium among sorption, desorption, and biotransformation rates established within the bioreactors.