IMPROVEMENT AND CONTROL OF THE MICROBIAL ACTIVITY OF A MIXED POPULATION FOR DEGRADATION OF XENOBIOTIC COMPOUNDS

A computer-aided sequencing batch reactor, CA-SBR, was used in order to monitor, improve and control the microbial activity for xenobiotics degradation. The control parameter for the reactor operation was the carbon dioxide evolution rate. Activated sludge was acclimated to 4-chlorophenol, 4CP, and was used as inoculum for the reactor. A specific substrate degradation rate, q(m), of 116 mg 4CP/gMLSS-h was obtained for the best conditions using the CA-SBR. Whereas, with a 24-hour SBR cycle policy, q(m) was 20 mg 4CP/g MLSS-h. The ability of acclimated micro-organisms to degrade 4CP decreased as a consequence of starvation periods. Inductive enzyme activity decreased by as much as 80 % after 6 hours of starvation. Furthermore, a loss of 60 % in cell viability was found after 20 hours of starvation.