Performance of an optimally filled discontinuous bioreactor degrading 4-chlorophenol.

The stability of a fed-batch bioreactor operated with a new control strategy (ED-TOC) during a long-term period was evaluated. The ED-TOC strategy uses solely measurements of DO concentration and volume of the reactor to control the influent flow rate, and so the substrate degradation rate oscillates around its maximal value during the whole filling phase. The bioreactor was tested for the degradation of a wastewater containing 4-chlorophenol (4CP) as a model of an inhibitory compound. The experiment was conducted twice in order to investigate whether results were reproducible. Each set of experiments consisted of two phases: acclimation of the biomass to 4-chlorophenol and operation using the ED-TOC strategy. The main conclusion is that the reactor operated by the ED-TOC strategy is robust and stable in large operation periods. Degradation efficiencies greater than 99% as 4CP and greater than 97% as COD degradation were obtained. Toxicity analysis demonstrates that the bioreactor operated by ED-TOC eliminates the toxicity in the wastewater. Community analysis by DGGE was also conducted.