Performance evaluation of an aqueous-silicone oil two-phase partitioning bioreactor using Rhodococcus erythropolis T902.1 to remove VOC from gaseous effluents.

BACKGROUND: In the framework of biological processes used for waste gas treatment, the impact of the inoculum size on the start-up performance must be better evaluated. Moreover, only few studies have studied the behaviour of elimination capacity and biomass viability in a two-phase partitioning bioreactor (TPPB) used for waste gas treatment. Lastly, the impact of ethanol as a cosubstrate remains misunderstood. RESULTS: Firstly, the results show that no benefit of the inoculation with a high cellular density (> 1.5 g.L-1) can be observed on start-up performances. Secondly, the TPPB was monitored during 38 days to characterise its behaviour for several operational conditions. The removal efficiency is kept at 63 % for an inlet concentration of 7g.Nm-3 isopropylbenzene (IPB) and at some times points reaches 92 % during an intermittent loading phase (10 h.day-1), which corresponds to an elimination capacity mean of 4.10-3 g.L-1.min-1 (240g.m-3react.h-1) for an IPB inlet load (IL) mean of 6.19.10-3 g.L-1min.-1 (390 g.m-3.h-1). At continuous IPB loading, the performances of TPPB fall but the biomass acclimation to this operational condition is shorter than five days. The biomass grows to approximately 10 g.L-1 but cellular viability strongly changes during experiment. It can be suggested an endorespiration phenomenon in the bioreactor. In present work, it is also shown a simultaneous degradation of IPB and ethanol suggesting that the ethanol improves the biodegradation without generating an oxygen depletion. CONCLUSION: The TPPB water-silicone oil, with ethanol as cosubstrate allows removing high inlet load of IPB during the 38 days experiment