An innovating process for pollutants concentration in gaseous effluents: application to high gas flow rates with low VOC concentrations

Among all kinds of atmospheric pollution, volatile organic compounds (VOCs) have raised a lot of interest recently. For high flow rates of low polluted gaseous effluents, the Bioprocess and Biotechnology Laboratory of the INSA of Toulouse has developed a costeffective process to concentrate polluting molecules into a smaller gas flow rate. The concentration process is based on mechanical desorption of dissolved gases. The first step consists in an absorption step. The next step is a desorption step. Micro-bubbles are then separated from the liquid flow using an in-house designed gas/liquid separator (improved gas/liquid cyclone) and constitute the high polluted gas effluent. The ratio between the high polluted gas flow rate and the initial low polluted gas flow rate is the concentration factor. The cleaned liquid phase is recycled for a new absorption step. First results have shown a 90% recovery of VOCs from the liquid flow to the high polluted gas flow with the three target molecules. According to these results, this concentration technology seems to be of particular interest to improve economic efficiency of degradation processes, such as thermal incineration, reducing the gas flow rate to treat. Thus, it would facilitate purification steps in the case of economically interesting molecules because of the smaller gas flow rate treated.