HC-0B-05: Two-Phase Partitioning Bioreactors for Treatment of Volatile Hydrocarbons

Nowadays air pollutants are becoming more widespread as the pace of industrial activity accelerates. Emission inventories reveal that atmospheric pollutant emissions have continuously increased since the beginning of the twentieth century, with volatile organic compounds (VOCs) representing about 7 % of these emissions. Despite this relatively low emission share, VOC emissions represent a major environmental and human health problem since most VOCs can be toxic depending on the concentration and exposure time and they also contribute to substantial damage to natural ecosystems. The negative effects of VOCs on human health and natural ecosystems have therefore led to stricter environmental regulations worldwide. VOCs emitted from industrial facilities are usually volatile hydrocarbons (VHs), which are extensively used in manufacturing processes. Among the available technologies for VHs treatment, biological processes in many cases constitute the most cost-effective technology for treating low pollutant concentrations and their implementation at industrial scale is growing exponentially. Unfortunately, several VHs can produce toxic effects to the microbial communities, leading to inhibition issues as in the case of aromatic compounds. Furthermore, some VHs used as monomers in the plastics industry or as industrial solvents exhibit a very low aqueous solubility, leading to mass transfer issues and poor removal performance. Two-phase partitioning bioreactors (TPPBs) emerged as innovative multiphase systems capable of overcoming the key limitations of traditional biological technologies such as the low mass transfer rates of hydrophobic VOCs and microbial inhibition at high pollutant loading rates. This work presents an updated state-of-the-art on the advances of TPPB technology for the treatment of VHs. The fundamentals of TPPB design, operation, microbiology and mass transfer are reviewed. Niches for future research, opportunities for TPPB optimization and challenges towards full-scale applications are identified and discussed.