“…100% polydimethylsiloxane (PDMS) has unlimited useful life, very less volatility, high resistance to oxidation and exceptional stability to chemical attack. Silicone oil serves as the ideal candidate for use as an organic phase, in biological waste-gas treatment applications, due to the following advantages; (i) safe to use, (ii) high stability, (iii) non-toxic to the microorganisms, (iv) allows high pollutant solubility, which enables the treatment of high pollutant concentrations, (v) increases the specifi c interfacial area (gaseous) available for microorganisms to utilize the pollutant, by reducing the surface tension of water, (vi) controls the delivery pattern of the pollutant to the aqueous phase, (vii) enhances 149 3 Novel Bioreactors for Waste Gas Treatment oxygen mass transfer rates and (viii) positive impact on downstream operations, such as product recovery (Daugulis 1997(Daugulis , 2001Kennes and Veiga 2001 ;Bailón et al 2009 ;Montes et al 2009 ;Darracq et al 2010 ;Mahanty et al 2010 ) . It is important to add only low amounts of organic phase to the system, since that additional phase will also result in an additional cost.…”