The subject matter of this application is using novel biological reactors for the fermentation of gases into liquid products. More specifically, the subject matter relates to the use of a Multiple-Pass Trickle Bed Reactor (MP-TBR) for the anaerobic or aerobic and biological fermentation of gases generated from industrial processes and/or from the gasification of biomass and other organic carbon sources. The products may include, but are not limited to, ethanol and other valuable chemicals.