Effect of Dry Periods in a “Mist-Foam” Bioreactor Designed for Gaseous Substrate

Abstract

The “Mist-Foam” concept for gaseous substrates involves mixing a gaseous substrate and a liquid nutrient solution using a nozzle to generate a mist which passes trough a synthetic foam. In this type of reactor, control of the active biomass growth is very important in order to permit an optimum activity in the filter-bed without clogging. A previous paper has presented a “pressure drop controller”, creating successive dry periods in a “Mist-Foam” reactor. This system was tested with spent liquor from citric acid fermentation as a model nutrient solution and air as gas. The results obtained showed that the pressure drop was successfully controlled even when filter-bed clogging was expected. This paper then presents the effects of dry periods on the degradation of a gaseous substrate using a “Mist-Foam” reactor.