Biological elimination of dilute methane through multi-channel Taylor flow capillary bioreactors

Abstract

Elimination of dilute methane (<5 % v/v) was investigated in several multi-channel capillary bioreactor con- figurations and evaluated for operating conditions and parameters relevant to long-term reliable performance. Although all reactors showed a high methane removal capacity, the addition of only surfactant or only silicone oil did not show enhancement in methane removal. The capillary bioreactor containing both silicone oil (up to 20 % v/v, 20 cSt) and surfactant (BRIJ 58) treated methane with very high elimination capacities of >200 g per m3 internal capillary channel per hour at gas contact times around 30 s, which is one order of magnitude lower than gas contact times of conventional biological gas treatment methods. No accumulation of biomass on the walls of capillary channels was observed during the 300 days of operation. Internal gas recirculation was applied to decouple gas-liquid turbulence conditions from the actual gas retention time. This work revealed that a capillary bioreactor can be a useful platform for the abatement of dilute methane emissions.