Syngas fermenting communities in Trickle Bed Reactors at different pH values

Biofilm and suspended communities in Trickle Bed Reactos (TBRs) fed with syngas (45% H2, 25% CO2, 20% CO, and 10% N2), at mesophilic conditions (37 C). The original inoculum (also included in the submission) was anaerobic sludge obtained from Lyngby-Taarbaek Wastewater Treatment Plant, which was heat-pretreated to remove methanogens. The pH is a key parameter controlling acetogenesis and chain elongation in syngas fermentation studies producing middle-chain fatty acids. The goal of the study was to analyze the microbial community present in the biofilm and in suspension in the liquid effluent of TBRs through a pH study in which two reactors were operated originally at pH 6, and subsequently at lower or higher pH values (depending on the reactor) until they were operated again at pH 6 at the end of the study. This data is compared with consumption and production data of the reactor to evaluate how pH affects the process, and if the original performance at pH 6 is restored at the end of the study.