A systematic comparison of two empirical gas-liquid mass transfer determination methodologies to characterize methane biodegradation in stirred tank bioreactors

摘要

This study aimed at systematically comparing the potential of two empirical methods for the estimation of the volumetric CH4mass transfer coefficient (klaCH4), namely gassing-out and oxygen transfer rate (OTR), to describe CH4biodegradation in a fermenter operated with a methanotrophic consortium at 400, 600 and 800 rpm. TheklaCH4estimated from the OTR methodology accurately predicted the CH4elimination capacity (EC) under CH4mass transfer limiting conditions regardless of the stirring rate (∼9% of average error between empirical and estimated ECs). Thus, empirical CH4-ECs of 37.8 ± 5.8, 42.5 ± 5.4 and 62.3 ± 5.2 g CH4m−3h−1vspredicted CH4-ECs of 35.6 ± 2.2, 50.1 ± 2.3 and 59.6 ± 3.4 g CH4m−3h−1were recorded at 400, 600 and 800 rpm, respectively. The rapid Co2+-catalyzed reaction of O2with SO3−2in the vicinity of the gas-liquid interphase during OTR determinations, mimicking microbial CH4uptake in the biotic experiments, was central to accurately describe theklaCH4.