An Experimental Study on the Effects of Oxygen in Bio-gasification – Part 2
DOI:
https://doi.org/10.24084/repqj08.732Abstract
In order to investigate the impacts of partial
aeration in anaerobic bio-gasification, a laboratory scale
bioreactor (5.5 L working volume) was operated for more than
120 days duration at 35 oC under the organic loading rate of
0.33 kg COD/m3 .d and hydraulic retention time of 33 days.
Different oxygenation conditions, 0, 2.5, 5.0 and 10.1 % (as %
of feed COD) induced by daily air injection after daily feeding,
were tested during the course of the experiment. Oxygenation,
under these operating conditions, reduced the methane
generation with only a trifling effect on biogas generation. The
accumulation of volatile fatty acids is extensively reduced by
oxygen introduction, significantly improving the digester
stability. Reduction of soluble COD and VFAs at increasing
aeration level, decrease of CH4 /CO2 ratio with increased
aeration, and immediate increase of CH4 content upon reducing
the aeration level at the end of the experimental duration, points
out that the observed digester behaviour can be explained
considering the substrate consumption by aerobic respiration
activity of facultative biomass present in the reactor. Partially
aerated anaerobic digestion can be a useful and a stable process
for enhanced waste treatment and resource recovery
