Kinetic modelling and microbial community assessment of anaerobic biphasic fixed film bioreactor treating distillery spent wash

Anaerobic digestion, microbial community structure and kinetics were studied in a biphasic continuously fed, upflow anaerobic fixed film reactor treating high strength distillery wastewater. Treatment efficiency of the bioreactor was investigated at different hydraulic retention times (HRT) and organic loading rates (OLR 5–20 kg COD m−3 d−1). Applying the modified Stover–Kincannon model to the reactor, the maximum removal rate constant (Umax) and saturation value constant (KB) were found to be 2 kg m−3 d−1 and 1.69 kg m−3 d−1 respectively. Bacterial community structures of acidogenic and methanogenic reactors were assessed using culture-independent analyses. Sequencing of 16S rRNA genes exhibited a total of 123 distinct operational taxonomic units (OTUs) comprising 49 from acidogenic reactor and 74 (28 of eubacteria and 46 of archaea) from methanogenic reactor. The findings reveal the role of Lactobacillus sp. (Firmicutes) as dominant acid producing organisms in acidogenic reactor and Methanoculleus sp. (Euryarchaeotes) as foremost methanogens in methanogenic reactor.

► Anaerobic digesters often exhibit significant stability problems that may be avoided through appropriate bioprocess models and assessment of microbial communities involved in the complex process of pollutant removal.
► High quality microbiological information will provide an invaluable tool in the design and process control of anaerobic digestion application.
► The results show the applicability of Stover–Kincannon model to the anaerobic biphasic reactor which is efficient to remove 50–80% COD at different OLR.
► Phylogenetic analyses reveal the presence of acidogenic organisms (Firmicutes) in AR and dominance of hydrogenotrophic methanogens (Euryarchaeotes) in MR.