Granule Development in Anaerobic Baffled Reactors

The mechanism of biomass granulation in anaerobic reactors has been widely studied in the hope that this could be helpful in manupulating the rate and extent of granule formation, particularly in wastewaters that show little intrinsic propensity to granulate (e.g. fat and oil containing effluents). Similarly, in this study, sets of sludge samples were taken from Normal Fed Anaerobic Baffled Reactors (NFABRs) and SplitFed Anaerobic Baffled Reactors (SFABRs) treating brewery and ice-cream wastewater in order to evaluate the development of granulation and compare the rate of compact granule formation in the reactors. The internal architecture of the granules and the role of extracellular polymers (ECPs) on granule formation were also investigated. SFABRs proved to be a potential anaerobic reactor configuration for granule formation. It was revealed that the ability of granule formation in SFABRs can even extend to complex wastewaters, i.e. fat-bearing wastewaters, in a considerably short time. The mechanism governing stratification of bacterial population in granules was explained. The internal architecture of the granules and the role of ECPs on granule formation were speculated on with the changes observed on SEM pictures. The findings confirmed that ECPs are central to the process of granulation. Based on the granular growth course, the granulation process is categorized into three phases: (i) initiation (ii) adaptation and maturation and (iii) granulation.