title: Granule development in a split-feed anaerobic baffled reactor.
abstract: Operating anaerobic reactors at high organic loading rates during start-up can lead to instability, accumulation of volatile fatty acids and low pH, such problems being exacerbated in reactors that exhibit plug-flow characteristics. Moreover, plug-flow conditions increase the exposure of biomass to any toxic components in the feed. To overcome these limitations, an anaerobic baffled reactor (ABR), a reactor exhibiting partial plug-flow characteristics, was modified by splitting the feed between the individual compartments to produce the split-feed ABR (SFABR). Consequently, more favourable conditions were created in the initial compartments, such as lower, longer hydraulic retention time and longer cell retention time; conditions in the final compartments were also improved by the increased food availability for microorganisms. Other benefits included better gas mixing characteristics as a result of the more balanced gas production across the reactor. Granule development was compared in SFABR and normally fed ABR by analysing sludge samples, taken during start-up and continuous operation, using scanning electron microscopy. Photomicrographs allowed tentative conclusions to be made concerning the effect of split-feeding on the distribution of bacterial populations within the granule architecture and the role of extracellular polymers on granule formation.
authors.affiliation: Environmental Engineering Group, School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, UK. p.j.sallis@ncl.ac.uk
authors.forename: P J
authors.initials: PJ
authors.lastname: Sallis
authors.forename: S
authors.initials: S
authors.lastname: Uyanik
mesh_terms: D000693:Anaerobiosis; D001421:Bacteria, Anaerobic / Q000378:metabolism; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D005740:Gases; D008855:Microscopy, Electron, Scanning; D012722:Sewage; D013997:Time Factors
chemical_list: D005740:Gases; D012722:Sewage