title: Biofilm architecture in a novel pressurized biofilm reactor.
abstract: A novel pure-oxygen pressurized biofilm reactor was operated at different organic loading, mechanical shear and hydrodynamic conditions to understand the relationships between biofilm architecture and its operation. The ultimate goal was to improve the performance of the biofilm reactor. The biofilm was labeled with seven stains and observed with confocal laser scanning microscopy. Unusual biofilm architecture of a ribbon embedded between two surfaces with very few points of attachment was observed. As organic loading increased, the biofilm morphology changed from a moderately rough layer into a locally smoother biomass with significant bulging protuberances, although the chemical oxygen demand (COD) removal efficiency remained unchanged at about 75%. At higher organic loadings, biofilms contained a larger fraction of active cells distributed uniformly within a proteinaceous matrix with decreasing polysaccharide content. Higher hydrodynamic shear in combination with high organic loading resulted in the collapse of biofilm structure and a substantial decrease in reactor performance (a COD removal of 16%). Moreover, the important role of proteins for the spatial distribution of active cells was demonstrated quantitatively.
authors.affiliation: a Shenzhen Key Laboratory of Sludge Treatment & Resource Reuse , Shenzhen Water (Group) Co. Ltd , Shenzhen , PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
authors.forename: Siqing
authors.initials: S
authors.lastname: Xia
authors.forename: Liang
authors.initials: L
authors.lastname: Duan
authors.forename: Slawomir W
authors.initials: SW
authors.lastname: Hermanowicz
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D019149:Bioreactors; D057446:Hydrodynamics; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D018508:Water Purification / Q000379:methods*
chemical_list: D010100:Oxygen
keywords: ASP, activated sludge process; CLSM; CLSM, confocal laser scanning microscopy; COD, chemical oxygen demand; CTC, 5-cyano-2,3-ditolyl tetrazolium chloride; CTF, CTC–formazan; Con A, concanavalin A; DAPI, 4,6-diamidino-2-phenylindole; DI water, deionized water; DO, dissolved oxygen; EPS, extracellular polymeric substances; HRT, hydraulic retention time; OLR, organic loading rate; PBR, pressurized biofilm reactor; PLC, programmable logic controller; SRT, solids retention time; SS, suspended solids; VSS, volatile suspended solids; biofilm architecture; novel biofilm reactor with mechanical control; shear stress; wastewater treatment