Browsing by Author "Reid, E."

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    Biomass effects on oxygen transfer in membrane bioreactors
    (Elsevier, 2007-03) Germain, Eve; Nelles, F.; Drews, A.; Pearce, Peter; Kraume, M.; Reid, E.; Judd, Simon J.; Stephenson, Tom
    Ten biomass samples from both municipal and industrial pilot and full scale submerged membrane bioreactors (MBRs) with mixed liquor suspended solids concentrations (MLSS) ranging from 7.2 to 30.2 g L−1 were studied at six air-flow rates (0.7, 1.3, 2.3, 3, 4.4 and 6 m3 m−3 h−1). Statistical analyses were applied to identify the relative impacts of the various bulk biomass characteristics on oxygen transfer. Of the biomass characteristics studied, only solids concentration (correlated with viscosity), the carbohydrate fraction of the EPS (EPSc) and the chemical oxygen demand (COD) concentration of the SMP (SMPCOD) were found to affect the oxygen transfer parameters kLa20 (the oxygen transfer coefficient) and α-factor. The relative influence on kLa20 was MLSS>aeration>EPSc>SMPCOD and on α-factor was MLSS>SMPCOD>EPSc>aeration. Both kLa20 and α-factor increased with increasing aeration and EPSc and decreased with increasing MLSS and SMPCOD. MLSS was found to be the main parameter controlling the oxygen transfer.
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    Media surface properties and the development of nitrifying biofilms in mixed cultures for wastewater treatment
    (Institute of Chemical Engineers, 2013-07-01T00:00:00Z) Stephenson, Tom; Reid, E.; Avery, L. M.; Jefferson, Bruce
    Plastic was tested to select biofilm support media that would enhance nitrification in the presence of heterotrophs. Eight different types (acrylonitrile butadiene styrene, nylon, polycarbonate, polyethylene, polypropylene, polytetraflouroethylene (PTFE), polyvinyl chloride and tufnol) were immersed in an aerobic fed-batch reactor receiving domestic settled wastewater. Nitrification rates did not correlate with biomass concentrations, nor surface roughness of the plastics as measured by atomic force microscopy (AFM). The maximum nitrification rate of 1.5 g/m2d1 was obtained from biofilms growing on PTFE which had the lowest surface adhesion force (8nN). Nitrification rates for the biofilms were inversely correlated with the attraction forces as measured by the AFM.