Full Description

Membrane bioreactors (MBRs) are an attractive technology for drinking water applicationsbecause they provide the advantages of biological treatment and simultaneously mitigate therisk of microorganism passage into the product water. However, current MBR configurationsresult in inherent antagonisms between the membrane performance and the biologicalprocess efficiency. This paper introduces a novel hybrid sorption-membrane-bioreactorconfiguration that resolves these antagonisms and provides additional synergies betweenprocess components. This process configuration consists of an upflow bed of biologicallyactive granular adsorption media situated directly below or adjacent to a microfiltration (MF)or ultrafiltration (UF) membrane and is abbreviated as MBR-UFGA (UpFlow GranularAdsorbent). In this study, a submerged-style UF membrane module was preceded by abiologically active upflow bed of granular pyrolusite (MnO2) adsorption media used forconcurrent biological removal of ammonia and physicochemical removal of iron andmanganese. The MBR-UFGA configuration was compared to a more traditional MBRprocess configuration, where the nitrifying biomass was instead located in the immediatevicinity of the membrane for ammonia removal while physicochemical removal of metalswas achieved with the addition of a powdered activated MnO2 adsorbent and aeration. Thissecond process configuration is abbreviated MBR-PA (Powdered Adsorbent) and provided abaseline for comparison of the proposed novel process. The MBR-UFGA processconfiguration resulted in superior membrane hydraulic performance as it extended thechemical cleaning intervals by over 250% when operated under the same flux and otheroperating conditions. Additional experiments performed without biomass addition indicatedthat the biomass or biologically derived compounds were responsible for the majority of theaccelerated fouling in the more traditional MBR-PA configuration. The novel MBR-UFGAprocess also resulted in a more stable and higher level of removal for ammonia andmanganese. With the MBR-PA process, steadily decreasing biological ammonia removalsresulted from mass transfer limitations that developed as the biomass migrated fromsuspension to the surface of the membrane over the course of the experimental runs.Removal of manganese in the MBR-PA process was initially poor, but increased over time asthe concentration of the powdered adsorbent accumulated in the reactor. This researchfocused on a specific drinking water application, but the findings have equally importantimplications for water reuse and wastewater MBR applications. Includes 8 references, tables, figures.

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Edition: Vol. - No. Published: 06/15/2003 Number of Pages: 11File Size: 1 file , 330 KB