Aerobic Fluidized Bed Reactor with Internal Media Cleaning

Abstract

An aerobic fluidized bed reactor process with internal media cleaning to control attached biomass thickness was developed. Biomass control was achieved by the periodic creation of a turbulent zone within a specially designed cylindrical screened region surrounding the effluent port. A screen washer aided in keeping the cylindrical screen clean. A bed lifter produced turbulence throughout the bed to allow individual media particles to enter the cleaning zone for the removal of excess biofilm. The reactor system operated continuously without excessive biomass buildup on the support media and without the need for external media cleaning or recovery. Four analytical methods—systematic scanning electron microscope (SEM) analyses, granular activated carbon drained density, phospholipid analyses, and fluorescein diacetate activity (FDA) measurements—were modified/developed for use in characterizing the microbial population attached to the media of the fluidized bed. The SEM analyses was valuable for monitoring changes the cleaning cycle caused to the biofilm. Phospholipid and FDA analyses were found to have potential for use as design and monitoring tools of the process.