The COD Removal Performance of an Aerobic Fluidized Bed Reactor

Abstract

Aerobic fluidized bed reactors (FBRs) are used as a new technology in wastewater treatment. In this study, an aerobic fluidized bed reactor with granulated activated carbon (GAC) as carrier material was operated under different conditions, including batch-loading, semicontinuous loading, and continuous loading. The FBR effluent was studied for changes in Chemical Oxygen Demand (COD). In this study, acetic acid was used as a carbon source. During the course of the study while the FBR was operating continuously initial COD influent concentration of the acetic acid was 1,000 ± 100 mg/L. Additional continuous flow investigations were conducted with the influent COD at 2000, 3,000 and 4,350 ± 125 mg/L. The total operation period was 5 months including a 1-month start-up process. Organic loading rate increased from 1.0 kg/day/m³ to 14.4 kg/day/m³. This was achieved by changing the influent water COD concentration and/or the hydraulic loading rate. The average effluent dissolved COD concentration was 141 ± 38 mg/L in this organic loading range. When the organic loading rate increased to 21 kg/day/m³, the effluent COD concentration sharply increased, and at the steady state the effluent COD was 928 mg/L. This can be attributed to an increase in the acetic acid concentration of the influent wastewater, because the hydraulic loading rate in the former mode of operation had remained stable. The biomass concentration in the fluidized bed was measured during continuous operation after the steady-state conditions were obtained. The total biomass concentration increased from 7500 mg/L to 17,300 mg/L during the study period.