Analysis of organic removal rates in the aerated submerged fixed film process

Performance data from a pilot-plant employing the four-stage aerated submer ged fixed film (ASFF) process treating domestic wastewater were analyzed to examine the organic removal rates. The process has shown high BOD removal efficiencies (> 90%) over a wide range of hydraulic loading rates (0.04 to 0.68 m(3)/m(2).d). It could also cope with high hydraulic and organic loadi ngs with minimal loss in efficiency due to the large amount of immobilized biomass attained. The organic (BOD and GOD) removal rate was influenced by the hydraulic loadings applied, but organic removal rates of up to 104 kg B OD/ m(2).d were obtained at a hydraulic loading rate of 0.68 m(3)/m(2).d. A Semi-empirical model for the bio-oxidation of organics in the ASFF process has been formulated and rate constants were calculated based on statistica l analysis of pilot-plant data. The relationships obtained are very useful for analyzing the design and performance of the ASFF process and a variety of attached growth processes. (C) 1998 Published by Elsevier Science Ltd. A ll rights reserved.