An Assessment of Dissolved Oxygen Limitations and Interstage Design in Rotating Biological Contactor (RBC) Systems,
ENGINEERING CONSULTANTS AND ASSOCIATES FT LEE NJ
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A limiting organic loading to the first stage of 6.4 lbsday1000 sf of BOD total BOD was found to be the organic loading beyond which nuisance organism growth and corresponding process performance problems occur. An interstage model was calibrated at organic concentration in a range of 50 - 100 mg1 BOD for systems which were not overloaded. The model illustrates the advantages of staging when high efficiencies are desired. The model did not indicate any advantage to step feeding in systems that are organically underloaded. The design of RBC system is best undertaken with two independent criteria. The first to establish the desired surface area and staging arrangements, and the second to ensure that no stage is organically overloaded. The organic loading limitation presented here is considered a good design criteria to prevent oxygen limitations. Additional data is required to establish an accurate rational interstage model to predict RBC performance.