ANFLOW, a mathematical model

The Oak Ridge National Laboratory (ORNL) has developed an anaerobic upflow (ANFLOW) reactor for treating domestic sewage. Numerous lab-scale and pilot-scale experiments have been run with an ANFLOW system; however, efforts at mathematically predicting ANFLOW reactor behavior to date has been limited to computer-based models. This report presents a simple model which can quickly predict the substrate utilization rate within a given ANFLOW reactor.

Raw data from the Loves Creek pilot plant was consolidated and rearranged into a form more traditionally used in describing aerobic treatment systems, then applied to each of the three major aerobic model formats: Monod, Eckenfelder/Ford, and Grady/Williams. It was found that a modified version of the Eckenfelder/Ford format best described the overall performance of the Loves Creek ANFLOW Reactor. This model was then applied to an independent set of experimental data, resulting in a close correlation between actual and predicted values for substrate utilization.

The developed model provides means of quickly predicting treatment efficiencies of an anaerobic filter processing relatively dilute wastewater at ambient temperatures. With this simplified model, effective design comparisons can be made between anaerobic and aerobic biological treatment systems.