Using carrier surface loading to design heterotrophic denitrification reactors

The effluent nitrite concentration of a heterotrophic denitrification reactor is mainly determined by the carrier surface loading of nitrate to the reactor. The surface loading is defined as the flow rate multiplied by the influent nitrate concentration and divided by the total biomass carrier surface area. Traditionally, the design of a heterotrophic denitrification reactor has been based on empty bed contact time (EBCT), nitrate volumetric loading, or hydraulic surface loading. This article theoretically and experimentally proves that nitrate carrier surface loading, instead of EBCT, nitrate volumetric loading, and hydraulic surface loading, is the primary design criterion for the heterotrophic denitrification reactor. This will improve the reliability of heterotrophic denitrification and should accelerate adaptation of the new approach for North America.