Low Energy Biological Nitrogen Removal by Cation Exchange, Thin Film Oxygen Transfer, and Heterotrophic Nitrification in Sequencing-Batch, Packed-Bed Reactors
Sustainable solutions for biological nitrogen removal (BNtR) in wastewater require new treatment process concepts to lower energy requirements. A novel configuration of six packedbed, flood and drain (PFAD) reactors were used in a pilot study to remove nitrogen from a manufactured wastewater comprised of urea, cheese whey, and well water. The reactors operated in a sequencing-batch manner in alternating sets. Oxygen transfer in the PFAD system is mostly via nitrification in drained phases of ammonium ions that adsorb to manufactured aggregate in flooded phases. This method of oxygen transfer is substantially more energy efficient for nitrogen removal than activated sludge. The PFAD system is estimated to have approximately 20% of the energy requirement of a corresponding activated sludge treatment system using the modified Ludzack-Ettinger (MLE) process.