KU Leuven works on N removal from greenhouse drainage water in Belgium
A high nitrate concentration drainage water (150-300 mg NO3-N/l) is produced at a limited flow rate. The drainage water is collected in a drainage well of 1.5 m3, which serves as a buffer. From the well, the drainage water is pumped into the MBBR having an active volume of 5 m3. Influent and effluent pumps are controlled by level sensors in the MBBR and the drainage well. The effluent pump is also used to circulate the water within the reactor.
An aeration system is present to prevent clogging of the carrier material and avoid odor problems. A hydraulic retention time of minimum 6 hours is maintained and Carbo ST (carbon source) and phosphoric acid (phosphorus source) are added to ensure optimal denitrification performance and biomass growth.
MBBR with AnoxKaldnes® K5
The biomass grows on AnoxKaldnes® K5 carrier material (filling ratio = 30%). Both the drainage well and the MBBR reactor are installed underground to limit temperature variations. The effluent of the MBBR is discharged directly in the surface water. An overview of the MBBR set-up is depicted in the accompanying figure.