Appts. and process for biological elimination of nitrogen - using microorganisms immobilising on carrier contg. iron turnings

In an appts. and process for the biological elimination of N, the micro-organisms capable of oxidn. of NH4/NH3 or nitrite or the redn. of nitrate, are immobilised on a granular carrier contg. Fe turnings, and are added in dependence on the capacity of the appts. at the time, and are removed again. The carrier is pref. sepd. from the slurry/water mixt. magnetically and is led into a washer for removal of unwanted sewage sludge organisms, esp. a washer supplied with a wash fluid contg. special nutrients for reactivation of the nitrificants and other special microorganisms. The carrier with the special mitroorganisms is led into an immobilisation reactor which is fed with inoculant amts. of the water to be treated and also with substances to be broken down. The immobilisation reactor is a cascade, in which each unit can be operated separately. The carrier is scooped out of the water and fed to a dry immobilisation reactor in the form of one or more spray towers. The carrier is conc. in the immobilisation reactor and fed in a controlled way, by a pump or conveyor belt, to the treatment process. The nitrification capacity or other metabolic productivity of the microorganisms is ascertained by continuous determn. of NH4 or other metabolites in the feed and run-off and a determn. of dry matter in the appts., and if capacity drops, carrier with nitrificants or other microorganisms is led into the bio-reactor until the requirement for active microorganisms has been covered. USE/ADVANTAGE - The process is more stable, and the microorganisms are recycled. The carrier is a source of carbonate, which buffers the medium. Used for treatment of drinking water, when denitrification with special microorganisms is needed, or for off-site treatment of waste water with mixed cultures.