Process and means for conducting the denitrification of water

Claim 1

In a process for the biological denitrification of water which is at least substantially free of carbon, and wherein the water is denitrified in a reactor in the presence of a carrier material supporting denitrifying microorganisms thereon, the improvement comprising conducting denitrification in a reactor in the presence of a carrier material which is not a carbon source for denitrifying microorganisms carried thereon and which is impregnated with organic substances separate from the carrier material in a manner such that the organic substances do not effectively enter into solution with the water being treated, with no substantial increase in BOD 5 , said organic substances being biodegradable and at least partially insoluble in water and being employed as a carbon source by the denitrifying microorganisms, and the carrier material having been impregnated with said organic substances prior to being placed in the reactor for conducting the denitrification process whereby the requirement of providing a separate carbon source for the denitrifying microorganisms to effect denitrification is avoided, said carrier material being non-surface active and comprising at least one of sand, gravel, plastic filler bodies, porous mineral material, urea-formaldehyde resins, polyethylene, polypropylene, polyurethane, silicone polymers and natural sponges, and is in at least one of open-celled, foam and sintered lump form, and wherein influent water introduced into the reactor has a COD-content of about 1-200 mg/l.