US Patent 7887706 Method of biofiltration of a liquid effluent

A method of biofiltration of a liquid effluent by simultaneous nitrification and denitrification uses the adding of an oxygen source at a predetermined rate and optionally the adding of a carbon source (such as whey) thus enabling the complete transformation of the nitrates (NO3) present in the effluent at the time of treatment through a biofilter. The specific operating conditions favoring the simultaneous nitrification and denitrification include the controlled injection of a slight quantity of air, adjustment of the level of nitrogen load (TKN+NO3) and the level of carbon load thereby making possible elimination for the most part of the release of unwanted nitrogen in the form of NO3 or NO2.