NITRIFICATION INHIBITION - A SOURCE IDENTIFICATION METHOD FOR COMBINED MUNICIPAL AND OR INDUSTRIAL WASTE-WATER TREATMENT PLANTS

Inhibition of nitrification at combined municipal and/or industrial treatment plants can cause serve problems in regard to the future low effluent standards for ammonia nitrogen. As inhibition problems often occur only for limited periods and are caused by different substances it is very difficult to find the sources of these substances within the sewer system. Using a two step strategy based on a respiration test it is possible to locate these sources within a short time and to concentrate then on the abatement of the inhibiting wastewaters. The method of the respiration test was developed and the relationship between dilution and inhibition could be described by a new mathematical inhibition model. The method was applied at an Austrian city (Linz) with more than 50% wastewater load coming from industry during the design period for the extension of the existing plant (800 000 PE).