NITRIFIKATIONSHÄMNING I KOMMUNALA AVLOPPSVATTEN – SKILLNADER OCH LIKHETER MELLAN DANMARK OCH SVERIGE / Inhibition of Nitrification in Municipal Wastewater- Differences and Similarities Between Denmark and Sweden
A Danish and a Swedish study of nitrification inhibition are compared. A considerably larger percentage of’ the Danish treatment plants received wastewaters strongly inhibitory to nitrification compared to the Swedish treatment plants. More than 20 % inhibition in a 50% dilution of the samples was noted for about a fourth of the investigated Danish wastewaters. In the Swedish study 4 % of the wastewaters exhibited more than 20 % inhibition for the same dilution. Presence of lower levels of inhibition was detected at about two thirds of the investigated treatment plants in both countries. Reasons for both the inhibition itself and for the differences found between the two neighbouring countries are discussed. The major part of the inhibition found in the inflow to municipal wastewater treatment plants is assumed to originate from the industry. However internal sources of’ inhibitory substances should not be neglected when the total inhibitory effect found at a treatment plant is investigated.