The Inhibition Effect of Nitrogen Compounds in Nitrification of Wastewater

Abstract

The aim of this work is to evaluate the influence of NH₃ and nitrites on the activity of nitrification bacteria in biological wastewater treatment. The experiments were performed by treating wastewater with NH₃ in a laboratory nitrification reactor with semicontinuous flow. No nitrification activity was observed in the first phase of reactor operation at the NH₃ input 600 mg l^–1. An increase in the activity of oxidising bacteria was observed only after 65 days of reactor operation. On the other hand, nitrite-oxidising bacteria were inhibited for another 12 month although the NH₃ input was gradually decreased. A gradual increase in the activity of nitrite oxidising bacteria was recorded after a decrease in NH₃ input to 75 mg l^–1. Subsequent gradual increase in NH₃ concentration to 1000 mg l^–1 did not induce inhibition of both groups of nitrification bacteria.