Nitrification inhibition – a method for the estimation of actual maximum autotrophic growth rates in activated sludge systems

Abstract

Since more or less severe nitrification inhibition was observed in several pilot and full-scale activated sludge plants, a means to quantify the extent of inhibition under operational conditions has been sought. Thus a method for the estimation of the actual maximum autotrophic growth rate μ^A,T was developed. This parameter helps to detect low nitrification capacity, before the effluent ammonia concentration increases. Two case studies show that nitrifying activated sludge plants may become acclimatized to inhibitory compounds but have to be protected from peak loads of both nitrogen and inhibitory compounds.

Implementing a respirometry-based model into BioWin software to simulate wastewater treatment plant operations

“…max,A and K NH4 values were evaluated by AUR tests with the maximum autotrophic growth rate determined by Eq. (7) [27]:…”

Combined anaerobic and activated sludge anoxic/oxic treatment for piggery wastewater

“…For determination of specific nitrification capacity of activated sludge samples, autotrophic oxygen uptake rates (OUR) were determined according to Nowak et al (1994). A fresh and well aerated sample of activated sludge collected from the aeration tank was poured into an aerated glass reactor (V = 10 L with a working volume of 6-7 L) equipped with an additional 0.4 L respiration cell as described by Boursier et al (2005).…”

Assessment of activated sludge stability in lab-scale experiments

“…Thirdly, it might be important to monitor the fate of the nitrifiers since they can also be regarded as sensitive indicators for stability (e.g., Nowak et al, 1994;Kotlar et al, 1996). While FISH related Table 2 Threshold values below which the mean slope criterion (Crit 1) and the max-min gap criterion (Crit 2) must lie in the here performed experiments to guarantee activated sludge stability.…”