Stability Monitoring of the Nitrification Process: Multivariate Statistical Analysis
Ewa Wąsik 1  
Agnieszka Cupak 1  
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University of Agriculture in Kraków, Department of Sanitary Engineering and Water Management, Kraków, Poland
Ewa Wąsik   

University of Agriculture in Kraków; Department of Sanitary Engineering and Water Management, Al. Mickiewicza 24/28, 31-059 Kraków, Poland
Online publish date: 2018-04-13
Publish date: 2018-05-30
Submission date: 2017-08-09
Final revision date: 2017-09-22
Acceptance date: 2017-09-24
Pol. J. Environ. Stud. 2018;27(5):2303–2313
The aim of this article is to define the possibilities of applying multivariate statistical analysis (PCA and control charts) in the monitoring of the effectiveness of biological nitrification in a wastewater treatment plant working for the municipality of Sanok. The difference in oxygen affinity between ammonium and nitrite oxidizers results in a bacteria competition between AOM and NOM. A more stable nitrification process was obtained in reactor I for mean oxygen concentration of 1.13-2.05 mgO2·dm-3. The lowest mean concentrations of ammonia nitrogen were obtained in the range 3.43-3.62 mgN-NH4+·dm-3. Reactor II worked at mean oxygen concentration 1.69-4.56 mgO2·dm-3, which caused lower stability in this study period. The mean concentration of ammonium nitrogen ranged from 4.06 to 9.08 mgN-NH4+·dm-3. April 2016 was considered the most stable period of work of nitrification reactors. In that month, in reactor I the upper specification limit USL was not exceeded. In reactor II the USL was exceeded only 10% of the time. The index of the process capacity Cpk was higher for reactor I, and achieved a value of 1.71. The process of nitrification in both reactors was qualified as stable when oxygen concentration was between 1 and 2 mgO2·dm-3.