Assessment of a two-step partial nitritation/Anammox system with implementation of multivariate data analysis

Complexity of biological wastewater treatment, in which a variety of physical and (bio)chemical processes concurrently take place, demands appropriate approach in the data analysis. In this study, the data set collected during a 20 month operation of a two-step partial nitritation/Anammox system for nitrogen removal from wastewater (semi-industrial pilot plant scale) are subjected to Principal Component Analysis (PCA) and Partial Least Squares projections to latent structures (PLS) analysis. Interpretation of PCA- and PLS models enable to discern relationships between different factors for the start-up period and stable operation of the pilot plant. Variables like conductivity, pH value, dissolved oxygen concentration and nitrite-to-ammonium ratio (NAR) appear to be the key factors in the process control and monitoring. Extension of the Anammox reactor capacity demands accurate monitoring, principally by scrutinizing nitrite nitrogen concentration in the reactor. These findings suggest that the two methods complement each other in assessing the partial nitritation/Anammox system. This study demonstrated that multivariate data analysis provides the powerful implement in the field of wastewater treatment, especially in investigating novel systems.