Transfer of a static PCA-MSPC model from a steady-state anaerobic reactor to an independent anaerobic reactor exposed to organic overload

Abstract

A static multivariate statistical process control model based on principal component analysis (PCA-MSPC) was developed for an anaerobic reactor maintained in steady-state, joining the biogas composition (CH4, CO2, H2) to the total solids (TS), volatile solids (VS), total inorganic carbon (TIC) and total ammonia nitrogen (TAN) contents of the slurry. The principal component analysis (PCA) highlighted a lack of correlation between the individual process variables (IPVs) measured in the slurry and the gas phase. The application of this model to the data set collected for an independent anaerobic reactor (fed with the same substrate) progressively led from steady-state to critical volatile fatty acids (VFA) intoxication did not allow evaluating its process status. A second static PCA-MSPC model was built for the steady-state reactor in excluding the TS and VS content of the slurry and was successfully transferred to the overfed reactor. The TA² and SPE control charts built for the overfed reactor using this second model closely reflected its process status and delivered valuable warning signals approaching the VFA intoxication. The gas phase composition (CH4, CO2, H2) brought the main contribution to these warnings.