Chemometric Analysis of Activated Sludge Parameters Variation Under Anaerobic Conditions as a Tool to Support Sustainable Wastewater Treatment Process

The activated sludge process, along with its modifications, is currently the most widely used wastewater treatment method to achieve desired environmental outcomes. However, it is also characterized by operational instability resulting from changing conditions, a wide range of quantitative and qualitative wastewater parameters, and technical and technological factors. Multi-parameter analysis of biological processes enables more comprehensive control through the use of chemometric techniques, modeling, artificial neural networks, and AI in the decision-making process. This article presents the results of a multivariate data analysis of parameters of activated sludge suspension held under anaerobic conditions. Several correlations were identified between parameters characterizing activated sludge and sludge liquid. PCA and HCA analyses enabled the extraction of three sets of parametric clusters. They reflect specific stages of sludge transformation under anaerobic conditions: initial high biological activity (cluster I), degradation and nutrient release (cluster II), and stabilization with minimal sludge activity (cluster III). These clusters indicate characteristic qualitative changes in sludge and sludge liquid, which can serve as effective control and optimization tools for biological wastewater treatment processes. Statistical and chemometric analyses demonstrate the potential to rapidly assess the condition of activated sludge or the stage of anaerobic transformation by correlating individual parameters. This is an example of how these tools can be used to control wastewater treatment processes more effectively, including in anaerobic conditions. Such control may improve treatment quality and the energy efficiency of the process. It will also help reduce the impact of treatment plants on the aquatic environment and enable the reuse of wastewater that is more effectively treated, which is undoubtedly an important element of sustainable development.