Assessing Oxygen Perturbation and Over-Aeration Impacts on Soluble Microbial Products (SMP) Production and Release in Activated Sludge Systems

Understanding the interplay between oxygen conditions and microbial activities in an activated sludge system is crucial for the optimization of wastewater treatment processes. This study explores the influence of various aeration patterns and dissolved oxygen (DO) levels on the microbial metabolic activities, with a particular focus on the synthesis and release of soluble microbial products (SMP), and the regulation of key metabolic genes and enzymes. The activated sludge system underwent different aeration patterns, including constant aeration, continuous perturbation, and intermittent perturbation under two distinct DO levels of 2mg/L and 8mg/L. We employed a combination of multi-omics techniques (metagenomics, metaproteomics, and metabolomics) along with chemical analytical methods for comprehensive sample analysis. Our results reveal an increased intracellular accumulation of amino acids and enhanced release of protein under the conditions of oxygen perturbation. Furthermore, elevated DO levels fostered the accumulation of poly-3-hydroxybutyrate intracellularly and the release of protein and fatty acids as SMP. This outcome is associated with the abundance of key metabolic genes and enzymes, thereby highlighting the metabolic flexibility of microbes under different oxygen conditions. These findings offer valuable insights into microbial metabolic dynamics under varying oxygen conditions, thereby providing guidance for more efficient and sustainable strategies in wastewater treatment and resource recovery.