Characterization of Extracellular Polymeric Substances by Combined Enzyme Hydrolysis and Size Exclusion Chromatography-Infrared Microscopy

This study suggests a new way of characterizing extracellular polymeric substances (EPS) using size exclusion chromatography (SEC) coupled with infrared microscopy (μFTIR) before and after enzyme hydrolysis. Previous research has established advantages to the enzymatic treatment of biosolids, through degradation of EPS. The chromatographic fingerprints of EPS were significantly altered using three different enzyme types. Application of either a commercial enzyme mix or an amylase/cellulase combination led to disappearance of molecular weight fractions above 0.5kDa. However protease application changed the chromatographic profile unexpectedly, forming very high molecular weight fractions (>4000 kDa). μFTIR results indicated that these large molecules result from mineral phase association with lower molecular weight organic molecules. EPS characterization confirmed that specific enzymes degraded their target compounds. Although the effect of enzyme treatment was observable using conventional sludge characterization methods, the SEC-μFTIR method provided more specific information on chemical mechanisms responsible for enzyme effects.