CHARACTERIZATION OF ENZYME-ACTIVITY IN ACTIVATED-SLUDGE USING RAPID ANALYSES FOR SPECIFIC HYDROLASES

The biodegradation activity of activated sludge was characterized by the API-ZYM and LRA-ZYM Esterase test systems. These systems provide rapid, semiquantitative information on the activity of hydrolytic enzymes associated with the biodegradation of lipids, proteins, carbohydrates, nucleic acids, and xenobiotic chemicals. Activated sludge was collected from several municipal wastewater treatment plants (WTPs) which varied with respect to their operating parameters and influent wastewater composition. Sludge samples were separated into various fractions (mixed liquor, sonicated mixed liquor, freeze-thaw, and extracellular fractions) and then assayed for enzyme activity relative to inactivated controls. Mixed liquor and freeze-thaw preparations from all sludge samples displayed a wide range of enzyme activities, with phosphatase and aminopeptidase activities dominating. Hydrolytic activity was not observed in inactivated mixed liquor fractions, or in extracellular fractions Prepared from any of the sludge samples collected. Sonicated mixed liquor samples displayed a wider range of enzyme activities than intact samples. A specific set of esterase (protein, lipid) and aminopeptidase (protein) activities found in mixed liquor fractions was also localized in freeze-thaw preparations. In general, patterns of hydrolase activitY were similar in sludges collected from the different WTPs, and decreased sharply in sludge samples incubated without aeration or nutrients for a 48-hour period. Our results indicate that the API systems Provide rapid. semiquantitative information concerning the hydrolytic enzyme profiles of activated sludge. This information is reproducible across different WTPs and can be useful in characterization of the physiological condition and biodegradation activity of activated sludge.