Purely ultrasonic enzyme extraction from activated sludge in an ultrasonic cleaning bath

Enzymes are important in biological wastewater treatment systems, since they are responsible for breakdown of macro- and micropollutants, thereby making the pollutants available for metabolism. Enzyme activity has been investigated in particular in activated sludge processes, since the activated sludge technology is the most important and widely spread wastewater treatment technology used today. Various methods have been used to extract enzymes from activated sludge in order to measure their activity, these include stirring with additives like detergents and cation exchange resins, ultrasonication (with probes) and combinations of the three [1], [2], [3]. In this article we describe a method for purely ultrasonic enzyme extraction from activated sludge using low power ultrasound generated by an ultrasonic bath and no additives. The method essentially consists of: • Sonication of the sludge sample using a glass beaker and an ultrasonic bath. • Filtration of the sample in order to obtain the enzyme extract. • Measurement of enzyme activity by fluorescence spectrometry using a substrate that yields a fluorescent product.