Ultrasonic Sludge Pretreatment for Enhanced Sludge Digestion
In: Water and environment journal, Band 14, Heft 1, S. 66-71
ISSN: 1747-6593
AbstractDuring recent decades, the anaerobic digestion process has been extensively studied and various methods for process enhancement have been explored. These methods include heat treatment, alkali addition, phase separation and membrane enhancement. In general, whilst technically feasible, the methods have not proved to be economically competitive.The pretreatment of sludges with high‐power ultrasound has been investigated as part of a twelve‐month research project funded by six UK water utilities. Cell lysis and particle‐size reduction (caused by ultrasonic cavitation) are thought to be the key parameters through which the digestion process is enhanced. A series of laboratory‐scale anaerobic digesters has been operated and significant increases in biogas yield have been noted following ultrasonication. Experiments have been completed with a variety of ultrasonic devices (of different geometries and construction materials) and sludge types (e.g. primary, secondary and co‐settled). Current experiments are investigating methods through which the technology can be successfully scaled‐up and applied on a full‐scale plant.