In recent years many Wastewater Treatment Plants have been under pressure to digest increased quantities of secondary sludge or thickened waste activated sludge (TWAS). Unlike primary sludge, TWAS is difficult to digest, leading to digester instability if too high a proportion is fed. Typically, the TWAS loading rates are limited to about 30% to achieve efficient and stable operation.

The rate limiting step of conventional anaerobic digestion, and in particular digestion of the secondary sludge portion of the feed, is cell lysis. By destroying the cell walls, the particle size in the waste stream is reduced and the organic matter within cells is released for bacterial consumption and conversion to biogas. Therefore, pre-treatment using sonix™ makes the cells more amenable to downstream processing and improves the subsequent anaerobic digestion process.

Sludge treatment and disposal are responsible for significant costs in wastewater treatment and are also subject to increasingly stringent legislation. sonix™ is a cost-effective technology that enhances gas production and minimises sludge production through increased solids destruction and better cake dewatering. It is therefore of great interest to the industry.