Applying rheological analysis to understand the mechanism of polyacrylamide (PAM) conditioning for sewage sludge dewatering

Nowadays, polyacrylamide (PAM) is widely used for sludge conditioning, while the interactions between PAM and sludge particles influencing the dewatering process remain to be clarified. This study focused on applying rheological analysis to understand the mechanism of PAM conditioning for sewage sludge dewatering. Effective solid-liquid separation was achieved mostly due to the changes of physical properties instead of biochemical properties for conditioned sludge. PAM addition enhanced the non-Newtonian properties and strengthened the solid-like character of sludge in the linear region, allowing initial enhancement of the network strength of sludge flocs. Due to these changes in rheological behavior and more free water being available to flow, the breakdown of the colloidal network of sludge in the non-linear viscoelastic regime allowed high-performance separation between water and solid-phase. These findings show that rheological analysis can serve as a useful indicator of the activated sludge dewatering process.