Impact of gas injection on physicochemical properties of waste activated sludge: A linear relationship between the change of viscoelastic properties and the change of other physiochemical properties

The results showed that in linear viscoelastic regime the viscous and elastic modulus decreases linearly with an increase in gas flow rate. The amount of stress imposed by gas injection also showed a direct relationship with gas velocity. Gas injection also showed a substantial impact on soluble COD, suspended solids, and zeta potential. Additionally, a linear relationship was observed between the percentage change in the above mentioned physical properties and stress imposed by gas injection. These results confirm that gas injection produces additional shear impacting sludge physicochemical properties and therefore changes its rheological behaviour. The extra stress induced by gas injection can be predicted using a simple model based on sludge concentration and gas velocity.