Rheological characteristics of the cationic polyelectrolyte flocculated wastewater sludge.

The rheological characteristics of the wastewater sludge were investigated by using a Haake Rheostress RS 75 rheometer. The stress-sweep experiments and the small-amplitude-oscillatory-shearing (SAOS) tests were conducted. The stress-sweep measurements demonstrate that addition of polymer coagulants to sludge samples could significantly influence the corresponding complex shear modulus G*. Furthermore, the SAOS tests indicate that the sludge samples treated with polymer coagulants will form more rigid structures. The original sludge samples mostly show typical viscoelastic liquid-like behavior. However, the solid-like behaviors were always observed in the samples treated with polymers.