Mechanism of Activated Sludge Floc Disintegration Induced by Excess Addition of NaCl

Abrupt salt intrusion in municipal wastewater treatment plants has triggered serious disturbances and deteriorated the biological treatment process from steady state into unsteady state. The effects of sodium (Na+) concentration on the structure and properties of activated sludge during the shock period were investigated in this paper. A floc disintegration characterized as the decreased floc size and increased porosity in the floc matrix was found when excess Na+ was added to the bioreactor. Increased Na+ resulted in a slight decrease in the normalized capillary suction time. About 53–57% of the total extracellular polymeric substances (EPS) derived from activated sludge was protein, at Na+ concentrations