Effect of surfactant on bound water content and extracellular polymers substances distribution in sludge

Abstract

In this study, the effect of surfactant conditioning on bound water and extracellular polymers substances (EPS) in sludge was investigated. Results showed that by adding dodecyl dimethyl benzyl ammonium chloride (DDBAC), loosely bound EPS (LB-EPS) and slime layer EPS (S-EPS) contents were increased, while tightly bound EPS (TB-EPS) and bound water contents (W_B) were reduced. As a result, the dewatering performance of sludge was enhanced. When 75 mg g⁻¹ of DDBAC were added, W_B in sludge decreased to 1.64 g g⁻¹, and the water content of dewatered sludge (W_C) dropped to 66.61%. EPS partially hydrolyzed into small molecular organics under DDBAC conditioning. Moreover, the quantity and species of organic functional groups in S-EPS were increased obviously. The TB-EPS content accounted for the majority of EPS in sludge, and the protein and polysaccharide in TB-EPS had a significant positive correlation with bound water, which was the main factor affecting W_B in sludge.