Improving sludge dewaterability by combined conditioning with Fenton's reagent and surfactant

The effect of Fenton's reagent combined with dodecyl dimethyl benzyl ammonium chloride (DDBAC) on sludge dewaterability was studied. The capillary suction time (CST) and water content (WC) of sludge cake were used to evaluate sludge dewaterability. Bound water content (W _B), extracellular polymeric substance (EPS) concentration, and organic acid concentration in the sludge supernatant were measured to explain the change of dewaterability in the conditioning process. Results indicated that Fenton's reagent combined with DDBAC could enhance sludge dewaterability significantly. When the dosage of Fe²⁺, H₂O₂, and DDBAC were 40, 40, and 60 mg g^-1 at pH 4, WC of 57.17 % and CST of 17.2 s could be achieved. The protein (PN) and polysaccharide (PS) concentrations in each layer of EPS decreased during the composite conditioning, especially in tightly bound EPS (TB-EPS) and slime layer EPS (S-EPS). And, approximately 68 % of the bound water was released in this process. Further studies through high-performance liquid chromatography (HPLC) demonstrated that the composite conditioning process could oxidize and hydrolyze EPS into small organic molecules, resulting in an increase of small-molecule organics in the species and quantities.