A rapid Fenton treatment technique for sewage sludge dewatering

• The Fenton reaction time was shortened to 5 min.
• Through optimization experiments, 96% SRF reduction efficiency was achieved.
• The composite conditioner acted both as an oxidant and a coagulant.
• The results were confirmed by high-pressure filtration experiments.

The study aimed to develop a rapid and practical Fenton treatment technique for sludge dewatering. The results indicated that the Fenton reaction time could be shortened to 5 min under suitable conditions. In addition, an orthogonal experimental design method was used to optimize the rapid Fenton treatment process. The optimal conditions were as followings, pH 3, Fe2+ of 50 mg/g DS (dry solids), H2O2 of 30 mg/g DS and lime of 50 mg/g DS, at which the specific resistance to filtration (SRF) reduction efficiency of 96% was achieved. The dosage of Fe2+ was demonstrated to be the most significant factor affecting sludge dewaterability. Furthermore, the lowest extracellular polymeric substances (EPS) concentration in the sludge supernatant was measured under the optimal conditions, suggesting that Fenton’s reagent acted both as an oxidant and as an effective coagulant for the sludge fragments. The morphology of the sludge cake exhibited a relatively regular and spongy block-like structure, which could maintain high permeability during high-pressure filtration. With the novel filter press achieved the squeezing pressure up to 40 MPa, the water content of sludge cake could be reduced to 55.1 ± 0.6%. Additionally, the economic assessment shows that the rapid Fenton treatment combined with high-pressure filtration can be a suitable technique for sewage sludge dewatering.