Effect of modified corn stalk combined with ultrasonic conditioning on sludge dewatering performance

Abstract

To address the challenge of high moisture content and difficulty in water removal in sludge, this study optimized the preparation conditions of modified corn stalk powder (MCSP) using solid waste corn stalk powder (CSP) as the raw material. The optimization was achieved through an alkalization–etherification process combined with response surface methodology (RSM). When the optimized MCSP was applied in combination with ultrasonic conditioning for sludge treatment, it was found that the optimal dosage of MCSP was 0.1 g g⁻¹ DS. At this dosage, the water content of the dewatered sludge and specific resistance to filtration (SRF) reached their lowest values, which were 1.23 × 10¹² m kg⁻¹ and 53.5%, respectively. Furthermore, the bound water content decreased from 8.53 g g⁻¹ DS to 4.64 g g⁻¹ DS. There was an increasing trend in the protein and polysaccharide contents across all extracellular polymeric substances (EPS) fractions, with the protein content in soluble EPS (S-EPS) increasing from 4.87 mg g⁻¹ to 21.31 mg g⁻¹. At the optimal dosage, the sludge particle size increased to 98.5 μm, and the absolute value of the sludge zeta potential approached zero. The outer boundaries of the flocs became smoother, and the floc structure became more compact, resulting in optimal sludge dewatering performance. Further data analysis revealed that EPS and one-dimensional fractal dimension were the primary factors influencing sludge dewatering performance.