Natural chitosan was used as raw material to prepare magnetic chitosan by cross linking with glutaraldehyde and Fe3O4for enhancement of the sludge dewatering. The effects of magnetic chitosan dosage, sludge pH and conditioning time on the performance of magnetic chitosan for sludge dewatering were investigated, and the enhancement mechanism was discussed. Subsequently, response surface methodology (RSM) was employed to optimize the process of sludge dewatering by the complex of CPAM and magnetic chitosan. When sludge pH value was 6.8, after conditioned by 20mg/L of magnetic chitosan for 30min, SRF and MC were decreased from 13.8×1012m/kg and 98.7% of the original sludge to 4.8×1012m/kg and 75.5%, respectively, indicated that the sludge dewatering was significantly enhanced. SRF and MC were settled as the target responses in the experiments designed by RSM, as the determination coefficients (R2) of 0.98and 0.95, the two quadratic models could agree with experimental data well. The optimal conditions for sludge dewatering were magnetic chitosan dosage of 18mg/L, CPAM dosage of 26mg/L, and conditioning time of 27 min, under this optimal condition, SRF and MC appeared as 3.3×1012m/kg and 59.5%, respectively, better than the individual using of the magnetic chitosan or CPAM in sludge dewatering.
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