Experimental Study on Flocculation Consolidation and Dewatering of High-water-content Slurry

To investigate the mud-water separation performance and enhance the treatment efficiency of waste slurry from slurry shield tunnelling, experimental studies were carried out using chemical flocculation and consolidation-dewatering methods. The flocculation-sedimentation effects of different flocculants (PAC and CPAM) and the consolidation-dehydration performance of flocculant-lime composite-conditioned slurry were comparatively analyzed. The results indicated that both PAC and CPAM effectively enhanced flocculation and sedimentation of the slurry, with the sediment treated by CPAM exhibiting lower water content. Both flocculants significantly reduced supernatant turbidity. As the dosage increased, the Zeta potentials of both systems stabilized around -4 mV. Notably, CPAM demonstrated stronger adsorption bridging capabilities, leading to a remarkable increase in characteristic particle size and the formation of denser flocs. The composite conditioning with lime improved the permeability coefficient of filter cakes during compression, increased the consolidation coefficient, and enhanced dewatering performance. Compared to PAC, the CPAM-lime composite conditioning significantly reduced consolidation completion time, thereby improving dehydration efficiency. The findings can provide a reference for the flocculation and dewatering treatment of waste slurry in similar slurry shield tunnelling projects.