Enhancing slurry dewatering through pressurized electro-osmosis and chemical treatment

Slurry, containing a high water content, requires dewatering before subsequent utilization. This study proposes the combination of pressurized electro-osmotic dewatering (PEOD) technology and chemical treatment to improve dewatering performance significantly. Laboratory tests were conducted to investigate the combined effect of both methods along with the effect of pH variations using HCl and NaOH. Additionally, changes in the slurry's physical, chemical, and geotechnical characteristics post-PEOD were analyzed. Results indicate that the dual approach effectively enhances dewatering efficiency. The dewatered cake's final moisture content was as follows: PEOD + electrodes reversal (ER) < PEOD < electro-osmotic dewatering (EOD) < mechanical dewatering (MD). Specifically, PEOD + ER with different pH in the slurry demonstrates different dewatering efficiencies. The dewatered cake with the NaOH solution outperforms that with the HCl solution, achieving a final moisture content of 47.4%. This is attributed to the higher initial pH, which increases electro-osmotic permeability and thereby improves drainage rate. Ion concentration profiles revealed that Ca2+ ions influence pore water transportation toward the cathode. With the increase in pH, both the absolute value of zeta potential and the slurry's electro-osmotic coefficient increase, enhancing electro-osmosis efficiency. Overall, comprehensive experimental analysis shows that combining PEOD with chemical treatment is a promising technique for optimizing slurry dewatering efficiency.