Laboratory studies using sodium-bearing waste simulant - ADL 26-94

The purposes of this study were to develop a chemical precipitation procedure that would treat the sodium bearing waste (SBW) and to determine if polymer addition could condition the resulting sludge. Chemical precipitation parameters such as impeller mixing speed, rate of base addition, amount of added calcium to SBW, and solution precipitation pH were studied to determine the conditions for each parameter to achieve optimal solids removal rates and resistance to filtration. The organic polymers were gauged by their ability to properly condition the sludge by use of capillary suction time (CST) apparatus and wedge zone simulator (WZS).

Low impeller mixing speeds cause less excess floc deterioration and lower resistance to filtration. Slower base addition rates increase the overall titration time but improve sludge characteristics. Adding calcium to SBW decreases the specific resistance of the sludge. The best dewatering rates occur when solution precipitation pH is between 8.5 and 9.5. This region provides the best cake solids and removal rates of the dissolved species. WZS and high speed centrifugation provide cakes solids above 20%. Medium to high molecular weight anionic polymers properly condition the SBW sludge.