K Basin Sludge Conditioning Process Testing Fate of PCBs During K Basin Sludge Dissolution in Nitric Acid and with Hydrogen Peroxide Addition

K Basin Sludge Conditioning Process Testing Partitioning of PCBs in Dissolver Solution After Neutralization/Precipitation (Caustic Adjustment)

“…The fi-action remaining with the dissolver solution decreased with increasing levels of chlorination on the PCB congeners. With respect to the dissolver solution, these results are very consistent with those obtained by Mong et al (1998). However, they found that 35°/0to 99°/0of the recovered PCB congeners were associated with the vessel rinse solutions.…”

“…Under the direction of Duke Engineering& Services Hanford and Numatec Hanford Corporation, Pacific Northwest National Laboratory (PNNL) performed tests to determine the chemical fate of polychlorinated biphenyls (PCBS) in potential processing steps within the K Basin Sludge Conditioning Process (Mong et al 1998). One set of tests examined the effect of hydrogen peroxide on the disposition of PCBS in a 0.5~nitric acidll~Fe(NOJJ solution, contacting the PCBS to an environment similar to "Fenton Reagent."…”

“…Based on the PNNL tests (Mong et al 1998) and engineering evaluations, the baseline plan for addressing PCBS within the K Basin Sludge Conditioning Process is to partition most of the PCBS to the acid insoluble solids (during sludge dissolution) and filter the dissolver solution (collecting some PCBS on the filter). The filtered dissolver solution will next be caustically adjusted to a pH of greater than 12 to meet Tank Waste Remediation System (TWRS) Double Shell Tank waste acceptance criteria.…”

“…In the previous study (Mong et al 1998), the entire series of processing steps (acid dissolution, filtration, and caustic adjustment) were examined during integrated testing. In the work described here, the caustic adjustment step was isolated and the fate of PCBs in this step was examined in much greater detail.…”

“…However, in the actual K Basin Sludge Conditioning Process, the dissolver solution will pass through a filter before caustic adjustment. Based on engineering studies and Mong et al (1998), filtration is expected to remove about 95% of the PCB in the dissolver solution.…”