Evaluation Of Chemical Additives For Glycolate Destruction In The Recycle Collection Tank

Abstract

Savannah River National Laboratory (SRNL) has completed a work scope in support of the Savannah River Remediation (SRR) Nitric-Glycolic flowsheet. Glycolic acid will replace formic acid as a reducing agent in the pre-processing of High-Level Waste sludge performed at the Defense Waste Processing Facility (DWPF). Glycolic acid will perform the same function as formic acid, namely reduction of mercury and adjustment of feed rheology and melter oxidation/reduction potential, while significantly reducing the potential for hydrogen generation in DWPF processing. Development testing has demonstrated glycolic acid virtually eliminates hydrogen production in the pre-processing steps.The Nitric-Glycolic flowsheet significantly improves DWPF's ability to address Savannah River Site's key challenge -the incorporation of effluent received from the Salt Waste Processing Facility (SWPF). SWPF will deliver significant effluent volume to DWPF, resulting in a concurrent increase in DWPF effluent returned to the Concentration, Storage and Transfer Facilities (CSTF). This work scope demonstrates that glycolate can be destroyed under the Nitric-Glycolic flowsheet prior to returning the DWPF recycle stream to CSTF.

Evaluations of the Fates of Alkali Metals, Actinides, Mercury, and Iodine During DWPF Recycle Diversion

“…It was shown that permanganate did not react with methyl mercury. 43 Another test was performed on the effectiveness of permanganate oxidation to destroy glycolate in a sample from the SMECT. 7 Analysis of the initial sample from the SMECT revealed that the methylmercury concentration was below the detection limit, so no information from that test is available on whether there is a reaction between methylmercury and permanganate.…”

Permanganate Oxidation of Defense Waste Processing Facility (DWPF) Recycle Collection Tank (RCT) Simulants Larger Scale Protocol Runs - Chemical Process Cell (CPC) Nominal and Foamover Conditions

“…It should be noted that during down select testing using smaller volumes (e.g., 1.8 L) with 10x scale purge rates, no H2 attributed to process was ever detected and CO2 is not expected in caustic conditions. 6 The analysis frequency for the FTIR and GC were <10 seconds and four minutes respectively.…”

“…The third phase of testing was to demonstrate nominal operation of the permanganate oxidation process under protocols similar to those used in the Defense Waste Processing Facility (DWPF). 7 6,7 In addition, equation (1) was found to best describe the observed reaction of glycolate with permanganate under nominal and low glycolate entrainment conditions. 7…”

“…5 The second phase was a matrix of 23 tests completed to inform a down-select decision by SRR and to complete testing needed to understand the influence of various factors in defining the optimum processing conditions for oxidation of organics. 6 From the results of this testing, oxidation by permanganate was chosen over Fenton's reagent with hydrogen peroxide. The third phase of testing was to demonstrate nominal operation of the permanganate oxidation process under protocols similar to those used in the Defense Waste Processing Facility (DWPF).…”

Modeling the Destruction of Glycolate in the Defense Waste Processing Facility (DWPF) Recycle Stream and Concentration Factors for Glycolate in the 2H Evaporator

“…The results from these laboratory studies were summarized in a series of reports. [5][6][7][8][9] Tests at caustic conditions demonstrated sodium permanganate was effective in converting glycolate to oxalate, and permanganate (Mn 7+ ) is reduced to manganate (Mn 6+ ) with no significant formation of carbon dioxide or carbonate. Equation (1) was found to best describe the observed reaction of glycolate with permanganate under nominal and low glycolate entrainment conditions.…”