AWWA MTC57669

AWWA MTC57669 Utilization of Membrane Processes for Waste Volume Reduction
Conference Proceeding by American Water Works Association, 03/05/2003

Hanson, Steve; Freer, Edward L.; McClenahan, Robert L.; Worland, V. Peter

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Los Alamos National Laboratory is a government owned, contractor operated facility, with theDepartment of Energy and the University of California being the respective primary partiesinvolved. Los Alamos National Laboratory (LANL) is located in northern New Mexico and isinvolved in a myriad of research activities, resulting in unique liquid waste characteristics.These wastes are treated at the Technical Area (TA-) 50 Radioactive Liquid Waste TreatmentFacility (RLWTF). Since the early 1960's, the main method of treatment of liquid wastes hasbeen the typical chemical precipitation approach. However, in the late 1990's, due to morestringent regulation of environmental discharges and the need to minimize the amount ofsecondary waste generated, the treatment scheme was modified to include various membranetechnologies, including: tubular ultrafiltration, centrifugal ultrafiltration, reverse osmosis andelectrodialysis.The current approach to secondary waste reduction, at the RLWTF, uses an electrodialysisreversal (EDR) unit to treat the reverse osmosis (RO) concentrate stream. An evaporator thentreats the EDR concentrate stream. Optimization of this secondary waste treatment schemehas been attempted. Improved clarifier operations resulting in increased radionuclide, calcium,and silica removal have enabled the RO to operate at ninety percent (90%) water recovery.Precipitation of calcium and silica from the RO and EDR concentrates have improved theperformance of the EDR and evaporator, respectively. However, operation of these units forthe past three years has shown that further improvement is needed in both product waterquality and volume reduction.A different secondary waste treatment scheme has been pilot tested at the RLWTF starting inDecember 2002. In this treatment scheme, RO concentrate is fed to a brackish water reverseosmosis unit. Concentrate from the brackish water RO is fed to a seawater reverse osmosisunit. This process reduces the RO concentrate volumes by as much as fifteen (15) times.Solidification of these concentrated liquid wastes by drum heaters will also be pilot tested. Thedata obtained from several months of testing will enable the assessment of this technology forpotential use as a full-scale process within the RLWTF. Includes 10 references, tables, figures.