AWWA MTC57669

Los Alamos National Laboratory is a government owned, contractor operated facility, with the Department of Energy and the University of California being the respective primary parties involved. Los Alamos National Laboratory (LANL) is located in northern New Mexico and is involved 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 Treatment Facility (RLWTF). Since the early 1960's, the main method of treatment of liquid wastes has been the typical chemical precipitation approach. However, in the late 1990's, due to more stringent regulation of environmental discharges and the need to minimize the amount of secondary waste generated, the treatment scheme was modified to include various membrane technologies, including: tubular ultrafiltration, centrifugal ultrafiltration, reverse osmosis and electrodialysis. The current approach to secondary waste reduction, at the RLWTF, uses an electrodialysis reversal (EDR) unit to treat the reverse osmosis (RO) concentrate stream. An evaporator then treats the EDR concentrate stream. Optimization of this secondary waste treatment scheme has 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 the performance of the EDR and evaporator, respectively. However, operation of these units for the past three years has shown that further improvement is needed in both product water quality and volume reduction. A different secondary waste treatment scheme has been pilot tested at the RLWTF starting in December 2002. In this treatment scheme, RO concentrate is fed to a brackish water reverse osmosis unit. Concentrate from the brackish water RO is fed to a seawater reverse osmosis unit. 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. The data obtained from several months of testing will enable the assessment of this technology for potential use as a full-scale process within the RLWTF. Includes 10 references, tables, figures.