This project demonstrated the innovative Waste Acid Detoxification and Reclamation (WADR) process at the Watervliet Arsenal in Watervliet, New York for recovering spent electropolish acid solutions used during the manufacture of large-caliber gun-tubes. The WADR system utilizes vacuum distillation technology to remove, and subsequently condense water from the spent acid bath contents. Large quantities of metal-bearing spent acids are generated from electroplating, surface finishing, and chemical milling/dissolution processes at Department of Defense (DoD) installations. For example, the Watervliet Arsenal produces 70 tons of waste sulfuric and phosphoric acids each year from its chrome-plating operations
WADR technology successfully purified spent electropolish solution by concentrating two component acids by 3.3 percent and 3.6 percent of the required processing specifications on average, thereby rendering the solution suitable for reuse during gun-tube manufacturing. Additionally, secondary waste streams generated from the treatment process were accepted for disposal at the Watervliet Arsenal industrial wastewater treatment plant.
The WADR process allows reuse of the recovered acid, thereby greatly reducing the amount of new acid purchased for replacement and the amount of hazardous waste generated. Unlike other acid recovery processes, the WADR system is fabricated with advanced materials of construction, which make it capable of operating under the harsh processing environment caused by high concentrations of acid. The WADR process showed a potential savings of over $80,000 per year for a system operating on a 3,400-gallon electropolish tank. Cost analysis showed an internal rate of return of 10.0 percent -16.4 percent, and a payback period of 7.0-12.6 years on the estimated $500-750k capital investment required for the WADR installation.
The WADR system is a technically feasible process with significant potential cost savings and a reasonable return on the capital investment. The success of this demonstration has encouraged the installation of a new WADR system at the Watervliet Arsenal, the "nation's only cannon factory." The system is also becoming part of other standard manufacturing operations. Application at other DoD facilities would save an estimated $10 million per year and allow the DoD to comply with new hazardous materials regulations and meet pollution prevention goals. Successful utilization would greatly reduce hazardous waste production, resulting in cost savings and a cleaner environment.