Hazardous Wastes Minimization by Reuse and Recycling at a Naval Air Rework Facility

A freeze crystallization process is being demonstrated for treating a wide variety of wastes generated in the plating and other industrial shops at the Norfolk, VA Naval Aviation Depot (NAD). As envisioned the freeze process will treat various rinses, plating baths, and cleaning solutions for recycle at the NAD, greatly reducing and even eliminating discharges to the industrial waste treatment plant. The manner in which the freeze process will be incorporated to do this includes:

• remove water with sufficient purity for recycle as rinse water and in bath makeup;
• concentrate the chemicals in rinse waters for recycle to plating baths;
• concentrate pickling wastes to recycle the concentrated acid while precipitating the dissolved metals for removal as innocuous sludge;
• concentrate paint strippers and solvents in rinses and other contaminated waters, separating useful organics from residual aqueous concentrates.

Preliminary economic feasibility analyses show that recycling of rinse waters from chrome, nickel and cadmium lines is economically justified by the recovery of metal values, savings in conventional treatment costs, and reduced hazardous material production. Benefits in meeting environmental discharge limits, reduced waste water treatment plant operating labor and maintenance costs, and treating contaminated bathes have not been accrued to the justification for this technology.