Current metal cutting and finishing operations use skimming and filtration to try to separate wastes from their water based cutting fluids. The residual liquid from the filtration consists of ultrafine metal particles containing hazardous heavy metals like lead, zinc, and cadmium and a tightly emulsified oil-in-water phase. This sludge is not amenable to further treatment and must be hauled off as hazardous waste. Also, at this level of cleaning, the water phase is not clean enough to discharge and must be controlled within the plant Furthermore, this liquid does not have the same properties as freshly prepared solutions. Hence, the cost of this problem to industry is much more than the apparent disposal cost. Ultrasonic coalescence can promote rapid agglomeration of particulate in a fluid. Once the particles are agglomerated, they can be efficiently separated by centrifugal or gravity separation. S. R. Taylor and Associates propose to use its combined experience with ultrasonics and multiphase coalescence processing to develop ultrasonic coalescence for separating oil and ultrafine metal particles from metal working wastewaters, to determine the appropriate operating conditions for successful coalescence, and to use this method to regenerate typical metal cutting fluids. Phase I studies will focus on demonstration of feasibility and preliminary design studies providing the support for the Phase II prototype development and actual continuous flow testing.
