Abstract: Performance of a rotating filter element for removing particulate matter from a liquid is enhanced by applying acoustic energy in the ultrasonic frequency range to the filter element by plural transducers affixed to the exterior of a bowl surrounding the rotating filter element. The bowl and filter element can be electrically isolated from each other and connected to a D.C. power supply for further enhancement of filter performance. The ultrasonic transducers, the power supply, and a discharge valve can all be operated by a controller, responsive to a sensor which senses the pressure drop across the filter element.

Abstract: Performance of a rotating filter element for removing particulate matter from a liquid is enhanced by applying acoustic energy in the ultrasonic frequency range to the filter element by plural transducers affixed to the exterior of a bowl surrounding the rotating filter element. The bowl and filter element can be electrically isolated from each other and connected to a D.C. power supply for further enhancement of filter performance. The ultrasonic transducers, the power supply, and a discharge valve can all be operated by a controller, responsive to a sensor which senses the pressure drop across the filter element.

Abstract: In a developing, etching and stripping apparatus, photoresist developing and stripping chemicals are drawn off into separate circulatory paths in each of which they are pumped through a heat exchanger, a series of tangential filters, an ultraviolet contactor and a collection tank. Permeate from the filters is returned to the developing or stripping stage, and solutions with high concentrations of solids are removed from the collection tanks for disposal. A similar system is used to recycle metal stripping solutions such as nitric acid-containing solutions, allowing recovery of metals.

Abstract: In a developing, etching and stripping apparatus, photoresist developing and stripping chemicals are drawn off into separate circulatory paths in each of which they are pumped through a heat exchanger, a series of tangential filters, an ultraviolet contactor and a collection tank. Permeate from the filters is returned to the developing or stripping stage, and solutions with high concentrations of solids are removed from the collection tanks for disposal.