Ion exchange membranes are sandwiched between spacers to form a series of cells. The spacers, in addition to supporting the membranes. provide the flow path and the hydraulic interconnection between the cells. Each membrane may be arranged hydraulically in a series configuration creating the opportunity for an extremely long flow path with enhanced membrane surface area. This extended membrane area combined with very low flow rates, results in a system that Is capable of efficiently removing acids to extremely low concentrations with almost no power consumption. The used acid is metered through the system in contact with one side of an anionic ion exchange membrane.
Water is metered in a countercurrent fashion on the recovery side of the membrane.
The majority of the acid migrates through the membrane into the water leaving contaminants such as heavy metal behind. The purified acid is directed back to the process tank. Fresh acid in proportion to the unrecovered amount is added to the bath to maintain the concentration within the correct operating window. The highly resistant nature of ion exchange membranes to strong acids enables the system to handle a wide variety of mineral acids at high concentrations. Common metal contaminants such as copper, chrome, nickel, iron, and aluminum can be economically separated allowing the reclaimed acids to be used indefinitely.