Made the Water, Now What Do I Do?: Disposal of High-purity Water Production Residuals

Ethanol refineries require various degrees of high-purity water for use as process water, cooling tower feed water, and boiler feed water. The water quality standards for the three uses are different from each other but are all more stringent than drinking water standards. As a result, the use of advanced treatment processes, such as reverse osmosis (RO) and ion exchange (IX), is required. Because ethanol refineries have been located in inland areas with no ocean outfall, disposal of the brine waste from these two processes poses a serious challenge. This paper explores the application of different treatment processes for three ethanol refineries in the United States and their respective waste residuals management solutions. The brine concentrate management strategies discussed here include discharging to storage ponds, a surface water receiving stream, and a mechanical zero liquid discharge (ZLD) system.