Pilot Testing of Membrane Zero Liquid Discharge (ZLD)
Membrane technology using reverse osmosis (RO) is an important tool for treating recycled water to high water quality standards. Yet the lack of options for the disposal of the RO waste stream (e.g. termed concentrate or brine) is frequently a barrier for the implementation of membrane technology and by extension, recycled water systems in arid or inland portions of the country.
Recognizing the importance of RO technology in developing recycled water resources in Colorado, the Colorado Water Conservation Board (CWCB) along with eight Colorado utilities and the US Bureau of Reclamation sponsored the Colorado Zero Liquid Discharge Project. We were selected to manage this project that included a desktop study of 27 brine minimization or zero liquid discharge (ZLD) technologies for their suitability for use in Colorado. From this analysis, an advanced treatment technology capable of obtaining very high recovery was selected for pilot testing. The technology, termed Zero Discharge Desalination (ZDD), is developed by the Center for Inland Desalination Systems at the University of Texas El Paso.
The ZDD technology was pilot tested at two locations, La Junta and Brighton Colorado. The project concluded that the ZDD technology could obtain recoveries in excess on 96 percent while producing excellent water quality. However, the project also concluded that additional development focused on reducing cost, increasing reliability and simplifying its operation, is needed before the technology is suitable for use by utilities.
- Screening analysis of 27 different brine minimization technologies
- Pilot testing of ZDD with 96 percent water recovery and excellent water quality