Concentrate Enhanced Recovery Reverse Osmosis: A New Process for RO Concentrate and Brackish Water Treatment

Concentrate Enhanced Recovery Reverse Osmosis:  A New Process for RO Concentrate and Brackish Water Treatment

Anthony Tarquin, PhD.; Guillermo Delgado, PhD Candidate

University of Texas at El Paso

Advances in reverse osmosis (RO) technology have led to a significant reduction in the production cost of water desalination.  Brackish water desalination, however, is often challenging because of the high costs associated with residual RO concentrate management, especially at inland locations.  The Concentrate Enhanced Recovery Reverse Osmosis (CERRO^©) process (UTEP Provisional patent application number 61/233,761) is a new batch treatment process to reduce the volume of concentrate produced during RO treatment.  The CERRO process has shown exceptional performance treating RO concentrate with high concentrations of silica and calcium sulfate (CaSO₄) without any indications of membrane fouling.  The CERRO process consists of one or several seawater reverse osmosis membranes in parallel working in a batch configuration system.  This process was designed as a part of a research project to reduce the RO concentrate generated in the Kay Bailey Hutchison (KBH) Desalination Plant located in El Paso, Texas.  The system showed a volume reduction of 70% to 90% in RO concentrate saturated with silica and calcium sulfate.  After that, the process has been tested with high calcium sulfate brackish water with recovery rates of 70% to 96% in some cases.

This presentation will include the operation of the process and three case studies where the CERRO process was tested.

Case Study 1:  KBH RO Concentrate Volume Reduction

The KBH Desalination Plant, located in El Paso, Texas, is the largest inland desalination plant in the United States.  This plant produces a concentrate volume of two million gallons per day when operated at full capacity.  This concentrate has a silica concentration of 130 mg/l.  Additionally this concentrate is rich in calcium and sulfate ions.  Multiple testing using the CERRO process showed that recoveries of 70% to 90% can be achieved.  Water samples taken during the process showed silica concentrations above 700 mg/L at the end of each test with no indications of membrane fouling in the system.

Case Study 2:  Treatment of Alamogordo, New Mexico Brackish Water

Alamogordo groundwater is naturally contaminated with gypsum.  Analysis made in the groundwater showed that 60% of the total dissolved solids are calcium and sulfate ions.  Under these conditions, membrane desalination systems will have low recovery rates due to precipitation of calcium sulfate.  Tests made using the CERRO process showed that up to 90% recoveries can be achieved using this process.

Case Study 3:  Treatment of Alto, New Mexico Brackish Water

Brackish groundwater found in Alto, New Mexico was treated using the CERRO process.  This water has high concentrations of calcium sulfate.  Test done using the CERRO process showed that 96% recovery can be achieved.