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California State University, Long Beach
Research at the Beach | CSULB Research Newsletter
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Making our Campus "Water Sustainable" Using Abandoned Water Waste

Professor Professor Jin Gi Hong

Nowadays, water shortage has become a key issue in California. California communities, farms, businesses, and natural ecosystems depend upon adequate and reliable supplies of clean water. One of the promising ways to increase available water supply beyond nature’s hydrological cycle is to develop engineering strategies for sustainable and energy-efficient technologies. Methods to conserve and secure water include the development of on-site recycling technologies, which will increase wastewater reuse and bring considerable savings in freshwater consumption.

One of the major water consumers in many industry, government and school buildings is a cooling tower. This technology has been commonly used since the 19th Century. However, given the ever-increasing urgency in water conservation of California, a more efficient cooling system technology is highly desirable. California’s drought conditions and increasing water usage have combined to decrease the availability and increase the cost of the good quality, low hardness water preferred for proper cooling tower water recirculation. At the same time, stricter environmental restrictions on discharge have resulted in increased fees for disposal of cooling tower wastewater to the sewers.

My research, funded by Metropolitan Water District of Southern California and the U.S. Department of the Interior’s Bureau of Reclamation, is focusing on developing the advanced zero liquid discharge (ZLD) wastewater treatment technology for potential water savings in our campus cooling system. Typically, a cooling tower system recirculates its water with losses of about 70-80% of the sourced freshwater due to evaporation, which leads to discharge of about 20-30% of wastewater. As water evaporates during the operation, the salts that are dissolved in the recirculation water accumulate over time which becomes a main contributor to corrosion, scale, and biofilm formation in the tower facility. Also, a direct discharge of such concentrates into the ocean can disrupt natural salinity balances and cause environmental damage to marine ecosystems.

CSULUB Cooling Tower Plant

CSULB Cooling Tower Plant

A great collaborative opportunity to work with industry allowed us to design a ZLD system using an ion exchange-based process. Our system is expected to purify and recycle virtually all the cooling tower wastewater produced. With a successful application of this research in a bench-scale, I hope that the technology will transition to a “real scale” deployment at our CSULB campus plant in the near future. I believe that the idea of a cooled water recycling program is one of the most effective means of saving fresh water, as well as offering a reliable strategy for a sustainable campus environment.

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