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Project Title: Zero-Liquid Discharge Systems for the Recovery of Cooling Tower Water in Geothermal Power Plants

Scope

The desired outcome of the proposed research is increased efficiency and productivity of power plants through conversion of the cooling system to as close to a zero liquid discharge (ZLD) system as possible. Existing ZLD systems are expensive, energy-intensive brine concentrators; membrane technologies that may be used individually or in combination will be evaluated as a brine treatment step to further concentrate the blowdown brine and recover more water at a lower cost. Novel membrane systems that have been developed and/or tested at the University of Nevada, Reno shall be investigated for enhanced recovery of blowdown water. These include, but are not limited to, a FO/RO hybrid process, an enhanced MD process, a combined UF/RO process, and a novel combined UF/dual-stage NF process.

Objectives

  • Investigate advanced treatment processes for recovery of water from blowdown brine in recirculated evaporative cooling towers at geothermal power plants through:

    • Hybrid pressure driven membrane processes
    • Novel membrane technologies

  • Assess cost-effectiveness of the various water treatment strategies in light of diminishing water resources

Status

Task 1:

Data collection and processing

  • Deliverable: Results from the literature review and power plant survey shall be documented.
Task 2:

Chemical analysis of blowdown brine

  • Deliverable: Deliverable: Results from the data collection and laboratory analysis shall be documented in the bi-monthly technical progress reports.
Task 3:

Bench scale testing of pressure-driven membrane processes

  • Deliverable: Results from the bench-scale testing of pressure-driven membrane processes shall be compiled and documented in the bi-monthly technical progress reports.
Task 4:

Bench scale testing of membrane contactor processes

  • Deliverable: Results from the bench-scale testing of membrane contactor processes shall be compiled and documented in the bi-monthly technical progress reports.

  • Deliverable: Data from Tasks 3 and 4 shall be compiled in an intermediate report (to be submitted at the end of month 15) that will compare the different water treatment approaches. Based on results from these tasks, preliminary design of a small-scale pilot system will also be provided. (Because the membrane cleaning and scale prevention tasks may not be completed by that time, they will not be included in the intermediate report but will be documented in the next bi-monthly technical progress reports.)
Task 5:

Economic analysis

  • Deliverable: Results from the economic analysis shall be documented in the bi-monthly technical progress reports.
Task 6:

Field testing

  • Deliverable: Results of the field-testing shall be documented in the bi-monthly technical progress reports.
Task 7:

Final report

  • Deliverable: Delivery of a final report (in draft and final versions) describing the project, the results, and the recommendations for future research and development.

Learn more about the current status of this geothermal project by downloading a recent power point presentation given at the NSWEP Program Review.
(PowerPoint 797 KB)

Contact

Dr. Amy E. Childress
University of Nevada—Reno
Department of Civil and Environmental Engineering
Bus: (775) 784-6942
E-mail: amyec@unr.edu