OVERVIEW
A 580 MW combined cycle power plant in Arizona, United States needed a reliable water treatment upgrade to support operations under severe water scarcity. The facility operates as a Zero Liquid Discharge (ZLD) site, reusing blowdown water from cooling towers containing high salinity, silica, and metals. ROTEC’s Flow Reversal Reverse Osmosis (FR-RO) turnkey installation replaced the plant’s aging HERO-based RO system, achieving stable high recovery, improved efficiency, and lower operating costs.
THE NEED
The combined cycle power plant faced significant operational challenges with its legacy HERO-based water treatment system. The cooling tower blowdown contained high levels of salinity and silica, leading to persistent scaling and fouling that limited system stability. Despite being designed for higher performance, the system typically achieved only around 65% recovery, resulting in increased brine volume and higher operational costs. Frequent chemical cleanings were required every two to four weeks due to unstable operation at elevated pH levels near 10.6. The limited capacity of the evaporation ponds further constrained brine management, while the rigid system design offered little flexibility to adjust flow rates in response to changing plant demand.
THE PROCESS
The combined cycle power plant faced significant operational challenges with its legacy HERO-based water treatment system. The cooling tower blowdown contained high levels of salinity and silica, leading to persistent scaling and fouling that limited system stability. Despite being designed for higher performance, the system typically achieved only around 65% recovery, resulting in increased brine volume and higher operational costs. Frequent chemical cleanings were required every two to four weeks due to unstable operation at elevated pH levels near 10.6. The limited capacity of the evaporation ponds further constrained brine management, while the rigid system design offered little flexibility to adjust flow rates in response to changing plant demand.
The main challenges in treating this wastewater effluent stream as demonstrated by the customer’s previous conventional RO systems were operational problems involving high CIP frequencies (biofouling growth), high acid consumption and limited recovery up to 80%.
THE RESULT
The FR-RO retrofit delivered major improvements across all operational parameters. Recovery increased to 88%, significantly boosting water reuse capacity and reducing brine volume, which in turn extended the lifespan of the site’s evaporation ponds and delayed major capital expenditure. Despite challenging feedwater conditions, the system maintained stable performance with permeate quality consistently below 400 µS/cm for boiler feed use.
Cleaning frequency improved substantially as well: CIP intervals expanded from every 2–4 weeks to 6–8 weeks, reducing annual cleanings by 25–50% while still effectively handling high-salinity, high-silica blowdown. Operating at a lower pH further reduced chemical consumption without compromising resistance to silica scaling. In addition, flexible flow control between 256 and 369 GPM enables the plant to modulate process water output in real time based on demand.
This success not only highlights a major leap in operational efficiency but also reinforces ROTEC’s commitment to sustainability. By maximizing water recovery and minimizing rejected brine, ROTEC FR-RO technology enables All Way Environmental and Everest to significantly reduce its environmental footprint while conserving valuable resources. Our approach emphasizes the importance of advanced water technologies that meet both operational and ecological goals.