When prison contractor CCA needed to correct TDS levels in facility well water, the company contacted AdEdge Water Technologies for a solution


In 2013, AdEdge Water Technologies was contacted by Valentine Engineering to participate in an ongoing design/build project at the Red Rock Correctional Center facility in Eloy, Arizona. CCA, the parent company and operator of privately owned and operated prisons throughout the U.S., signed an agreement with the State of Arizona to administer up to 1,500 prisoners at Red Rock. However, to secure the contract, the well supplying the facility had to be treated to ensure TDS entering the facility was under the 500 mg/L secondary MCL standard for potable drinking water.

The TDS of the raw well water was in the 865 mg/L TDS range, so a reverse osmosis system was required using a blend of raw well water into the RO permeate water to produce a final blended water quality under 500 mg/L TDS. The system is currently providing a final blended product in the 450 mg/L TDS range.

The ADRO8-4L-5H RO system was custom designed to allow field upgrade in the future as water usage increases at the facility. The current system produces up to 140 gpm blended product with a blend ratio of 80 gpm RO permeate to 60 gpm raw well water. The RO system is integrated to the well pump and distribution atmospheric storage tanks so the reverse osmosis runs as water is required in the storage tank. 

Related: Pall Corp. to present at Mine Water Solutions in Extreme Environments Conference

Additional components of the system include an antiscalant feed system to protect the RO membranes from fouling due to water hardness and silica. A second chemical feed system doses sodium hydroxide to the final blended product to increase pH, which reduces potential for corrosion in the piping system. A pH controller interfaces to the RO and chemical feed pump, maintaining a final pH of 7.5 to 7.6. 

The system was also provided with a clean-in-place system, which allows cleaning of the RO membranes on site without removal from the RO pressure vessels. System operators have been trained to monitor the system operating pressure and flow rates, and when certain conditions are reached, the CIP cycle is performed. CIP cleaning includes use of low pH and high pH cleaners to primarily remove biofilm and organic scaling due to hardness minerals — calcium and magnesium — and silica in the raw well water. 

The system went into operation in February and March 2014. Since system operation, TDS has been treated below the treatment goals.

Related: Pall Corp. to present at Mine Water Solutions in Extreme Environments Conference

About AdEdge Technologies
AdEdge has extensive experience in the removal of arsenic, iron, manganese, fluoride and uranium from water, and to date has installed hundreds of water systems for public, municipal and industrial clients throughout all of North America as well as some projects in some of the most challenging locations in the world including China and Indonesia. For more information, visit www.adedgetech.com.


Related Stories

Like this story? Sign up for alerts!