El Paso desalination hits record results with Desalitech process

The Kay Bailey Hutchison (KBH) desalination plant at El Paso, Texas has deployed Desalitech's ReFlex reverse osmosis (RO) process to achieve a "record high" in groundwater purification with unprecedented water recovery rates.

The findings emerged following the completion of eight months' of tests by the University of Texas' Centre for Inland Desalination Systems (CIDS).

CIDS recorded brackish water desalination operation at 94% recovery with no silica or other scaling. This outstripped recovery rates possible with traditional RO technology according to Desalitech.

"The demonstration establishes a new standard for water efficiency in reverse osmosis processes with significant global financial and environmental implications," the company said.

The 110 Ml/d KBH plant pumps groundwater from an onsite wellfield to treatment works that include sand strainers, cartridge filters and RO equipment. It is currently operating at 82.5% recovery, using a conventional multi-stage RO system operating at high silica concentrations. This is generating a wastewater stream that is sent to disposal wells.

Silica is present in most ground water and it precipitates during membrane processes including desalination to form a
dense coat that is all but impossible to remove. This coating limits
the recovery rates at which an RO can operate. Low-recovery results in a high-volume waste stream that requires difficult and expensive treatment or disposal.

"Sustainable inland RO operation at recovery rates that exceed the saturation concentrations of these salts represents a technological breakthrough for industrial and municipal water purification," says Desalitech.

CIDS installed a mobile containerized Desalitech RO pilot unit at the KBH plant in June 2015. The pilot unit was equipped with standard reverse osmosis membranes, pumps and other components, which operated at typical membrane flux and crossflow rates.

Desalitech said the pilot sustained recovery rates above 90% during "days of continuous testing." The firm said the highest recovery achieved without scale formation was 94%, corresponding to silica supersaturation of 273%. A conventional RO and distillation system is generally limited to 100% silica saturation.

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