Brackish Water Reverse Osmosis

Brackish water RO (BWRO) systems are designed for feed water from 1,000 to 10,000 TDS, covering the full range of inland groundwater brackishness. Feed above 10,000 TDS requires seawater-class membranes and higher operating pressure. A feed water analysis is the starting point for any BWRO system design, confirming TDS, ion composition, hardness, and scaling potential.

Brackish water systems operate at 100 to 400 PSI, roughly one-third to one-half the pressure of seawater RO at 800 to 1,000 PSI. Lower operating pressure means lower energy consumption per gallon. At 2,000 TDS feed, energy use is typically 0.4 to 0.6 kWh per 1,000 gallons, compared to 4 to 6 kWh per 1,000 gallons for seawater desalination.

Standard BWRO membranes achieve 95 to 98 percent NaCl rejection. High-rejection variants reach 99.5 percent and are used when softening or nitrate removal is the primary treatment goal. For agricultural water applications where some residual mineral content is desirable, standard 96 to 97 percent rejection membranes are typically the right choice.

The most common applications are municipal water systems drawing from brackish aquifers, agricultural processing facilities, food and beverage production requiring low-TDS process water, power plant makeup water, and light industrial manufacturing. AMPAC USA also supplies BWRO systems to hospitals and commercial laundries where high-TDS source water causes equipment scaling and product quality problems.

Antiscalant chemical injection upstream of the membranes inhibits carbonate, sulfate, silica, and barium scaling. Dosage is calculated from a Langelier Saturation Index analysis of the feed water. For very high hardness feeds, a water softener pre-treatment stage may be added. AMPAC USA provides feed water analysis review and antiscalant dosing recommendations with every system.

Standard BWRO system recovery is 75 to 85 percent, meaning 75 to 85 gallons of permeate per 100 gallons of feed. Higher recovery reduces concentrate disposal volume, which matters in water-scarce inland locations without ocean or river discharge options. Recovery is optimized against concentrate scaling risk; high silica or sulfate feeds may be limited to 70 to 75 percent to stay below saturation thresholds.