Concentrate, also called brine or reject, is the portion of feed water that does not pass through the RO membrane. It carries the rejected salts at concentrations 1.5–2× the feed, exiting the last membrane vessel at near-feed pressure. In a 40%-recovery SWRO system, every 100 m³ of feed produces 40 m³ of permeate and 60 m³ of brine. The brine retains ~95% of the feed's hydraulic pressure, which an energy-recovery device captures to repressurize new feed. Brine handling drives both the economics (energy recovery) and the permitting (discharge regulations) of every desalination project. Disposal requires diffusers or zero-liquid-discharge for inland systems. At 40% recovery, SWRO brine is roughly 1.67× the feed TDS — about 58,000–65,000 ppm from typical 35,000 ppm seawater. Yes, with proper diffusers that dilute the dense plume to within 2 ppt above ambient salinity within a regulated mixing zone, per local discharge permits. ZLD evaporates and crystallizes the brine to recover salt as a solid, eliminating liquid discharge entirely. Used for inland BWRO where ocean disposal is unavailable. ForeverPure has supplied desalination, high-pressure pumps, and energy-recovery devices to commercial and industrial customers since 2003. Contact our engineers for sizing, quotes, or technical support.Concentrate (Brine)
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What is zero liquid discharge (ZLD)?
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