Residential Commercial Ultra-low pressure membrane element Extremely low pressure series High-desalination membrane element High flux brackish Series Oxidation Resistance brackish series Fouling Resistance membrane element High desalination of seawater membrane element High flux membrane desalination membrane element
Internal pressure Tubular Membrane Submerged Column-Type Submerged MBR Horizontal UF Membrane External pressure
1. Pressure – a minimum threshold of pressure must initially be reached to overcome the natural osmotic pressure. Flux (the rate at which the membrane makes product water) increases as pressure is increased. A practical limit exists because salt rejection does not continually improve as pressure increases. The result can be scaling or fouling problems.
2. Temperature – membrane flux is very dependent on temperature. If temperature increases and pressure remains constant, water production increases. Unfortunately, higher temperatures also result in a drop-off in salt rejection due to an increase in diffusion rate for salt ions through the membrane. RO units are volume rated at 77°F.
3. Recovery – the percent of feedwater converted to the product water. A practical limit exists for the recovery rate – too high of a rate requires a more concentrated waste stream, which increases the likelihood of membrane fouling as salt precipitates and forms scale on the membrane surface.
4. Pretreatment/Posttreatment – the need for additional water treatment steps either before or after the RO process varies, depending on water conditions and quality requirements. If raw water contains chlorine, hardness, iron, turbidity, and high total dissolved solids, then pretreatment should be considered to extend membrane life and improve system performance. If water quality requirements require ultra-pure or sterilized water, then posttreatment steps should be considered.
Reverse osmosis is typically used for boiler feed/makeup water, chemical process water, cosmetics, drinking water, electronics, food and beverage processing, horticulture, humidification, ice making, laboratories, manufacturing process water, metal finishing, pharmaceutics, photographic processing, printing, and vehicle washes. All of these industrial water applications could benefit by the installation of a Nancrede reverse osmosis system.
