Water Filtration

Sea Water Reverse Osmosis, or SWRO, is a reverse osmosis water treatment that has been in use since the early 1970s.  SWRO removes the salt from seawater–a process  called desalination–without need for heating or phase changes.  The typical single-pass SWRO process consists of intake, pre-treatment, a high-pressure pump, a membrane assembly, a pH and remineralization adjustment, and disinfection.  Pre-treatment is essential when working with SWRO due to the spiral wound design of filtration membranes, which only allow for one-way water flow.  Since the water being filtered cannot backpulse or agitate for scouring or solids removal from its surface, any accumulated material cannot be removed from the membrane surface and the water is vulnerable to loss of production capacity.  The pump used in SWRO supplies the pressure needed to push water through the membrane, which is simultaneously allowing and rejecting salt to pass through it.  Once water has been desalinated in this fashion, it is initially extremely corrosive and has to be stabilized by adding lime to protect pipelines and storages downstream.  Liming water will also allow the treated water to meet potable water specifications for effective disinfection.  Water must next be prepared for distribution.   Desalination processes have proven to be effective in blocking pathogenic (disease-causing) organisms, but disinfection is performed to kill any lingering harmful bacteria or virus that may have bypassed the SWRO process to remain in the water.  Disinfection may include UV lamps, the use of chlorine, or the use of chlorine combined with ammonia. 

New research and testing of reverse osmosis water treatment systems is constantly under development for both large- and small-scale operations.   With so many people drinking filtered water these days, and the large population of the planet, we will doubtless need further innovation in the water treatment field to maintain a healthy existence in the future.

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