During normal operation of an R/O water treatment system, the membrane elements will often suffer a reduction in performance due to the accumulation of small particles, colloids, microorganisms, or precipitated salts collecting on the membrane surface.
Pretreatment Equipment - Theory of Operation
Some raw feed waters contain suspended particulate material. This material is commonly sand, iron oxides, clay or elemental sulfur.
Introduction of such materials into the membrane system can cause the development of excessive system differential pressure (dP), or even complete blockage of the brine channels with the resultant reduction of permeate flow. It can also cause physical damage to the membranes themselves. This usually results in a decrease of permeate quality and reduction of membrane life. Cartridge filtration is normally a simple and cost-effective way to reduce the amount of particulate matter reaching the membrane surface.
Recovery is the amount of water permeated per unit time - usually in gallons per minute (gpm) and expressed as a percentage of the raw water feed flow rate. The design recovery is calculated as follows:
Membrane filtration can be explained as a method of allowing certain materials to permeate a surface while blocking others. For water, this means allowing clean water to flow through the membrane while eliminating sediments and other materials or pathogens. Membrane filtration is a multiple-step process which is considered to be one of the most cost-effective water treatments available.
Variable frequency drives (VFD) are becoming the popular choice for many industrial processes that need to make use of motors with changing speeds. In membrane plants, these motors are used to feed the pressure and flow of the water as it moves through the various areas of the treatment cycle.
Membrane filtration systems are helping water treatment providers simplify and automate their processes while significantly improving water quality. Replacing or augmenting conventional treatment with membrane processes helps avoid heavy use of chemical processes and methods and can provide a superior finished water quality.