Methods For Making Ultrapure Water
All water is not created equal. While, yes, the prerequisite two-parts hydrogen, one-part oxygen defines water in all of its forms, in practice every drop will be defined by the infinitely diverse combination of impurities and contaminants that come with it.
Some water may be salty, and that’s fine for some thermoelectric power generation. Water that has been treated for human consumption may still retain benign, microscopic impurities. But only that which has been treated to the strictest possible standards can be considered ultrapure water.
Highly sensitive operations such as pharmaceutical production, laboratory research, and supercritical boiler power generation call for ultrapure water, also known as UPW or high purity water. These operations are so precise that if any of the minute contaminants that are safe even for human consumption were present, they would interfere.
The ultrapure water process begins with pretreatment, typically through a reverse osmosis water filter (RO), activated carbon water filter, or UV purification, before employing a deionizing water system of ion exchange (IX) or electrodionization (EDI). Ultrapure water is created through varying riffs on this formula and the exact quality standards of the final product differ depending on what it will be used for.
To break down the treatment options in no particular order, here are three popular ultrapure treatment processes from leading technology suppliers:
This water purification chain allows the user to take potable water and turn it ultrapure in a four-piece system. It first creates pure (not to be confused with ultrapure) grade water from the tap through use of an EDI system, combined with a pretreatment regimen of RO and bactericidal UV.
The pure water is then stored in a polyethylene tank that protects against airborne contaminants and biofilm formation. The water then passes through a dual wavelength UV lamp and a polishing cartridge removes any ionic or organic contaminants remaining below trace levels.
The Milli-Q is primarily for laboratory applications, with a maximum output reaching 15 liters (or 3.96 gallons) per hour.
When charged with setting up the capability to generate steam for high-pressure boilers on behalf of the Israel Electric Company, RWL designed and manufactured an ultrapure water system. It included pre-filtration with alum dosing and pre-chlorination; activated carbon filtration; chemical pre-treatment with pH adjustment and antiscalant dosing; cartridge filtration; first and second pass RO; gas transfer membranes; and finally EDI.
Each “containerized” system, employed at a series of more than 15 Israel Electric plants, was housed by two 40-foot cubic containers.
This LED-powered decentralized ultrapure water system contains a nanotechnology coated mesh which activates five photochemical processes to purify the water. By destroying contaminants rather than filtering them into a wastewater stream, the Shield is a greener option than many other ultrapure water systems, while also reducing contaminants to the parts-per-trillion range. The system is capable of producing up to 4,000 liters (1,056 gallons) of ultrapure water a day.