SNOWPURE, LLC, 2005-2018
VERSION 3.5 (XL+EXL)
–FEBRUARY 2018
PAGE 6
Electropure™ EDI Description
The need to satisfy the increasing demand for high purity water can be achieved using
SnowPure LLC’s proprietary Electropure™ electrodeionization (EDI) equipment.
SnowPure, formerly Electropure and HOH Water Technology, pioneered EDI in the
1980’s. The O’Hare patent
1
, issued in 1984, forms the basis of all EDI technology.
EDI process systems replace conventional DI mixed resin beds to produce deionized
water. Unlike DI resin, EDI does not require shutdowns for replacing resin beds or for
resin regeneration using chemicals. Because of this, EDI:
minimizes water quality upsets and
minimizes operating costs.
EDI removes ions from aqueous streams, typically in conjunction with reverse osmosis
(RO) and other purification devices. Our high-quality modules continually produce
ultrapure water up to 18.2 MΩ.cm. EDI may be run continuously or intermittently.
Advantages of EDI over Conventional DI
EDI is Continuous, does not require shutdowns or changeovers
Provides water of consistent quality
EDI does not require chemicals (as does DI resin regeneration)
Electropure™ EDI modules are the smallest and lightest per unit flow on the
market; EDI skids are therefore compact
Requires little energy
Economic use of capital
—saves operating expense
Process of Electrodeionization
The Electropure™ EDI design combines two well-established water purification
technologies
—electrodialysis (ED) and ion-exchange resin deionization. Through this
revolutionary technique, dissolved salts can be removed with low energy cost and
without the need for chemical regeneration; the result is high-quality pure water of multi-
MΩ.
……
cm resistivity which can be produced continuously at substantial flow rates.
Electropure’s EDI removes ions from water by forcing them out of the feed stream into
adjacent streams via an electric potential. EDI is different from ED by using resins in the
diluting chambers
—the resins allow for more efficient migration of ions in very low
conductivity water. The resins operate in steady state; they act not as an ion reservoir
but as an ion conduit.
1
US 4,465,573
Chapter 1: Electropure™ EDI Technology