Current practical methods of deionization include Ion
Exchange, Reverse Osmosis and Electrodialysis. Additional methods of
deionization may be approved subject to the presentation of evidence of
satisfactory reliability.
All properly developed groundwater sources having water
quality exceeding 2,000 mg/l Total Dissolved Solids and/or 500 mg/l Sulfate
shall be either properly diluted or treated by the methods outlined in this
section. Deionization cannot be considered a substitute process for
conventional complete treatment outlined in R309-525.
(1) Ion Exchange.
(a) General.
Great care shall be taken by the designer to avoid loading
the media with water high in organics.
(b) Design.
(i) Pretreatment shall be provided per the
manufacturer's recommendation.
(ii)
Upflow or down flow units are acceptable.
(iii) Exchangers shall have at least a three
foot media depth.
(iv) Exchangers
shall be designed to meet the recommendations of the media manufacturer with
regard to flow rate or contact time. In any case, flow shall not exceed seven
gpm/sf of bed area. The plant shall be provided with an influent or effluent
meter as well as a meter on any bypass line.
(v) Chemical feeders used shall conform with
R309-525-8.
All solution tanks shall be covered.
(vi) Regenerants added shall be uniformly
distributed over the entire media surface of upflow or downflow units.
Regeneration shall be according to the media manufacturer's
recommendations.
(vii) The wash
rate capability shall be in excess of the manufacturer's recommendation and
should be at least six to eight gpm/sf of bed area.
(viii) Disinfection (see R309-520) shall be
required ahead of the exchange units where this does not interfere with the
media.
Where disinfection interferes with the media, disinfection
shall follow the treatment process.
(c) Waste Disposal.
Waste generated by ion exchange treatment shall be disposed
of in accordance with
R309-525-23.
(2) Reverse Osmosis.
(a) General.
The design shall permit the easy exchange of modules for
cleaning or replacement.
(b) Design Criteria.
(i) Pretreatment shall be provided per the
manufacturer's recommendation.
(ii)
Required equipment includes the following items: pressure gauges on the
upstream and downstream side of the filter; a conductivity meter present at the
site; taps for sampling permeate, concentrate and blended flows (if practiced).
If a continuous conductivity meter is permanently installed, piping shall be
such that the meter can be disconnected and calibrated with standard solutions
at a frequency as recommended by the manufacturer.
(iii) Aeration, if practiced, shall conform
with provisions of
R309-535-9.
(iv) Cleaning shall be routinely done in
accordance with the manufacturer's recommendations.
(v) Where the feed water pH is altered,
stabilization of the finished water is mandatory.
(c) Waste Disposal.
Waste generated by reverse osmosis treatment shall be
disposed of in accordance with
R309-525-23.
(3) Electrodialysis.
(a) General.
(b) Design.
(i) Pretreatment shall be provided per the
manufacturers recommendation.
(ii)
The design shall include ability to: measure plant flow rates; measure feed
temperature if the water is heated (a high temperature automatic cutoff is
required to prevent membrane damage); measure D.C voltage at the first and
second stages as well as on each of the stacks. Sampling taps shall be provided
to measure the conductivity of the feed water, blowdown water, and product
water. D.C. and A.C. kilowatt-hour meters to record the electricity used shall
also be provided.
(c)
Waste Disposal.
Waste generated by electrodialysis treatment shall be
disposed of in accordance with
R309-525-23.