Current through Register Vol. 48, No. 38, September 20, 2024
a)
Pre-treatment Requirements. Pre-treatment under Section
604.1010 is required when a
combination of iron and manganese exceeds
0.5 mg/L.
b) Anion Exchange Treatment Design
1) Automatic regeneration based on volume of
water treated must be used unless manual regeneration is justified and is
approved by the Agency.
2) If a
portion of the water is bypassed around the units and blended with treated
water, the following requirements must be met:
A) the maximum blend ratio allowable must be
determined based on the highest anticipated raw water nitrate level;
and
B) a totalizing meter and a
proportioning or regulating device or flow regulating valves must be provided
on the bypass line.
3) A
manual override must be provided on all automatic controls.
4) Adequate freeboard must be provided to
accommodate the backwash flow rate of the unit, ensuring the resin will not
overflow. The freeboard must be calculated based on the size and specific
gravity of the resin.
5) The system
must be designed to include an adequate under drain and supporting gravel
system and brine distribution equipment.
6) Sampling Taps
A) Smooth-nosed sampling taps must be
provided for the collection of representative samples.
B) The taps must be located to provide for
sampling of the softener influent, effluent, and blended water.
C) The sampling taps for the blended water
must be at least 20 feet downstream from the point of blending.
D) Petcocks are not acceptable as sampling
taps.
7) Brine and Salt
Storage Tanks
A) Salt dissolving or brine
tanks and wet salt storage tanks must be covered and must be
corrosion-resistant.
B) The make-up
water inlet must be protected from back-siphonage. Water for filling the tank
must be distributed over the entire surface by pipes above the maximum brine
level in the tank. An automatic declining level control system on the make-up
water line is recommended.
C) Wet
salt storage basins must be equipped with manholes or hatchways for access and
for direct dumping of salt from truck or railcar. Openings must be provided
with raised curbs and watertight covers having overlapping edges similar to
those required for finished water reservoirs.
D) Overflows, where provided, must be
protected with corrosion-resistant screens and must terminate with either a
turned downward bend having a proper free fall discharge or a self-closing flap
valve.
E) The salt must be
supported on graduated layers of gravel placed over a brine collection
system.
F) Alternative designs that
are conducive to frequent cleaning of the wet salt storage tank may be approved
by the Agency.
G) Total salt
storage must provide for at least 30 days of operation.
c) Exchange Capacity. The design
capacity for nitrate removal must not exceed 10,000 grains per cubic foot when
the resin is regenerated at 15 pounds of salt per cubic foot of
resin.
d) Number of Units. At least
two units must be provided. The treatment capacity must be capable of producing
the maximum average daily demand at a level below the nitrate/nitrite MCL, with
one exchange unit out of service.
e) Type of Media. The anion exchange media
must be of the nitrate selective type.
f) Flow Rates. Unless otherwise approved by
the Agency under Section
604.145(b), the
following flow rates apply:
1) The treatment
flow rate must not exceed 5 gal/min/ft2 of bed
area.
2) The backwash flow rate
must be between 4.0 and
6.0
gal/min/ft2 of bed area.
3) The regeneration rate must be
approximately 1.0
gal/min/ft2 of bed area with a fast rinse
approximately equal to the service flow rate.
g) Cross-Connection Control. Backwash, rinse,
and air relief discharge pipes must be installed to prevent any possibility of
back-siphonage.
h) Construction
Materials. Pipes and contact materials must be resistant to the aggressiveness
of salt. Plastic and red brass are acceptable materials. Steel and concrete
must be coated with a non-leaching protective coating that is compatible with
salt and brine.
i) Housing. Dry
bulk salt storage must be enclosed and separated from other operating areas to
prevent damage to equipment.
j)
Preconditioning of the Media. Prior to startup of the equipment, the media must
be regenerated with no less than two bed volumes of water containing sodium
chloride followed by an adequate rinse.
