- aquafer
- waterSource
Design and Testing of a Physical Water
Treatment Device
Summary: Within
the water treatment industry, few subjects raise more eyebrows
than the discussion of physical water treatment devices, which
often come in the form of "magnets" Questions and concerns
about the efficacy of such a technology usually revolve around
the testing methods used and how they're applied. One particular
case study with the specifics is presented here.
About 10 years ago, the term physical water
treatment wasn't in our vocabulary. High Langelier Saturation
Index (LSI) numbers experienced in commercial reverse osmosis
(RO) concentrates were giving us operational problems with large
reverse osmosis systems. LSI is a determination of when calcium
scale begins to form. When the calcium hardness, alkalinity (M),
and pH of a particular water are known they can be applied to
a simplified chart. This chart establishes the pH (pHs) at which
the calcium carbonate will come out of solution and begin to
form scale for the temperature selected. This pH value is then
subtracted from the actual pH of the water. A positive number
indicates probable scaling. 0 is a balance point and a negative
number would indicate no scaling and possible corrosion. Many
customers require recoveries in excess of 50% ( % Recovery =
permeate / concentrate + permeate x 100) or more. As recovery
increases there is a need to bring some concentrate water back
thru the pump (re-circulation of concentrate) to provide adequate
flushing water flow across the membrane surface. The combination
then of high recovery and recirculation dramatically increases
the calcium carbonate seen by the element. The classic "cure"
for this situation is to exchange the calcium for sodium through
a conventional water softener or by feeding a commercially available
liquid scale prevention chemical. Both of these methods are extremely
effective but there can be high operating costs and in some cases
sewer discharge regulations that prevent their use. Thus, the
need for non-chemical (physical) treatment was established.
Existing products and patents were studied,
but the basic concept for the design came from an out-of-print
Permutit booklet explaining the Spiractor process of dropping
water pressure to release carbon dioxide, thus reducing the solubility
of calcium carbonate. A controlled pressure drop independent
of a flow rate occurs in chamber A. the result is the creation
of sub-micron size particles of calcium. In chamber B , a stainless
steel mesh constructed of a high nickel alloy is present. Because
of the flexibility of the mesh during changed in flow, the scaling
found in many catalytic based devices isn't encountered. Chamber
C contains multiple rare earth magnets. We were hesitant to use
magnets because of the controversy surrounding their use. However,
early experiments with available catalytic devices were not too
successful especially if the water resided in a holding tank
before being fed to an R.O. unit. We theorized that perhaps the
particles that had been formed were so small that they were being
re-dissolved in a short period of time. We further theorized
that if we could get these small particles to cling to one another
to form a more substantial size, the tendency to re-dissolve
would be reduced. The same small particles that we had created
in the catalytic chamber would logically have the same charge
so they would repel one another. This repulsion of like charged
particles is usually referred to as the zeta potential. a chemical
coagulant could be used to neutralize this charge but this would
defeat our purpose of elimination chemicals. We then thought
to try a magnetic field to see if it would cause these particles
to coagulate. In the absence of instruments and electron microscopes,
we could only run tests to confirm our theory. With proper water
velocity, magnetic field pattern and field strength, we were
able to use the water from the catalytic process without scaling
taking place after days of storage where we had experienced problems
after hours of storage with the catalytic process only.
Setting the parameters
1) A test water was selected. It contained:
- a) Calcium hardness 220 to 260 mg/l with
a 245 mg/l average.
- b) pH of 8.03 to 8.3 with an 8.1 average.
- c) Alkalinity (M) 130 to 160 mg/l with a
145 mg/l average.
- d) Total dissolved solids (TDS) of 556 to
745 mg/l with a 651 mg/l average
- e) Iron <0.1 mg/l
- f) LSI averages +0.7 at 75F and +1.4 at 150F
-
- Establish if calcium hardness particles are
formed during flow through the combined catalytic and magnetic
physical water treatment device. Water at 45 psi and 75F
was run alternately through a 2" x 10" ultrafiltration
(UF) element at 80 percent recovery. Calcium hardness as measured
with a LaMotte PHT-CM-DR kit was reduced 60 -75 percent in the
treated water line. There was no measurable change in the hardness
of the water that was not treated by the physical water treatment
device. UF had a 100,000 molecular weight (MW) cut-off.
-
- Conduct a long term test to establish a basis
for offering the device as a scale prevention device. The test
protocol was as follows:
-
- a) Inlet water temperature was 54 to 91F
- b) Heated water temperature range was 146
to 151F
- c) Water flow in each heater varied from
1.86 to 2.1 gallons per minute
- d) Water -on cycle was set at 91 seconds
- e) Cycles set for heat six hours and a drain/fill
of 91 seconds and repeat
- f) Test duration was 324 days. No interruptions
measured with a duration of over 10 minutes.
- g) Estimated water flow was 5,830 gallons
per heater.
-
- Test Results:
Prior to the test, all components were weighed to the nearest
one tenth gram. After the test, all items were air dried and
again weighed. The most dramatic changes were seen on the galvanized
pipe sections. The section of pipe (1/2" x 12" galvanized
for both) gained 36.9 grains of scale on the untreated water
heater and 2.8 grains on the treated unit. This was considered
a successful test and field samples followed. In-field testing
indicated that the process is affective on water suppliers with
a LSI up to +1.6
-
- Conclusion:
-
- The physical water treatment device has been
incorporated into a tank along with KDF in a upward service flow
pattern called The aquafer waterSource. With this flow
pattern there is a constant " backwash" so there is
no need to have a valve or timer on the unit. (See
our Frequently Asked Questions) The aquafer waterSource uses
the physical water treatment device to control hard water scale
while KDF is used for chlorine taste and odor filtration. A United
States (US) Patent has been issued for this unit.
-
- See our complete water softening website
@ www.raindancewatersystems.com
- RainDance Water Systems Inc:
P.O. Box 2312 Ramona, Ca. 92065
- U.S. Toll Free: 1-877-788-8387 /
Outside The U.S. 760-788-8387
- | Home
| Frequently Asked Questions |
| Installation Instructions
| How To Order |
- | Water Conditioner
Model: AWS-8 | Water Conditioner Model:
AWS-9 |
- | Water Conditioner
Model: AWS-10 | Water Conditioner Model:
AWS-12 |
- | aquafer
waterSource Technical Design | Commercial
Applications |
- | Distributorships
| Contact Us |
|
