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Water Treatment Water Quality



Water Quality Parameters

 

Hardness can be converted from mg/L to grains per gallon by dividing mg/L by 17.1.

So 150 mg/L hardness shown above is equal to 8.8 grains per gallon hardness.


Norman’s Annual CCR


 WWW.NormanWater.com


The Environmental Protection Agency requires Water Utilities to inform the customers about the quality of water produced for consumption by the community.  A brochure called the Consumer Confidence Report (CCR) must be mailed to each customer and the utility must make a substantial effort to inform the public with press releases, internet access, and make it available in public places like libraries. 

Every year the Norman Water Treatment Division has collected this information into an annual Consumer Confidence Report.  The CCR is posted on our utility web site and a press release is issued letting the public know it is available. The EPA allows the Water Utility to produce and distribute the annual CCR electronically.  This has allowed us to minimize the carbon footprint by reducing paper, chemicals, and energy to printand mail the documents to the community.  Anyone interested in having apaper copy of the report can request a copy be mailed to their residence by calling 405-321-2182 and placing a request wit the Water Treatment Division.  We receive requests for print copies of the CCR each year and will accommodate anyone needing a printed copy.  This will also help as a cost controlling measure and the city estimates savings of  $7,500.00 annually.  For most of our citizens, the notice in the utility bill directing them where to go to view an electronic version has been a success.  


 Water Conservation Tips

You can do your part to reduce the need for additional system expansion by conserving water and using water wisely. The City has material available on water conservation tips available at the City Hall, Building C, behind the drive-in window where you pay your water bills. Some are included here.

  • Take brief showers and/or open faucets half or three-quarters open to minimize the total water use per shower. Installing a simple restrictor in the shower head or installing a low water use shower head can reduce water use by 25 to 35 percent. However, only opening the faucets part way will accomplish the same thing with no cost or installation required.
  • Place plastic bottles or bags filled with water and a few stones in the toilet tank to reduce the volume of water used with each flush. There are also alternatives of toilet dams or low water use toilets available. These may reduce the total water used by 5 to 20 gallons per day. However, be aware that if your toilet is a newer model, it probably is a low water use model, and reducing the volume of water per flush may cause improper flushing.
  • Encourage the use of faucet aerators on all kitchen and bathroom faucets, as these reduce the water flow while enhancing the rinsing action of the faucet stream.
  • Use automatic dishwashers sparingly and only for full loads. Most dishwashers use 20 to 30 gallons per wash, and most or all of it is hot water. By washing only full loads or hand washing small amounts, you will save in both water and energy. When cleaning dishes for the dishwasher, wipe them out with a paper towel or napkin rather than rinsing, as this will save from 3 to 5 gallons.
  • Wash only full loads of clothes, or match the water setting of the washer to the size of the load.
  • Use a nozzle with a cutoff feature on your garden hose when washing your car or other outdoor items. This will let you cut off the water flow when not needed.
  • Sweep driveways or patios rather than hosing them off, unless they border a flower bed or garden. If so, wash so the water will run to the garden or flower bed. Get double duty from the water used.
  • Plant trees, shrubs and ornamentals that are adapted to dry conditions. Mulch around plants and shrubs to help limit evaporation and retain water. Use sprinklers sparingly and water after the sun goes down to limit evaporation. Where possible, use soaker hoses instead of sprinklers, as they are more efficient. Don't over fertilize your lawn, since this will make it require more water than normal.
  • Keep a bottle of water in the refrigerator for a cool drink. Do not run the faucet to chill the water.
  • If you have a swimming pool, cover it when not in use to control evaporation.


Water Conservation Plan


Alum vs Ferric       


HISTORY:

The Norman Water Treatment Plant is a lime softening plant and has
been using Aluminum Sulfate (Alum) for their coagulation process since
1966.  Norman softens the water from approximately 180 mg/l to 120 mg/l
total hardness.  The treatment system utilizes Solids Contact Clarifiers
and feeds straight to filters without a sedimentation basin.  Ferric
sulfate (Ferric) was trialed in the 1990’s and showed great results but at the
time was twice the cost of Alum.  Also several polymers have been trialed
at the water treatment plant and have had adequate results but heavily depended
on seasonal changes which caused large temperature swings.  Additionally,
since the treatment train does not have intermediate settling basins, the
polymers were too slow to react and would sometimes coagulate in the water on
top of the filters causing blockage of flows.  This study reinvestigated
the comparison of Alum versus Ferric as a treatment coagulant for the Norman
water treatment plant and yielded promising results.

COSTS:

Ferric Sulfate requires a much higher pH to perform properly than
alum.  The higher pH requires a higher lime feed rate, and also requires
more CO2 following the softening reaction to reduce the pH to proper levels for
the tap.  This increases both lime and CO2 costs.  However, ferric
sulfate requires a much lower dosage to work, and is somewhat cheaper per pound
than alum.  The result is a net savings in chemical costs.  The
bottom line is that our average cost for coagulant, lime and carbon dioxide is
about $109.74 per million gallons when using alum, and about $127.84 per
million gallons when using ferric sulfate.  Costs for the other chemicals
(chlorine, ammonia, activated carbon and fluoride) will be the same for either
coagulant.

The savings of $18.10 per million gallons should translate to an
annual total savings of approximately $55,784 based on our total allocation
from Lake Thunderbird.

PERFORMANCE:

Average tap turbidity for ferric sulfate was 0.086 NTU versus
0.097 NTU for alum.  The difference is probably not significant.

We have tested for iron in the tap and seen no significant
increase due to the ferric sulfate.  We believe we had a problem several
years ago when we first tried ferric sulfate.  Since then we learned that
ferrous sulfate tends to carry through the treatment process and show up as tap
iron.  We specified a ferric sulfate with a low ferrous content and
believe this has solved the carry-through problem.

When using alum, the two small clarifiers were fairly easy to
upset and required fairly close observation.  The large clarifiers were
much more stable in treatment and could survive larger excursions of operation
without major changes in water quality.  Using ferric sulfate, the
operators report that the behavior has switched.  The large clarifiers are
more prone to upset, and the small clarifiers are more stable.  Staff will
continue to investigate this phenomenon. 

Another performance difference is that carbon dioxide has become
much more critical with ferric versus alum.  When operating with alum, we
frequently only increased the pH slightly with lime, and had to feed very
little carbon dioxide to lower the pH back to desired levels.  This meant
that a failure of the carbon dioxide feed had only slight effects.  Using
ferric sulfate, we are always making significant changes in pH with the carbon
dioxide.  Failure of the carbon dioxide feed results in a significant
increase in filter turbidity and reduction in filter run times.  We can
only operate without carbon dioxide feed for a very short time (several hours)
without significant impact.  We have some redundancy built into the
system, but will continue to monitor for summer peak flows.

SLUDGE PRODUCTION:

We do not have an estimate of the difference in sludge production. 
The increased softening will probably outweigh the lower coagulant dosage, and
we believe we are producing more sludge with ferric sulfate than with
alum.  From the literature we expect it to dry more easily and be easier
to handle.  We cannot evaluate sludge handling costs at this time.

Ferric sulfate sludge should be more amenable to land application
than alum sludge.  Farmers are not as accepting of sludge with aluminum content
but are fine with iron content.  So it might offer more options when we
have to find an alternate sludge disposal method.

CORROSION:

It is reported that ferric sulfate (and ferric chloride even more)
is corrosive and can shorten the life of clarifier mechanisms.  We took
pictures before we started using ferric sulfate to attempt to evaluate this
claim but don’t have any “after” photos for comparison.  We need to
monitor our clarifier mechanisms and if we see any problems arise, we may need
to look at repainting more often, or installing other corrosion control
alternatives. We have noted the ferric sulfate must be diluted with water prior
to applying it to the clarifier to prevent corrosion of piping.

CONCLUSION:

We see no serious problems associated with using ferric sulfate,
and see several advantages.  We expected the staining from the iron to
cause house-keeping problems, but have not seen any serious problems so
far.  We will continue to monitor corrosion on the steel clarifier
equipment, and may need to increase our frequency of repainting, but we believe
ferric sulfate is a very good option to alum as our primary coagulant.







While on alum (July, 2013 through October, 2013) we saw the following


average performance:






Alum

362

Pounds
per million gallons



Lime

1026

Pounds
per million gallons



CO2

323

Pounds
per day




Flow

11.1

MGD





CO2

29.0

#/MG





Tap
Turbidity

0.097

NTU














The complete switch to ferric sulfate began in November, 2013.  From November,

2013 to July, 2014 we saw the
following average performance:



Ferric
Sulfate

214

Pounds
per million gallons



Lime

1213

Pounds
per million gallons



CO2

300

Pounds
per day




Flow

8.4

MGD





CO2

35.7

#/MG





Tap
Turbidity

0.086

NTU













Alum

Ferric

Lime

CO2


Costs per lb

0.145

0.130835

0.0805

0.062








Cost per MG







Alum

Ferric




Coagulant

 $   52.51

 $   27.98




Lime

 $   82.61

 $   97.65




CO2

 $    1.80

 $    2.21




Total

 $  136.92

 $ 127.84










Savings:

 $    9.08

per
million gallons









Production

3082                                                

MG/year
(if we just use our allocation)







Annual savings

 $27,995.18