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B TEST MATERIAL - TCEQ CLASS B SURFACE WATER
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B TEST MATERIAL - TCEQ CLASS B SURFACE WATER
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B TESTMATERIAL -
TCEQ CLASS B
SURFACE WATER
What is the most important factor affecting the useful life of service lines? - Answers -It
is the ability of the material to resist internal and external corrosion
When does Suction Head exist? - Answers -Suction head exists when the source of
supply is above the centerline of the pump.
What is Net positive Suction Head (NPSH) - Answers -NPSH is the pressure under
which water enters the eye of the impeller in a centrifugal pump. Insufficient NPSH is
the main cause of pump cavitation
Explain and expand on Chlorine Dioxide (what it reacts with, oxidizes, etc) - Answers -
Chlorine Dioxide is a gas used in small quantities to disinfect water. It does not react
with organics to form THMs and HAAs. It oxidizes phenols, manganese, iron, sulfurous
and organic compounds which aids in the removal of tastes and odors. It is a very
effective bactericide and a superior virocide. It dies not combine with ammonia. Chlorine
Dioxide MRDL is .8 mg/L and monitoring procedures are the same as for chlorine. The
Chlorite MCL is .q mg/L and must be monitored daily.
What is texas drinking water pH requirements? - Answers -The texas drinking water
requirements require a pH > 7.0 for the water treatment plant finished water. EPA
requires that pH analysis be preformed within 15 minutes of the sample being caught.
How does pH affect Chlorine activity? - Answers -When chlorine is added to water it
forms hypochlorous acid (HOCL) and hydrochloric acid (OCL). The hypochlorous acid is
the effective disinfectant. At a pH of 4.0 there is 100% hypochlorous acid. At a pH of 11
there is 100% hypochlorite ion. At a pH of 7, the hypochlorous acid is at about 80% and
,the hypochlorite ion makes up about 20% of the chlorine content. The lower the pH is
more effective chlorine is because you have more hypochlorous acid.
What is meant by water stability? - Answers -Stable water is defined as water that will
neither deposit or dissolve a calcium carbonate film or scale. Since no water is stable
indefinitely, chemical treatment of water usually is intended to produce water that is
slightly scale forming without being liable to cause stoppages in small lines and
services. Bayliss curve is the simplest determination of stability. The Langelier
saturation index is also used.
What/how are above ground tanks and piping protected from corrosion? - Answers -
Corrosion protection for above ground tanks and piping is prevented by: cathodic
protection, use if protective linings/coatings, eliminating different types of metals in the
distribution system, and treating the water with chemicals to make it less corrosive
How do you tests fir alkalinity? - Answers -The two tritiation methods of analysis are a
standard acid to titrate a sample. The end point of the titration is determined by the
following: an indicator that changes color at a certain pH, or potentiometric titration to
end - point pH. Using either of the methods, a measured amount of sample is titrated
with a standard sulfuric acid to a predetermined pH. Nomograph are a graphical form of
determining alkalinity. If the pH, total alkalinity, temperature and total dissolved solids
are known, any or all of the alkalinity forms may be estimated.
What is Turbidity? - Answers -Turbidity can be described as a measure of the relative
clarity of water. Turbidity is an expression of the optical property that causes light to be
scattered and absorbed rather than transmitted in straight lines through the sample.
What causes Turbidity? - Answers -Turbidity is caused by clay, slit, finely divided
organic and inorganic material. Other suspended matter and microscopic organisms
can also cause turbidity. There is one approved method for running turbidity - the
Nephelometric Method (NTU)
What is chlorine Demand? - Answers -The amount of chlorine used up to completely
react with the water and its suspended or dissolve material
What is chlorine residual? - Answers -When all the demand of the water is met any
additional chlorine produces a chlorine residual
What is chlorine dosage? - Answers -Demand plus residual is the chlorine dosage.
Chlorine Dosage = Demand + Residual
What determines rate of disinfection? - Answers -Chlorine concentration and contact
time determines the rate and degree of disinfection. If concentration increases, the time
can be reduced; if concentration is reduced the time must be increased.
, How does temperature effect chlorine effectiveness? - Answers -Chlorine effectiveness
is greater at higher temperatures, up to the point that chlorine volatizes. At low
temperature, chlorine is more stable, but disinfection time increases.
Is removing turbidity important for disinfection? - Answers -Turbidity must be removed to
low levels by sedimentation and filtration to allow chlorine to contact pathogens.
What happens to dissolved solids on contact with chlorine? - Answers -Dissolved solids
are oxidized on contact further reinforcing the importance of contact time.
No residual is formed until reducing agents are destroyed. What are examples of
reducing agents? - Answers -Manganese, iron, turbidity, organic matter, ammonia, or
nitrates
If you are over feeding CL2 what is noticed? - Answers -Taste, odor, Di and Tri CL2,
nitrification
What are the advantages and disadvantages of a Free Chlorine disinfection system? -
Answers -Advantages:
More powerful
not affected by temperature
Requires 10 minute contact time
Disadvantages:
May form Trihelomethanes
What are the advantages and disadvantages of a Combined (Chloramines)? - Answers
-Advantages:
Lasts longer
No trihelomethanes produced
Disadvantages:
Requires 60-minute contact time
Is affected by temperature changes
Where are trihelomethanes (THM) usually found? - Answers -In the farthest point from
entery into the distribution system
Calcium carbonate saturation is what? - Answers -A pre cursor for trihelomethanes
Free Cl2 added to water makes Hydrochlorous Acid (HCOL) and Hydrochloric Acid
(HCL) which is strongest? - Answers -Hydrochlorous Acid (HCOL)
The lower the turbidities are what becomes more effective? - Answers -Chlorine
disinfection
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