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B test material - TCEQ Class B Surface Water questions and answers rated A+ 2024/2025
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B test material - TCEQ Class B Surface Water questions and answers rated A+ 2024/2025
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B test material - TCEQ Class B SurfaceWater
What is the most important factor affecting the useful life of service lines? - ANSIt is the
ability of the material to resist internal and external corrosion
When does Suction Head exist? - ANSSuction head exists when the source of supply is
above the centerline of the pump.
What is Net positive Suction Head (NPSH) - ANSNPSH 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) - ANSChlorine
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? - ANSThe 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? - ANSWhen 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? - ANSStable 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? - ANSCorrosion
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? - ANSThe 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? - ANSTurbidity 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? - ANSTurbidity 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? - ANSThe amount of chlorine used up to completely react with
the water and its suspended or dissolve material
What is chlorine residual? - ANSWhen all the demand of the water is met any additional
chlorine produces a chlorine residual
What is chlorine dosage? - ANSDemand plus residual is the chlorine dosage. Chlorine
Dosage = Demand + Residual
What determines rate of disinfection? - ANSChlorine 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? - ANSChlorine 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? - ANSTurbidity 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? - ANSDissolved 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? - ANSManganese, iron, turbidity, organic matter, ammonia, or nitrates
What the 4 stages of the Chlorine Demand Curve chart? - ANSStage 1: No residual is
formed because inorganic demand destroys the chlorine. (Flat Line)
, Stage 2: Monochloramines are formed as chlorine combines with organics containing
ammonia (rising curve). The chlorine to ammonia weight ratio at this point is 5:1. Combined
and total residual increases, chloro-organics are formed.
Stage 3: Increasing chlorine dosage (failing curve) to a chlorine/ammonia weight ratio of
7.6:1 destroys chloramines and chloro-organics. Combined decreases and free chlorine
increases.
Stage 4: Enough chlorine is added to reduce all demand. The combined residual remains
the same, but free residual increases with dosage. This stage is called "breakpoint"
chlorination. The chlorine to ammonia ratio of 10:1 satisfies all demand and disinfects the
distribution system. ( second rising curve)
What is the difference between free chlorine and combined chlorine
(chloramines/chlorine-ammonia) systems? - ANSFree chlorine is more powerful than
combined chlorine, but combined chlorine lasts longer.
- combined chlorine requires a 60-minute detention time while free chlorine requires 10
minutes.
-If combined residual is replaced by a free residual, less taste and odor in the water usuals
occurs.
- if combined residual is used : ph and temperature must be monitored closely and the
residual adjusted accordingly. For example, as the temperature decreases the combines
residual must be increased. Free residual does not require such monitoring in the 6.0 - 8.0
pH range. Free chlorine residual concentration is not affected by temperature changes.
What is the minimum chlorine residual at the far reaches of the system for both free and
combined? - ANSFree chlorine residual = .2mg/L
Chloramine (combined) residual = .5 mg/L
- Surface water systems should not exceed a maximum free chlorine or chloramine residual
of 4 mg/L as a running average. Limiting residuals reduces disinfection byproducts such as
trihalomethanes and haloacetic acids. These byproducts, consumed over a long period of
time, may cause cancer.
What are the proper techniques for chlorine cylinder storage? - ANS- secure the ton
cylinders in a horizontal position and move with a lifting bar and hoist. Never roll them
- 150lbs cylinders shall be chained to rigid support and keep capped unless in use.
- Check all chlorine systems for leaks before putting into service with a 10% ammonia
solution. Household ammonia is not approved. When ammonia contacts chlorine gas white
smoke results.
What are the steps to do before entering a room with a chlorine leak? - ANS1: notify other
operators and have standby help for possible notification of emergency personnel
2: Be trained in emergency procedures and have knowledge of chlorinators, tools, and
ammonia use.
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