TCEQ FINAL PAPER QUESTIONS AND
CORRECT ANSWERS FULL REVIEW
RESOURCE
●● When does Suction Head exist?
Answer: Suction head exists when the source of supply is above the
centerline of the pump.
●● What is Net positive Suction Head (NPSH)
Answer: 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)
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
, Answer: The amount of chlorine used up to completely react with the
water and its suspended or dissolve material
●● What is chlorine residual?
Answer: When all the demand of the water is met any additional
chlorine produces a chlorine residual
●● What is chlorine dosage?
Answer: Demand plus residual is the chlorine dosage. Chlorine Dosage
= Demand + Residual
●● What determines rate of disinfection?
Answer: 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?
Answer: 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?
Answer: Turbidity must be removed to low levels by sedimentation and
filtration to allow chlorine to contact pathogens.
CORRECT ANSWERS FULL REVIEW
RESOURCE
●● When does Suction Head exist?
Answer: Suction head exists when the source of supply is above the
centerline of the pump.
●● What is Net positive Suction Head (NPSH)
Answer: 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)
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
Answer: 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?
, Answer: The amount of chlorine used up to completely react with the
water and its suspended or dissolve material
●● What is chlorine residual?
Answer: When all the demand of the water is met any additional
chlorine produces a chlorine residual
●● What is chlorine dosage?
Answer: Demand plus residual is the chlorine dosage. Chlorine Dosage
= Demand + Residual
●● What determines rate of disinfection?
Answer: 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?
Answer: 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?
Answer: Turbidity must be removed to low levels by sedimentation and
filtration to allow chlorine to contact pathogens.
