TCEQ SURFACE WATER B COMPREHENSIVE
EXAMS LATEST QUESTIONS AND ANSWERS SURE
A+
✔✔What is chlorine Demand? - ✔✔The amount of chlorine used up to completely react
with the water and its suspended or dissolve material
✔✔What is chlorine residual? - ✔✔When all the demand of the water is met any
additional chlorine produces a chlorine residual
✔✔What is chlorine dosage? - ✔✔Demand plus residual is the chlorine dosage.
Chlorine Dosage = Demand + Residual
✔✔What determines rate of disinfection? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔Manganese, iron, turbidity, organic matter, ammonia, or nitrates
✔✔What the 4 stages of the Chlorine Demand Curve chart? - ✔✔Stage 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? - ✔✔Free 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? - ✔✔Free 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? - ✔✔- 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? - ✔✔1: 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.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
✔✔What is the maximum withdrawal rate for 150lbs chlorine cylinders? - ✔✔The
maximum sustained gas withdrawal rate for 150lbs cylinders (vacuum transmission) is
1lbs per day per degree F.
The equivalent rate for ton cylinders (vacuum transmission) is 8 lb per day per degree
F.
Pressure transmission rates are 42 lbs per day for 140lb cylinders and 336 lb per day
for ton containers, based on an air temp of 70 degrees F.
✔✔What are chlorine cylinders equipped with to help/prevent gas leaks in extreme
temperatures? - ✔✔Chlorine cylinders are equipped with a fusible plug designed to melt
between 158 and 165 f
✔✔Is chlorine the most cost effective and best disinfectant product? - ✔✔Yes
✔✔Chlorine is available is what three forms? - ✔✔Gas - 100%
Solution - 5.25 to 15% chlorine (bleach)
Granular (solids) - 65 chlorine (calcium hypochlorite)
✔✔Types of waterborne pathogens - ✔✔- typhoid
- partyphoid
- bacillary dysentery
EXAMS LATEST QUESTIONS AND ANSWERS SURE
A+
✔✔What is chlorine Demand? - ✔✔The amount of chlorine used up to completely react
with the water and its suspended or dissolve material
✔✔What is chlorine residual? - ✔✔When all the demand of the water is met any
additional chlorine produces a chlorine residual
✔✔What is chlorine dosage? - ✔✔Demand plus residual is the chlorine dosage.
Chlorine Dosage = Demand + Residual
✔✔What determines rate of disinfection? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔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? - ✔✔Manganese, iron, turbidity, organic matter, ammonia, or nitrates
✔✔What the 4 stages of the Chlorine Demand Curve chart? - ✔✔Stage 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? - ✔✔Free 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? - ✔✔Free 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? - ✔✔- 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? - ✔✔1: 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.
3: Put on a self-contained breathing apparatus (SCBA)
4: wear a safety harness and lifeline
✔✔What is the maximum withdrawal rate for 150lbs chlorine cylinders? - ✔✔The
maximum sustained gas withdrawal rate for 150lbs cylinders (vacuum transmission) is
1lbs per day per degree F.
The equivalent rate for ton cylinders (vacuum transmission) is 8 lb per day per degree
F.
Pressure transmission rates are 42 lbs per day for 140lb cylinders and 336 lb per day
for ton containers, based on an air temp of 70 degrees F.
✔✔What are chlorine cylinders equipped with to help/prevent gas leaks in extreme
temperatures? - ✔✔Chlorine cylinders are equipped with a fusible plug designed to melt
between 158 and 165 f
✔✔Is chlorine the most cost effective and best disinfectant product? - ✔✔Yes
✔✔Chlorine is available is what three forms? - ✔✔Gas - 100%
Solution - 5.25 to 15% chlorine (bleach)
Granular (solids) - 65 chlorine (calcium hypochlorite)
✔✔Types of waterborne pathogens - ✔✔- typhoid
- partyphoid
- bacillary dysentery
