AWWA Water Treatment
Grades 1 & 2 Practice
Questions | Treatment Process
Study Guide
What must the effluent NTU for a slow sand filter be kept at during operation?
Less than 1.0 NTU
When water is added too fast to this treatment chemical, it will generate heat
and splattering of the chemical.
Sulfuric acid
In the lime-softening process, besides CaCO3 being precipitated, what other
carbonate hardness chemical is precipitated?
Magnesium hydroxide
Dry alum has a formula of
Al2(SO4)3 · 14H2O
What is the most common chemical used for pH and alkalinity adjustment?
Lime
After breakpoint chlorination, what may remain besides the free chlorine?
Chloroorganics
,Although algae do not typically pose a health concern, some do produce
__________ that can be a concern. Other problems they frequently cause in
regard to treatment are __________.
neurotoxins and hepatoxins, tastes and odors and filter-clogging
The oxidation process using chlorine will also consume
alkalinity
Dry chemicals should be in solution before mixing them with the water to be
treated. What water is recommended to mix the dry chemical in some cases to
avoid precipitates?
Softened water
How are manganese greensand beds regenerated?
Backwashed with permanganate solution
Once breakpoint chlorination has been reached, what percentage of the original
reducing agents are typically still present in a particular water sample?
0%
The most preferable method of removing manganese is by using
potassium permanganate.
When iron alone is treated using manganese greensand filters, the chlorine feed
rate should be about
1.0 to 1.2 times the iron concentration.
What problem can be solved in a sedimentation basin by recycling some
previously settled sludge?
Slow floc formation
To eliminate hydrogen sulfide (H2S), the pH of the water should be lowered to
____ or less before beginning aeration.
6.0
, What factor will make chlorination successful?
Higher concentration
How can an operator compensate for low temperature water and thus slower
floc formation when using alum?
Increase alum dosage
What is (are) the combined chlorine residual(s) at pH values ranging from 6.5 to
8.5?
Monochloramine and dichloramine
What is an advantage for installing a pressure filter for a small water system?
Air binding will not occur
How is magnesium noncarbonate hardness removed?
With lime, then soda ash
When adding chlorine and sodium hydroxide to water containing manganese,
the oxidation works best in a pH range of
6 to 10
Why can rapid sand filters handle higher filtration rates compared to slow sand
filters?
Coarser sand
UV is used as a disinfectant because it is effective in the inactivation of
_________ and because it __________.
Cryptosporidium, does not produce DBPs
Industrial bleaches used in water treatment disinfection range in percentage
strength of available chlorine from
9% to 15%
Grades 1 & 2 Practice
Questions | Treatment Process
Study Guide
What must the effluent NTU for a slow sand filter be kept at during operation?
Less than 1.0 NTU
When water is added too fast to this treatment chemical, it will generate heat
and splattering of the chemical.
Sulfuric acid
In the lime-softening process, besides CaCO3 being precipitated, what other
carbonate hardness chemical is precipitated?
Magnesium hydroxide
Dry alum has a formula of
Al2(SO4)3 · 14H2O
What is the most common chemical used for pH and alkalinity adjustment?
Lime
After breakpoint chlorination, what may remain besides the free chlorine?
Chloroorganics
,Although algae do not typically pose a health concern, some do produce
__________ that can be a concern. Other problems they frequently cause in
regard to treatment are __________.
neurotoxins and hepatoxins, tastes and odors and filter-clogging
The oxidation process using chlorine will also consume
alkalinity
Dry chemicals should be in solution before mixing them with the water to be
treated. What water is recommended to mix the dry chemical in some cases to
avoid precipitates?
Softened water
How are manganese greensand beds regenerated?
Backwashed with permanganate solution
Once breakpoint chlorination has been reached, what percentage of the original
reducing agents are typically still present in a particular water sample?
0%
The most preferable method of removing manganese is by using
potassium permanganate.
When iron alone is treated using manganese greensand filters, the chlorine feed
rate should be about
1.0 to 1.2 times the iron concentration.
What problem can be solved in a sedimentation basin by recycling some
previously settled sludge?
Slow floc formation
To eliminate hydrogen sulfide (H2S), the pH of the water should be lowered to
____ or less before beginning aeration.
6.0
, What factor will make chlorination successful?
Higher concentration
How can an operator compensate for low temperature water and thus slower
floc formation when using alum?
Increase alum dosage
What is (are) the combined chlorine residual(s) at pH values ranging from 6.5 to
8.5?
Monochloramine and dichloramine
What is an advantage for installing a pressure filter for a small water system?
Air binding will not occur
How is magnesium noncarbonate hardness removed?
With lime, then soda ash
When adding chlorine and sodium hydroxide to water containing manganese,
the oxidation works best in a pH range of
6 to 10
Why can rapid sand filters handle higher filtration rates compared to slow sand
filters?
Coarser sand
UV is used as a disinfectant because it is effective in the inactivation of
_________ and because it __________.
Cryptosporidium, does not produce DBPs
Industrial bleaches used in water treatment disinfection range in percentage
strength of available chlorine from
9% to 15%
