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CLASS B WATER OPERATOR: QUESTIONS WITH COMPLETE SOLUTIONS
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CLASS B WATER OPERATOR: QUESTIONS WITH COMPLETE SOLUTIONS
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CLASS B WATER OPERATOR: QUESTIONS WITHCOMPLETE SOLUTIONS
The quality of ground water can be described as follows: Right Ans -
•Quality of water doesn’t change much
•not many pathogens (if any)
•High iron and manganese content
•Very hard water
•high levels of undesirable gases
•Often corrosive
•Possibility of high fluoride, radioactivity, and nitrate levels is greater than
surface water
• Potential for ammonia is especially high in illinois
What undesirable gases may appear in ground water? Right Ans - Carbon
dioxide (CO2) Ammonia (NH3) Methane (CH4) and Hydrogen Sulfide (H2S)
The quality of surface water can be described as follows: Right Ans -
•Quality changes frequently, requiring changes in treatment methods
•Pathogen potential is certain of high
•High manganese and iron content mostly occurs during turnover or runoff
•Taste and odor problems may occur from Algae, decaying vegetation, spills
and runoff
Nuisance bacteria Right Ans - Not pathogens; Includes iron bacteria, Sulfate
reducing bacteria and methane forming bacteria
What are the three types of Nuisance Bacteria? Right Ans - Crenothrix,
Leptothrix and Gallionella
What is the most common Iron bacteria? Right Ans - Crenothrix
When it comes to iron bacteria, it is difficult to tell the difference between
which two? Right Ans - Crenothrix and Leptothrix
All iron bacteria does not grow well in temperatures below..? Right Ans -
50°F
,Crenothrix does not grow well in water with more than...? Right Ans -
4mg/L of oxygen
Gallionella bacteria prefers...? Right Ans - Dark places to grow
Nuisance bacteria does what to iron and manganese compounds? Right
Ans - They convert them from soluble compounds into insoluble compounds
that can plug well screens and distribution system pipes
When soluble iron is converted to insoluble compounds, what types of
deposits may be formed Right Ans - Brown, slimy jelly like deposits that
contain ferric hydroxide
What can indicate the presence of Sulfate reducing bacteria? Right Ans -
Black deposits of iron sulfide and the rotten egg odor of hydrogen sulfide
indicate the presence of sulfate reducing bacteria
What conditions to sulfate reducing bacteria prefer in order to grow? Right
Ans - Anaerobic conditions (meaning they can also develop in tubercles in the
distribution system, where anaerobic conditions exist)
Methane forming bacteria are usually only be find in...? Right Ans - Ground
water supply
Methane forming bacteria prefer what type of conditions? Right Ans -
Anaerobic
In order to control nuisance bacteria, what can be done? Right Ans -
Chlorinating a well at 50mg/l for a few hours and continuously pumping a
dosage of 1mg/l after initial disinfection for about a week to prevent receding
bacteria can be done to control nuisance bacteria
Adequate removal of iron should be provided at a water treatment plant, why
is this? Right Ans - To prevent iron bacteria from forming and turning the
water red
What is the usual order of treatment techniques for improving ground water?
Right Ans - Oxidation —> Reaction Basin —> Filtration —> Sequestration
, When is chlorine usually added during ground water treatment? Right Ans
- After oxidation and filtration
When is fluoride usually added to ground water during treatment? Right
Ans - After filtration
When do the Ten States Standards require sedimentation basins before the
filters? Right Ans - When treating water with high iron and/or manganese
content or where chemical coagulation is used to reduce the load on filters
What is the primary purpose of ground water treatment? Right Ans - To
remove undesirable gases (Like hydrogen sulfide and methane) and solids
(like iron and manganese)
What is the first step in ground water treatment? Right Ans - Oxidation
How is oxidation achieved? Right Ans - Through aeration alone or by
chemical oxidation via chlorine, Potassium permanganate, ozone or chlorine
dioxide
What are the important effects of oxidation? Right Ans - - Iron and/or
manganese become insoluble (which allows them to be filtered)
- Undesirable gases are reduced or removed from the water
-Organics are reduced or removed
How is water pH important when it comes to oxidation? Right Ans - Iron
and manganese are removed more rapidly at a High pH
Undesirable gases are most rapidly removed at a Low pH
After oxidation you will be left with either ferrous bicarbonate (Fe(OH)3) or
Manganese dioxide (MnO2). These are..? Right Ans - Insoluble compounds
What is the main purpose of Aeration? Right Ans - To remove or reduce the
level of undesirable gases and organics and to begin the oxidation of soluble
iron and/or manganese compounds
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