Temperature has no effect on the sedimentation rate of a particle.
Chloramines are toxic to healthy humans.
If head loss is a problem but breakthrough is limited, larger sized media may be appropriate.
A slow sand filter should be backwashed when the head loss through the filter becomes excessive.
Coagulation and flocculation are used to remove materials, especially non-settleable solids and color.
The inlet zone of a sedimentation basin is designed to minimize velocities near the bottom of the basin to prevent scouring.
Smooth circular particles will settle slower than irregular particles.
Backwash at too high a rate is much less destructive than at too low a backwash rate
Water with low turbidity is just as difficult to treat as those with increased turbidity.
The detention time may be defined as the actual time that a small amount of water is retained in the sedimentation basin.
Chlorine gas is extremely toxic and corrosive in moist atmospheres.
In most types of filtration, particles are removed mainly by straining.
Free available residual chlorine has the greatest disinfecting action of the chlorine compounds.
A long, narrow rectangular sedimentation tank is the shape most likely to have short-circuiting problems.
The Interim Enhanced Surface Water Treatment Rule does not address Cryptosporidium.
The turbidity requirement under the Interim Enhanced Surface Water Treatment rule is < 0.3 NTU.
150 lb. chlorine cylinders may be stored on their sides
Ozone is highly reactive.
When water temperatures increase, the flow through a sedimentation basin must be decreased.
Too high a backwash rate may cause excessive loss of filter media.
Chlorine gas is lighter than air.
Alum Sludge is often returned to plant to "condition" raw water.
Rapid Sand filters trap suspended matter in the biologically active Schmutzdecke.
There is no minimum requirement for distribution chlorine residual under the SWTR.
Floc gathers together during the flash-mixing process.
If the chlorine demand has been met and there is still chlorine in the water, what is the remaining chlorine called?
Breakpoint
Residual
Dose
Demand
Gas Chlorine is ______________________?
2.5 times heavier than air
A greenish-yellow cloud
An oxidant
All of the above
What is the difference between conventional and direct filtration?
No sedimentation
No coagulation
No Flocculation
No disinfection
Turbidity is the expression of the _____________ of the water?
Alkalinity
pH of the water
Clarity
Water temperature
Which of the following is more resistant to disinfection
Turbidity
Cysts
Coliform
All of the Above
Water with a pH of 9 would be considered?
Acidic
Neutral
Ugly
Basic
Currents within a settling basin could cause _____________.
Low turbidity readings
Color in the finished water
Short-circuiting
Oxygen depletion
The main purpose of the jar test is to determine the best?
Chlorine residual
Coagulant dosage
Detention time
Particulate settling velocity
Filtration technologies used to comply with Surface Water Treatment Rule include
Conventional
Slow Sand
Direct
Organic matter combined with chlorine can create?
Septic conditions
Trihalomethanes
Acidic water unfit for human consumption
Legionella
The coagulation process usually occurs within?
30 seconds
5 minutes
15 minutes
30 minutes
What is coagulation?
Clumping together of very fine particles into larger particles by the use of chemicals
Very small, finely divided solids that remain dispersed in a liquid for a long time
Gathering together of fine particles to form larger particles by a process of gentle mixing
Removal of particles through gravity
Field test method for chlorine is conducted using _________ method
Electrometric
Spans
DPD
OPR
Which is not a characteristic of a rectangular sedimentation basin?
Tolerates changes in water quality
Cost effective
Predictable performance
More likely to short circuit
Why should a minimum of two sedimentation basins be provided in all water treatment plants?
To allow for cleaning of a basin without requiring a plant shutdown
To minimize short-circuiting problems
To reduce the number of operators needed for O & M
Take advantage of common-wall technology
The Surface Water Treatment Rule requires ______ and ______ of Giardia
Coagulation and sedimentation
Removal and inactivation
Disinfection and flocculation
Coagulation and disinfection
What is the purpose of the filtration process?
Cause very fine particles to clump together into larger particles
Kill disease-causing organisms
To remove particulate impurities and floc
Settle out larger suspended particles
What is the purpose of the effluent zone in the sedimentation basin?
To provide smooth transition from the sedimentation basin to the settle water channel
To provide compression settling of the sludge
To reduce short-circuiting of water in the basin
To provide calm, undisturbed storage of flocculated water
When added to water, chlorine will react with?
Organic substances
Hardness
Inorganic substances
Both a and c
On the chlorination breakpoint curve, between points 2 & 3 chlorine reacts with ammonia to form?
Monochloramine
Free chlorine
Dichloramine
Trichloramine
What is flocculation?
Gathering together of fine particles to form larger particles by the process of gentle mixing
Removal of iron and manganese
A disinfected water supply is one in which
Bacteria and viruses have been sterilized
Algae has been destroyed
Pathogenic organisms have been inactivated or destroyed
Which is not a form of Chlorine?
Calcium Hypochlorite
Gas
Sodium Chloride
Sodium Hypochlorite
Why is ozone prepared onsite?
Because it acts quicker when produced at the application point
Because it is difficult to store in conventional containers
Because it is produced on demand
Because it is very unstable
Which is the correct order of filter materials in a multi-media or mixed media gravity filter (From top to Bottom)?
Coal, Garnet, Sand
Coal, Sand, Garnet
Garnet, Sand, Coal
Sand, Coal, Garnet
Flash mixing includes
Blinders
Surface currents
Baffled chambers
Barometric loops
Tube settlers
Create mini basins
Are not cost effective
Increase the operational cost of sedimentation
None of the above
Most natural occurring particles in water are ____________
Positive charged
Have no charge
Negatively charged
Are bi-polar
The disinfectant with the greatest disinfection potential is?
Hypochlorous Acid (HOCI)
Hydrochloric Acid (HCI)
Hypochlorite Ion (OCI)
The removal efficiency of a filter depends on the _____________
Chemical characteristics of the water being treated
Degree/type of pretreatment
Nature of suspension
In determining the purity of a water sample, it is usually tested for the presence of coliform bacteria because ___________.
It can be detected using a microscope
It can be done in the field
It is one of the disease-bearing bacteria
Its presence may indicate that the water has been contaminated
Most important filter effluent water quality change is?
Chlorine demand
Nutrients
pH
Factors affecting particle settling include
Size
Density
Charge
How are particles removed by slow sand filtration?
By chemical and physical disinfection
By straining, adsorption and biological action
By operation and maintenance procedures
By coagulation, flocculation and sedimentation
Good filter media characteristics include?
Soft material
Highly soluble in water
Non-permeable
Inert
Why is the turbidity of the water important when disinfecting water?
Excessive turbidity will cause a significant shift in pH
Excessive turbidity will greatly reduce the efficiency of the disinfection chemical process
Excessive turbidity will cause a change in the hardness
Excessive turbidity will cause an adjustment
What could be the cause of floc size breaking up in flocculates?
Coagulent chemicals are inadequately mixed
Detention time too long
Mixing intensity is too high
Polymer dosage is too high
Short circuiting in a sedimentation basin can be caused by
Poor inlet baffling
Improper design
High inlet velocities
Which is not a zone in a sedimentation basin?
Inlet zone
Sludge zone
Aeration zone
Settling zone
Destruction of harmful bacteria by chlorine is directly related to
Contact time and chlorine concentration
Efficient chlorine dosage levels
Whether or not breakpoint chlorination is practiced
Whether perchlorination is practiced
Which is not an important factor when evaluating jar test results?
Amount of floc formed
Floc settling rate
Size of floc
Visual checks of the sedimentation basin include?
Floc settling characteristics
Clarity of laundered water
Distribution of floc at basin inlet
The surface water treatment rule requires which removal rate for Giardia?
3 log
2 log
4 log
1 log
The Interim Enhanced Surface Water Treatment Rule requires the maintenance of a minimum distribution chlorine residual of?
0.2 mg/L
1.0 mg/L
2.0 mg/L
0.5 mg/L
Weak floc _____________?
Does not adhere to filter media
Can be carried deep into filter
Causes increased turbidity of filtered water
What operation changes in the sedimentation process should be considered by operators when colder water temperatures develop?
Faster sludge removal rates must be Implemented
Surface skimming rates must be increased
Chemical dosages must be adjusted
For conventional filtration plant under the IESWTR, the allowable filter effluent turbidity measured in 95% of the samples collected in a month is ___________ NTU?
0.5
0.3
1.0
5.0
What is a limitation of using ultraviolet rays for disinfection?
The disruption of selective organic components of the cell
The removal of destroyed pathogenic microorganisms
The lack of a measurable residual
The selection of the optimum wave length
The "Total Coliform Rule" of the SDWA regulations requires the result of coliform testing to be given as?
MPN
Colony forming units (CFUs)
mg/L
presence/absence
What is the maximum feed rate in pounds per day from a 150lb. chlorine cylinder?
10 lbs.
20 lbs.
40 lbs.
80 lbs.
The inactivation of pathogenic organisms is called?
Sterilization
Oxidation
Pasteurization
Disinfection
The use of gas chlorine tends to _____________ the pH
Lower
No effect
Raise
Neutralize
Parameters which affect disinfection include
Color
Temperature
Both b and c
Chlorine Dioxide is composed of ______________ and chlorine
Ammonia
Oxygen
Hydrogen Dioxide
Sodium Hypochlorite is the active ingredient in _______________
Liquid chlorine
Powdered chlorine
Granular chlorine
Gas chlorine
The reaction zone in a solids contact clarifier is 15 feet in diameter and 8 feet high. What is the detention time in minutes if the flow is 5 million gallons per day?
3 gallons per minute
3472 gallons per minute
3.04 minutes
10,562.2 gallons
A well has a flow of 2500 rpm and a chlorine residual of 2.0 mg/L is required. The demand is 0.5 mg/L. If calcium hypochlorite 65% available chlorine is used, how many lbs./day of hypochlorite is required?
3.6 lbs/day
65 lbs/day
75 lbs/day
92 lbs/day
115 lbs/day
Calculate the filtration rate in gallons per minute, per square foot (GPM/ft2) for a filter with a length of 50 feet by 40 feet when the applied flow is 3 million gallons per day?
10 GPM/ft2
3.5 GPM/ft2
2.0 GPM/ft2
2.5 GPM/ft2
1.0 GPM/ft2
Treatment plant has a flow of 900 GPM and an average turbidity of 10 ntu. A total of 180 lbs. of alum is used in 24 hours. What is the alum dosage in mg/L?
0.6 mg/L
10 mg/L
17 mg/L
28 mg/L
138 mg/L