Water Treatment Exam Prep

Questions and Answers

What is potassium permanganate most effective in?

Coloring water

Disinfecting water

Removing iron (correct)

Adding nutrients

A total coliform positive sample must be tested for the presence of?

Salmonella

Cholera

Fecal Coliforms (correct)

E.coli

A change in the water elevation from the normal level to the pumping level is?

Drawdown

What type of self-contained breathing apparatus should be used at water plants?

Positive pressure Signup and view all the answers

What type of water violation requires an all-clear notification be given to the public?

Tier 1 Signup and view all the answers

The fusible metal plugs on chlorine containers are designed to melt at what temperatures?

158 - 165 degrees Fahrenheit Signup and view all the answers

What percentage of solids sludge is produced in the precipitative softening plant?

5% Signup and view all the answers

What type of algae would most likely be found in nutrient-rich water?

Blue-green algae Signup and view all the answers

The loss of chloramine residuals in a water line or storage tank is due to?

Nitrification and an increase in heterotrophic bacteria levels Signup and view all the answers

What adjustments will the operator of a surface water treatment plant have to make if the raw water is very high in turbidity levels?

Use the Maximum Flocculator Paddle Speed Setting Signup and view all the answers

When 0.3 mg/L chlorine is added to water, the residual will increase by 0.3 mg/L.

True Signup and view all the answers

What tests are performed most frequently in drinking water systems?

Turbidity and coliform bacteria Signup and view all the answers

Shellfish grown in polluted waters have been known to contain the organism that causes infectious hepatitis.

True Signup and view all the answers

What is the main purpose for adding coagulant chemicals to raw water?

To destabilize colloidal particles Signup and view all the answers

What is the depression around the well of the water surface caused by pumping water from a well?

Cone of depression Signup and view all the answers

Most totalizer meters at treatment plants are commonly?

Venturi Signup and view all the answers

The organism that causes Giardiasis is best controlled by filtration followed by disinfection.

True Signup and view all the answers

The temperature range at which coliform bacteria samples must be stored before being delivered to a lab is?

4-10 degrees Celsius Signup and view all the answers

Where does most of the carbon dioxide in groundwater originate from?

Biological oxidation of organic matter Signup and view all the answers

Regulations require that wastes from water treatment be monitored?

Daily Signup and view all the answers

The injection of fluoride should be as far away as possible from any chemical containing?

Calcium Signup and view all the answers

What is the best disinfectant against Cryptosporidium?

Ozone Signup and view all the answers

Organic chemistry is concerned with compounds containing what element?

Carbon Signup and view all the answers

The chlorine demand will vary with?

Temperatures Signup and view all the answers

Why is water softening a part of the water treatment process?

To reduce scale formation on pipes, valves, and fittings through ion exchange Signup and view all the answers

What oxidant should be fed as early as possible in the treatment process to allow for complete reaction before it enters the distribution system?

Potassium permanganate Signup and view all the answers

What is used for detection of chlorine gas leaks?

10% solution of ammonia hydroxide Signup and view all the answers

When using the lime soda ash process, it is impossible to produce water with a hardness of less than?

25 mg/L Signup and view all the answers

What chemical can be added to the water system to sequester iron and manganese?

Polyphosphates Signup and view all the answers

Which forces will pull particles together once they have been destabilized in the coagulation-flocculation process?

Van Der Waals Forces Signup and view all the answers

What changes does an operator need to make when there are issues with floc formation?

Adjust coagulation dosage, change coagulant type, adjust flocculator mixing intensity Signup and view all the answers

What type of chlorine gas feeder is most commonly used?

Vacuum Signup and view all the answers

What will accurately measure a 500mL solution?

500-ml volumetric flask Signup and view all the answers

One of the ways an optimum coagulant dosage can be established is?

Performing jar test Signup and view all the answers

A property that is important to water treatment that is physical as opposed to chemical is?

Turbidity Signup and view all the answers

What does pinpoint floc, fish eyes, and high turbidity in settled water indicate?

Operating problems and need further investigation Signup and view all the answers

When responding to a chlorine gas leak, the responder should have an SCBA and a?

Level A suit Signup and view all the answers

A 50% solution of caustic soda will begin to crystallize if the temperature drops below?

54 °F Signup and view all the answers

Records of sanitary surveys must be kept for?

3 years Signup and view all the answers

All chlorine gas rooms should have what for safety?

A window in the door so an operator can look into the room to detect any abnormal conditions Signup and view all the answers

What effect will an increase in total dissolved solids in water to be treated be?

An increase in the time required for coagulation Signup and view all the answers

What is the maximum feed rate when adding fluoride to drinking water?

1.0 mg/L Signup and view all the answers

OSHA stands for?

Occupational Safety and Health Administration Signup and view all the answers

Filtration rates vary from what of filter surface area?

0.15-5 GPM/sq ft Signup and view all the answers

What would be the most probable solution to control algae in the source water if the algae is clogging the filters in the water plant?

Control nutrients Signup and view all the answers

During daylight hours, algae growth in a reservoir will do what?

Increase DO and pH levels Signup and view all the answers

Dissolved-air flotation is particularly good for?

Removing algae Signup and view all the answers

What type of filtration is permitted under the Surface Water Treatment Rule?

Diatomaceous Earth Filters Signup and view all the answers

What test is used to determine the presence of coliform bacteria?

Presumptive Signup and view all the answers

An organic particle that is stabilized by attracting a layer of water molecules to its surface is known as a?

Hydrophilic particle Signup and view all the answers

What do long filter runs tend to cause?

Slime growths Signup and view all the answers

What type of polar bonds are between the hydrogen atoms and the oxygen atom in water?

Covalent Signup and view all the answers

In gram staining, part of the coliform verification is?

Completed test Signup and view all the answers

The C2 residual in water may be determined by using the reagent?

DPD - Diethyl-p-phenylenediamine Signup and view all the answers

What is the process that is used to dewater sludge?

Sand bed Signup and view all the answers

Water treatment chemicals are added based on?

Weight Signup and view all the answers

The most probable cause of a problem with a chlorinator is?

Clogged ejector Signup and view all the answers

What national law regulates underground disposal of wastes in deep wells?

Safe Drinking Water Act Signup and view all the answers

A sedimentation basin with mechanical sludge removal equipment should be drained and inspected?

Once a year Signup and view all the answers

What is a physical separation between a water supply outlet and the flood-level rim of a receiving vessel that must be at least twice the diameter of the water supply outlet and never less than one inch?

Air gap Signup and view all the answers

What does the operator use to adjust the amount of liquid or gas delivered to water?

Rotameter Signup and view all the answers

In a permit entry confined space, who is responsible for terminating entries?

Entry supervisor Signup and view all the answers

If iron bacteria is causing corrosion problems in the filters, what is the best solution?

Superchlorinate Signup and view all the answers

A system that fails to collect water samples in their distribution system would fall under which public notification system?

Tier 1 Signup and view all the answers

Bar screens are used to?

Remove debris Signup and view all the answers

CTs are based on?

Concentration of chlorine, contact time, pH, and temperature Signup and view all the answers

For surface water systems without filtration, the Surface Water Treatment Rule requires public water systems to?

Maintain a C x T value above the minimum value Signup and view all the answers

Coagulation is a chemical and physical reaction that converts?

Non-settled solids into settable solids Signup and view all the answers

What is the MCL for THM's?

0.080 mg/L or 80 ppb Signup and view all the answers

What is usually used to disinfect the gravel packing of a groundwater well?

Powder of calcium hypochlorite tablet Signup and view all the answers

How often should the fluoride feed system be checked?

Every hour Signup and view all the answers

How much carbon is approximately lost during the reactivation process for granular activated carbon?

5% Signup and view all the answers

Why are polyphosphates used in drinking water?

To keep iron and manganese in sequestration Signup and view all the answers

The Colilert test (ONPG-MUG) shows the presence of total coliforms is shown by?

A yellow water color Signup and view all the answers

What does it mean when a filter is ripening?

Becoming more efficient in particle removal Signup and view all the answers

What determines whether or not colloidal-sized particles in suspension repel each other, stay in suspension, or agglomerate and eventually settle?

The magnitude of the charges Signup and view all the answers

What could happen if the sludge in a sedimentation basin becomes too thick?

Solids can become resuspended or taste and odors can develop Signup and view all the answers

What is the principal form of alkalinity found in raw water from both surface and ground sources?

Calcium bicarbonate Signup and view all the answers

What sludge dewatering process requires a pre-coat of diatomaceous earth and its use has declined due to other newer methods?

Vacuum filters Signup and view all the answers

At what temperature does the maximum density of water occur?

4 degrees C Signup and view all the answers

In a thermally stratified reservoir, water located beneath the thermocline may?

Contain tastes and odors due to H2S formation Signup and view all the answers

Where are samples taken for lead and copper?

At the consumer's tap Signup and view all the answers

Adding CO2 to water will?

Lower pH Signup and view all the answers

The scattering of light by the particles in finished water is from the turbidity caused by?

Silt and clay Signup and view all the answers

What is the MCL for HAA5s?

0.060 mg/L Signup and view all the answers

Pure water can be found?

In a lab Signup and view all the answers

What is the most probable solution if nematodes are interfering with the disinfectant?

Optimize the settling process Signup and view all the answers

Which natural electrical force keeps colloidal particles apart in water treatment?

Zeta potential Signup and view all the answers

Under the Surface Water Treatment Rule, a multiple barrier treatment consists of?

Removal by filtration and inactivation by disinfection Signup and view all the answers

Floc is produced when there is a chemical reaction between the coagulant and alkalinity. If the alkalinity of raw water is too low the floc formation will be poor. Some form of alkalinity must be added if the amount that is naturally found in the water source is less than?

80 mg/l Signup and view all the answers

If the chlorine demand suddenly increases from 0.4 mg/L to 2.8 mg/L, what could be the reason?

Pollution Signup and view all the answers

Alachlor, Lindane, and Toxaphene are examples of?

SOCs Signup and view all the answers

What zone in a lake or reservoir has weeds that grow underwater that may cause taste & odor complaints?

Littoral Zone Signup and view all the answers

What is a hypochlorinator used for?

Feed liquid chlorine into a water supply Signup and view all the answers

The sampling points located for required sampling of natural radionuclides are located?

Each entry point to the water system Signup and view all the answers

The porous material just above the water table that holds small quantities of water by capillary action is called?

Capillary fringe Signup and view all the answers

To unclog the head of a chemical feed pump an operator should first?

Remove it then soak it in a weak solution of hydrochloric acid Signup and view all the answers

A water sample that is acidified must have a final water pH of?

Less than 2 Signup and view all the answers

Study Notes

Water Treatment and Quality Control

Potassium Permanganate is effective in removing iron from water.
A total coliform positive water sample necessitates testing for fecal coliforms (E. coli).
Drawdown refers to the change in water elevation between normal and pumping levels.

Safety and Regulations

Use a positive pressure self-contained breathing apparatus (SCBA) at water plants.
Tier 1 water violation requires immediate public notification.
Fusible metal plugs on chlorine containers melt between 158-165°F.

Treatment Processes

5% of solids sludge is produced in precipitative softening plants.
Blue-green algae thrive in nutrient-rich water.
The loss of chloramine residuals in water systems arises from nitrification and increased heterotrophic bacteria.

Water Chemistry and Testing

Operators increase the maximum flocculator paddle speed when raw water turbidity is high.
Chlorine added at 0.3 mg/L increases the residual by the same amount.
The most frequent tests in drinking water systems include turbidity and coliform bacteria.

Pathogens and Contaminants

Shellfish from polluted waters can carry infectious hepatitis.
Coagulant chemicals destabilize colloidal particles, vital for efficient water treatment.
Giardiasis organism control involves filtration and disinfection methods.

Equipment and Operations

Venturi meters are commonly used for totalizer measurements in treatment plants.
To detect chlorine gas leaks, use a 10% ammonia hydroxide solution.
Adjustments in floc formation issues include modifying coagulation dosage, changing coagulant types, or altering mixing intensity.

Chemical Management and Dosage

Monitor fluoride feed rates to stay below 1.0 mg/L.
Maximum density of water is at 4°C.
Vacuum filters for sludge dewatering require a pre-coat of diatomaceous earth, with diminished use due to newer methods.

Environmental Considerations

Increasing total dissolved solids prolongs coagulation time; likewise, an increase in DO and pH during daylight hours promotes algae growth.
Turbidity results from scattered light by silt and clay particles; measuring this is fundamental to assess water clarity and treatment effectiveness.

Safety Standards and Monitoring

OSHA refers to the Occupational Safety and Health Administration which enforces safety regulations in workplaces, including water treatment facilities.
For lead and copper testing, samples should be collected at consumer taps.

Innovative Solutions

Hydrophilic particles attract water molecules ensuring stability, while zeta potential represents the electrical forces keeping colloidal particles separated.
If nematodes disrupt disinfectant efficacy, optimizing settling processes is advised.

Additional Key Terms

CT Values must be maintained above minimum levels for effective disinfection under the Surface Water Treatment Rule.
Air gap separates a water supply outlet from a receiving vessel's flood level, ensuring contamination prevention.
Coliform testing employs a presumptive method to ascertain the presence of bacteria, indicated by a yellow water color in relevant tests.

These notes provide vital information to effectively understand water treatment processes, safety regulations, and necessary chemical management for water quality and public health.

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Prepare for your water treatment exam with these flashcards covering essential terms and definitions. Each card provides crucial information on water quality testing, chemical usage, and more, making it an excellent resource for anyone studying this field.