Water D

Intrusion of seawater into groundwater basins results from…?

overpumping fresh water

What is the basic objective of the operation of water treatment plants?

produce safe, aesthetically pleasing drinking water at a reasonable cost

What is one characteristic of a community water system?

regularly serves at least 25 full-time residents

Which of the following influence the size of a water treatment plant as well as the number and types of processes it uses?

impurities in raw water and cost considerations

Which plant operating guidelines are routinely monitored by water treatment plant operators?

Flows and water quality indicators

What is one purpose of clearwells or plant storage reservoirs?

provide operational storage to average out high and low flow demands

How would you verify the actual raw water flow rate after adjusting the pumping rate to a water treatment plant?

read the raw water flow measuring device

How are the initial selection of chemical types and anticipated feed rates for a given application in a water treatment plant usually determined?

pilot-plant tests

What is the best source of information about dangerous chemicals?

Safety data sheets

Which of these chemicals is one of the most dangerous common alkalies?

caustic soda

What should you do if an operator is not breathing due to chlorine gas exposure?

Perform hands-only or conventional CPR

Water samples taken to measure compliance with water quality standards are usually collected at…?

entrance to the distribution system

Turbidity is commonly monitored at…?

Source water, flocculation effluent, sedimentation effluent, filter effluent

The range of turbidity removal effectiveness is important because of the relationship between turbidity and…?

Pathogenic organisms

Fed laws include sludge from a water treatment plant as a …… waste

industrial

What should an operator do promptly when a treatment process upset results in the failure to meet a specific drinking water quality standard?

notify appropriate local health authorities

If a water treatment plant must be dewatered for emergency repairs, how would you prepare for this event?

fill all storage reservoirs by early evening

what kinds of records are operators required to keep on file for specified time periods for regulatory compliance?

Water quality analysis and customer complaints

What is one way of keeping track of how much time and money is spent doing various types of work?

work order system

How can energy requirements for lighting be reduced in a water treatment plant?

turn off lights in unoccupied spaces

What regulations require that accurate records of water treatment plant operations be maintained?

Safe Drinking Water Act

What contributes to most treatment plant accidents?

Carelessness and negligence

What is the responsibility of water treatment plant operators?

Produce safe and pleasant drinking water

What do most states require for someone to work as a water treatment plant operator?

Operator certificate

Short-circuiting

a condition that occurs in tanks or basins when some of the flowing water entering a tank or basin flows along a nearly direct pathway from the inlet to the outlet

Head

the vertical distance, height, or energy of water above a reference point

Adsorption

the gathering of a gas, liquid, or dissolved substances on the surface of another material

Coliform

a group of bacteria found in the intestines of warm blooded animals, indicate the possibility of pathogenic organisms in water

Cross-connection

a connection between a drinking water system and an unapproved water supply

Toxic

A substance that is poisonous to a living organism

Turbidity

The cloudy appearance of water caused by the presence of suspended and colloidal matter

Anaerobic

A condition in which atmospheric or dissolved oxygen is NOT present in the water environment

Eutrophic

Reservoirs and lakes that are rich in nutrients and are very productive in terms of aquatic animal and plant life

Potable water

water that does not contain objectionable pollution, contaminations, minerals, or infective agents and is considered satisfactory for drinking

What is stratification in lakes and reservoirs?

Formation of separate layers of temperature, plant, or animal life

What causes the elevation and slope of water tables to change?

Seasonal variations in the supply of water

How extensive should the treatment be for reclaimed water?

depends on potential exposure to the public

What are water rights?

Permission to use water

Who should conduct a sanitary survey?

People trained in public health engineering and the epidemiology of waterborne diseases

Which of the following water quality problems are not usually related to algal blooms?

Reduced water temperature

Under what circumstances are tastes and odors in a domestic water supply most noticeable?

at or above room temperature

What is the impact on water treatment plants from increased organic loadings caused by algal blooms?

increased chlorine demand and color

How can a water agency meet acceptable trihalomethane levels?

change disinfection methods

Reservoir water quality mgmt programs can control or eliminate what types of water quality problems?

frequency and intensity of algal blooms

How can iron, manganese, and hydrogen sulfide problems be controlled in a reservoir?

by preventing dissolved oxygen depletion

How can the recreational values of a reservoir be improved by proper reservoir mgmt?

Reduction of algal problems

What is the best tool for managing watersheds?

regulatory process

How can water quality problems caused by septic tank leaching systems be solved?

replace septic tanks with sewer systems

What is the destratification of a lake or reservoir?

vertical mixing to eliminate separate layers or temperature, plant, and animal life

Why might complete destratification of a reservoir be undesirable?

Water may become too warm

What water quality indicators should be monitored in domestic water supply reservoirs that develop anaerobic zones?

Hydrogen sulfide, iron, and manganese

How can the entrance of silt into the intake system be minimized?

Locate intake away from low point

What is the major advantage of multilevel intake systems in domestic water reservoirs?

Access to water with different characteristics at different depths

What is the purpose of coagulation and flocculation?

To remove particulate impurities

What is coagulation?

Clumping together of fine particles into larger particles with chemicals

What is flocculation?

gathering together of particles by gentle stirring

How long should the coagulation reaction last

a few seconds

Why are coagulant aids used?

To add density and toughness to flocs

What is the most commonly used coagulation chemical?

alum

How can an operator verify the effectiveness of the coagulant chemicals and dosages being applied at the flash mixer?

perform series of jar tests

What is the disadvantage of mechanical mixer in coagulation?

higher electricity use than other methods

What is the purpose of the flocculation process?

to create floc of good size, density, and toughness

How are the proper type and amount of coagulant chemicals be determined?

by conducting jar tests at least daily

How can poor process performance be spotted early so that corrective measures can be taken?

monitor water quality throughout the water treatment process

What is the basic purpose of the jar test?

Duplicate plant detention times and mixing and settling conditions in the laboratory

After a jar test is completed, what does a hazy settled water indicate?

poor coagulation

Which of the following factors are not important when evaluating jar test results?

paddle construction

What is a desirable floc appearance?

popcorn flake

Why should operators keep polymer powders off of the floor?

They become extremely slippery when wet

Which items are adjusted in the enhanced coagulation process?

pH and coagulant dosage

What is the purpose of the hydro cyclones in ballasted flocculation?

to separate the micro sand from the sludge

Why should operators maintain a diluted feed solution in ballasted flocculation?

to minimize micro sand losses and the hydro cyclone

What is the first step on optimizing a ballasted flocculation process?

optimize coagulant dose

What is one purpose of presedimentation facilities?

reduce the solids-removal load at the water treatment plant

What size particles can be removed from water by sedimentation?

> 10 microns

What property of alum attracts negatively charged particles?

Positive charge

What happens to the settling rate of particles in water when the water temperature drops?

decreases

What is the largest portion of the sedimentation basin?

settling zone

What is the major means by which operators can control water treatment processes?

Adjusting chemicals and chemical feed rates

_______ combine the coagulation, flocculation, and sedimentation processes in a single basin.

solid contact process units

Sludge produced by a solids-contract clarification unit is recycled through the process to act as a _______.

coagulant aid

Changes in which process variables cause instability in solids-contact units?

flow, temperature, and turbidity

What does the volume over volume test result tell an operator about the solids-contact unit?

Percentage of slurry

What is the primary factor in determining the frequency of sludge removal?

Rate of sludge buildup

Low turbidity source waters may not require _______.

Sedimentation

Which water quality indicators should be monitored in the normal operations of the sedimentation process?

Temperature and turbidity

In solids-contact clarifiers, what should an operator do if the sludge blanket is of normal density but very close to the surface?

Waste more sludge

What does frequent clogging of the sludge discharge line indicate?

Sludge concentration is too high

How can operators measure turbidity levels at the sedimentation basin inlet and outlet to get a rough idea of process removal efficiency?

Grab samples

What is the most common reason to shut down a sedimentation basin?

Annual maintenance and cleaning

Which task should be performed immediately following dewatering of a sedimentation basin?

Grease and lubricate previously submerged mechanical moving parts

Process water samples must be _______ of actual conditions in the treatment plant/

Representative

How can operators determine if sludge pumping lines are clogged?

check pump’s suction and discharge pressures

Breakthrough

A crack or break in a filter bed allowing floc or particular matter to pass through a filter, causing increased filter effluent turbidity

Mudball

material round in shape that forms in filters and gradually increase in size when not removed by the backwashing process

Diatomaceous Earth

fine, siliceous earth composed mainly of the skeletal remains of diatoms

Direct filtration

a method of treating water hat consists of the addition of coagulant chemicals, flash mixing, coagulation, minimal flocculation, and filtration

Turbidity meter

an instrument that measures and compared the turbidity of liquids by passing light through them and determining how much light is reflected by the particles in the liquid.

Head Loss

The head, pressure, or energy lost by water flowing in a pipe or channel due to turbulence from the velocity of the flowing water and the roughness of the pipe, channel walls, or fittings restrictions

Backwashing

the process of reversing the flow of water back through the filter media to remove the entrapped solids