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101 Cards in this Set
- Front
- Back
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Which items should operator's check when troubleshooting poor ultraviolet (UV)disinfection performance? |
Biofilms on UV channel walls and equipment Particles shielding bacteria System hydraulics |
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What is the chlorine demand of a water that is doses at 5.0 mg/L? The chlorine residualis 1.5 mg/L after a 30-minute contact period/ |
3.5 mg/L |
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What should be the setting on a chlorinator (lbs chlorine per 24 hours) if a pump usually delivers 500 GPM and the desired chlorine dosage is 5.0 mg/L? |
30 lbs chlorine/24 hours |
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At 9:00 am on Wednesday morning, a chlorine cylinder weighs 72 pounds. At 9:00 am on Thursday morning, the same cylinder weighs 58 pounds. What is the chlorinator feed rate in pounds per 24 hours? |
14 lbs per 24 HOURS |
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What is the chlorine dose in mg/L is a chlorinator feeds at a rate of 30 lbs per 24 hours and the flow is 0.50 MGD? |
7.2 mg/L |
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Water from a well is being treated by a hypochlorinator. If the hypochlorinator is set at a pumping rate of 24 gallons per day (GPD) and uses a two percent available chlorine solution, what is the chlorine dose in mg/L if the pump delivers 125 GPM? |
2.7 mg/L |
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What is the water velocity in a channel in feet per second if a float travels 32 feet in seconds? |
4.0 ft/sec |
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That is the water flow rate in an open channel in cubic feet per second (SCS) if the channel is three feet wide, the water depth is 2.0 feet, and the water velocity is two feet per second? |
12/0 cu ft/sec |
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What is the water flow rate in a 15-inch diameter pipe in gallons per minute (GPM) when the flow velocity is 1.6 feet per second? (end of chapter 7) |
884 GPM |
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Corrosion is a very simple problem, involving numerous chemical, electrical, physical,and biological factors |
False |
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Corrosion can occur only on the interior of metal piping and equipment. |
False |
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If the rust film inside a pipe is flushed away, the corrosion reaction accelerates again. |
True |
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The degree to which a particular metal will become anodic (corrode) in a galvanic reaction is related to its tendency to enter into solution |
True |
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The types of coatings or other protective measures taken on both the inside and outside of pipes and tanks play a major role in corrosion activity. |
True |
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The rate of chemical reactions usually increases as temperature drop. |
False |
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The hydrogen ion is extremely active (Corrosive) at pH values above 4 |
False |
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Chloride and sulfate ions in water may inhibit the formation of protective scales by keeping hardness ions in solution |
True |
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If no oxygen is present in well water, the water cannot be corrosive |
True |
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A positive Langelier Index indicates that the water is supersaturated with calciumcarbonate and will tend to be corrosive |
False |
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The calculations used to determine the chemical dose required to saturate water with calcium carbonate ar exact |
False |
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To achieve and maintain a high degree of corrosion control, operators must regularlyinspect and test the operation of the cathodic protection systems and it’s parts |
True |
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Electrolysis of water mains can result from stray currents generated by cathodic protection installed by the gas company |
True |
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The EPA specifically allows the utility to dispute the accuracy of a first-draw samplecollected by a resident |
False |
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All utilities must provide a notification of tap water monitoring results for lead to owners and/or occupants of homes and buildings |
True |
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What is the electrolyte? |
A substance which dissociates (separates) into two or more ions when it isdissolved in water |
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The seventy and type of corrosion depend on which factors |
The chemical and physical characteristics of the water and the material |
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Electrochemical corrosion caused by the joining of dissimilar metals is called what type of corrosion? |
Galvanic corrosion |
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What is a sacrificial anode? |
An easily corroded material deliberately installed in a pipe or tank |
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What is a corrosion inhibitor? |
A substance that slows the rate of corrosion |
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What action is responsible for the foul odors usually found is the dead ends of water mains? |
Action of anaerobic bacteria on traces of organic matter and on reducing thesulfate ions to sulfide |
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What is a coupon? |
A steel specimen inserted into water to measure the corrosiveness of water |
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Why should accurate records be maintained of drinking water complaints? |
To help determine where corrosion problems are occurring and indicate how theproblem can be corrected |
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The selection of a chemical to achieve calcium carbonate saturation will depend on which factors? |
The water quality characteristics of the water and the coast of chemicals |
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What is the major use of sodium polyphosphates in water treatment? |
To control scale formation in waters that are supersaturated with calcium carbonate |
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Why is cathodic protection of flocculators, clarifiers, and filters a very effective means of controlling corrosion? |
Maintenance and repair of protective coatings on these facilities is very difficult |
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How does lead primarily enter drinking water? |
As a result of the corrosion, or wearing away, of materials containing lead in the water distribution system and household plumbing |
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The number of samples to be collected for lead and copper analysis is based on which factor? |
Size (population served) of the distribution system |
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The success of corrosion inhibitor addition depends on which factor? |
The ability of the inhibitor to provide a continuous coating throughout thedistribution system |
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What is a negative side effect of controlling corrosion using silicates? |
May reduce the useful life of domestic hot water heaters due to glassification |
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Which physical factors influence corrosion? |
Soil moisture Stray electric current System construction System pressure Temperature of water |
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Which chemical factors influence corrosion? |
Alkalinity Chloride and sulfate Dissolved oxygen Hardness pH |
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Which biological factors influence corrosion? |
Iron bacteria Sulfate-reducing bacteria |
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Which items are indicators of corrosion problems in a water distribution system? |
Chemical tests on the water indicate corrosiveness Consumers are complaining about dirty or red water Materials removed from the distribution system show signs of corrosion damages The distribution system has an increasing number of leaks |
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Which approaches are commonly used by water treatment plant operators to determine the calcium carbonate saturation level of their water? |
Langelier Index Marble Test |
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How can internal pipe corrosion be detected? |
By examining the insides of pipes for evidence of corrosion By examining the insides of pipes for pitting and tubercles By rusty water complaints |
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How can external pipe corrosion be detected? |
By observing pinhole leaks By observing rust on the outside of pipes |
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The 2007 revisions and clarifications to the Lead and Copper Rule (LCR) enhance the implementation of the 1991 rule in which areas?) |
Customer awareness Lead service line replacement Monitoring Treatment |
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If routine monitoring indicates that a lead and copper problem exists in the source water feeding the distribution system, the utility must remove the contaminant from the source water by selection one of which treatment methods? |
Coagulation/filtration Ion exchange Lime softening Reverse osmosis |
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Public education programs are designed to provide the consumer with information on how to minimize the exposure to lead in the water through which activities? |
Checking new plumbing for lead solder Cooking with cold rather than hot tap water Flushing the taps before use Testing their water for lead |
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What horsepower must a pump deliver to water that must be listed 90 feet? The flow is 40 GPM. |
0.9 HP |
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If the required water horsepower of a pump is 40 HP, what must be the motor horsepower if the efficiency of the pump is 75 percent and the efficiency of the motor is 90 percent? |
59 HP |
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How many kilowatt-hours per day are required by a pump with a motor horsepower of 45 horsepower when the pump operates 24 hours per day? |
806 kW-hr/day |
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What is the wire-to-water efficiency of the pump if the water horsepower is 7.2 horsepower and the power input is 10.3 horsepower? (end of chapter 8) |
70% |
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Tastes and odors in drinking water are among the most common and difficult problems that confront waterworks operators |
True |
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Operators must treat for tastes and odors before the problem occurs |
True |
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When searching for the causes of tastes and odors, each water system must be evaluated individually since each will have unique characteristics that may significantly affect water quality |
True |
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Pollutants themselves normally cause the oxygen concentration in the water to decrease |
False |
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When algae produce oxygen, carbon dioxide is removed from the water and the pH will increase during the daylight hours. |
True |
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Inadequate or incomplete maintenance of water treatment plants and water distributionsystems will result in water quality deterioration |
True |
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Comprehensive flushing program should be used by utilities as part of a system water quality maintenance effort |
True |
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Sometimes a taste and odor problem is traceable directly to the consumer’s plumbing system |
True |
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Dewatering a treatment plant during a taste and odor episode is a practical means of removing the source of the problem |
False |
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Cross connections in the distribution system are potentially very hazardous and can be a source of taste and odor complaints |
True |
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One single treatment process is applicable to all taste and odor problems |
False |
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In plants where chlorine is added to the head works, a decrease in odor levels may occur due to the destruction of algal cells by the chlorine |
False |
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In general, volatile compounds will be noticed as objectionable odors, while less volatile compounds are more often associated with objectionable tastes |
True |
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By application of a strong oxidant, objectionable taste and odor compounds are chemically modified or broken down into less objectionable by-products |
True |
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Never store permanganate in the same area where activated carbon is stored because they are both highly flammable |
True |
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Ozone is a stable form of oxygen that is an extremely powerful oxidant |
False |
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Powdered activated carbon (PAC) may be applied to the water at any point in the processafter filtration |
False |
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From an economic standpoint, it is good practice to apply chlorine and powdered activated carbon (PAC) near the same location |
False |
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If the air around the plant contains the odor of concern, none of the people at the plant site will be able to perform the threshold odor number (TON) test |
True |
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Every water utility must have an effective communications network to deal with all types of consumer complaints |
True |
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What is the secret to successful taste and odor control? |
Prevent tastes and odors from ever developing |
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When ammonia is added to the treatment process, what common taste and odor compounds may be formed? |
Odoriferous inorganic chloramines |
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How does the depletion of oxygen in the bottom layers of reservoirs contribute to taste and odor problems? |
By providing suitable conditions for the growth of microorganisms capable of production objectionable compounds such as hydrogen sulfide |
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What must be the primary concern of water utility operators after a chemical spill? |
Health-related effects due to the toxicity of spilled chemicals |
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How does urban runoff contribute to tastes and odors, especially in areas where precipitation occurs only during a limited portion of the year? |
During dry periods, oil, grease, gasoline and other residues accumulate on paved surfaces and are washed into the local receiving water |
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What should be the first step in determining the cause of tastes and odors? |
To locate where in the overall system the problem is originating |
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What is often the first warning that a water supplier has a cross-connection problem? |
Complaints about a musty, septic, or other strange odor in the water |
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What is a distinct advantage of ozone over chlorine treatment for tastes and odors? |
Objectionable by-products of the ozone reaction do not normally form |
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What is the most common adsorption technique used specifically for taste and odor control at water treatment plants? |
Powdered activated carbon (PAC) |
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Why do carbon slurry tanks require continuous mixing |
To prevent settling and caking of the carbon |
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How can an operator determine the necessary powdered activated carbon (PAC) dose required to treat the specific taste and odor problem that exists? |
Use jar test |
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What is a slurry? |
A watery mixture or suspension of insoluble (not dissolved) matter |
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Why should bags of powdered activated carbon (PAC) be stored off the floor? |
To prevent caking due to spilled or sprayed water |
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How is it possible for a water utility to predict the start of taste and odor problems and take corrective action before consumers are affected? |
By keeping complete and accurate records of taste and odor outbreaks |
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What is required to provide the public with high-quality, safe, and pleasing supplies of drinking water? |
Adequate training of operators responsible for water treatment |
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Water utilities commonly receive which types of drinking water quality complaints? |
Water has an objectionable taste Water looks dirty of colored Water smells bad |
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What are the causes of taste and odor problems water utilities may experience? |
Biological growth in source water Environmental conditions Human activities in the environment Specific taste and odor compounds |
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Which types of algae are known to produce taste and odor compounds? |
BLue-green algae Diatoms Dinoflagellates Yellow-green Algae |
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The contribution to municipal drinking water taste and odor problems by agricultural runoff depends on which factors? |
Local irrigation practices Nature and extent of farming in the watershed Precipitation patterns |
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Many municipal water intake facilities are located upstream of major agricultural areas to avoid possible contamination of the water supply by which items? |
Fertilizers Herbicides Microbial contaminants (Crypotosporidium and Giardia) Pesticides |
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Cross connections commonly occur in which types of situations? |
A hose connected to the house is left in a swimming pool A hose connected to the house is used to apply chemical fertilizers or pesticides A hose connected the the house is used to flush a car radiator A potable water source used as a seal supply is connected to a pump deliveringunapproved or non potable water A sprinkler system using nonpotable water is connected to a potable water supply |
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The success of chlorination as a taste and odor treatment will depend on which factors? |
Contact time between chlorine and the water prior to delivery Dose applied Seriousness of the problem Type of odor |
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A standard water quality complaint form should include a place for recording which items? |
Date and time of the complaint Description of the problem Location (address) Name of the person taking the complaint |
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What is the volume of a rectangular sedimentation basin 8 feet deep, 20 feet wide, and 55 feet long? |
8,800 cu ft |
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What is the theoretical detention time in hours for a rectangular sedimentation basin with a volume of 65,000 gallons when the flow is 1.0 MGD? (end of chapter 9) |
1.56 hr |
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Primary drinking water regulations establish maximum contaminant levels (MCLs) based on aesthetic considerations and secondary standards are based on the health significanceof the contaminants |
False |
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Water treatment plant operators should prepare a checklist of daily operating activities for their plant |
True |
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To achieve calcium carbonate saturation, which chemicals should be added to waters with high levels of hardness and alkalinity? |
Caustic soda Soda Ash |
