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Flashcards in Water Deck (154):
1

Humans consume an average of __ to __ lbs of water per day

3 to 5 lbs per day

2

The ocean contains nearly ______ % of all our water

97%

3

The _____ powers the hydrological cycle

sun

4

What is thermal stratification

the change in temperature of water at different depths in a body of water. it occurs because colder water is more dense.

5

name the three sections of thermal stratification from top to bottom

epilimnion -upper layer
thermocline
hypolimnion - lower layer

6

in winter what layers exist in thermal stratification?

ice exists above the water layer

7

name the three ages of lakes

oligotrophic - young
mesotrophic - middle
eutrophic - old or mature lake

8

a lake is considered "dead" when it has been depleted of _________

oxygen

9

why are plants important to a lake?

because they provide oxygen

10

What is eutrophication

a lake condition of algal blooms due to over enrichment of nutrients such as phosphates and nitrates.

can be natural or manmade

11

if left untreated manmade eutrophication can result in a ______ lake because the algae depletes the ______

dead
oxygen

12

What chemical can be used to control algae

copper sulfate CuSO4 can be used but in limited concentrations so it doesn't kill fish and other aquatic life

13

what two chemicals can be used to prevent evaporation from lakes

hexadecanol and octadecanol

they are non toxic

14

so why don't we convert ocean water into drinking water?

because it's too costly due to the high salinity and minerals in the water

15

what are some types of surface waters

spring
pond
swamp
stream

16

what is an aquifer?

an underground layer of water with permeable rock or other materials through which a well can be drilled

17

what is the water table

the area of the start of the zone of saturation

18

What three things should be considered in the construction of the well

expensive
depth of water table
type of construction

19

why do higher water tables have less potable water?

because the water did not have enough time to naturally filtrate through the soil

20

What are the 3 types of wells

case driven well
bored well
dug well

21

case driven well

best quality
bottom of casing is perforated to allow water in
used with a submergible pump that is lowered into the water source

22

bored well

an auger is used to drill into the earth

23

dug well

manual dug by man or machine. lined with concrete, bricks, tile or clay pipes.

not deep

24

what is a rainwater cistern

a tank with a simple filter of sand/gravel to filter rain water.

used for non drinking purposes

25

What are weep holes?

holes in tanks so that if water freezes it can escape out of the tank to prevent tank damage from expansion

26

what is the hydraulic gradient?

the movement of water downward by earths gravitational pull

27

What is an injection well

a way to dispose of contaminated water into an isolated well. Typically it's a well into limestone or sandstone.

not allowed anymore. most are closed?

28

What is an unconfined aquifer

water confined by both upper and lower impermeable layers (typically clay)

usually not vulnerable to contamination

29

What is an unconfined aquifer

only confined by a lower impermeable layer

30

What is the purpose of the well casing

prevents the collapse of the bore hole
keeps surface and subsurface pollutants from entering the water source
provides a column to store water for positive well upmp
houses the pump and discharge pipe

31

What are the two types of casing

blank casing - pvc or steel depending on soil
screened casing - slotted, louvered - to keep sand and gravel out but allow water in

32

What is an annular seal

a cement or bentonite filling around the open space left around the outside of the well casing.

to prevent contamination

33

What are two types of pumps used in wells

vertical turbine pump (pump motor is on the surface)

submersible pump (more common)

34

What percent of Americans are on private wells/drinking water

15%

35

The recycling of water is known as _________

the hydrologic cycle

36

Water weights ______ lbs/gallon

8.34

37

_______ gallons of water are in 1 cubic foot volumne

7.48

38

What are some gases that can be found in water?

CO2
Oxygen
Hydrogen Sulfide
Methane

39

CO2 in water

corrosion, especially in steam and condensate lines

treatment: aeration, deaeration, neutralize with alkalies

40

Oxygen gas in water

O2
corrosion of water lines, heat exchange equipment

treatment: deaeration, sodium sulfite, corrosion inhibitors

41

Hydrogen Sulfide gas in water

H2S
Rotten Egg odor, Corrosion

treatment: aeration, chlorination, highly basic anion exchange

42

What is hard water

Water that has a high dissolved mineral content. Typically has a lot of salts and bicarbonates.

Mainly calcium and magnesium

43

What is the benefit of hard water and the drawbacks of it?

good cleanser for the human circulatory system.

cons: hard water neutralizes soap and makes it hard to lather. stains sinks and bathing areas and calcifies pipes due to electrolysis.

44

What are some areas with hard water and why?

limestone areas such as Colorado river, Arizona.

south Carolina has the softest water.

45

calcium concentration must exceed ____ mg/l to be labeled as hard water

100 mg/l

46

What are the two main ways to soften water?

lime soda process
magnesium soda ash process

47

Water softening is achieved by increased the ______ concentration which precipitates the calcium and magnesium minerals out of the water

sodium

48

lime soda process to soften water

quicklime - CaO and H2O is mixedhe slurry is added to the water and calcium ions are precipitated out as insoluble calcium carbonate CaCO3

can't be done at home

49

magnesium soda ash process is also called

aka zeolite or ion exchange method

50

excessively soft water can pull ________ out of the pipes such as ______ and ______ and into the water

pulls metallic ions

such as copper and lead from the pipes into the water

51

What are some radioactive materials that can get into water? how did they get into the water?

name 3

from mining wastes and improper haz waste disposal

radium
strontium 90
uranium

52

What is the MCL for strontium 90 a radioactive nuclide?

8 pCi/L

53

What is the MCL for combined Radium (226 and 228)

5 pCi/L

54

What is the MCL for Uranium?

20 pCi/L

55

Which two elements found in water are most known for causing stains

iron and manganese

56

What are the secondary standards?

limits for other elements in water that may not pose a health risk but my adversely affect the appearance, test, or odor of drinking water

57

What are the some of the elements addressed in secondary drinking water standards

iron
zinc
turbidity
color
odor
manganese
TDS
Sulfates
Chlorides

58

What is the acceptable limit for Iron

.3 mg/L

59

1 mg/L = ____ ppm

1 they are the same

60

What are the metals that are monitored in public drinking water?

There are 12

arsenic, barium, cadmium, chromium, lead, copper, mercury, selenium, nickel, thallium, antimony, and beryllium

61

Copper in water - what are the effects? What is the MCL

mcl is 1 mg/L

can lead to liver damage

62

Nitrates in water - effects and MCL

nitrates are usually the final product of organic decomposition. so if there are nitrates in the water that is an indication of pollution.

MCL is 10 mg/L

effects: blue baby syndrome methemoglobinemia (begins at 45 mg/L)

63

Zinc in water - effects and MCL

MCL 5 mg/L

metallic taste and vomiting

64

MCL categories are broken down to 4 categories which are

inorganics
radionuclides
VOCs
SOCs

65

Fluoride in water - effects, MCL

high levels actually mottle (break down enamel) of the teeth

2 mg/L is the MCL

66

What was the purpose of fluoridating water?

do provide chemical protection against dental decay

67

what level of fluoride will cause teeth mottling?

3 mg/L

68

What are the tree forms of available fluoride

sodium fluoride - commonly a powder
sodium silico-fluoride - also a powder
fluorosilic acid - liquid form - only 22% available fluoride

69

What is the idea percent of fluoride in the water

.8 mg/L - 1.7 mg/L

70

What are two ways to defluoridate water?

bone char
activated alumnia

71

What is the maximum units of color allowed in water?

15 units

72

Most major metropolitan cities have ______ units of color in their water

4 to 5 units/L

73

What is the maximum units of turbidity allowed in water?

5 units/L

74

What are two devices used to test for turbidity?

the Jackson turbid meter
the secchi disk

75

Jackson turbid meter

with a flame under a test tube the sample water is poured into the test tube until the flame is no longer visible

a very old style of testing

76

the secchi disk

used to test turbidity. common for recreational swimming

the disk is submerged in water until it is no longer visible. the length is then measured.

for swimming it should still be visible at 4 feet from the surface

77

What is the odor threshold of water?

3 units/L

78

What is TDS

total dissolved solids - doesn't necessarily mean that that the water is polluted, some water, like hard water just has more dissolved minerals

79

What is the MCL for TDS

1,000 mg/L for long term

80

Chlorides in water - effects and MCL

can cause bad taste and heart problems

MCL 500 mg/L

81

Sulfates in water - effects and MCL

can give a laxative effect

MCL 500 mg/L

82

Natural water has a pH range of ___ to ____

5 to 8.3

83

a chemical examination of water includes determining the following.....

suspended solids
BOD
DO
COD
nitrates
hydrogen sulfide
pH

84

a Bacterial examination of water includes determining the following....

coliform MPN
presumptive and confirmed testing for MPN
membrane filter

85

What are some of the common diseases which can come from contaminated drinking water

bacterial and viral gastroenteritis
legionella
cryptosporidiosis
giardiasis
infectious hepatitis
shigellosis/dysentery
cholera/vibrio
salmonella/typhoid/paratyphoid
polio
leptospirosis
entamoeba histolytica

86

lead in water - effects and MCL

.05 mg/L
in the bloodstream it can cause mental and brain dysfunction

87

What is the indicator test

a coliform test - will indicate potential contaminated water

88

Why is e-coli a great indicator organism

because it is excreted in large numbers in feces. you can expect from 30 million organisms in a 100 mL sample.

89

What is the average number of coliforms in 100 ml of drinking water? and also the maximum acceptable limit for human consumption

1 per 100 ml
1 colony per 100 ml

90

in polluted water, there is approximately ___ pathogenic bacteria for every ______ coliform bacteria

1 to 1 million

91

in polluted water there is approximately ___ viruses to every _________ coliforms

1 to 100,000

92

What chemical is in a water sample bottle and why?

sodium thiosulfate - it dechlorinates the sample so you can keep any potential coliforms alive for testing

93

most coliforms are what shaped bacteria?

rod shaped

94

What is the MPN?

most probable number - a bacteriological study looking for possible fecal contamination (coliforms)

95

How is the presumptive test (multiple tube fermentation) performed?

to test for coliform.

performed with inverted durham tubes to detect fermentation of the sample

if at least 2 of the 5 tubes are positive than it's said that 1 in 100ml coliform exisists

a confirmation test is performed if 3 or more tubes are positive

96

What is the confirmation test

ETT elevated temperature test performed after a presumptive MPN test to determine if the coliforms are of fecal origin

97

What is the colilert test?

a 24 hour test that detects total coliforms and e-coli

a yellow color change indicates a positive

98

How does aerating water a form of treatment? What are the tree methods?

By oxygenating the water the organic matter will precipitate out

cascade - water falls
blowers - air is blown into water (bubbles)
jet nozzles - water is sprayed into the air

99

What treatment is often used to remove odors in water?

activated charcoal process

100

What are two chemicals that are often added to coagulated/flocculate the water

aluminum sulfate (alum)

poly-electrolites (Polymers)

101

How does flocculation/coagulation help in water treatment process

by coagulating organic and inorganic solids and helping them fall to the bottom and get disposed of as sludge

102

What is the purpose of a sedimentation tank?

for water to travel slowly through it to allow particle matter to gravitate down and settle out

103

how does sedimentation work in a vertical tank?

water flows in through bottom and its motion is slowed down by a baffle. particulates settle down and cleaner water flows out the top.

104

how does sedimentation work in a horizontal tank?

the water enters from one side and exits the other. the tank bottom is continuously cleaned for settling solids.

105

What are some problems with sand filters in water treatment processes?

Alum should not go through filters in high concentration. so alum for flocculation processes should be removed before filtration

106

What are mud balls?

clumping of dirt on filter media. filters must be backwashed to prevent.

107

three types of chlorine, and their concentrations

liquid NaOCL 5-15 %
calcium hypochlorite is the dry form 70% available chlorine
chlorine gas can yield 100% available chlorine

108

What is breakpoint chlorination?

adding enough chlorine so that it doesn't all get used up and there is a residual left

109

What are chloramines?

a byproduct when organic material is broken down with chlorine ammonia.

strong smell
undesirable

110

in solution chlorine breaks down into ______ and ________ which is the stronger disinfectant and thus chlorine works better when the pH is _____________

hypochlorite ion and hypochlorite acid (better)
lower pH

111

most municipal water system require a chlorine residual of_______ mg/l

.2 mg/l

112

what are some other types of water disinfection

ozone (expensive, no residual)
iodine (affects color, taste, odor)
UV light (required shallow water and longer duration)
boiling (the best method)

113

What are two tests that can be used to detect chlorine levels

OT orthotoludene test (ortho test) older test sensitive to heat

DPD N-N-diethyl Phenylene Diamine more accurate

114

What are the four methods commonly used to remove dissolved solids from water?

distillation
electrodialysis
ion exchange (water softening)
reverse osmosis

115

water distillation

most expensive and time consuming
gives the purest form of water
water is boiled and vaporized steam is condensed

doesn't taste good since there are NO minerals at all

116

electrodialysis of water

positive charge causes dissolved ions to leave the water

117

reverse osmosis of water

moves lower concentration of dissolved solids to a higher concentration

most effective

118

What is a cross connection

any connection or arrangement, physical or otherwise, between a potable water supply system and any plumbing fixture through which it may be possible for non-potable contaminated water to enter any part of the potable water system

119

What is an air gap

the physical separation of a drain pipe and a drain.

prevents backflow or negative pressure

120

an air gap should be _____ times the diameter of a pipe or a minimum of _____

two times the diameter
minimum 1 ''

121

How does an atmospheric vacuum breaker work

backflow pressure releases atmospheric pressure thus shutting a valve and preventing backflow

common on toilet tanks and food facility sinks fauces

122

What is the safest type of drinking fountain

a diagonal jet with a guard.

123

how does a hose bib vacuum breaker work

there is a ball cock inside the hose bib connection. when flow reverses (back pressure) the ball backs up inside the bib preventing flow.

124

where would one install a pressure type vacuum breaker?

above the usage point

125

Where is a reduced pressure backflow prevention usually used?

at commercial water mains. must be certified and checked annually

126

What is a flushometer valve?

usually used in toilet tanks.

127

What is a double check valve

has to spring or ball valves incase one fails

128

What is back siphonage

a form of backflow when the pressure in the potable water supply drops below the pressure in the flow of contaminated water

129

Name 4 organic water contaminants

trihalomethanes (THM)
1, 2-dibromo-3-chloropropane (DBCP)
Trichloroethylene (TCE)
Perchloroethylene (PCE)
Carbon Tetrachloride

130

THM

Trihalomethanes
an organic contaminant
formed during chlorination
potential carcinogen
10 different types

131

DBCP

1,2-dibromo, 3-chloropropane
organic contaminant
pesticide used to control nematode parasites
strong carcinogen
sterility problems

132

TCE

Trichloroethylene
organic contaminant
solvent/degreasing agent used in past
carcinogen

133

PCE

Perchloroethylene
organic contaminant
solvent
carcinogen

134

Carbon Tetrachloride

an organic contaminant
used to manufacture chlorofluoromethanes (CFC for refrigeration)
carcinogen
skin cancer

135

What is a public water system

piped water for human consumption that has at least 15 service connections, or regularly services an average of at least 25 individuals at least 60 days out of the year

136

When was the safe drinking water act established?

1974

137

What does VOC stand for

volatile organic chemicals

138

What does SOC stand for

synthetic organic chemicals

139

what are three methods used for coliform testing

colilert
multiple tube fermentation
plate count

140

what is the most common water disinfectant

chlorine

141

three water treatment processes that are normally linked together are ...

coagulation/flocculation
sedimentation
filtration

142

______ is required for surface water treatment to insure that no pathogens end up in the water supply

filtration

143

what are the most common types of filters used in potable water treatment

granular media filters

144

which type of well is least likely to become contaminated

drilled
bored
driven
dug

drilled

145

diatomaceous earth filters

a. should be supplemented by a chlorination system
b. should be integrated into a rapid sand filtration system.
c. can be used for public water treatment systems
d. can be used in public sewer treatment systems.

a. should be supplemented by a chlorination system

146

microbial pollution travels only a short distance through:

sandstone
smooth clay
fissured rock
limestone

smooth clay

147

what type of filter is recommended for use in small communities and rural places?

DE
granular
cartridge
slow sand

slow sand

148

all of the following are used to disinfect water except:

chlorine
bromine
fluorine
iodine

fluorine

149

backsiphonage may be prevented by all of the following methods except:

hydrostatic loops
vacuum breakers
air gap separation
backpressure units

hydrostatic loops

150

which of the following is the least effective method for cadmium removal from drinking water:

activated carbon
iron coagulation
lime softening
ion exchange

activated carbon

151

before a drinking water sample is taken, the sampling tap should be clean, free of leaks, and flushed for how long?

1-1.5 mins
2-3 mins
4-5 mins
6-7 mins

2-3 minutes

152

what contaminant has been associated with learning and cognitive disorders in children who drink contaminated water?

manganese
copper
lead
parathion

lead

153

What is EDTA used for

to dissolve limescale in water

154

new pipes or wells must be chlorinated with ____ to ____ mg/l for ____ to _____ hours and then flush out until acceptable level is achieved

50 to 100
12 to 24 horus