Water Flashcards
1
Q
Humans consume an average of __ to __ lbs of water per day
A
3 to 5 lbs per day
2
Q
The ocean contains nearly ______ % of all our water
A
97%
3
Q
The _____ powers the hydrological cycle
A
sun
4
Q
What is thermal stratification
A
the change in temperature of water at different depths in a body of water. it occurs because colder water is more dense.
5
Q
name the three sections of thermal stratification from top to bottom
A
epilimnion -upper layer
thermocline
hypolimnion - lower layer
6
Q
in winter what layers exist in thermal stratification?
A
ice exists above the water layer
7
Q
name the three ages of lakes
A
oligotrophic - young
mesotrophic - middle
eutrophic - old or mature lake
8
Q
a lake is considered “dead” when it has been depleted of _________
A
oxygen
9
Q
why are plants important to a lake?
A
because they provide oxygen
10
Q
What is eutrophication
A
a lake condition of algal blooms due to over enrichment of nutrients such as phosphates and nitrates.
can be natural or manmade
11
Q
if left untreated manmade eutrophication can result in a ______ lake because the algae depletes the ______
A
dead
oxygen
12
Q
What chemical can be used to control algae
A
copper sulfate CuSO4 can be used but in limited concentrations so it doesn’t kill fish and other aquatic life
13
Q
what two chemicals can be used to prevent evaporation from lakes
A
hexadecanol and octadecanol
they are non toxic
14
Q
so why don’t we convert ocean water into drinking water?
A
because it’s too costly due to the high salinity and minerals in the water
15
Q
what are some types of surface waters
A
spring
pond
swamp
stream
16
Q
what is an aquifer?
A
an underground layer of water with permeable rock or other materials through which a well can be drilled
17
Q
what is the water table
A
the area of the start of the zone of saturation
18
Q
What three things should be considered in the construction of the well
A
expensive
depth of water table
type of construction
19
Q
why do higher water tables have less potable water?
A
because the water did not have enough time to naturally filtrate through the soil
20
Q
What are the 3 types of wells
A
case driven well
bored well
dug well
21
Q
case driven well
A
best quality
bottom of casing is perforated to allow water in
used with a submergible pump that is lowered into the water source
22
Q
bored well
A
an auger is used to drill into the earth
23
Q
dug well
A
manual dug by man or machine. lined with concrete, bricks, tile or clay pipes.
not deep
24
Q
what is a rainwater cistern
A
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
