Drinking Water Part 2

Question 0

What health effects are associated with microbes in drinking water?

Answer 0

gastroenteritis, death in immunocompromised

Question 1

What contaminants are regulated under the EPA Safe Water Act?

Answer 1

Microbes, radionuclides, inorganics, volatile organics, synthetic organics, disinfectants, disinfection by products

Question 2

What standard exists for microbes in drinking water?

Answer 2

No standard, instead specifies a treatment technique (e.g., removal of 99.99% of microbe)

Question 3

What are the three groups of biological pollutants in drinking water?

Answer 3

bacteria, parasites, viruses

Question 4

List 6 examples of viruses.

Answer 4

rotavirus, human caliciviruses, hepatitis A virus, adenovirus 40 & 41, astrovirus, enteroviruses

Question 5

List 6 types of bacteria.

Answer 5

Escherichia, Salmonella, Yersinia, Campylocabacter, Vibrio, Clostridium

Question 6

What are 5 examples of parasites?

Answer 6

Giardia, Cryptosporidium, Microsporidia, Cyclospora, Toxplasma gondii

Question 7

What is an example of a radionuclide and why are they bad?

Answer 7

Radon; increases cancer risk

Question 8

What are examples of inorganic chemicals?

Answer 8

Arsenic, cadmium, lead, nitrate/nitrite

Question 9

What are examples of synthetic organics?

Answer 9

Dioxin, pesticides, Di(2-ethylhexyl) phthalate (DEHP)

Question 10

What are examples of volatile organics?

Answer 10

Benzene, toluene, trichloroethylene

Question 11

What are disinfectants?

Answer 11

Water additives used to control microbes

Question 12

Why do disinfectants have maximum residual levels?

Answer 12

They can be harmful (eye/nose irritation, stomach discomfort, anemia)

Question 13

What are Disinfection Byproducts (DBPs)?

Answer 13

DBPs are formed when disinfectants used in H2O treatment plants react with bromide and/or natural organic matter present in the source water

Question 14

What are 3 examples of DBPs?

Answer 14

trihalomethanes, haloacetic acids, bromate

Question 15

Why are pharmaceuticals/personal care products a concern for drinking water?

Answer 15

They are ending up in the water supply and are not always removed (see video on Potomac River)

Question 16

What are the four stages of water treatment?

Answer 16

coagulation, floccuation/sedimentation, filtration, disinfection

Question 17

What is coagulation?

Answer 17

chemicals are added to water to create a coagulant

Question 18

What is flocculation?

Answer 18

further agglomeration of particles achieved by rapid mixing (particles removed, dissolved contaminants remain)

Question 19

What is sedimentation?

Answer 19

the water is allowed to undergo a period of quiescence, allowing the floc to settle to the bottom of the settling tank for removal and disposal

Question 20

What is filtration?

Answer 20

Settled water is further treated by filtration (rapid and filtration is common, also any backwash to clear filters must be discharged into sewage)

Question 21

What is disinfection?

Answer 21

removal of infectious material to a level such that disease cannot be detected, i.e. elimination of a pathogen that causes waterborne disease

Question 22

What factors affect disinfection?

Answer 22

disinfectant concentration, contact time, temperature, pH, encapsulation

Question 23

List the 3 biological contaminants in order of most to least resistant to disinfection.

Answer 23

Parasites, viruses, bacteria

Question 24

Describe the kinetics of disinfection.

Answer 24

- gradual process that involves a series of physical-chemical and biochemical steps - effectiveness is (C X t), c= disinfectant concentration, t=time required to inactivate certain % of population under set conditions - lower Ct value= more effective disinfectant

Question 25

What are the three types of water disinfectants?

Answer 25

Chlorine, ozone, and UV radiation

Question 26

What are the pros and cons of chlorine as a disinfectant?

Answer 26

Pros: cheap, good disinfectant, provides residual Cons: relatively unstable, forms DBPs that are possibly carcinogenic

Question 27

What are the pros and cons of ozone as a disinfectant?

Answer 27

pros: good disinfectant, limited DBP formation cons: no residual, expensive

Question 28

What are the pros and cons of UV radiation?

Answer 28

pros: effective on cryptosporidium, no DBPs, no storage problems cons: no residual, interference by solids and turbidity

Question 29

Why is a strong residual good for drinking water?

Answer 29

Provides protection from contamination later in the water distribution system

Question 30

What causes DBP formation?

Answer 30

DBPs are formed when Cl reacts with naturally occurring dissolved organic material in water

Question 31

What are the potential adverse health effects of DBPs?

Answer 31

adverse pregnancy outcomes (stillbirths, neonatal deaths), possible increased risk of birth defects, cancer

Question 32

Why is fluoride added to drinking water?

Answer 32

To reduce tooth decay/cavities

Question 33

Why is fluoridation controversial?

Answer 33

Young children with excessive fluoride intake can develop mottled tooth enamel, excessive consumption over a lifetime can increase skeletal fractures or cause skeletal fluorosis

Question 34

Which agency is responsible for regulating bottled water?

Answer 34

FDA

Question 35

What types of bottled water are available?

Answer 35

Artesian, fluoridated, ground, mineral, purified, sparkling, spring, sterile, well

Question 36

What is artesian well water?

Answer 36

from well that taps an aquifer; often more pure due to natural filtration

Question 37

What is mineral water?

Answer 37

water from underground source w/ at least 250 ppm dissolved solids from the source of the water (can't be added later)

Question 38

What is spring water?

Answer 38

drawn from underground formation from which water flows naturally to the earth's surface

Question 39

What is well water?

Answer 39

water from a hole bored or drilled into the ground, which taps into an aquifer

Question 40

Can bottled water be drawn from municipal sources (the tap)?

Answer 40

YES. It may undergo distillation, reverse osmosis, absolute 1 micron filtration, or ozoanation

Question 41

What is the environmental impact of bottled water?

Answer 41

producing the bottle uses 17 million barrels of oil a year, produces 2.5 million tons of CO2, it takes 3L of H2O to make 1L of bottled H2O, only 20% of plastic bottles are recycled