Lecture 14 - Microbiology of the built environment

Question 1

in microbial leeching, what is dumped in a large pile?

Answer 1

low-grade ore

Question 2

what is added to the large pile of low-grade ore?

Answer 2

dilute sulfuric acid (pH2)

Question 3

what happens to the liquid emerging from the bottom of the pile?

Answer 3

its enriched in dissolved metals and transported to a precipitation pond

Question 4

what is critical in the oxidation pond and for what?

Answer 4

the bacterial oxidation of ferrous ion to ferric ion because Fe3+ is used to oxidize other metals in the ores

Question 5

what does uranium leeching depend on?

Answer 5

the oxidation of U4+ to U6+ by Fe3+ with acidithiobacillus ferrooxidans redoxidizing Fe2+ to Fe3+

Question 6

true / false
U6+ in the form or uranyl sulfate (UO2SO4) is highly soluble and can be concentrated

Answer 6

true

Question 7

what is gold leeching

Answer 7

gold deposited with minerals containing arsenic and FeS2

Question 8

what leeches the aresenic and pyrite

Answer 8

acidithiobacillus ferrooxidans and related bacteria

Question 9

what happens to gold in gold leeching?

Answer 9

it is complexed with cyanide

Question 10

what is responsible for environmental damage?

Answer 10

microbial leeching

Question 11

what are coal and minerals rich in

Answer 11

sulfides

Question 12

what does the oxidation of metal sulfide result in?

Answer 12

acidic conditions

Question 13

what is acid mine drainage?

Answer 13

an environmental problem in coal-mining regions

Question 14

how does acid mine drainage occur?

Answer 14

occurs when acid mine waters are mixed with natural waters and the lakes pH can drop <1

Question 15

what is the problem with acid mine drainage?

Answer 15

it degrades water quality because both the acid and the dissolved metals are toxic to aquatic environments

Question 16

bioremediation of uranium-contaminated environments

Answer 16

where uranium has been processed or stored, groundwater can be contaminated with uranium

Question 17

what can happen to the uranium in the groundwater

Answer 17

some bacteria can convert U6+ to U4+, U6+ is water soluble, U4+ is not, uranium is contained not removed

Question 18

what can happen to organic polluants over time?

Answer 18

they can be converted to CO2 by microbes

Question 19

what organisms can oxidize petroleum products aerobically?

Answer 19

fungi, bacteria, cyanobacteria, green algea

Question 20

what are potential habitats for hydrocarbon-oxidizing microbes?

Answer 20

gasoline and crude oil storage tanks

Question 21

what happens if there is sufficent sulfate present in the oil?

Answer 21

sulfate-reducing bacteria can grow and consume hydrocarbons while in the tank

Question 22

what are xenobiotic compounds?

Answer 22

synthetic chemicals that are not naturally occuring

Question 23

why do xenobiotic compounds degrade extremely slowly?

Answer 23

organisms lack the enzymes to recognize these compounds

Question 24

what is wastewater?

Answer 24

domestic sewage or liquid industrial waste

Question 24

true / false polyethylene terephthalate is the only petroleum-based plastic that can be extensively degraded by microorganisms

Answer 24

true

Question 25

what is gray water?

Answer 25

water resulting from washing,bathing,cooking

Question 26

what is sewage?

Answer 26

water contaminated with human and animal fecal material

Question 27

what is the main goal of wasterwater treatment?

Answer 27

to reduce organic and inorganic materials to a level that no longer supports microbial growth and to eliminate potentially toxic materials

Question 28

what is primary treatment?

Answer 28

seperation of solid and particulate organic and inorganic materials from wastewater

Question 29

what does aerobic secondary treatment use?

Answer 29

digestive reactions carried out by microbes under aerobic conditions to treat wastewater with low levels of organic materials

Question 30

what is activated sludge?

Answer 30

microorganisms in the aeration tank are responsible for oxidative degradation of the organic components of the wastewater

Question 31

steps in involved in water purification

Answer 31

1. sedimentation to remove particles 2. coagulation and flocculation to form additional aggregates for sedimentation 3. filtration 4. disinfection - typically chlorine gas or UV irradiation

Question 31

what is tertiary treatment?

Answer 31

any physiochemical or biological treatment processes for further processing of secondary treatment effluent

Question 31

what happens in secondary anaerobic treatment

Answer 31

a series of digestive and fermentative reactions carried out by various microbes under anoxic conditions in large enclosed tanks (sludge digestors or bioreactors)

Question 32

how can microorganisms accelerate corrosion of metals?

Answer 32

1. changing pH 2. changing redox 3. production of corrosive metabolites 4. production of corrosive microenvironments (biofilms)

Question 33

what are some bacteria implication in metals corrosion?

Answer 33

sulfate-reducing bacteria ferric-ion-reducing bacteria ferrous-ion-oxidizing bacteria methanogens