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Water quality and public health Flashcards

1
Q

Water

A

The most important potential common source of infectious diseases
-ensuring water purity for public health

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2
Q

What schemes use microorganisms to identify, remove, degrade

A

Treatment and purfication

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3
Q

Water can be sampled for the presence of

A

specific indicator mircoorganisms

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4
Q

Coliform group includes

A

Enterobacter, e.coli, klebsiella pneumonia

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5
Q

what is used for indicator for contamination in water?

A

ooliform microbes

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6
Q

What reduces incidence of water borne diseases and when did it take placfe

A

water treatment

twntieth century

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7
Q

what methods were used and adapted in 1905?
What was treatment limited to?
in 1910, what was used as a disinfectant in water

A

coliform-counting methods
treatment limited to filtration
chlorine

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8
Q

Name steps of purification

A

sedimentation- remove particles
coagulation and flocculation- form aggregates to settle out
filtration- remove parasites, charcoal to remove taste, odor, chemicals

disinfection- residual

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9
Q

understand drinking treatment plan

A

Coagulants such as anionic polymers and alum are added
Many of microbes and cysts removed during this process
Filtration removes rest of protozoan cysts
Chemical/UV disinfection kills viruses and unfiltered bacteria

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10
Q

? historically most common drinking water disinfectant

A

chlornation
Chlorine gas or sodium hypochlorite (bleach)▪Kills bacterial and viral pathogens
▪Ineffective against Cryptosporidium, not very effective against Giardia

▪Oxidizes taste and smell compounds

▪Must leave residual, after it has reacted with organic matter (0.6 ppm)▪

Can produce disinfection by products

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11
Q

? used in some places, does not leave residual

A

UV
It is effective against Cryptosporidium and Giardiacysts (text is wrong)
▪Being promoted for lack of disinfection by-products and chemical addition
▪Requires highly clear water for maximum effectiveness
▪Suspended solids quickly reduce effectiveness
▪Pretty

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12
Q

Ozone

A

also used in some places, does not leave residual

▪Works as an oxidizer, gasgenerated on site

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13
Q

Wastewater treatment is a

A

multistep operation employing both physical and biological processes

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14
Q

Major goal of wastewater treatment is to

A

reduce nutrients or biochemical oxygen demand

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15
Q

Primary, secondary, and sometimes tertiary treatments are used explain primary

A

Uses physical separation methods to separate solid and particulate organic and inorganic materials from wastewater
▪Still many pathogens and high nutrient load
Primary methods remove much of suspended solids

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16
Q

Secondary Methods

A

degrade or remove “food” (organics) and more suspended solids

Goal is to break down solid and dissolved organic matter, reduce organic nutrient load –Biological processes
▪(Reduce BOD, N and P nutrients)
▪Most treatment plants chlorinate the effluent after secondary treatment to further reduce the possibility of pathogen contamination

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17
Q

Tertiary Treatment or AKA

A

Advanced Wastewater Treatment

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18
Q

Tertiary Treatment

A

Any physiochemical or biological process employing bioreactors, precipitation, filtration, or chlorination procedures similar to those used for purification of drinking water▪Reduces the levels of inorganic nutrients further (e.g., phosphate, nitrate, nitrite)▪Most complete method of treating sewage but it has not been widely adopted due to costs

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19
Q

Sterilization

A

The killing or removal of all viable organisms within a growth medium

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20
Q

Inhibition

A

Effectively limiting microbial growth

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21
Q

Decontamination

A

The treatment of an object to make it safe to handle

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22
Q

Disinfection

A

Directly targets the removal of all pathogens, not necessarily all microbes or endospores

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23
Q

Heat sterilization

A

is the most widely used method of controlling microbial growth

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24
Q

High temperatures

A

denature macromolecules

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25
decimal reduction time
Amount of time required to reduce viability tenfold is called the
26
Can survive heat that would rapidly kill vegetative cells
ednospores
27
▪Pasteurization
s the process of using precisely controlled heat to reducethe microbial load in heat-sensitive liquids: heat, then rapidly cool▪Doesn’t kill all organisms so it is different than sterilization
28
autoclave is a sealed heating device that uses
steam under pressure ▪Allows temperature of water to get above 100°C ▪Not the pressure in an autoclave that kills things, but the high temperature
29
? can all reduce microbial growth
Microwaves, UV, X-rays, gamma rays, and electrons
30
UV
has sufficient energy to cause modifications and breaks in DNA▪UV is useful in decontamination of surfaces▪Cannot penetrate solid, opaque, or light-absorbing surfaces
31
Ionizing Radiation
Electromagnetic radiation of sufficient energy to produce ions and other reactive molecular species▪Generates electrons, hydroxyl radicals, and hydride radicals
32
Some microbes are
more resistant to radiation than others
33
Microbes tend to be more
tend to be moreorganisms
34
Sources of radiation include
cathode ray tubes, X-rays, and radioactive nuclides
35
Radiation
is used for sterilization in the medical field and food industry
36
Radiation is approved by the WHO and is
Used in the USA for decontamination of foods particularly susceptible to microbial contamination
37
Susceptibility to food spoilage is based in large part on
moisture content
38
Perishable foods have higher
moisture content than nonperishable foods
39
Fresh foods are spoiled by both
bacteria and fungi Spoilage organisms are those that can gain access to the food and use available nutrients▪May or may not be pathogenic (usually not)▪Carried on raw foods (vegetables, etc) or introduced by consumer, or during processing, etc.
40
Cold food
Slows microbial growth rate and delays spoilage ▪Psychrotolerant bacteria and fungi can grow at refrigerator temperatures ▪Freezing allows for longer storage, but isn’t suitable for all foods
41
Pickling and acidic foods
pH is an important factor in microbial growth▪Most foods are neutral or acidic ▪At pH less than 5 most spoilage organisms are inhibited ▪During pickling process acetic acid is added to a solution with sugar or salt ▪Pickled foods include pickles, fish, peppers and fruits
42
Drying and Dehydration
``` Moisture content (water activity) is critical for microbial metabolic processes ▪Sugar and salt reduce the availability of water for microbial growth (in effect, dehydrating it) ``` ▪I.e., jams, jellies, meats, fish ▪Lyophilization(freeze-drying) is the physical removal of frozen water under vacuum▪Very expensive, but very effective
43
Heating/ canning
Used to reduce the bacterial load (i.e., pasteurization) of a product or to actually sterilize it (i.e., canning)▪Canning isn’t always 100% effective▪Results in swollen cans (DO NOT EAT!)
44
What significantly extends shelf life of finished?
Chemical Preservation ▪Various added chemicals may be used to control microbial growth▪I.e., sodium propionate, sodium benzoate, nitrites, etc. ▪Some, such as nitrites, are controversial because studies show they may be harmful to human health (cancer?)
45
Many commons foods are
preserved, produced, or enhanced by the actions of microbes
46
Fermentation is the anaerobic catabolism of organic compounds (generally carbohydrates), without
external electron acceptor
47
Important bacteria in the fermented food industry are
lactic acid bacteria, propionic acid bacteria, and acetic acid bacteria
48
Fermentation becomes ? when pH drops
self-limiting
49
Filtration avoids
he use of heat for sterilization of sensitive liquids and gasses
50
pore filtrs
Pores of filter are too small for organisms to pass through | ▪Pores are large enough to allow liquid or gas to pass through
51
HEPA filters
are depth filters
52
Membrane Filters
Function more like a sieve | ▪(i.e., Nucleopore filters)
53
Antimicrobial agents can be classified as
bacteriostatic, bacteriocidal, and bacteriolytic
54
Minimum inhibitory concentration (MIC)
is the smallest amount of an agent needed to inhibit growth of a microbe
55
Disk diffusion assay
Zone of inhibition: diameter depends on conc., solubility, diffusion into cell, and effectiveness of agent
56
These antimicrobial agents can be divided into two categories
Products used to control microorganisms in commercial and industrial applications, largely to prevent fouling or spoilage▪E.g., air-conditioning cooling towers, textile and paper products, fuel tanks ▪Products designed to prevent growth of human pathogens in inanimate environments and on external body surfaces▪Sterilants, disinfectants, sanitizers,and antiseptics
57
Sterilant:
destroys all forms of microbial life (sterilizes)▪Gases →ethylene oxide, formaldehyde, H2O2; liquid like sodium hypochlorite
58
Disinfectant
kill microorganisms, maybe not spores | ▪Ethanol, detergents; used for decontamination of surfaces
59
Sanitizer:
Reduce microbial numbers; detergents, Lysol, ethanol
60
Antiseptic:
non-toxic enough to use on tissue; ethanol, triclosan, listerine, benzalkonium chloride, hydrogen peroxide dilute solution ▪Handwashing, wounds, oral care, etc. ▪Triclosan issues, phasing out for benzalkonium chloride instead
61
Paul Ehrlich initially began studying
selective toxicityin the early 1900s
62
Selective toxicity is
the ability to inhabit or kill a pathogen without harming the host, or with limited side effects
63
Salvarsan
one of the first effective antimicrobial drugs; a dye containing arsenic, used against syphilis
64
Growth factor analogs:
structurally similar to growth factors but don’t function in cell ▪Analogs known for many important biomolecules i.e. vitamins, amino acids, etc.
65
Sulfanilamide
Inhibits folic acid synthesis
66
Sulfa drugs:
Gerhard Domagk in the 1930s
67
Nucleic acid base analogs:
used against viral and fungal infections.
68
Nucleic acid base analogs formed by
Formed by the addition of bromine or fluorine

Microbiology (12 decks)

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