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BI374 Final > Wastewater treatment > Flashcards

Wastewater treatment Flashcards

1
Q

Need to consider treatment to remove pathogens both entering ( ___ _____) and leaving ( ____ ____ ____) the watershed

A
  • from wastewater
  • for drinking water
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2
Q

What is the law on returning water?

A
  • must return to the source it came from
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3
Q

What is portable water?

A
  • safe to drink
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4
Q

Is tap water sterile?

A

No

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5
Q

How does the shower expose you to possible contaminants?

A
  • diffuses and aerosolizes water
  • can inhale and are exposed dermally
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6
Q

What is used to remove organic matter from domestic/industrial effluent?

A
  • microorganisms
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7
Q

What is domestic waste made up of?

A
  • gray water and wastewater from food processing
    –> everything but sewage
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8
Q

Where does sewage go?

A
  • septic system
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9
Q

Where does sewage go?

A
  • septic system
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10
Q

What does opportunistic mean?

A
  • pathogenic potential but not a pathogen
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11
Q

What does BOD stand for? What is it?

A
  • biochemical oxygen demand
  • measure of amount of dissolved oxygen consumed by microorganisms for oxidation of organic and inorganic matter
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12
Q

Why does BOD need to be reduced?

A
  • heavy organic material has high demand for degradation
  • releasing it increases demand in receiving water depriving it of oxygen
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13
Q

What does low available oxygen cause?

A
  • low aquatic life
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14
Q

What is used to lower BOD

A

microorganisms

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15
Q

What is the difference in sizing of pipes from toilet vs sink?

A
  • toilet large diameter
  • sink small diameter
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16
Q

How do some microorganisms reduce toxicity of poisonous substances (ex. cyanide/heavy metals)?

A
  • oxidation, precipitation or volatilization
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17
Q

contaminant levels should be low enough to be capable of ____ ______ after discharge into flowing, well-aerated surface water

A
  • self purification
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18
Q

What is self-purification?

A
  • capacity to finish clean up
  • natural process of purifying (ability of body of water to rid self of pollutants)
    –> contaminant level must be low enough that when discharged the body of water can clean on its own
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19
Q

What is the best form of self-purification?

A
  • dilution - decreases levels of what is coming in and increases degradation
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20
Q

What are the levels of wastewater treatment? What does this include?

A
  • primary
  • secondary
  • tertiary
  • physical and biological removal
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21
Q

What is physical removal?

A
  • filtration, physically pulling it out/depositing
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22
Q

What is biological removal?

A
  • degradation
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23
Q

What is chemical removal?

A
  • addition of compound that reacts
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24
Q

What are the steps of primary treatment?

A
  • physical separation where large floating material is screened out
  • water flows through setting chambers (sand/grit removed, suspended solids sediment out)
  • sewage solids collected
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25
Q

What is primary sludge?

A
  • sewage solids
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26
Q

What removes oil and grease from water?

A
  • skimmers
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27
Q

What is a biosolid? What happens to it?

A
  • pulls out easy stuff (toilet paper/feces)
  • left to sit and compost or transported
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28
Q

Explain setting chambers and give an example

A
  • water sits to separate
  • ex. salt in water not dissolved settles at bottom
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29
Q

Why is secondary treatment used?

A

to reduce organic load of sewage to an acceptable level

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30
Q

biological treatment procedures can be _____ or _____

A
  • Anoxic
  • anaerobic
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31
Q

What is used to measure the efficiency of secondary treatment process?

A
  • biochemical oxygen demand
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32
Q

What is removed before secondary removal?

A
  • as much as possible
  • biofilm, bacteria and microbial masses
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33
Q

What is the goal moving to secondary treatment?

A
  • having cleaner water
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34
Q

What is the goal of secondary treatment?

A
  • reduce organic material (biological removal)
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35
Q

What is anoxic secondary treatment?

A
  • series of digestive/fermentative reactions carried out by many different bacterial species
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36
Q

What is anoxic treatment carried out in?

A
  • sludge digestors or bioreactors designed to support growth of anaerobic bacteria
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37
Q

What is an example of an anaerobic bacteria?

A
  • methane-producing bacteria
38
Q

What are the major products of anoxic treatment?

A
  • methane and CO2
39
Q

What needs to be considered in anoxic treatment?

A
  • amount of space and equipment needed ESP W OXYGEN
40
Q

What are digestive reactions?

A
  • gases generated (carbon cycle under anoxic conditions)
  • methane generated used as energy
  • bacteria do the work
41
Q

What is aerobic secondary treatment?

A
  • trickling filter and activated sludge systems
42
Q

What is a trickling filter?

A

wastewater sprayed onto bed of crushed rock; organic matter oxidized and adheres and microbial growth takes place (looks after itself)

43
Q

What does trickling filter cause?

A
  • mineralization of organic material to CO2, ammonia, nitrate, sulfate and phosphate
44
Q

Why can’t trickling filter be used in the city?

A
  • need massive spaces and need to make sure nothing is added/aerosolization occurs
45
Q

What is mineralization?

A
  • broken down into minerals (basic)
46
Q

Give an example of anoxic and aerobic treatment

A
  • Anoxic - sludge digestor, activated by injection of oxygen
  • anaerobic - trickling filter
47
Q

What are activated sludge systems?

A
  • wastewater is mixed and aerated in a large tank
48
Q

What is a slime flock?

A
  • suspended solid (bacteria, yeasts and molds) form mixture and are pumped into a clarifier
  • want bacteria to adhere
  • degrades, encourages breakdown
  • flocks drop and settle
49
Q

What is a clarifier?

A
  • holding tank
50
Q

What are flocs transferred to once they occur?

A
  • anaerobic digestor
51
Q

What do flocs go through first? What does this do?

A

activated aerated systems (activated sludge)
- rid easy stuff (more bacteria available to breakdown)

52
Q

What is tertiary treatment?

A
  • uses physical-chemical processes of precipitation, filtration and chlorination to reduce levels of inorganic nutrients
53
Q

What inorganic nutrients does tertiary treatment reduce?

A
  • phosphate and nitrate
54
Q

Where does water go after tertiary treatment?

A
  • river
55
Q

What is ozone?

A

-O3
- highly reactive

56
Q

What does water treatment focus on?

A
  • “portable” water free of disease-producing microorganisms and chemical substances harmful to public health
57
Q

What does water treatment attempt to decrease?

A
  • turbidity
  • taste and odour
58
Q

What is used to decrease turbidity taste and odour

A
  • Nuisance chemicals (Fe)
59
Q

What does salmonella in water cause?

A
  • typhoid
60
Q

What does removing particles do? why?

A
  • removes bacteria because they are attached
61
Q

What are the 3 main stages in drinking water treatment process?

A
  • sedimentation
  • filtration
  • disinfection
62
Q

What is coagulation?

A
  • liquid changing states to solid/semisolid
63
Q

What is sedimentation?

A
  • large reservoirs during holding period to remove sand, gravel and other large particles
64
Q

What is flocculation?

A
  • addition of aluminum sulfate
  • grabs suspended parts and clumps together to remove bacteria and organic material
65
Q

What does addition of alum aid in?

A
  • formation of flocculent insoluble precipitate and absorbs organic matter and sediment material
66
Q

approximately 80% of ____, ____ and _____ is removed during sedimentation stage.

A
  • bacteria
  • colour
  • turbidity
67
Q

What happens during filtration?

A
  • large sand filters, dual or tri-media filters for municipal treatment (periodic backwashing)
  • suspended particles and microorganisms removed
68
Q

Why is filtration important in the removal of cysts or oocysts?

A
  • resting and designed to hang to mammalian gut to complete life cycle
  • TOLERANT TO CHLORINE IN DISINFECTION (MUST BE FILTERED)
69
Q

What % of microorganisms are removed after filtration?

A
  • 89-99.5%
70
Q

What is filtration important in?

A
  • removal of cysts/oocysts as they are tolerant to chlorine
71
Q

What forms oocysts? What forms cysts?

A
  • cryptosporidium (hidden spore)
  • Giardia
72
Q

What do tri-media filters use?

A
  • carbon
  • anthracite
  • sand
73
Q

What is disinfection used for?

A
  • used primarily to ensure protection against post-treatment contamination (chlorine reacts with everything but consumed by organic material)
74
Q

Why would disinfection be used prior to filtration?

A
  • reduces biological growth in filter columns
75
Q

What are the common chemical oxidizing agents in filtration?

A
  • sodium or calcium hypochlorite
76
Q

What is the use of UV lamps?

A
  • final step of sterilization
77
Q

What is filtration important in?

A
  • removal of cysts/oocysts as they are tolerant to chlorine
78
Q

What is chlorine demand? What is it also referred to as?

A
  • amount of chlorine that reacts with organic matter, reduced ions and microorganisms
  • break-point chlorination
79
Q

What is break-point chlorination?

A
  • consume everything that must be consumed
80
Q

What is residual chlorine?

A
  • “free” chlorine after microorganisms and organic matter have been treated to “break-point”
81
Q

total chlorine added = _______ + ________

A

chlorine demand + residual

82
Q

What is the most common source of infection?

A
  • water
83
Q

What is HPC?

A
  • heterotrophic plate count (total coliforms)
  • indicates water quality is hazardous
84
Q

What is an indicator organism?

A
  • associated with intestinal tract, presence indicates fecal contamination of water supply
  • ex. coliform bacteria
85
Q

What is the operational definition of coliforms?

A
  • aerobic and facultatively anaerobic gram-negative, non-spore forming bacteria that ferment lactose with gas formation
86
Q

What is an example of a coliform bacteria?

A
  • E. coli
87
Q

What are the criteria for indicators?

A
  • must be around when suspect organisms are around (associated with polluted water)
  • must be stronger than harmful pathogens (live longer)
  • must have high enough numbers to detect
88
Q

What is the most desirable characteristic in indicator organisms?

A
  • if it reflects both human and animal fecal pollution
89
Q

What are the two procedures used to detect and enumerate coliform bacteria?

A
  • MPN (most probable number
  • MF (membrane filter)
90
Q

What happens during MPN and MF

A
  • water sample filtered onto membrane and placed in a culture medium
  • grey is positive

BI374 Final (12 decks)

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