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sewage waste treatment Flashcards

1
Q

what is sewage?

A

waste water from communities, industries and commercial institutions which contain human solid and liquid excretion as well as waste water from various sources

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2
Q

what is sullage?

A

waste water that does not contain any human excreta, and is generally derived from domestic activities

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3
Q

what are environmental problems due to sewage?

A

1- contamination of food
2- nuisance
3- unpleasant odor
4-breeding of flies and mosquitoes
5-pollution of soil
6- pollution of water supply
7- increase in incidence of disease

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4
Q

what are disease that are transmitted through soil called?

A

helminthic disease

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5
Q

what is a disease caused due to contamination of food?

A

typhoid fever/ enteric fever

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6
Q

what are the constituents of waste water

A

99.9% water
0.1% inorganic and organic solids in solution or suspended

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7
Q

what type of solid in waste water causes odor?

A

organic solids

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8
Q

outline the recycling of water

A

grey water- used water without toxic chemicals/excrement and can be re-used

blackwater- contaminated water with toxic chemicals/excrement

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9
Q

what are the goals of waste water treatment?

A

produce effluent
produce sludge
discharge or reuse effluent

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10
Q

what are the stages of water treatment and outline them?

A

1-primary
- solids are separated
2-secondary
-dissolved matter is converted into solid mass via use of bacteria
3-tertiary
-biological solid are neutralized and disposed
- treated water disinfected chemically or physically

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11
Q

what are the types of treatments?

A

1-mechanical treatments
2-biological treatment
3-chemical treatment

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12
Q

what are the types of mechanical treatment?

A

1- remove of large object
2-removal of sand and grit
3- primary sedimentation
4-influent:waste water flowing into reservoir, treatment plant

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13
Q

what are the types of biological treatment?

A

1- trickling bed filter
2- activated sludge

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14
Q

what are the types of chemical treatment?

A

disinfection

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15
Q

what are the preliminary treatment

A

1- removing any waste water constituent which could clog up equipment
2- raked screen: screens the water
3-remove large objects

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16
Q

what are the types of primary treatment stage?

A

1-sand catcher
2- sedimentation tank

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17
Q

what are the advantages and disadvantages of sand catcher?

A

advantages
- remove sand and grit
- controls wastewater velocity
* suspended organic matter kept in water
*sand grit and stone settle

disadvantages
-landfills
-damage equipment’s in the remaining treatment stage

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18
Q

describe sedimentation tank

A

1-remove grease and oils
2-settles fecal matter to the bottom, where it is pumped to sludge treatment plant
3-produces homologues liquid for later biological treatment

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19
Q

type of material removed during primary treatment stages

A

1- fats,oil,grease
2- sand,gravels and rocks
3-floating materials
4- large solid able to settle

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20
Q

what is secondary treatment?

A

process on dissolved organic matter

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21
Q

what are the types of secondary treatment?

A

1- fixed film system
2-lagoon system
3- suspended film system

22
Q

what is fixed film system?

A

growing microorganism on substrate medium such as rocks, plastic and gel which forms a thick slime layer, and waste water is spread over the substrate

23
Q

what are examples of fixed film system?

A

1-trickling filter
2- rotating biological contactors

24
Q

explain how a trickling filter works

A

waste water is poured onto a medium having slime like layer of microorganism, this medium is contained in a coke/limestone material

25
Q

what is a lagoon system?

A

holds the waste water for several months, allowing natural degradation of sewage and contains reed, a particular type of grass plant

26
Q

what is a suspended film system?

A

stir and suspend microorganism in waste water, and settle out as sludge

27
Q

what is activated sludge?

A

mixed community of microorganism, both anerobic and aerobic may exist, forming a biological floc which is a large mass of bacteria in a mesh like structure

28
Q

what is a feature of primary and secondary sludge?

A

primary sludge: strong odor
secondary: high concentration of microorganism

29
Q

what are the goals of sludge treatment?

A

1- reduce odor 2-remove water 3-decompose organic matter

30
Q

how much water does untreated sludge contain?

A

97% water

31
Q

how much water does the treated sludge contain?

A

water reduced by 97-96% and the dried sludge is known as sludge cake

32
Q

what are the components of activated sludge process?

A

1- aeration tank
2- aeration source
3-secondary clarifiers
4- activated sludge outflow line
5- effluent outflow line

33
Q

what is aeration tank?

A

oxygen introduced into system

34
Q

what is aeration source?

A

provides pure oxygen or compressed air and makes sure an adequate amount of oxygen is delivered

35
Q

what is secondary clarifiers?

A

activated sludge solid separated from surrounding waste water

36
Q

what is activated sludge outflow line?

A

activated sludge pumped into aeration tank again

37
Q

what is effluent outflow line?

A

discharge effluent into sea/river or tertiary treatment plant

38
Q

what are the types of sludge treatment?

A

aerobic digestion
anaerobic digestion
composting

39
Q

what does aerobic digestion produce?

A

CO2

40
Q

what does anaerobic digestion produce?

A

biogas used in electricity production

41
Q

outline composting

A

type of aerobic process, where carbon, nitrogen, oxygen, water and sludge are mixed and produces a lot of heat

42
Q

what occurs in sludge disposal?

A

1- sludge cake is spread out in fields
2-sludge is heated and converted into small granules rich in N2, which act as fertilizer
*all this saves landfill space

43
Q

what are the types of tertiary treatment?

A

chlorination
uv light radiation
ozonation

44
Q

advantages and disadvantages of chlorination

A

advantages
- low cost
-effective

advantages
- chlorine residue could be harmful to the environment

45
Q

advantages and disadvantages of UV light radiation

A

advantages
- damages genetic structure of microorganism
- water taste more natural
- no chemicals used

disadvantages
-high maintenance of UV light

46
Q

advantages and disadvantages of ozonation

A

advantages
- safer than chlorination
- fewer by products of disinfection

disadvantages
- expensive

47
Q

what is the use of effluent?

A

1- discharged into rivers, lagoon and bay
2- irrigation of parks, golf course,etc
3- ground water recharged: surface water moves underground

48
Q

what are the advanced treatments?

A

1- nitrogen removal
2- phosphorus removal

49
Q

describe nitrogen removal

A

ammonia—nitrite—nitrate

50
Q

describe phosphorus removal

A

precipitation with iron or aluminum salt

51
Q

what do the advanced treatments cause?

A

eutrophication and algae blooms

Environmental (5 decks)

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