sewage waste treatment Flashcards
what is sewage?
waste water from communities, industries and commercial institutions which contain human solid and liquid excretion as well as waste water from various sources
what is sullage?
waste water that does not contain any human excreta, and is generally derived from domestic activities
what are environmental problems due to sewage?
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
what are disease that are transmitted through soil called?
helminthic disease
what is a disease caused due to contamination of food?
typhoid fever/ enteric fever
what are the constituents of waste water
99.9% water
0.1% inorganic and organic solids in solution or suspended
what type of solid in waste water causes odor?
organic solids
outline the recycling of water
grey water- used water without toxic chemicals/excrement and can be re-used
blackwater- contaminated water with toxic chemicals/excrement
what are the goals of waste water treatment?
produce effluent
produce sludge
discharge or reuse effluent
what are the stages of water treatment and outline them?
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
what are the types of treatments?
1-mechanical treatments
2-biological treatment
3-chemical treatment
what are the types of mechanical treatment?
1- remove of large object
2-removal of sand and grit
3- primary sedimentation
4-influent:waste water flowing into reservoir, treatment plant
what are the types of biological treatment?
1- trickling bed filter
2- activated sludge
what are the types of chemical treatment?
disinfection
what are the preliminary treatment
1- removing any waste water constituent which could clog up equipment
2- raked screen: screens the water
3-remove large objects
what are the types of primary treatment stage?
1-sand catcher
2- sedimentation tank
what are the advantages and disadvantages of sand catcher?
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
describe sedimentation tank
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
type of material removed during primary treatment stages
1- fats,oil,grease
2- sand,gravels and rocks
3-floating materials
4- large solid able to settle
what is secondary treatment?
process on dissolved organic matter
what are the types of secondary treatment?
1- fixed film system
2-lagoon system
3- suspended film system
what is fixed film system?
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
what are examples of fixed film system?
1-trickling filter
2- rotating biological contactors
explain how a trickling filter works
waste water is poured onto a medium having slime like layer of microorganism, this medium is contained in a coke/limestone material
