4. Water supply.pdf water supply of some environment

This is concerned with environment deeply

1. Community Water Supply
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2. Community Water Supply
•Thereisanoldsayingwhichstatesthat
“Waterislife”.
–Itistruethatwaterisoneofthemostbasic
necessitiesoflife.Withoutwaterourexistenceis
countedindays.
•Waterisalsoimplicatedwiththetransmissionof
diseases.
–Basedonthis,thereisanothersayingthatstates
“Waterisguiltyunlessprovedinnocent”.
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3. Definition of some technical
terms
Rawwater
–isuntreatedwaterfromsuspicioussourcessuchas
river,lakeorfromunprotectedwellandsprings.
Safewater
•Itiswaterthatdoesn’tcontainharmfulchemical
substancesormicroorganismsinconcentrationthat
couldcauseillnessinanyform.
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4. Definition of some technical terms cont…
Adequatewatersupply
isonethatprovidessafewaterinquantities
sufficientfordrinking,culinary,domestic&
otherhouseholdpurposes,soastomake
possiblethepersonalhygieneofmembersof
thehousehold.
Asufficientquantityshouldbeavailableona
reliable,year–roundedbasistoorwiththe
household.
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5. Definition of some technical terms cont…
Potablewateriswaterwhichissafe,clean
andwholesomeforhumanconsumption
andshouldbe
-Freefrompathogenicorganisms
-Freefromharmfulsubstance
Palatablewateriswaterthatispleasantto
drink.Itisnotnecessarilypotablewater;
itcanbepleasanttodrinknevertheless
maybecontaminated.
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6. Definition of some technical terms cont…
•Pollutedwater-waterthathascomeincontact
withsubstancesthatalteritsphysicalqualities,so
thatitchangesincolor,taste,andsmell.Polluted
watercanbedetectedbysenseorgans.
•Asarulepollutedwatershouldbe
consideredascontaminatedwater.
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7. Definition of some technical terms cont…
Contaminatedwater
•Itiswaterwhichmaycontainharmful
micro-organismsortoxicchemicals
whichmakeitunfitforuse.
–Generally,thesecontaminantscannot
bedetectedbytheorgansofsight,
taste,andsmell.
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8. Importance of water
•Universalsolvent
•Physiologicalneeds:Drinking.It
constitutes70%ofourbodyweight.
•Domesticuse:cleaning,washing,
swimming,livestockwatering,…
•Recreationalpurposes:swimming,
boating,fishing,…
•Agricultural(irrigation),transportation,power
generation,construction,industrialuse,etc.
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9. Occurrence of water
•Globally,72%oftheearthiscoveredby
water.
•However,themajority97%issalty.
–Only3%oftheearth’swaterisfresh.Of
this,
–2%islockedupintheicecapsglaciers.
–Only0.8%rawwaterisavailablefor
humanuseanditisunevenlydistributed.
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10. 1011/25/2021 Prepared by: Digafe Ts

11. Impurities of water
Source of impurities
•-Atmospheric condition (in case of rain water) –
microorganisms, dust, smoke, gases in the
atmosphere
-Condition of the catchment area (surface
water)-dirt, microorganisms
-Nature of under ground formation(under
ground water) –suspended impurities, chemicals
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12. Impurities of water cont…
Impurities are generally divided into:
1. Suspended impurities
-microorganisms
-solids
-algae
2. Dissolved impurities
-gases
-minerals
-plant dyes
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13. Impurities of water cont…
1. Suspended impurities
Micro-organisms
-When water polluted with human and
animal excreta
-Water from the air with dust, etc as rain
falls
Solids: Include
-Solids and clays
-Dead leaves and other insoluble materials
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14. Impurities of water cont…
Algae
-Are minute plants that grow in still or
stagnant water
-Their presence in water cause change
of taste, color and turbidity.
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15. Impurities of water cont…
2.Dissolvedimpurities
-Manysolidsandgasesaresolublein
water.
•Thus,iftheyareputinwater,they
disappearseemingtobecomeliquids.
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16. Impurities of water cont…
Theseare:
Gases
-SuchasCO
2(intheabsenceofO
2will
causeacidity),H
2Swhichcouldresult
fromanaerobicdecompositionoforganic
mattergivesbadodor
Plantdye
-Originatesfromplantwhichgrowsin
oraroundwaterandtheycauseacidity
andcolor.
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17. Impurities of water cont…
•Minerals
-getintowaterasitpercolatesdown
throughtheearthlayers
-Calciumandmagnesium(causehardnessof
water)
-Sodiumandpotassium(causealkalinityof
water)
…… other minerals such as lead, arsenic,
mercury, chromium are also toxic when the
water contain in excess amount.
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18. WATER AND DISEASE
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19. Water and disease
•IncountrieslikeEthiopia,sincelarge
majoritiesofthepeoplegettheirwater
supplyfromunprotectedsources,water
bornediseasesarenotathingofthepast
butoneofthemostsignificantpublic
healthproblemsofthepresent.

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20. Water and disease cont…
Communicable diseases associated with
water can be categorized in to:
1. Water born
2. Water washed
3. Water based
4. Water related
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21. Water and disease cont…
1.Waterborndiseases
–Thediseaseswhicharespreadthrough
contaminatedwaterarecalledwaterborne
diseases.
–Watersetsonlyasapassivevehicleforthe
infectingagent.
–Qualityofwatermatters.
•Allthediseasesherearegenerallyknownas
“filth-bornediseases’’becausethesourceof
infectionishumanexcreta.
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22. Water and disease cont…
•Topreventthesediseases
-treatmentofdrinkingwater,
-provisionofsafewater,
-sanitarydisposalofexcretaarevery
essential.
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23. e.g Table –water born disease with their etiology
Type of organisms
Disease type
Bacteria Typhoid and paratyphoid fever
Cholera
Bacillary dysentery ( shigellosis )
Virus Hepatitis-A
Poliomyelitis
Viral gastroenteritis
Protozoa Amoebic dysentery
Giardia
Helminthes Balantidiasis
Helmenthiasiscaused by ascarisand
trichinas
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24. Waterborne disease infection cycles
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Infected
person
Pathogens
in excreta
Contaminated
water sources
Consumption of
untreated water
Susceptible
person
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25. Water and disease cont…
2.Waterwasheddiseases
-Diseasesduetolackofwater.
-Lackofadequatequalityofwater&poor
personalhygienecreateconditions
favourablefortheirspread.
-Quantityofwatermatters.
-Allwaterbornediseasesarewater
washed.
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26. Water and disease cont…
e.g.-Dermatologicaldiseasesuchasscabies
-Ophthalmicdiseasesuchas
trachomaandconjunctivitis
-Louse-bornediseasessuchaslouse
borntyphusandrelapsingfever
•Topreventthistypeofdiseaseprovision
ofanampleamountofwaterandpersonal
hygienepracticeareessential.
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27. 3.Waterrelated/vectorrelateddiseases
-Diseasestransmittedbyinsects,which
liveclosetowater.
-Infectionsarespreadbymosquitoes,flies
insectsthatbreedinwateroraroundit.
Water and disease cont…
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28. -Themostprominentwater-related
vector-bornediseaseismalaria,whichis
transmittedbymosquitoesthatneed
waterforreplication.
-eg:-Yellowfever,Sleepingsickness,
Dracunculiasis,Onchocerciasis,Malaria
Water and disease cont…
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29. Water and disease cont…
•Topreventthistypeofdisease,making
thewaterunsuitableforbreedingof
insects(forexamplebydrainingstagnant
water,emptyingwaterintires,…)is
essential.
•Besidespropersiteselectionofhouse,
usingpersonalprotectionmaterials,
destroyingbreedingsitesarecrucial.
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30. Water and disease cont…
4.Waterbased(contact)diseases
•Diseasescausedbyinfectiousagentsthat
spreadbycontactwithoringestionof
water.
•Anessentialpartofthelifecycleof
infectingagenttakesplaceinaquatic
animals.
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31. Water and disease cont…
•Manyofthediseasesinthisclassare
causedbyworms,whichinfestthenew
host.Andtheyproduceeggs,whichare
thendischargedinfecesorurine.
•Someparasiticeggsorlarvaearenot
directlyinfectivetomanbuttospecific
invertebratewateranimalssuchassnails
orcrustaceans.
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32. Water and disease cont…
•Theyundergodevelopmentwithinthis
invertebrates(intermediatehost)from
whichafteraperiodofdaysorweeks
furthermaturedlarvaemaybeshedinto
thewaterandbecomeinfective.
e.g.Schistosomiasis
Guineaworm
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33. Sources of water supply
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34. Sources of water supply
•Innature,therearefourmainsourcesof
waterforhumanuse.Theseare:
1.Rainwater-theprimaryandrelatively
puresourceofwater.
2.Surfacewater-rivers,lakes,ponds,
streams,reservoirs.
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35. Sources of water cont…
3.GroundWater-wells,springs
4.Oceanorseawater
-contains35mg/lsalt
-Require-desalinationplantwhichis
expensive.
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36. Rainwater
•Rainwater may be used for domestic purposes
in remote districts where
–groundwater is contaminated, or
–where there are no alternative sources.
•As a practical source of domestic supply its use
is limited since particular care is required to
reduce any pollution from
–extraneous sources such as bird droppings from the
roof or
–other surface the water is collected from.
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37. Surface water
•It is taken from rivers, lakes or man-made
reservoirs.
•It provides a consistentand manageable
source for public supply, but it is subject to
greater risk of contamination.
–Thus, requires careful and suitable treatment.
•There is also the possibility of accidental
or deliberate pollutionby irresponsible
industrialists or the agricultural community.
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38. Surface & underground water
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39. Surface water
•Generally, Water abstracted from rivers is:
–Poorer quality than reservoirsand lakesand
varies in quality throughout the year
depending on the weather, particularly heavy
rainfall.
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40. Groundwater
•Water that has percolated through the
ground can be used for drinking purposes,
either via:
–Springs
–Wells or boreholes.
•The quality of the water varies depending
on:
–the depth it is taken from and
–the types of rock it has passed through.
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41. Groundwater
•Water from deep sources, often provides
good microbiological quality although its
quantity may not always be sufficient for
public water supply demands.
•Ground water can come from one of the ff
sources:
1.springs;
2.wells: shallow, deep or artesian
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42. Groundwater
Springs
•A spring is a simple outcropping of water that
has percolated into a permeable subsoil and run
along the top of an impermeable stratum to a
point at which it reaches the surface.
•Spring water will vary in volume & contamination
levels according to the rainfall.
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43. Groundwater …
•It is obviously liable to pollution by direct
percolation through the top soil.
•A spring supply issuing from deep, water-
bearing strata can produce both a
consistent volume and a better quality
supply.
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44. Groundwater …
•Animals should be excluded from the area
by:
–A stock-proof fence and
–Any water overflowing the land after rain
should be diverted by a suitable ditch.
•The immediate area where the spring
arises should be protected by a suitable
housing or collection chamber with a
concrete apron to divert contamination
away.
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45. Groundwater
Wells
–The practice of obtaining water from wells is
universal and well water is an important source
of supply in many developing countries.
–A well should be situated uphillfrom any
possible sources of pollution.
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46. Groundwater
•Types of wells
i.Shallow
ii.Deep wells
iii.Artesian spring
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47. Groundwater
–A well that taps water above the first
impermeable stratum is known as a shallow
well.
–Deep wells are those derived from water-
bearing strata below at least one impervious
stratum.
–A deep well must be constructed so as to
exclude subsoil water and contamination from
aquifersabove the level where the well takes
its water.
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48. Groundwater
–Well water from below impervious strata is
sometimes under pressure because the
natural surface of the water table may be
above the level of the stratum the water is
contained in.
–The water will rise in any well or borehole up
to the level of the natural water table, this is
the potentiometric surface and may actually
be above the surface of ground & it is known
as an artesian spring.
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49. Artesian spring
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50. Contamination of water sources
Contaminationofrainwater
Fromthesanitarypointofview,rain-water
maybethepurestofallsourcesofwaterin
nature,butitisliabletocontamination
underthefollowingconditions:
-Asitfallsthroughtheatmosphereintheway
pickvariousgases,dust,particulates,soot,plant
pollen,bacteria,etcifthesubstancesarepresent
intheair.
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51. Contamination of water sources cont…
-Asittouchesthecollectionsurface,its
puritydependsonthecleanlinessof
collectingsurface.
-Itmaybecontaminatedduringstorage,
distributionandhandling.
Thusitsprotectionbasicallyaimsat
eliminatingtheabovethreewaysinwhich
itislikelytobecontaminated.
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52. Contamination of water sources cont…
Contaminationofsurfacewater
•Assurfacewaterflowsovertheearth’s
crust,itwillpickupanythinginitspath
thatcanbemovedordissolved.
•Consequentlythequantityandquality
ofsuchwatersdependontheconditions
ofthesurfaceorcatchmentsareaover
whichitflows.
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53. Contamination of water sources cont…
Pollutantsmaybedividedinto:
--Humanandanimalwastes–excreta,
domesticsewage,animalwastes,etc.
--Industrialeffluents(sewages,toxic
chemicals)
-Chemicalsfromagriculturalfields
(herbicides,pesticides,fertilizersetc.)
-Soilintheformofsilt.
Inanycase,surfacewatershouldneverbe
usedasasourceofwatersupplywithout
treatment.
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54. Surface water contamination
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55. Contamination of ground water
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56. Groundwater contamination cont…
Advantagesofgroundwater
•Relativelyfreefromdiseasecausingorganisms
•Itcanbeusedwithoutfurthertreatmentif
properlyprotectedandtreatedimmediately
afterthecompletionofconstructionworkon
thewellorothersourcewheregroundwateris
available
Disadvantageofgroundwater
•Itmaycontainexcessamountofdissolved
minerals
•Itispoorinoxygencontent
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57. Water Treatment
Defn:
•Watertreatmentistheprocessofremoving
allthosesubstanceswhetherbiological,
chemicalorphysical,whichispotentially
dangerousorundesirableinwatersupplies
forhumananddomesticuse.
•Inshortitisaprocessofmakingthewater
potableandpalatableforusage.
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58. Objectives of water treatment
–Toremovepathogenicorganismsand
consequentlytopreventwater-borne
diseases.
–Toremovesubstanceswhichimpart
color,tasteorodortothewater.
–Toremoveexcessorundesirable
chemicalsormineralsfromthewater.
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59. Objectives of water treatment cont…
–Toregulateessentialelementsor
chemicals,whichmaybeinexcessor
lackinginacertainwater-supply
system,e.g.fluoridationor
defluoridationofwater,softeningof
water.
–Toremoveexcessorundesirable
dissolvedgases.
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60. Water treatment types
1.Smallscalewatertreatment
e.g.-Boiling,Filtration
2.Municipalwatertreatment
2.1. Ground water
Aeration DisinfectionStorage Distribution
2.2. Surface water treatment
Screening Coagulation Mixing 
SedimentationFiltration Disinfection 
StorageDistribution
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61. 1. Small scale water treatment
Whenisused?
•-Inemergencysituation
-Temporarysettlementareas
-Atthehouseholdlevel
-Inareawherethemunicipalwater
treatmentisnotwellorganized
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62. Small scale water treatment cont…
1.Boiling
•Oneofthemostreliablemethodsof
disinfectingwaterathouseholdlevel.
–Providedwaterbroughttotheboiling
pointandiskeptboiling15-20minutes,
allformsofmicroorganismsincluding
themostresistantsporesorcystswillbe
destroyed.
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63. Small scale water treatment cont…
-Effectiveforallkindsofrawwater,unless
thewatercontainstoxicchemicalswhich
boilingcannotdestroy.
Drawbacks
--Itcanrequirelotsoffuelandcooking
equipment
-Cannotbethenusedimmediately,asit
needstocooldown.
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64. Small scale water treatment cont…
-Waterhasflat-tasteduetothelossof
dissolvedgas(Co
2andO
2)andminerals
duringboiling.However,canberemedied
bykeepingtheboiledwaterforafewhours
inpartiallyfilledcontainer.
Greatcaremustbetakentoavoid
recontaminationoftheboiledwatereither
duringstorageorconsumption.
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65. Small scale water treatment cont…
2.Filtrationisaprocessofpassingliquid
throughoneormoreporoussubstances,
whichwillnotallowthesuspended
mattertopassthrough.
Therearedifferentkindsoffiltration
methods
•Home made sand filter
•Home candle filter
•Cloth filtration
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66. Small scale water treatment cont…
Homemadesandfilter(Slowsandfilter)
-Filtrationprocessofwateroversand
medium
-Rateoffiltrationgraduallydecreasesdue
toclogging,therefore,removing(scraping)
of5cmto10cmdepthofsandand
replacingafterwashingisnecessary.
-Cleaningintervalvariesdependingonthe
qualityofthewatertobefiltered.
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67. Small scale water treatment cont…
•Itismoreefficient
-canremove99%ofpathogens
-determinedbyitsproperconstruction
andcarefulmaintenance
-removemostofthesubstancethatcause
turbidity,tasteandodor
•Theminimumdepthoffiltersandshould
notbelessthan60cm.
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68. raw water in
any amount
Faucet
clean course
sand
clean fine sand
Clean round gravel
Stand of the barrels
lid
60 cm
20 cm
20 cm
Home made sand filter
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69. Small scale water treatment cont…
Homecandlefilters
-Commerciallymadeforfiltering
individualwatersupply.
-Efficiencydependsontheporesizeof
thecandle.
-Poresize-0.3-50µm.
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70. Small scale water treatment cont…
Limitation
•Virusandsmallsizebacteriamaynotbe
removed.
•Rateoffiltrationisverylow.
•Thecandleneedsdismantlingonceaweek,
forwashingandsterilizationinboiling
water.
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71. Small scale water treatment cont…
3.Chemical disinfection at household level
•Iodine and its compounds
•Chlorine or its compounds
•Bromine solution
4. Household water storage
•Helps to reduce turbidity, sediment
bacteria and eggs of parasites
•Reduces survival of some parasites if
storage is for above 24 hours
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72. Small scale water treatment cont…
•Safe handling in household
Storage container should be clean, covered
& out of reach of children
Hand washing before handling water
•Container
Narrow necked-prevent contamination but
difficult to clean
Wide necked-easily contaminated but
easily cleanable
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73. Municipal water treatment
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75. 2. Municipal water treatment
Steps
1. Preliminary water treatment
-Source and intake of water supply
-Screening (course and fine screening)
2. Pumping station
3. Pre sedimentation (Aeration and pre-chlorination)
4. Sedimentation, coagulation/flocculation
5. Filtration
6. Disinfection (Post chlorination)
7. Supplementary treatment
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