Study the following flow chart and describe in about 100 words how drinking water is supplied
in Kolkata from Palta Water Works,
Points: Extraction of raw Ganga water purification by mixing alumn → reservation in a big tank,
filteration in filter beds → super purification in filter houseschlorine charged testing taken into
pressure house
(Runt Benode Manpuns. Pustnya. Paliba Widyalaya's
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Answers
Answer:
Hooghly River is the main source of potable surface water for the city of Kolkata supplied from the age-old Palta Water Works now rechristened as Indira Gandhi Water Treatment Plant. The Palta Water Works ,spreading over a sprawling strechh of 480 acres,was the first intake point constructed during 1864-1870 for generation and supply of water . Initiated with a humble capacity of 6 mgd (million gallon per day),filtered water was generated through sedimentation in pre and final settling tanks and slow sand filteration in the Old Series of 12 filter beds. Further addition of 24 beds with a capacity of 1 mgd per bed,was made during the period 1888-1893. In 1905,filter beds with 2 mgd capacity ,called New Series was started . Further addition took place in between 1920 and 1936 when 17 nos.of 3mgd capacity and 1 no.of 2mgd capacity filter beds,called Extension Series were introduced.
It is said that old is gold and the relentless service of this age-old pumping station is certainly proving the point. With an output of 130 mgd,the plant seems to have perenial capacity to serve.
The slow sand filternation system is an effective and reliable system which does not required daily washing. A single bed can work upto 100 to 120 days.Formation of a biological mat soon after effective charging removes turbidity,colour and microoraganisms,by 95%. Due to this process,requirement of chlorine as a disinfectant of about 10 to 20 mm of top sand layerr every 100 day,make the bed ready for reuse.
Further development took place with the introduction of rapid gravity filter with 12 beds and 20 mgd capacity during 1952. This process helped in reducing the sedimentation time. In 1968,another 60 mgd rapid gravity filteration unit was added.
The present arrangement did not however,seem to suffice the demand level. In 2002,KMC supplied 281 mgd of water,falling short of the demand by almost 50 mgd. However,in 2003,the average supply rose to 334 mgd, meeting nearly 90% of requirement. Keeping in tune with the growing rate of population and proportionally accelerating rate of demand,KMC has undertaken several capacity enhancement and upgradation programmes and hopes to exceed the demand by 2005.
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Explanation:
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