this is the WWTP section of NCERT SCIENCE BOOK CLASS 7

1. WASTE WATER
TREATMENT PLANT
(WWTP)
MADE BY – ARYAN PATEL, AARAV JAIN, ASMI PALMULKAR, MAUKTIKA GHARIYA,

2. TOPICS WE ARE GOING TO LEARN IN THIS
CHAPTER:
• WHAT IS WWTP
• PROCESS OF WASTE WATER TREATMENT
BAR SCREENING
SCREENING
PRIMARY CLARIFIER
AERATION
SECONDARY CLARIFIER
CHLORINATION (DISINFECTION)
WATER ANALYSIS AND TESTING
EFFLUENT DISPOSAL
• WHAT CAUSES CONTAMINATION OF WATER
• WHY IS TREATING WASTE WATER IMPORTANT
• DID YOU KNOW (2)
• FUTURE WASTE MANAGEMENT AR

3. WHAT IS WASTEWATER TREATMENT
PLANT?
A WASTE WATER TREATMENT PLANT IS A PROCESS USED TO REMOVE CONTAMINANTS FROM
SEWAGE WATER IS CALLED WASTE WATER TREATMENT PLANT. IT HAS 8 STAGES IN WHICH IT
PURIFIES WASTEWATER.
AS

4. PROCESS OF WASTE WATER TREATMENT
• STAGE ONE — BAR SCREENING
• STAGE TWO — SCREENING
• STAGE THREE — PRIMARY CLARIFIER
• STAGE FOUR — AERATION
• STAGE FIVE — SECONDARY CLARIFIER
• STAGE SIX — CHLORINATION (DISINFECTION)
• STAGE SEVEN — WATER ANALYSIS & TESTING
• STAGE EIGHT — EFFLUENT DISPOSAL
AS

5. STAGE ONE
BAR SCREENING
WHATDOYOUUNDERSTANDBY BARSCREENING
MA

6. STAGE ONE — BAR SCREENING
BAR SCREENING IS A PROCESS WHERE LARGE OBJECTS ARE FILTERED FROM
WATER LIKE ROCKS , PLASTICS , PEBBLES , ETC. THIS PROCESS IS CALLED
BAR SCREENING.
MA

7. STAGE TWO
SCREENING
WHATDOYOUUNDERSTANDBYSCREENING
BH

8. STAGE TWO — SCREENING
SCREENING IS A WASTEWATER PRE TREATMENT WHICH PREVENTS COARSE
AND SMALLER SOLIDS SUCH AS RAGS , MUD , TRASH , ETC. IN THIS PROCESS
SMALLER SOLIDS WASTES GET TRAPPED BY BAR RACKS. THIS PROCESS IS
CALLED SCREENING.
BH

9. STAGE THREE
PRIMARYCLARIFIER
WHATDOYOUUNDERSTANDBYPRIMARYCLARIFIER
AA

10. STAGE THREE — PRIMARY CLARIFIER
• PRIMARY CLARIFIER IS A PROCESS IN WHICH THE WASTEWATER IS HELD IN A
CIRCULAR TANK FOR A PERIOD OF TIME TO ALLOW HEAVIER SOLIDS LIKE
DIRT , ORGANIC MATTER , INORGANIC MATTER , ETC TO SETTLE TO THE
BOTTOM AS SLUDGE AND LIGHTER MATERIALS TO FLOAT ON THE WATER
SURFACE AND THIS PROCESS IS CALLED PRIMARY CLARIFIER.
AA

11. STAGE FOUR
AERATION
WHATDOYOUUNDERSTANDBYAERATION
AR

12. STAGE FOUR — AERATION
• AERATION IS THE PROCESS BY WHICH AIR IS CIRCULATED THROUGH, MIXED
WITH OR DISSOLVED IN A LIQUID OR SUBSTANCE. AERATION BRINGS WATER
AND AIR IN CLOSE CONTACT IN ORDER TO REMOVE HARMFUL AND CHEMICAL
GASES. THIS IS ALSO KNOWN AS AERIFICATION. THIS PROCESS IS CALLED
AERATION.
AR

13. STAGE FIVE
SECONDARYCLARIFIER
WHATDOYOUUNDERSTANDBYSECONDARYCLARIFIER
AS

14. STAGE FIVE — SECONDARY CLARIFIER
• IN THIS PROCESS THE FILTERS REMOVE MICROSCOPIC SOLIDS AND
BACTERIA FROM THE WASTE WATER BEFORE IT MOVES ONTO
DISINFECTION. THIS PROCESS IS CALLED SECONDARY CLARIFIER.
AS

15. STAGE SIX
CHLORINATION(DISINFECTION)
WHATDOYOUUNDERSTANDBYCHLORINATION(DISINFECTION)
MA

16. STAGE SIX — CHLORINATION (DISINFECTION)
• IN THIS PROCESS THE KILLING OR REMOVAL OF PATHOGENIC MICRO
ORGANISMS. THEY ARE KILLED RESULTING IN TERMINATION OF GROWTH AND
REPRODUCTION. THIS PROCESS IS CALLED CHLORINATION. WHEN MICRO
ORGANISMS ARE NOT REMOVED FROM DRINKING WATER , THE USAGE OF
DRINKING WATER WILL CAUSE PEOPLE TO FALL ILL. THIS PROCESS IS
CALLED CHLORINATION.
MA

17. STAGE SEVEN
WATERANALYSIS&TESTING
WHATDOYOUUNDERSTANDBYWATERANALYSIS &TESTING
BH

18. STAGE SEVEN — WATER ANALYSIS & TESTING
• IN THIS PROCESS THE WATER QUALITY TESTS WILL GIVE INFORMATION ABOUT THE
HEALTH OF THE WATER WAY. BY TESTING WATER OVER A PERIOD OF TIME THE
CHANGES IN THE QUALITY OF WATER CAN BE SEEN. PARAMETERS THAT MAY BE
TESTED INCLUDE TEMPERATURE , PH VALUE , SALINITY , NITRATES AND PHOSPHATES.
THIS PROCESS IS CALLED WATER ANALYSIS & TESTING.
BH

19. STAGE EIGHT
EFFLUENTDISPOSAL
WHATDOYOUUNDERSTANDBYEFFLUENTDISPOSAL
AA

20. STAGE EIGHT — EFFLUENT DISPOSAL
• AFTER MEETING ALL PERMIT SPECIFICATIONS, CLEAN WATER IS
REINTRODUCED INTO THE ENVIRONMENT. ALTHOUGH TESTING IS
CONTINUOUS THROUGHOUT THE WASTEWATER TREATMENT PROCESS TO
ENSURE IF THERE IS ANY BACTERIA , CHEMICALS , ETC PRESENT.

21. WHAT CAUSES CONTAMINATION OF WATER
• HUMAN ACTIVITIES LIKE BATHING AND WASHING CLOTHES IN RIVERS AND
LAKES.
• ANIMALS BATHING IN RIVERS AND LAKES.
• INCREASE IN POPULATION FORMS THE MAJOR CAUSE FOR WATER
CONTAMINATION.
• UNTREATED SEWAGE.
• INDUSTRIAL WASTES.
• AGRICULTURAL WASTES.

22. COMPONENTS OF WASTE WATER
THEREAREMANYCOMPONENTSOFWASTEWATER.
• SEWAGEORLIQUIDWASTEMAKESUPTHEMAINCOMPONENTOFWASTEWATER.
• HUMANEXCRETAINTHEFORMOFFAECESISTHEMAINSUSPENDEDIMPURITYINTHESEWAGE.
• OILANDGREASEFLOATASLAYERSORFROTHONTHEWASTEWATER.
• INDUSTRIALLIQUIDWASTESARETHEEFFLUENTSCONTAMINATINGWATER.
• AGRICULTURALWASTESLIKEPESTICIDES,FERTILIZERSDONOTDISSOLVEINWATERBUTREMAININTHEWASTE
WATER.
AR

23. WHY IS TREATING WASTEWATER IMPORTANT
• WASTEWATER TREATMENT PROTECTS HUMANS AND
ECOSYSTEM
• WASTEWATER CONTAINS ELEMENTS TOXIC TO HUMANS
AND THE ECOSYSTEM. ... WASTEWATER TREATMENT
ALSO PROTECTS THE ECOSYSTEM. FISH AND AQUATIC
LIFE REQUIRE FRESH WATER. WHEN THEIR WATER
ENVIRONMENT IS LADEN WITH WASTEWATER, THEY
CANNOT SURVIVE.

24. DID YOU KNOW
• WASTEWATER DISCHARGES AND THE RESULTING POLLUTION MAKE A GREATER IMPACT THAN
WATER USED DURING THE PRODUCTION PROCESS
• INDUSTRIES THAT RELY ON ORGANIC RAW MATERIALS CREATE THE LARGEST AMOUNT OF
ORGANIC POLLUTION.
• A LOT OF INDUSTRIAL, UNTREATED WASTEWATER IS RELEASED INTO OPEN WATERWAYS, WHICH
NEGATIVELY AFFECTS THE QUALITY OF WATER OVERALL BY POTENTIALLY ENTERING AQUIFERS
AND GROUNDWATER.
• INDUSTRIAL WATER USAGE MAKES UP ABOUT 22 PERCENT OF GLOBAL WATER USAGE.
• IN 2009, EUROPEAN AND NORTH AMERICAN INDUSTRIES USED 50 PERCENT OF ALL WATER,
COMPARED WITH ONLY 4 PERCENT TO 12 PERCENT USAGE IN DEVELOPING COUNTRIES.
• ACCORDING TO ESTIMATES FROM THE UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
(US EPA), ROUGHLY 23,000 TO 75,000 SANITARY SEWER OVERFLOWS HAPPEN EACH YEAR.
• AN ESTIMATED 3 BILLION TO 10 BILLION GALLONS OF UNTREATED WASTE IS RELEASED FROM
SEWAGE TREATMENT PLANTS ANNUALLY

25. DID YOU KNOW
• THE US EPA REPORTS THAT 53 PERCENT OF THE MILES IN RIVERS AND STREAMS, 98
PERCENT OF SHORELINE MILES ON THE GREAT LAKES, 71 PERCENT OF ACRES IN LAKES,
AND 79 PERCENT OF ESTUARINE SQUARE MILES ARE NOT ACCEPTABLE FOR AT LEAST ONE
TYPE OF WATER USE.
• PUBLIC TREATMENT FACILITIES MUST TREAT MORE THAN 8 MILLION TONS OF DRY-WEIGHT
SLUDGE PER YEAR, CONSUMING ONE-THIRD OF ALL ITS ELECTRICITY USE.
• ABOUT 80 PERCENT OF WASTEWATER WORLDWIDE FLOWS BACK INTO THE ECOSYSTEM
WITHOUT BEING TREATED OR REUSED. THAT MEANS 1.8 BILLION PEOPLE USE A
CONTAMINATED SOURCE OF DRINKING WATER.
• THE 600,000 MILES OF SEWER SYSTEMS IN THE COUNTRY HAVE A 50-YEAR LIFE
EXPECTANCY.
• TREATMENT EQUIPMENT HAS A LIFE EXPECTANCY OF 15 TO 20 YEARS.
• DETERIORATED SEWER PIPES WILL INCREASE FROM 10 PERCENT OF THE SEWAGE

26. FUTURE OF WASTEWATER MANAGEMENT
• A GROWING NUMBER OF COMPANIES ARE APPLYING FOR CERTIFICATION THROUGH ISO
14001, WHICH IS THE INTERNATIONAL STANDARD FOR ENVIRONMENTAL MANAGEMENT
ADMINISTERED BY THE INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.
• IN 1993, MORE THAN 46,000 COMPANIES WORLDWIDE WERE ISO 14001 CERTIFIED. BY 2010,
THIS NUMBER REACHED MORE THAN 400,000 IN MORE THAN 171 COUNTRIES.
• IN 2010, THE STATE OF CALIFORNIA RECYCLED ROUGHLY 650,000 ACRE-FEET OF WATER PER
YEAR. THE STATE HOPES TO INCREASE WATER RECYCLING TO REACH A MINIMUM OF 1
MILLION AC-FT PER YEAR BY 2020 AND 2 MILLION AC-FT PER YEAR BY 2030.
• AFTER STABILIZATION, MORE THAN HALF OF QUALIFIED BIOSOLIDS CAN BE APPLIED TO
AGRICULTURAL SITES, FORESTRY APPLICATIONS, RECLAMATION SITES, AND URBAN PARK
AREAS.

27. A VIDEO ABOUT WWTP
HTTPS://WWW.YOUTUBE.COM/WATCH?V=FVPAKZQM3H8
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28. QUIZ TIME
• HTTPS://QUIZIZZ.COM/ADMIN/QUIZ/61E7DF7AF93082001D814C24/WWTP
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