TREATMENT OF WATER

TREATMENT OF WATER

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  GUIDED BY:- Asst. Prof.Department of Civil Engineering MONIKA DAS Presented BY:- BUSAM DOLA SASIDHAR LIPSA RANI PAGADA DEBASISH BEHERA AKASHAYA PRADHAN SIBANI PRADHAN SUBHAM PATNAIK
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  CONTENTS • INTRODUCTION • LeaRNINgObjeCTIves • MeThODs • CRITeRIa fOR The seLeCTION Of The sITe fOR waTeR TReaTMeNT pLaNT • aRTIfICIaL MeThODs • pURIfICaTION Of waTeR ON LaRge sCaLe • waTeR TReaTMeNT TeChNOLOgIes • pURIfICaTION Of waTeR TeChNOLOgIes • INTake wORks • pLaIN seDIMeNTaTION • seDIMeNTaTION wITh COagULaTION
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  • fILTRaTION • sLOwsaND fILTRaTION (bIOLOgICaL fILTeR) • saND beD • UNDeR-DRaINage sYsTeM • fILTeR bOX • fITeR-CLeaNINg • aDvaNTage Of sLOw saND fILTRaTION • RapID saND fILTeRs ( MeChaNICaL fILTeRs) • fILTeR beDs • baCk washINg • aDvaNTage Of RapID saND fILTRaTION • DIsINfeCTION Of waTeR • waTeR sOfTeNINg • CONCLUsION CONTENTS
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  INTRODUCTION
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  Water Sources
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  Reasons for WaterTreatment The two main reasons for treatment water are:- * To remove those contaminants that are harmful to the health. * To remove contaminants that make the water look, taste, or smell bad.
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  Criteria for theselection of the site for water treatment plant:-
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  Learning Objectives: The participantwill be able to define: • Purification of Water.
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  Purification Of Water •Purification of is done by TWO ways: 1.Natural Methods 2.Artificial Methods
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  Natural Methods
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  Artificial Methods
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  Artificial Methods • Theymay be carried out at: A.Purification of Water on Large Scale B.Purification of Water on Small Scale
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  A. Purification ofWater on Large Scale • Quantity of water per capita demand
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  Purification of Wateron Large Scale • The purpose of water treatment is to produce water that is safe & wholesome. • The method of treatment to use depends upon the nature of raw water & the desired standards of water quality. Ex: Ground water (wells & springs) may need no treatment other than disinfection. • Surface water (e.g River water) which tends to be turbid & polluted, require extensive treatment. • The components of a typical water purification system comprise one or more of the following
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  Water Treatment Technologies
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  Purification of Watertechnologies 1. Intake works 2. Plain sedimentation 3. Sedimentation with coagulation 4. Filtration 5. Disinfection of water 6. Water softening
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  1.Intake works • Wateris drawn out from the source and impounded in natural or artificial reservoirs. • Storage provides of a reserve of water from which further pollution is excluded. • As a result of storage, a very considerable amount of purification takes place. • Intakes are divide into following types :- A- Lake intake , B- Reservoir intake, C-River intake , D- Canal intake
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  Intake works
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  2. Plain Sedimentation •The main objective of plain sedimentation is to remove suspended impurities of large size • Plain sedimentation tank is divided into following three types:- A- Rectangular Tank B- Circular Tank C- Hopper Bottom Tank
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  3. Sedimentation withcoagulation The main aim of sedimentation with coagulation is to remove the small suspended particle of size 0.06 mm to 0.02 MM of 10 hours detention period
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  Sedimentation with coagulation •Here we add chemical coagulant Alum. ALUM – AL2(So4)3 • The Dose is 35 mg/Liter & is kept for 4 – 6 hours. It is very necessary. • Prior to filtration and helps in Preventing the Rapid Clogging of filter. • The reaction is:- 1) Al2 (So4)3 + Ca (Hco3) → Al(OH)3 + 6Co2 + CaSo4 2) Al2(So4)3 + 3Na2Co3 + H2O → 3NaSo4 + 2Al(OH)3 + 3Co2
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  4. Filtration • Itis the oldest and Universal method of purification. • Filtration is the second stage in the purification of water. • This filtration reduces the bacterial content by 98- 99%, turbidity by 50 PPM to 5 PPM and colour to colurless.
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  Filtration • There aretwo types of Filters:  SLOW SAND FILTERATION (BIOLOGICAL FILTER).  RAPID SAND FILTERS ( MECHANICAL FILTERS).
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  SLOW SAND FILTRATION(BIOLOGICAL FILTER)
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  SAND BED • Thethickness of the sand bed is a about 1 meter. • The sand should be clean and free from clay & organic matter. • The sand bed presents a vast surface area, one cubic meter of filter sand presents some 15,000 sq.meter of surface area. • Water percolates the through the sand bed very slowly, process taking 2 hours or more. • The designed rate of filtration of water usually lies b/w 0.1 to 0.4 m3/ hour/ per square meter of sand bed surface.
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  UNDER-DRAINAGE SYSTEM • Atthe bottom of the filter bed is the under-drainge system. • It consist of porous or perforated pipes which serve the dual process of providing an outlet for filtrated water and supporting the filter medium above. • Once filter bed been laid, the under-drainage system can not be seen.
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  FILTER BOX • Thefilter box is an open box, usually rectangular in shape, from 2.5 to 4 meters deep & is bulit wholly or partly below ground. • The walls may be made of stone, brick or cement. • The filter box consist from top to bottom: 1.Supernatant water 1 to 1.5 meters. 2. Sand Bed 1.2 meters 3. Gravel Support 0.30 meter 4. Filter bottom 0.16 meter
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  FITER-CLEANING • Naturally thefilter may run for weeks or even months without cleaning. • When the bed resistance increases to such extent that the regulating valve has to be kept open fully. • It is time to clean filter bed, since any further increase in resistance is bound to reduce the filtration rate. • After several years of operation & say 20 to 30 scrapings, the thickness of the sand bed will have reduced to about 0.5 to 0.8 meter. • Then the plant is closed down & a new bed is constructed.
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  ADVANTAGE OF SLOWSAND FILTRATION • Simple to construct & operate. • The cost of construction is cheaper than that of rapid sand filters. • The physical, chemical & bacteriological quality of filter water is very high. • It will reduce total bacterial count by 99.99 percent & E. coli by 99.9 %.
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  RAPID SAND FILTERS( MECHANICAL FILTERS) • Since that time, they have gained considerable popularity even in developing countries. • Rapid Sand Filters are of two types: • A. Gravity type (e.g Paterson’s Filter) • B. Pressure type ( Candy’s Filter) • Both types are in use. • Following steps are involved in the purification of water by Rapid Sand Filters.
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  RAPID SAND FILTERS( MECHANICAL FILTERS) Mixing Chamber Flocculation Chamber Sedimentation Tank Fitters Chlorine Clear water storage RiverWater Consumption Alum
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  FILTER BEDS • Eachunit of filter bed has a surface of about 80 to 90 m2 (900 sq. feet). • Sand is the filtering medium. • The effective size of the sand particles is b/w 0.4 to 0.7 mm. • The depth of the sand bed is usually about 1 meter. • Below the sand bed is a layer graded gravel 30 to 40 cm deep. • The gravel supports the sand bed and permits the filtered water to move freely towards under the drain.
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  FILTERATION • As filtrationproceeds, the “alum-floc” not removed by sedimentation is held on the sand bed. • It absorbs bacteria from the water & effects the purification. • Oxidation of ammonia takes place during the passage of water through the filters. • As filtration proceed the suspended impurities and bacteria clog the filters. • The filters soon become dirty & begin to loose their efficiency. • When the “loss of head” approaches 7-8 feet, filtration is stopped & the filters are subjected to a washing process known as “Back Washing”.
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  BACK WASHING • Rapidsand filters need frequent washing daily or weekly depending upon the loss of head. • Washing is accompanied by reversing the flow of water through the sand bed which is called Back Washing. • It removes impurities & cleans the sand bed. • The whole process of washing takes about 15 minutes. • In some rapid sand filters compressed air is used as part of back washing.
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  ADVANTAGE OF RAPIDSAND FILTRATION • Rapid sand filter can deal with raw water directly. No preliminary storage is required. • The filter bed occupy less space. • The initial cost is high but becomes cost effective in future. • Filtration is rapid, 40 to 50 times that of slow sand filters. • The washing of the filters is easy. • There is more flexibility in operation.
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  5. Disinfection ofwater • Chlorination is one of the greatest advances in water purification. • Chlorine kills pathogenic bacteria, but it has no effect on spores & certain viruses (e.g Polio, viral hepatitis). • Apart from its germicidal effect, chlorine has several important secondary properties in water treatment. • It oxides' iron, manganese & hydrogen suphide. • It also helps in destroying some odour producing constituents, so improves the taste and odour. • It controls algae and slim organisms & acid coagulation. • The minimum recommended concentration of free chlorine is 0.5 mg/Liter for one hour.
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  USE OF CHLORINEIN PURIFICATION OF WATER • Chlorine can be used in different ways to purify the water. 1. Simple Chlorination 2. Chloramination 3. Super chlorination followed by Dechlorination
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  6. Water Softening •The main objective of a water softening is to reduce the hardness of water it removed by the following methods:- i. Boiling ii. Chemical disinfection
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  Assurance of waterquality • This is done by THREE ways: 1) Physical examination 2) Chemical examination 3) Bacteriological examination
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  Physical examination • Inthis we see for a) Turbidity < 5 nephelometric turbidity unit b) Colour 15 True colour unit (TCU) c) Taste and odour (should be palatable) d) Temperature cool e) No smell
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  Chemical Examination a) PH6.5 – 8.5 b) Chloride 250 mg/Litre c) Iron .3 mg/litre d) Na 200 mg/Litre e) Hardness 200 mg/litre f) Copper 1 mg/litre g) Zinc 3 mg/litre h) Arsenic .01 mg/litre i) Lead .01 mg/litre
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  Bacteriological Examination • Itshould be free from bacteria, viruses and helminths and protozoa • To see for bacteria’s we perform a) Presumptive Coliform test It is done on McConkey’s media for 48 hours We take
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  Conclusion • By completingthis project, we were made more aware of other water filtration methods, their practicality, and their benefits. Low quality water can lead to health hazards that can be avoided by putting into place these safe, inexpensive, and effective water filtration techniques.