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Environmental Engineering-I (Water Supply Engineering) Prof. Rajesh Bhagat

Environmental Engineering-I (Water Supply Engineering) Prof. Rajesh Bhagat Asst. Professor, CED, YCCE, Nagpur B. E. (Civil Engg .) M. Tech. ( Enviro . Engg .) GCOE, Amravati VNIT, Nagpur Experience & Achievement:

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Environmental Engineering-I (Water Supply Engineering) Prof. Rajesh Bhagat

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  1. Environmental Engineering-I (Water Supply Engineering) Prof. Rajesh Bhagat Asst. Professor, CED, YCCE, Nagpur B. E. (Civil Engg.) M. Tech. (Enviro. Engg.) GCOE, Amravati VNIT, Nagpur Experience & Achievement: Selected Scientist, NEERI-CSIR, Govt. of India. GATE Qualified Three Times. Selected Junior Engineer, ZP Washim. Three Times Selected as UGC Approved Assistant Professor. Assistant Professor, PCE, Nagpur. Assistant Professor, Cummins College of Engg. For Women (MKSSS, Nagpur) Topper of Pre-PhD Course Work at UGC-HRDC, RTMNU Nagpur Mobile No.:- 8483002277 / 8483003474 Email ID :- rajeysh7bhagat@gmail.com Website:-www.rajeysh7bhagat.wordpress.com

  2. UNIT –III WaterQuality : General idea of water borne diseases, Physical, Chemical and biological characteristics of water, Standards of drinking water. Water Treatment : Objective of treatment, unit operations andprocesses. Treatment Flow sheet of conventional water treatmentplant. Aeration: Purpose, types of aerators. Coagulation&Flocculation:Definition, Principals, types of coagulants and Reactions, coagulant doses, types of mixing and flocculationdevices.

  3. Types ofWater:- PureWater:- It is chemical compound (H20), which contains two parts of hydrogen and one part ofoxygen. It is not good forhealth. It is not possible to find absolutely pure water in nature water drops just emitting out of the clouds may be considered as chemically purewater. Distilled water is the purewater. PotableWater:- 1. The water have both the characteristics of ‘wholesome water’ and ‘palatable water’ is known as Potablewater.

  4. WholesomeWater:- It is that water which is not chemically pure but does not contain anything harmful to human health. It also have sufficient amount of necessary elements orminerals. PalatableWater:- 1. Water which is aesthetically looking good and tasteful fordrinking. PotableWater:- 1. The water one which have sufficient amount of mineral, tasteful fordrinking, aesthetically looking good and doesn’t contain anything harmful to human health is known as Potablewater.

  5. ContaminatedWater:- 1. It contains pathogenic bacteria and unfit fordrinking. PollutedWater:- It contains undesirable substances making it unfit for drinking and other domestic use. The contaminated water is always polluted water but polluted water is not always contaminated water because contaminated water contents pathogens & Polluted water may or may not be contentspathogens.

  6. Water Quality & Water QualityStandards • Water quality is determined by assessing three attributes or parameter: Physical, Chemical &Biological. • Water Quality Standards are the criteria which describes the parameter for drinking water. • Standards are any definite measure or limited level of concentration established by regulatory authority for the purpose of protecting or preparing a water resources for one moreuses. • United States (Federal government's) Environmental Protection Agency(EPA). • World Health Organization's Guideline for DrinkingWater.(WHO) • Bureau of Indian Standards gives the specification for drinking water (IS-10500) • American Water WorkAssociation. • Central Pollution ControlBoard. • State Pollution ControlBoard. • Ministry of UrbanDevelopment. • Central Public Health & Environmental Engineering Organization(CPHEEO).

  7. WaterAnalysis Water analysis is the assessmentordetermination of quality of water, whether water is good for various domestic purpose ornot. Water analysis is the determination of various physical, chemical & biological characteristics ofwater. Various types of impurities present in water & it can be determined by water analysis.

  8. Water BorneDiseases:- Amoebiasis(hand-to-mouth) Protozoalinfections Cryptosporidiosis (oral) Protozoalinfections Cyclosporiasis Giardiasis (fecal-oral) (hand-to-mouth)Parasite Dracunculiasis (Guinea Worm Disease)Parasite Cholera (bacteria) Dysentery(bacteria) Typhoid fever(bacteria) Hepatitis A ( Virusinfection) Other: Polio, Fluorosis, Trachoma, Hepatitis, Diarrhea, Giardiasis, Ascariasis, Trichuriasis, Arsenicosis, Malnutrition, Legionellosis, Leptospirosis, Schistomiasis, Dracunculiasis, Onchocerciasis, Lead poisoning, Cryptosporiodiosis, Campylobacteriosis, Lymphatic filariasis, Hookworm infection, Ring Worm or Tinea, Methaemoglobinemia, Cyanobacterial toxins,Japanese encephalitis,etc.

  9. Purpose of WaterAnalysis: To classify the water with respect to general level of mineralconstituents. To determine the degree of clarity and ascertain the nature of matter in suspension. To determine the chemical & bacteriological pollution ofwater. To determine the presence or absence of an excess of any particular constituents. To determine the level of organicimpurities. Toascertainwhetherpurificationofwaterhasreachedtherequiredstandards ornot. Todecidetreatmentisnecessaryornotandifitis necessary then what extent of treatmentneeded.

  10. Characteristics ofWater:- • Physical Characteristics ofwater: • Color • Taste • Odor • Temperature • Turbidity • Chemical Characteristics ofwater: TotalSolids Chloride pH Conductivity Hardness Alkalinity NitrogenContents Metal & Other Chemical Substances( Iron, Manganese, Sulphate, Copper,etc.) Dissolved Gasses (DO, BOD &COD) • Biological Characteristics ofwater: • Micro-organism like aquatic plants, aquatic animals, bacteria, viruses,etc.

  11. Turbidity:- Turbidity is a measure of how clear the wateris. It is the property of water which measures the resistance to passage of light through thewater. Itisameasureofthedegreetowhichthewaterloosesitstransparencyduetothe presence of suspendedparticulates. It is imparted by the suspended, colloidal & dissolved matter present inwater. More turbidity more pollutedwater. NTU: Nephelometric TurbidityUnits. Nephelometer, colorimeter or turbidimeter, which measures the intensity of light scattered at 90 degrees as a beam of light passes through a watersample.

  12. Turbidity:- On olden days turbidity measured by Baylis Turbidimeter, Jackson Turbidimeter,Turbidity Rod,etc. Jackson’s turbidimeter measures the influence to light passage in a straight line while nephelometer measure the scattering of light fromparticles The more intensity of light scattered, more will beturbidity. 1 NTU = 1 FTU (Formazin Turbidity Unit) 1 mg of formazin polymer can produce same 1NTU turbidity if added in 1 liter distilledwater. Desirable 1 NTU and Permissible 5 NTU, according toIS-10500.

  13. Color:- Color due to presence of organic matter, suspended matter, colloidal matter,etc. It can be measured against various standard or scale such as Hazen, Platinum, Cobalt, Platinum Chloride scale usingtintometer. Color on platinum cobalt scale should not exceed 20 & preferably be less than 10ppm. 10ppm color on platinum cobalt scale means 10mg of platinum cobalt powder in 1 liter distilled water gives same kind ofcolor. Color, Hazen Units, IS 10500-2012, Desirable : 5 Hz. , Permissible : 15Hz. If color is more, acceptancedecreases. Treatment: Filtration, Reverse osmosis,etc.

  14. Taste &Odor:- It is due to dissolved organic matter, inorganic matter, dissolved gases, minerals, salts, microscopic organism chemicals compounds,etc. Threshold Number is the standard unit for measuring taste andodor. Taste is expressed as FTN ( Flavor ThresholdNumber). Odor is expressed as TON ( Threshold OdorNumber). 1 to 3 is permissible.(pleasant) As per IS-10500, it should beagreeable. Temperature:- The temperature of water should be between 100c to200c. Temperature higher than 250c is consideredobjectionable.

  15. pH:- pH value of water indicates the logarithm of reciprocal of hydrogenion conc. Present in water. Lower H+ ions means highpH. It can also measure of degree of acidity or alkalinity ofwater. 3) pH = -log10(H+) 4) Measured by potentiometer or colorimetricmethod.

  16. Conductivity:-:- It depends on dissolved saltcontent. μ mho/cm (SpecificConductivity) Measuring the conductivity is an accurate way to determinesalinity. Freshwater= microSiemens (uS) Saltwater = milli Siemens(mS)

  17. Chloride:- Generally it present in the formNaCl. It imparts saltytaste. Desirable = 250mg/L & Permissible =1000mg/L Presence of high conc. indicates pollution fromsewage. It can be measured by titrating the water with standard silver nitratesolution using potassium chromate (1ML) as indicator (100ML watersample). Mohr Method (pH range 6.5 to9) Ag+ + Cl- → AgCl (whiteprecipitate) 2 Ag+ (excess) + CrO 2- →AgCrO (brownish or red precipitate isendpoint) 4 2 4

  18. Total Solids:- All matter except water containing liquid materials classified as solidmatter. Total solids as that matter which remains as a residue after drying& evaporation at 1050C (+ -50C). Suspended Solids can be found by filtering water sample throughWhatman filter paper no.44. Material retained on the filter is dried &weighed.

  19. Hardness:- It prevents the formation of sufficient lather or foam withsoap. Expressed in terms of mg/L ofCaCO3. Temporary & Permanenthardness. Temporary or carbonate hardness due to HCO3 & CO3 of Mg & Ca. (removed by boiling &lime) Permanent or non-carbonate hardness by SO4, Cl, NO3, of Ca, Mg.(water softening methods like lime soda process, zeolite process,etc.) Versenate Method is used to determine the hardness by titrating againstEDTA using EBT indicator. (Buffer + EBT + EDTA + wine red to skyblue) Soft = 0 to 100, Moderate = 100 to 150, Hard = 150 to 300 & Very Hard = >300

  20. Alkalinity:- It is the acid neutralizing capacity ofwater. It is caused by bicarbonate (HCO3), hydroxide (OH), carbonate (CO3) andvery little -ve alkalinity is also caused byH+ Total Alkalinity = HCO3+ OH + CO3 -H+ 100 ML Water + 2 Drops Phenolphthalein Indicator + H2S04 TillColorless. 2 Drops Mixed Indicator + H2S04 Blue toRed. Highly alkaline water isunpalatable. Desirable =200mg/L & permissible = 600 mg/L in terms ofCaCO3.

  21. Nitrogen Content:- • The presence of nitrogen in water indicates presence of organicwater. • The presence of the organic may occur in followingform: • Freeammonia 2) Albuminoid orOrganicnitrogen 3)Nitrites 4)Nitrates • Free ammonia indicates presence of undecomposed organic matter & represents first stage decomposition. (permissible limit < 0.15mg/L) • Albuminoid nitrogen indicates decomposition of organic matter has started, limit shall not exceed 0.3mg/L. • Nitrites indicates partly decomposed organic matter, permissible limit isNIL. • Nitrates indicates fully oxidised organic matter, permissible limit <45mg/L • Excessive conc. of nitrates can causemethaemoglobinaemia. • Sum of ammonia nitrogen & organic nitrogen is called kjedahlnitrogen. • Nitrates or nitrites present in water can be measured by color matchingmethods.

  22. Metal & other chemical substances:- Iron (0.3) & Manganese (0.1 & 0.3): High concentration is undesirable, as it may cause discoloration of cloth washed in such waters. They also cause incrustation in water mains due to deposition of ferric hydroxide and manganese oxide. Fluoride: concentration less than 1 mg/L may cause dental caries like tooth decay. Concentration greater than 1.5 mg/L may cause spotting & discoloration of teeth or fluorosis & deformation ofbones. Lead (0.01), Copper (0.05 & 1.5) , Arsenic(0.01), Selenium (0.01)& barium are toxic therefore very low concentration isprovided. High conc. of Copper affect the human lungsadversely. The most of the metals and other chemical substances present in water can be estimated by using color matching method by using differentindicators.

  23. Dissolved Gases:- The various gases may get dissolved in water due to its contact with the atmosphere or the ground surface. (nitrogen, methane, hydrogen sulphide, carbon dioxide &oxygen) H2S even at small amounts may give bad taste and odor towater. PresenceofCO2indicatesbiologicalactivity&impartsbadtaste,odor&cause corrosion. DissolvedOxygen. Biochemical OxygenDemand.

  24. Dissolved Oxygen:- Capacity of water to absorb DO depends ontemperature. Winkler method is used to measureDO. 4 mg/L- fish survival, 14.6 mg/L at O0C, 9.1 mg/L at 200C , 7mg/L350C.

  25. BOD:- Amount of free oxygen required by micro-organism for stabilization of organic matter under aerobic condition at a specified temp. & time (200C & 5Days). Theoretically infinite time required to complete biological oxidation, butall practical purpose, the reaction may be complete in 20days. However20daysistolongperiodtowaitforresult&alarge%ofBODis exerted in 5days.

  26. Biological Characteristics:- • Pathogen is a bacteria, virus, or other microorganism that cancause disease. • It can be living things or non-livingthings. • Non-pathogenic bacteria are harmless exE-coli. • E-coli is used as indicator & it should be Nil /100ml. • Measurement of E-coli by Total count Test, E-coli Test & Membranefilter. • The various micro-organism found in waterare: • Aquatic plants (algae) • Bacteria • Viruses • Protozoa

  27. Water Treatment:- It is the removal impurities from the water, which are harmful the human health (Environment). Itistheprocessforenhancingthequalityofwatersothatitmeetswaterquality criteria for its fitness for particularpurpose. Watertreatmentisprocessesthatmakeswatermoreacceptableforanend-use, which may be used for drinking, industry, ormedicine.

  28. Objectives of Water Treatment:- To make water fit for various industrial & domestic uses such as drinking, cooking, washing,etc. To remove the unpleasant & objectionable color, odor & taste from thewater. To remove obnoxious gases from thewater. To kill all the pathogenic germs, which are harmful to humanhealth. To eliminate the tuberculating & corrosive properties of water which affects the conduits andpipes. To achieve technical feasibility &economy. To provide required quantity and quality of water toconsumer. To maintain the water quality as perrequirements.

  29. Water Treatments:- • Water treatment is a combination of physical, chemical & biologicalprocesses. • These are three types of unit operation and unitprocesses. • Physical Unit Operation: in which physical forces are predominate for removal of impurities. (screening, equalization, mixing, flocculation, sedimentation, floatation,etc.) • Chemical Unit Processes: in which removal of contamination are brought about by chemical activity. (chemical precipitation, disinfection, gas transfer, adsorption,etc.) • Biological Unit Processes: : in which removal of contamination are brought about by biological activity. (Aerobic, Anaerobic & Aerobic-anaerobic Biological Unitprocesses)

  30. Biological UnitProcesses: • in which removal of contamination are brought about by biological activity. (Aerobic , Anaerobic & Aerobic-anaerobic Biological Unitprocesses) • AerobicBiologicalUnitProcesses:removalofimpuritiesordecompositionof • organic matter in presence of oxygen (RSF, Trickling filter, aerated lagoons,etc) • AnaerobicBiologicalUnitProcesses:removalimpuritiesordecompositionof • organic matter in absence of oxygen (anaerobic lagoons,etc) • Aerobic-Anaeerobic Biological Unit Processes: combination of above two (stabilization pondetc)

  31. Methods of Water Treatment:- Screening Aeration Plain Sedimentation or PrimarySedimentation. Coagulation &Flocculation Secondary Sedimentation or Sedimentation with Coagulant(Clarifier, Clariflocculator) Filtration Disinfection Softeningetc.

  32. Treatment Units & Function:- Screens : To remove large size floating matter like debris, fish, vegetation, garbage, etc. from the raw water by protective barscreen. Aeration: To add dissolved oxygen inwater. Plainsedimentation:Toremovesettleablesuspendedsolids&othermatterby passing water through large volume tanks where the flow speed slowsdown. Coagulation: To Add coagulant inwater. Flocculation: To form floc inwater. Secondary sedimentation (Clarifier, Clariflocculator): water is applied to large volume tanks where the flow speed slows down and the suspended solids or floc areremoved. Filtration: To trap remaining impurities by physicalstraining. Disinfection: To killpathogens. Softening: To remove hardness ofwater.

  33. Screens:- Screening devices are the 1st unit operation in treatmentplant To remove large size floating particles such as debris, animals, bushes, pieces of woods, plastics, leaves, aquatic plants, rags, solids, lumber, tree, branches, roots, etc. Itconsistsofparallelbars,rodsorwire,grating,wiremeshorperforatedplate, having opening of any shape but circular & rectangular arecommon. The materials removed by these devices are termed asscreening. Thescreeningsareusuallynobiodegradablematerials&canbeusedforland fillingpurposes. To prevent the pump, pipe, other equipment from getting damage orclogging. To increase the efficiency of other treatmentprocess.

  34. Screens:- • To prevent the pump, pipe, other equipment from getting damage orclogging. • To increase the efficiency of other treatmentprocess. • Types ofScreens:- • Fine Screens (Opening < 25mm) • Medium Screens (Opening = 25 to 50mm) • Coarse Screens (Opening = 50 to 150mm)

  35. Coarse Screens:- Are classified as either bar racks (trash racks) or barscreen. It consists of parallel bars or rods of steel or stainlesssteel. It can be used to entrap the coarse materials to protect the damaging ofpumping units. Bar racks are used as pretreatment applications. These bar racks may be hand cleaned if small in size or mechanical cleaned if largesizes. To prevent the settling of coarse materials in the channel, the velocity inthe approach channel must be in range of 0.3 m/sec to 0.6m/sec. Width of the bar 5 mm to 15mm. Allowable headloss 150mm.

  36. Aeration:- Aeration is the process of exchange of gases by creating good interfacebetween liquid phase and gasphase. It is the process of bringing water in intimate contact with air, while doing sothe water absorbs oxygen from theair. CO2 can remove upto60%. Iron,Manganese. H2S & other gases are also removed up-to certain extent from thewater.

  37. Objectives of Aeration:- To add the oxygen, to impart freshness towater. To remove or decrease the CO2 content of water & thereby raisesits pHvalue. To remove H2S content of water & thereby removal ofodor. To remove CH4 & taste caused due to organicdecomposition. To convert iron & manganese from their soluble states to their insolublestates, so that these can be precipitated & removed and thereby we can remove color, taste &odor. To add oxygen, to oxidize organic matter & thereby removal ofvolatile substances.

  38. Factors Affecting Aeration Process:- If the partial pressure is more, more will be the solubility & rate of exchange of gas & thereby more will beaeration. If the temperature of water is less, less will be the solubility & less will beaeration. If the concentration of impurities is more then solubility will be less & thereby aeration will be less. If the surface area of interface is more, more will be the rate of exchange of gases & thereby aeration will bemore. If the thickness of interface is more, less will be the rate of exchange of gas & thereby aeration will beless. If time of contact is more then more will be exchange of gas & thereby aeration will be more. If degree of under saturation is more then fast will be rate of exchange & thereby aeration will bemore.

  39. Limitation of Aerations:- It is not an efficient process for removal of tastes & odors caused by relativelynon- volatile substances such as oils, algae & industrialwastewater. Odor removal is 50% when symura bacteria ispresent. Aeration may add more oxygen in water & making it morecorrosive. Fe & Mn can not be precipitated by aeration when organic matter ispresent. Possibility of air borne contamination isthere. Additional lime may be required to neutralize the CO2 that would be removed byaeration Aeration is not economical in colder months or state orarea.

  40. Types of Aerators:- • SprayAerators. • Diffused Air Aerators. • GravityAerators: • CascadeAerator • Multiple TrayAerator • Inclined ApronAerator • Slopping TrayAerator.

  41. Cascade Aerators:- Simplest free fallaerator. Waterfalls & weirs of any kind are cascadeaerator. Water allowed to fall through a certain height of 1 to 3 m due to this water comesinto close contact withair. It consist of 3 to 9 steps of concrete ormetal. Rise of steps should be 20 to 50cm.

  42. Inclined Apron Aerators:- Water allowed to fall along an inclined apron which is usually studded with riffleplates. Due to the riffle plates water jumps into the atmosphere causing moreaeration.

  43. Multiple Tray Aerators:- Consists of closely stack perforated trays or panel. Water is allowed to fall freely from tray to tray due to which water comes in contact with air.

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