octnik gaunte zakaryus
Arabella Kochanski
UNIT-I Systems of sanitation: Conservancy and water carriage system. Patterns of sewage collectionsystems. Quantity of storm water and sanitarywastewater. Hydraulic Design of sewers - capacity, size, grade, shapes andmaterials. 2
Refuse: Anything rejected or left asworthless. (Solid & Liquid) Sullage: Wastewater from bath rooms, kitchens, etc. & does not include human or animal excreta. Sewage: Liquid waste from community & includes sullage, discharge from latrines, urinals, industrial wastewater & stormwater. SanitarySewage:Liquidwasteofdomestic&industrialplaces.Extremelyfoulinnature&required to be disposed off verycarefully. Sewer: Underground conduits or drains through which sewage is conveyed are known as sewers. Sewerage:The entire science of collecting and carrying sewageby water carriage system through sewers is known as sewerage. Sanitation: Science of preserving health of public & such condition which will prevent the outbreak of diseases dangerous for general health of public. Sanitary Engineering : Branch of Public Health Engg. which deals with all the aspects of provision of sanitation facilities. 25
Importance of SanitationSystem:- Spent water from bathroom, kitchens, basins, house washing, street washing, from industrial processes, semi liquid waste of human and animal excreta, dry refuse of houses, etc are produceddaily. If proper arrangement for collection, treatment & disposal of all waste produced are not made, they will go on accumulating & creates such foul condition that the safety of the structure such as building, roads will be in danger due to accumulation of wastewater in the foundation. The disease producing bacteria spread up in the stagnate water & the health of public will be indanger. All the drinkable water will bepolluted. Total insanitary conditions will be developed in thetown. It will be impossible for public to live in thecities. Therefore in the interest of community or society it is most essential to collect treat & dispose of all the waste products in such a way that it may not cause any havoc to the people residing in thetown. 11
Points are to be considered before finalizing a SanitationProject:- Financialaspects: Population: Quality ofsewage: Rainfall: Rate ofsewage: Sources ofsewage: Topography ofarea: Present method ofdisposal: TreatmentMethods: Trends of towndevelopment: 14
Site for Sewage TreatmentWorks:- Good foundation soil should be available for various units to rest firmly on theground. The general slope of the site should be moderate, so that flow from one unit to the othertake place by gravityonly. Site should be lowest level area of the town, so that sewage from entire town canbe collected by gravityonly. Enough area is available for futureexpansion. Safe fromflood. Site should be situated on the leeward side ofwind. Not far way fromcity. Subsoil water level at the site should be remain low even duringmonsoon. 15
Sewage or Wastewater: Used water or liquid waste generated by the community due to its variousactivities. Any water or liquid that contains impurities in such a concentration that isharmful if disposed into theenvironment. It is 99.9% water & 0.1%solids Quantity of sewage = 75 to 80 % of the watersupplied Lesser the supply of water greater the strength &vice-versa. 16
Partially SeparateSystem: 1) Part of the storm water especially collected from roofs and paved courtyards of the buildings is admitted in the same sewer along with sewage from residences and institutions, etc. The storm water from the other places is collected separately using separateconduits. Advantages: Economical and reasonable size sewers arerequired. Work of house plumbing is reduced as rain water from roofs, sullage from baths and kitchen, etc. are combined with discharge from waterclosets. Flushing of sewers may not be required as small portion of storm water is allowed to enter in sanitarysewage. Disadvantages: The quantity of storm water admitted in sewer may increase the load on pumping and treatmentunits. Self-cleansing velocity may not develop in the sewers in dryweather. 29
Patterns of CollectionSystem: PerpendicularPattern InterceptorPattern RadialPattern Fanpattern ZonalPattern The patterns of collection system dependupon: The topographical and hydrological features of thearea. The location and methods of treatment and disposalworks. The type of sewerage system employed,and Extent of area to beserved. 31
Quantity of SanitarySewage: The quantity of sanitary sewage is mainly affected by the followingfactors: Rate of watersupply Population Type of area served as residential, commercial, industrial,etc. Ground waterinfiltration. Determination: Quantity of sanitary sewage should be equal to the quantity of water applied by water works but actually subtraction are done due to leakage or water being consumed indrinking, cooking, sprinkling,etc.After doing all calculation, addition & subtraction, Quantity of sanitary sewage = 75 to80% of the total watersupplied.
Variation in Quantity of SanitarySewage: Practical average never flow in sewer, it continuously varies from hour to hour of theday and season toseason. The design of sewer should be done for the maximum possibleflow. Fluctuation is due to outcome certain local condition, habits, customs, holidays, season,etc. Self cleansing velocity should be maintained in the case of minimumflow.
DesignPeriod Thefutureperiodforwhichtheprovisionismadeindesigningthecapacitiesofthe variouscomponentsofthesewerageschemeisknownasthedesignperiod. The design period depends upon thefollowing: Ease anddifficulty in expansion, Amount andavailability of investment, Anticipatedrateofpopulationgrowth,includingshiftsincommunities,industries and commercialinvestments, Hydraulicconstraintsofsystemsdesigned,and Lifeofmaterialandequipment. Laterals less than 15 cm diameter : Fulldevelopment Trunk or main sewers : 40 to 50years Treatment Units : 15 to 20years Pumping Plant : 5 to 10years
Important Factors Considered for SelectingMaterialforSewer :Resistance tocorrosionResistance toabrasionStrength anddurabilityWeight of thematerialImperviousnessEconomy andcostHydraulicallyefficient Materials forSewers : Asbestos Cement Sewer Plain Cement Concrete RCC Vitrified Clay or Stoneware Sewers Brick Sewers Cast Iron Sewer Steel Pipe Sewer Ductile Iron Pipes Plastic Sewers or PVC Pipe
Egg ShapedSewer:- Thedepthoftheseseweris1.5mtimesoftheirwidth. Constructed at site & made of concrete and brick arch with special invert at bottom ofRCC. Betterhydraulicpropertythancircularwithlowdischarge. Usedinbothcombined&separatesystem. MostsuitableforcombinedsystembcozgivesselfcleansingvelocityeveninDWF. Equally suitable for separatesystembcozeasily accommodate the flow of sewage withthedevelopmentofthetown. Disadvantages are construction is difficult, less stable &requires good masonary backing.
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