ENVIRONMENTAL ENGINEERING II

1 A Course Material onENVIRONMENTAL ENGINEERING IIByMrs. Arul selviASSISTANT PROFESSORDEPARTMENT OF CIVIL ENGINEERINGSASURIE COLLEGE OF ENGINEERINGVIJAYAMANGALAM 638 056 QUALITY CERTIFICATEThis is to certify that the e-course materialSubject Code:CE2354 Subject: ENVIRONMENTAL ENGINEERING IIClass:IIIYear CIVILB eing prepared by me and it meets the knowledge requirement of the university of the AuthorName:ARUL : AP/CIVILThis is to certify that the course material being prepared by selvi is of adequate has referred more than five books among the minimum one is from abroad of HDName: KUMARSEALTABLE OF CONTENTSNOTITTLEPAGE NO1 Unit I planning For Sewerage Of Some Common Terms Used In TheSanitary Different Methods Of Domestic Waste Water DisposalInclude (Systems Of Sanitation) System of Partially Combined Or Partially Separate Sources of Effects Of Flow Variation On Velocity In A Of StormWater122 UNIT IISEWER DESIGN142 Learning And Step 2-Preliminary Horizontal Infiltration To Sewer Infiltration To Sewer Storm Water Design Of Sanitary Sewer Design Procedures183 Unit IIIP rimaryTreatment Of Pre-Aeration Primary Sedimentation Odour Septic Tank274 Unit IVSecondary treatment Of The Phosphorus At Slightly Acidic Process Chemical wastewater Improved Analytical Importance Of Improved wastewater Combined SewerOverflows (Csos), Sanitary SewerOverflows (Ssos)

2 , And Nonpoint Future Trends In wastewater wastewater Reclamation And Biosolids And Residuals Future Trends In Biosolids Processing43CE2354 ENVIRONMENTALENGINEERINGIILTPCOBJECTIVET oeducatethestudentsontheprinciplesanddes ignofSewageCollection,Conveyance,treatme ntanddisposalUNITIPLANNINGFORSEWERAGESYS TEMS9 Sourcesofwastewatergeneration Effects Estimationofsanitarysewageflow Estimationofstormrunoff FactorsaffectingCharacteristicsandcompos itionofsewageandtheir significance Effluentstandards Hydraulicsofflowinsewers Objectives Designperiod-Designofsanitaryand stormsewers Smallboresystems-Computerapplications Laying,joining&testingof sewers appurtenances Pumps UnitOperationandProcesses Selectionoftreatmentprocesses Onsitesanitation-Septictank,Greywaterhar vesting Primarytreatment Principles,functionsdesignanddrawingofsc reen,gritchambersandprimarysedimentation tanks SelectionofTreatmentMethods Principles,Functions,DesignandDrawingofU nits-ActivatedSludgeProcessandTricklingf ilter,othertreatmentmethods Oxidationditches,UASB WasteStabilizationPonds ReclamationandReuseofsewage-RecentAdvanc esinSewageTreatment ConstructionandOperation &MaintenanceofSewage dilution Selfpurificationofsurfacewaterbodies Oxygen sagcurve Landdisposal Sewagefarming Deepwellinjection Soildispersionsystem-Sludgecharacterizat ion Thickening Sludgedigestion Biogasrecovery SludgeConditioningandDewatering disposal , , ,KhannaPublishers,NewDelhi, , ,Jain, , ,EnvironmentalEngineering, ,LakshmiPublications,Newsletter, treatment ,CPHEEO,MinistryofUrbanDevelopm ent,GovernmentofIndia,NewDelhi, TreatmentandReuse, ,NewDelhi.

3 2003CE2354 ENVIRONMENTAL ENGINEERING IISCE1 Department of Civil EngineeringUNITIPLANNINGFORSEWERAGESYSTE MSS ourcesofwastewatergeneration Effects Estimationofsanitarysewageflow Estimationofstormrunoff FactorsaffectingCharacteristicsandcompos itionofsewageandtheirsignificance Effluentstandards wastewater isessentiallythewatersupplyofthecommunit yafterithasbeenfouledbyavarietyofusessuc hasspentwaterfrombathroomkitchen,lavator ybasins,houseandstreetwashings,from variousindustrialprocessessemisolidwaste sofhumanandanimalexcreta,dryrefuseofhous eandstreetsweepings,brokenfurniture, ,treatmentanddisposalarenotmade, , , ,itismostessentialtocollect, , ,solidwaste,liquidorgaseousawayfromthepr emisesofdwellingsasfastas possibleafteritisproduced,toasafeplace, , , ENGINEERING IISCE2 Department of Civil EngineeringEnvironmentalEngineeringServi ces,theimportanceofseweragesystemcannotb elastsightandcannotbeallowedtolagbehind, asallthewaterusedbythecommunity hastoflowbackasthesewageloadedwiththewas tesofcommunityliving,unlessproperlycolle cted,treatedanddisposedoff,this wouldcreateaserious :Thisisthemost generaltermtoindicatethewasteswhichinclu dealltherejectsleftasworthless,sewage,su llage :Itisadryrefusewhichincludes,wastepapers ,sweepingsfromstreetsandmarkets, quicklyas :Itconsistsofsundrysolidwastesfromtheres idencies, ,paper, :Itisthedischargefromthebathrooms,kitche ns,washbasinsetc.

4 ,itdoesnotincludedischargefromthelavator ies,hospitals,operationtheaters, :Itisadilutemixtureofthewastesofvarioust ypesfromtheresidential, ,urinals,hospitals,stables, :Itisthesewageobtainedfromtheresidential buildings&industrialeffluentsestablishme nts .Beingextremelyfoulitshouldbecarriedthro ugh ENGINEERING IISCE3 Department of Civil EngineeringDOMESTICSEWAGE:Itisthesewageo btainedfromthelavatorybasins,urinals&wat erclosetsofhouses,offices& greathandling& :Theentiresystemofcollecting,carrying& (DWF):Domesticsewageandindustrialsewagec ollectively, :-Aerobicbacteria:theyrequireoxygen& : ENGINEERING IISCE4 Department of Civil treatment , ofdomesticwastewaterdisposalinclude(Syst ems ofSanitation)1)CONSERVENCYSYSTEM2) excreta are collected separately in conservancylatrines. Theliquid and semi liquidwastes are collected separately after removal of night soil it is taken outside the town in trucksand buried in trenches.

5 After 2-3 years the buried night soil is converted into excellent manure. Inconservancy system sullage and storm water are carried separately in closed drains to the po intCE2354 ENVIRONMENTAL ENGINEERING IISCE5 Department of Civil Engineeringof disposal where they are allowed to mix with river water without , :1)SEPARATESYSTEMOFSEWAGE2)COMBINEDSYSTE MOFSEWAGE3) ,theyaretobeconstructedawayfromlivingroo msobuildingcannotbeconstructedascompact , , , ;thereis ,thereisnosuchproblemasincaseofconservan cysystemCE2354 ENVIRONMENTAL ENGINEERING IISCE6 Department of Civil EngineeringAdvantages:1)Sizeofthesewersa resmall2)Sewageloadontreatmentunitisless 3)Riversarenotpolluted4) )Seweragebeingsmall,difficultyincleaning them2)Frequentchokingproblemwillbetheir3 )Systemprovescostlyasitinvolvestwosetsof sewers4)Theuseofstormsewerisonlypartialb ecauseindryseasonthewillbeconvertedinto :1)Sizeofthesewersbeinglarge, )Itproveseconomicalas )Becauseofdilutionofsanitarysewagewithst ormwaternuisancepotentialisreducedDisadv antages:1) Size of the sewers being large, difficulty in handling and ) Load on treatment plant is unnecessarily increased3) It is uneconomical if pumping is needed because of large amount of combined ) Unnecessarily storm water is pollutedCE2354 ENVIRONMENTAL ENGINEERING IISCE7 Department of Civil :-1.

6 Duringdryweather, :-Aseparatesystemwouldbesuitableforuseun derthefollowingsituations:Whererainfalli s , ofboththesystems, ,likeIndiaandevenintemperateregions, ENGINEERING IISCE8 Department of Civil ,becausenotreatmentofstormwateris , , , , :-Sanitarysewageis ,itisusedforvariouspurposeslikebathing,u tensilcleaning,forflushing ,cinemas,hotels,railwaystations,etc., :-Sewageisadilutemixtureofthevarioustype sof wastesfromtheresidential, , ,Virus, protozoa, etc. sewage may also contain toxic or other similar materials which mighthave got entry from industrial discharges. Before the design of any sewage treatment plantthe knowledge of the nature of sewage is of Sanitary Sewage and Storm Water:-The determination ofsanitary sewage is necessary because of the following factors whichdepend on ,shapeanddepthofsewers ENGINEERING IISCE9 Department of Civil :-Sanitarysewageismostlythespentwateroft hecommunityintosewersystemwithsomeground waterandafractionofthestormrunofffromthe area, , , ( ),whichincludesthedomesticsewageobtained fromresidentialandresidentialandindustri alsetc.

7 , Quantity of Sewage:-It is usualto assume that the rate of sewage flow, including a moderate allowance forinfiltration equals to average rate of water consumption which is 135 litre/ head /day accordingto Indian Standards. It varies widely depending on size of the town etc. this quantity is knownas Dry Weather Flow ( ). It is the quantity of water that flows through sewer in dryweather when no storm water is in the of flow varies throughout 24 hours and is usually the greatest in the fore-noon and verysmall from midnight to early morning. For determining the size of sewer, the maximum flowshould be taken as three times the Discharge of Sanitary SewageThe total quantity of sewage generated per day is estimated as product of forecasted populationat theend of design period considering per capita sewage generation and appropriate peakfactor.

8 The per capita sewage generation can be considered as 75 to 80% of the per capitawater supplied per day. The increase in population also result in increase in percapita waterdemand and hence, per capita production of sewage. This increase in water demandoccurs due to increase in living standards, betterment in economical condition, changes in habitof people,and enhanced demand for public affecting the quantity of sewage flow:-The quantity of sanitary sewage is mainly affected by the following factors:1. Population2. Type of area3. Rate of water supply4. Infiltration and exfiltrationIn addition to above, it may also be affected by habits of people, number of industries andwater pressure ,industrialorCE2354 ENVIRONMENTAL ENGINEERING IISCE10 Department of Civil ,whichisexpressedalitres/ dependsontheirvariousindustrialprocesses , that all the water supplied does not reach sewers owing to such losses as leakage in pipesor such deductions as lawn sprinkling, manufacturing processes etc.

9 However, these lossesmay be largely be made up by such additions as surface drainage, groundwater infiltration,water supply from private wells etc. On an average, therefore, the quantity of sewage maybeconsidered to be nearly equal to the quantity of water supplied. Groundwater infiltration quantity of sanitary sewage is also affected by groundwater infiltration through quantity will depend on, the nature of soil, materials of sewers, type of joints in sewerline, workmanship in laying sewers and position of underground water increase to the legitimate flows in urban sewerage represents a slow response process resulting in increased flows mainly due toseasonally-elevated groundwater entering the drainage system, and primarily occurringthrough defects in the pipe ,resultinginreducedconveyanceflowsandis duetoleaksfrom defectsinthesewerpipewallsaswellasoverfl owdischargeintomanholes, ,rootpenetration,illicitconnections, biochemicalcorrosion,soilconditionsandtr afficloadingsas physical defectsinthesewerfabricandtheywillofteno ccurconcurrentlyduringfluctuationsingrou ndwaterlevels,andparticularlyinassociati onwithwetweatherevents.

10 Bothofwhichcangeneratelocallyhigh gains, ,beingdispersedintermsoftheirspatialdist ributioninthesewerpipe, pumping :CE2354 ENVIRONMENTAL ENGINEERING IISCE11 Department of Civil EngineeringMinimumMaximumLitre/day/hecta re5,00050,000 Lpd/ ,000 Design design period can be considered for different components of sewerage Laterals less than 15 cm diameter : Full development2. Trunk or main sewers : 40 to 50 years3. treatment Units : 15 to 20 years4. Pumping plant : 5 to 10 yearsVariations in sewage flow:-The sewage flow, like the water supply flow, is not constant in practice but varies. The fluctuationmay, in a similar way, be seasonal or monthly, daily and occurs in the flow of sewage over annual average daily flow. Fluctuation in flow occursfrom hour to hour and from season to season. The typical hourly variation in the sewage flow isshown in the Figure . If the flow is gauged near its origin, the peak flow will be quite peak will defer if the sewage has to travel long distance.