Wastewater TreatmentWastewater generationCollection SystemsSlide 4Slide 5Four levels of wastewater treatmentSlide 7Preliminary Treatment: ScreensPreliminary Treatment: grit removalSecondary TreatmentSlide 11Slide 12Biological TreatmentTerminal electron acceptorSlide 15Slide 16Terminal Electron Acceptor (TEA)Wastewater TreatmentCE 326 Principles of Environmental EngineeringProf. Tim EllisSpring 2008Wastewater generationTABLE 1Typical wastewater flowrates from various sourcesFlow, L/unit - dSource Unit Range TypicalAirport Passenger 8-15 11Cabin, resort Person 30-190 150Cafeteria Customer 4-11 8Employee 30-45 38Campground (developed) Person 75-150 115Cocktail lounge Seat 45-95 75Coffee shop Customer 15-30 23Dormitory, bunkhouse Person 75-190 150Collection SystemsSeparate sewersCombined sewersCombined sewer overflowsCombined sewer overflowsPhoto courtesy of Water Environment Federation Collection Systems Committee –cMOM SubcommitteeRegulations Federal Water Pollution Control Legislation, USRefuse Act of 1899Water Pollution Control Act of 1948Federal Water Pollution Control Act of 1956Amendments tothe FWPCA of 1961Water Quality Act of 1965Clean Water Restoration Act of 1966Federal Water Pollution Control Act Amendments of 1972(Clean Water Act)Clean Water Act of 1977Municipal Wastewater TreatmentConstruction Grant Amendments of 1981Water Quality Act of 1987Ocean Dumping Ban Act of 1988Infuent1) Preliminary Treatment2) Primary sedimentation3) Biological Process: Conversion to settleable solids4) Secondary sedimentation5) Sludge solids to further treatment and disposal5) Sludge solids to further treatment and disposalReceiving waterWastewater TreatmentProcess stepsFour levels of wastewater treatmentP_______________ScreensGrit removalP_______________Solids settlingS_______________Biological treatment Settling of biological solidsT______________FiltrationScreens:sticks, rocks, logs, shoes, dead animals, etc.Grit Removal:grit causes undue wear downstream unit processesWastewater TreatmentPreliminary TreatmentPreliminary Treatment:ScreensBar ScreensBar RacksPreliminary Treatment: grit removalSecondary TreatmentBiological treatmentClassification of microorganisms by their c______ and e______ source.Secondary TreatmentH________________Utilize organic matter to supply their carbon and energy needs. These are the predominant organisms in biological wastewater treatment plants, responsible for converting organic pollutants tocarbon dioxide, water, and additional heterotrophic biomass.Secondary TreatmentA________________get their energy from an inorganic source and their carbon from carbon dioxide. An example of autotrophs in wastewater treatment is nitrifying bacteria. Nitrifiers use ammonia for energy and carbon dioxide for a carbon source.End products of nitrification arenitrate, water, andhydrogen ions additional nitrifying (autotrophic) biomass.Biological TreatmentClassification of microorganisms by their t__________ e__________ a__________Terminal electron acceptorA___________:microorganisms transfer electrons from the energy source to oxygen, O2. In the process oxygen and organic matter is converted to carbon dioxide, CO2, and water, H2O. Oxygen is termed the terminal electron acceptor or TEA.Terminal electron acceptorA___________:microorganisms utilize some other oxidized compound to accept electrons. In the case of denitrifying microorganisms, nitrate, NO3-, serves as the TEA, as nitrate is converted to nitrogen gas, N2Terminal electron acceptorA___________:utilize CO2 and organic compounds as terminal electron acceptors. In this process, organic compounds are converted to fermentation products and carbon dioxide. In anaerobic digestion of wastewater solids, the fermentation products are converted tomethane, CH4, and carbon dioxideTerminal Electron Acceptor (TEA)Process TEA Predominant Reactions ExampleAerobicAerobicAnoxicAnaerobic O2 O2NO3-CO2 organic matter + O2  CO2 + H2ONH3 + O2  NO3- organic matter + NO3-  N2 + CO2 + H2Oorganic matter  CH4 + CO2 + H2OCBOD removalnitrificationdenitrificationanaerobic