Wastewater treatment


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Wastewater treatment

  1. 1. Wastewater TreatmentWastewater Treatment EngineeringEngineering
  2. 2. Environ. Engineering Course Sequence CE4501 Env.Chem P-Chem GE3850 Geohydrol. CE4508, 4507,4509 Drinking & WasteWater ce4505 Surf.Water CE3501 CE3502 CE4504 Air Quality CE4506 Regs,P2,3 Fluids BL4451 Limnology FW4220 Wetlands CE4620 Open Channel Flow CE3620 Water Resources Thermo CE4630 Hydraulic structures CE5508: Biogeochem., CE5504: Surf.Water Qual. Modeling
  3. 3. Historical BackgroundHistorical Background Public Health Environmental Protection Investigation of an outbreak of cholera in London in 1854 provided one of the first links between sewage disposal, drinking water supply and waterborne disease. A 1920s, study of the East and Fox Rivers in Green Bay was commissioned because workers in downtown could not open windows in summer due to the stench. Environmental problems plague this system to this day.
  4. 4. What’s in wastewater?  human feces and urine  food from sinks  soaps and other cleaning agents  runoff from streets and lawns  industrial discharges Nature of WastewaterNature of Wastewater
  5. 5. … and water … lots of it!  Urinal - 1 gallon per flush – 0.4 gal/flush  Toilet - 4 gallons per flush – 2 gal/flush  Shower - 20 gallons per use  Overall - 55 gal/person/day Nature of WastewaterNature of Wastewater
  6. 6. So what’s the problem? Pollutant Problem Solids Aesthetics Pathogens Disease Organic matter Oxygen Nutrients Plant growth Organics/Metals Toxicity Nature of WastewaterNature of Wastewater
  7. 7. Level Approach Removed Primary (1°) Physical Solids, organic matter Secondary (2°) Biological Organic matter, nutrients Tertiary (3°) Various Nutrients, toxics Disinfection Various Pathogens Levels of TreatmentLevels of Treatment
  8. 8. Regulatory BasisRegulatory Basis Clean Water Act of 1972 (since amended) • Technology-based standards (2°) • Water quality-based standards • Fishable-swimmable • NPDES (permitting system) • TMDLs (maximum daily loads)
  9. 9. Scope of ApplicationScope of Application On-Site Rural - Municipal Urban - Municipal Industrial
  10. 10. Portage Lake Wastewater Treatment Plant Lift Station Bar Screens Grit Chamber Flow Equalization 1° Clarifier 1° Clarifier 2° Clarifier 2° Clarifier Aeration Tank UV Disinfection 1st Stage Anaerobic Digester 2nd Stage Anaerobic Digester Land Application Sludge Storage Filter Press Recycle Supernatant RAS RAS WAS 1°S PolymerAdded Fe added Fe added
  11. 11. Bar Racks and Screens Wastewater TreatmentWastewater Treatment (Preliminary)(Preliminary) Bar racks and screens remove large solids which could clog pumps and pipes in the wastewater treatment plant. Solids are collected and sent to a landfill.
  12. 12. Settling Tank Wastewater Treatment (Primary)Wastewater Treatment (Primary) Settling tanks remove the large solids which remain suspended in the wastewater and about 50% of the oxygen-demanding substances. The solids are sent on for further treatment (sludge digestion) and ultimate disposal.
  13. 13. Activated Sludge Wastewater Treatment (Secondary)Wastewater Treatment (Secondary) In the activated sludge process, bacteria and other microorganisms are used to remove small solids and oxygen-demanding substances present in the wastewater. Outflow from this tank undergoes settling and the excess sludge is sent on for further treatment (sludge digestion) and ultimate disposal.
  14. 14. Wastewater Treatment (Tertiary)Wastewater Treatment (Tertiary) Phosphorus removal by precipitation … Ferric chloride, Fe(Cl)3 producing FePO4 and Fe(OH)3 Alum, Al2(SO4)3·18H2O producing AlPO4 and Al(OH)3 Tertiary treatment refers to any of a variety of biological, chemical, and/or physical methods used to reduce levels of specific pollutants in a wastewater stream. Among these are levels of solids and oxygen-demanding materials, toxic metals and organic chemicals, and algal nutrients such as nitrogen and phosphorus. All wastewater treatment plants (>2 MGD) discharging to the Great Lake are required to remove phosphorus. This is often accomplished through chemical precipitation as described below.
  15. 15. Wastewater Treatment (Tertiary)Wastewater Treatment (Tertiary) Carbon adsorption Carbon adsorption is an incredibly effective means of removing organic chemicals from wastewater … chemicals which would otherwise pass through the plant and enter the environment. This technology is also applied in drinking water treatment, both municipally and with consumer-installed devices.
  16. 16. Wastewater Treatment (Disinfection)Wastewater Treatment (Disinfection) Ultraviolet Light Disinfection is the most important step in wastewater treatment because it removes pathogens and thus protects receiving waters used for contact recreation and as a drinking water supply. Chlorine is the most commonly used disinfectant. Because of adverse effects on the environment, chlorine is being replaced by other methods such as ozonation and ultraviolet light (the method used a our plant in Houghton.
  17. 17. Incineration Wastewater Treatment (Sludge)Wastewater Treatment (Sludge) A variety of means are available for ultimate disposal of sewage sludge. Landfilling and incineration are the most common. Here, the sludge is introduced to the top of a multiple-hearth furnace. The sludge dries and ultimately ignites as it moves down the surface toward the fire. The product is ash (landfilled) and stack gases which are collected for further treatment.
  18. 18. Wastewater TreatmentWastewater Treatment (Effluent)(Effluent) Pollutant Removal Solids >90% Pathogens >99.9% Organic matter >90% Nutrients >90% Organics/Metals trace
  19. 19. • CE4507 - Wastewater Collection & Water Distribution • CE4508 – Water & Wastewater Treatment and Design • CE4509 – Environmental Process Simulation • CE5501 - Environmental Process Engineering • CE5502 - Biological Waste Treatment Processes • CE5503 – Physical-Chemical Treatment Processes • CE5507 - Sorption and Biological Processes CourseworkCoursework Students have the option of building a ‘concentration’ in water and wastewater treatment as part of the B.S. in Environmental Engineering at Michigan Tech.
  20. 20. • Government (MDEQ, City of Detroit) • Industry (GM, Kodak) • Consulting (CH2M-Hill, Montgomery-Watson) • Graduate Study & Research (U.S. EPA, MTU) EmploymentEmployment Check out the web pages of these organizations for professional opportunities.
  21. 21. Study QuestionStudy Question Where does the wastewater from your home go? What kind of treatment system is utilized? Reading AssignmentReading Assignment Take a wastewater treatment plant tour (“Go With the Flow”) courtesy of the Water Environment Federation. http://www.wef.org/publicinfo/#