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Wastewater TreatmentWastewater Treatment EngineeringEngineering
Environ. Engineering Course Sequence
CE4501Env.Chem
P-Chem
GE3850Geohydrol.
CE4508, 4507,4509Drinking & WasteWater
ce4505Surf.Water
CE3501
CE3502
CE4504Air Quality
CE4506Regs,P2,3
Fluids
BL4451Limnology
FW4220Wetlands
CE4620 Open Channel Flow
CE3620Water Resources
Thermo
CE4630 Hydraulic structures
CE5508: Biogeochem., CE5504: Surf.Water Qual. Modeling
Historical BackgroundHistorical BackgroundPublic Health Environmental Protection
Investigation of an outbreak of cholerain 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.
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
… 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
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
Level Approach Removed
Primary (1 ) Physical Solids, organicmatter
Secondary (2 ) Biological Organic matter,nutrients
Tertiary (3 ) Various Nutrients,toxics
Disinfection Various Pathogens
Levels of TreatmentLevels of Treatment
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)
Scope of ApplicationScope of Application
On-Site
Rural - Municipal
Urban - Municipal
Industrial
Portage Lake Wastewater Treatment Plant
LiftStation
BarScreens
GritChamber
FlowEqualization
1°Clarifier
1°Clarifier
2°Clarifier
2°Clarifier
AerationTank
UVDisinfection
1st StageAnaerobicDigester
2nd StageAnaerobicDigester
LandApplication
SludgeStorage
FilterPress
Recycle
Supernatant
RAS
RAS
WAS
1°S
Polym
er Added
Feadded
Feadded
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.
Settling Tank
Wastewater Treatment Wastewater Treatment (Primary)(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.
Activated Sludge
Wastewater Treatment Wastewater Treatment (Secondary)(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.
Wastewater Treatment (Tertiary)Wastewater Treatment (Tertiary)
Phosphorus removal by precipitation …
Ferric chloride, Fe(Cl)3
producing FePO4 and Fe(OH)3
Alum, Al2(SO4)3·18H2Oproducing 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.
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.
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.
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.
Wastewater TreatmentWastewater Treatment(Effluent)(Effluent)
Pollutant Removal
Solids >90%
Pathogens >99.9%
Organic matter >90%
Nutrients >90%
Organics/Metals trace
• 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.
• 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.
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/#