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. 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. … 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. 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. 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. 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)
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. 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. 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. 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. 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. 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. 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. 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.
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. • 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. 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/#
