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/#