ce3503 environmental engineering

Dr. Martin T. AuerMTU Department of Civil & Environmental Engineering

Wastewater Treatment

The Clean Water ActThe Clean Water Act

‘fishable-swimmable’

Total Maximum Daily Loads

Technology-Based Standards

Water Quality-Based Standards

Discharge Permits (NPDES)

yes

noyes

POTW DesignPOTW Design

Federal Water Pollution Control Act Amendments of 1972 (The Clean Water Act)

• Technology-based effluent limits

• Water quality-based effluent limits

• Total Maximum Daily Loads (TMDLs)

• National Pollutant Discharge Elimination System (NPDES)

Add Clark

In A Watershed – Everyone Lives Downstream

ReceivingWaterImpacts

River DO ModelQ = 8C = 0, 250, 100

MichiganNPDESPermit

TreatmentPlantDesign

Design ModelCin = 250

k = 0.1V = 0, 250, 750

Aluminum Forming Battery Manufacturing;Cement Manufacturing; Coil Coating & Can Making;Copper Forming; Dairy Products Processing; Electrical & Electronic Component Manufacturing;Electroplating & Metal Finishing; Explosives Manufacturing; Fruit & Vegetable Processing; Ferroalloy Manufacturing; Fertilizer Manufacturing; Glass Manufacturing; Gum & Wood Chemicals Manufacturing;Ink Formulating; Inorganic Chemical Manufacturing;Iron & Steel Manufacturing; Leather Tanning & Finishing; Meat Products Processing; Metal Molding & Casting; Mining Operations; Nonferrous Metals Processing; Organic Chemicals, Plastic & Synthetic Fibers Manufacturing;Paving & Roofing Materials Manufacturing;Soap & Detergent Manufacturing; Petroleum Refining; Pesticide Manufacturing; Porcelain Enameling; Pharmaceutical Manufacturing; Plastic Molding & Forming; Pulp, Paper and Paperboard ManufacturingTimber Products Processing; Textile Mills

Federally-Regulated Non-Domestic Sources

http://www.socwa.com/indwaste.htm

Chemicals Designated as Priority Pollutants (126)

• AROCLOR 1254 (industrial product; banned)• BENZENE (industrial product)• BENZO(A)PYRENE (asphalt roofing manufacture)• CADMIUM (heavy metal; electric/gas industries)• CHLORDANE (pesticide; banned or restricted)• CHROMIUM (heavy metal; widely used in industry)• DDT (pesticide; banned or restricted)• ENDRIN (pesticide; banned or restricted)• MERCURY (heavy metal; electric/gas and chemical industries)• PENTACHLOROPHENOL (industrial chemical – wood products)• TOLUENE (widely used industrial chemical)• TRICHLOROETHYLENE (industrial solvent, degreaser)

http://www.scorecard.org/chemical-groups/one-list.tcl?short_list_name=pp

What’s in wastewater?

Waste

human feces and urine food from sinks soaps and other cleaning agents runoff from streets and lawns industrial discharges

What’s in wastewater?

Water

lots of it! Urinal - 1 gallon per flush Toilet - 4 gallons per flush Shower - 20 gallons per use Overall - 55 gal/person/day

It’s mostly water!

There are about 500 parts of waste in every 1 million parts of wastewater; that’s500 ppm.

It’s like trying to find this class at a sold out Packers game!

H2O

So what’s the problem?

P SNOT: it’s not a pretty picture!

Pollutant Problem Pathogens Disease Solids Aesthetics Nutrients Algae Organics Oxygen Toxics Wildlife

Solids

Composition of Domestic Wastewater

Constituent Influent Effluent

Suspended Solids 200-300 30

BOD5 200-400 30

Ammonia Nitrogen 20-40 1-2

Phosphorus 7-10 1

Fecal Coliforms 104-106 200

All concentrations are mg/L, except fecal coliformswhich are colony forming units (cfu) per 100 mL.

Where does it go when you flush the toilet?

This is really not something I’ve given a lot of thought to.

Collection Systems

Portage Lake Sewer System

HancockHoughton

Franklin Sq.

Super 8

MTU

M&M Bldg.

POTW

PP

G

G

G

G

P

Surface; 30”

10’;36”

Lake; 48”

20’; 48”

Near Surface; 30”

Metcalf & Eddy

Diurnal Variation in Wastewater Flow

Metcalf & Eddy

Wet-Dry Variation in Wastewater Flow

Preliminary Treatment Overview(plant protection)

Bar Rack or Screen or Comminutor

Grit Chamber

Flow Equalization

from pumps or wet well

to primary treatment

Preliminary Treatment: Bar Rack

Preliminary Treatment: Screen

ComminutorPreliminary Treatment: C

Preliminary Treatment: Grit Chamber

Preliminary Treatment: Flow Equalization

The Henry Fork Wastewater Treatment Facility, Hickory, NChttp://www.hickorync.gov/egov/docs/1222790452442.htm

Bar Rack or Screen or Comminutor

Grit Chamber

Flow Equalization

from pumps or wet well

to primary treatment

Preliminary Treatment Overview(plant protection)

(Kiely, 1997)

Primary Treatment(solids, sedimentation)

Primary Treatment – Design

In Out

vp

The critical particle is defined as that particle will be captured prior to exiting the sedimentation tank. This particle, and all particles which settle more rapidly, will be retained.

The critical settling velocity, vc, is that of the critical particle.

0c

hv

Primary Treatment – Design

The design parameter for primary treatment is the surface overflow rate,

which can be shown to be equivalent to the critical settling velocity,

0c

hv

QSORA

3

3

22

md

mm m

m d d

In Out

0 0 0

0c

h h Q h Q Qv SORV h A A

Primary Treatment – Design

In Out

Vc, SOR

vp1

The design objective then is to reduce vc (SOR) in order to capture the target particle.

vp2

The steeper the slope,the higher the settling velocity

0 0 0

0c Sh h Q hv Q

VOQ

h A AR

Primary Treatment – Design

In Out

vc

vp2

vp1

This is accomplished by manipulating the tank residence time () by changing the surface area (A),

0 0 0

0c

h h Q h Q Qv SOV A A

Rh

The steeper the slope,the higher the settling velocity

(Kiely, 1997)

Primary Treatment – Design

Primary Treatment: Rectangular Clarifier

Primary Treatment – Circular Clarifier

Secondary Treatment(biological)

Simple carbohydrates (a form of organic matter) are produced by plants through the process of photosynthesis. These are then converted to more complex carbohydrates and other forms of organic matter such as starches, fats and proteins.

The sun’s energy, captured during photosynthesis, is stored in the chemical bonds of this organic matter.

2 2 22( )CO H O OC H O

Organisms (from bacteria to humans) take up and metabolize organic matter to obtain the energy required to support life.

In secondary or biological treatment, we utilize microorganisms to remove the dissolved and small particulate organic matter which would exert an oxygen demand if it were released to the environment. The waste (actually organic matter) is simply converted into another form (microorganisms) which can then be separated from the waste stream by settling yielding a clean effluent.

microbe2

s2 2 2( )C OO O OH C H

The Microbial Loop in Nature

Microorganisms in Secondary or Biological Treatment

Source: http://www.college.ucla.edu/webproject/micro7/studentprojects7/Rader/asludge2.htm

The Microbial Loop in Secondary Treatment

Secondary Treatment: Trickling Filter

Secondary Treatment: Trickling Filter Media

Image Source: Wastewater Engineering, Metcalf & Eddy

Secondary Treatment: Trickling Filter Design

Hydraulic Load (Wh)4-10 m3m-2d-1

Organic Load240-480 gBODm3d-1

hydhyd

AQ QWWA

0 0org

org

Q S Q S VW VV W

AH

Secondary Treatment: Rotating Biological Disks

Secondary Treatment: Activated Sludge

Activated Sludge: aeration (mechanical)

Activated Sludge: aeration (diffuser)

Activated Sludge Design: microorganism growth rate

In the aeration tank, microorganisms take up food (soluble and particulate BOD) and grow, converting waste to microorganisms.

Since the concentration of microorganisms in the aeration take is held constant, the ‘growth’ must be removed or wasted.

The rate of sludge wasting (dX/dt) divided by the mass of sludge in the aeration tank is equal to the microorganism growth rate,

/wdX dtX

Activated Sludge Design: relation to BOD concentration

Gro

wth

Rat

e (

)

Food (BOD)

As the steady state food concentration in the aeration tank increases, the growth rate increases.

High Low

Activated Sludge Design: growth phases

High BODPoor settling

Low BODGood settling

Activated Sludge Design: solids retention time

/wdX dtX

The solids retention time (SRT) or sludge age is defined as the average time that a microorganism spends in the aeration tank and is equal to the inverse of the growth rate,

1/w

XSRTdX dt

Thus, the longer the SRT, the lower the growth rate, the lower the effluent BOD and the better the settling characteristics of the sludge.

The design should seek to operate toward the upper end of the range of SRT values (2-20 days) to achieve the best removal.

Activated Sludge Design: food:microorganism ratio

0 0/ S QF M

X V

The solids retention time or sludge age varies with the rate at which the microorganisms are fed, i.e. the food:microorganism ratio,

Low F/M ratios equate to high SRTs and generate the desired effluent characteristics (low BOD, good settling).

Since S0 and Q0 are fixed and X must be maintained between some bounds, the design parameter becomes V, the volume of the aeration tank.

Note, however, that there are practical limits on the volume of the aeration tank, requiring consideration of less ‘optimal’ treatment.

3

3

33

gBOD mgBODm d

gMLSS gMLSS dmm

(From Kiely, 1997)

EndogenousGrowth

LogGrowth

DecliningGrowth

/wd tXS

XRT

d

Activated Sludge: design and operation

0 0/ SX V

QF M

Design Operation

Activated Sludge: Plug Flow Configurations

(From M&E)

Plug Flow (Conventional)

Activated Sludge: Plug Flow Configurations

(From M&E)

Activated Sludge: Plug Flow Configurations

(From M&E)

Activated Sludge: Completely Mixed Flow Configurations

(From M&E)

Activated Sludge: Completely Mixed Flow Configurations

(From M&E)

Secondary Clarifier

Disinfection (UV light)

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

Polymer A

dded

Feadded

Feadded

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

Polymer A

dded

Feadded

Feadded

putrid: in a state of foul decay, as animal or vegetable matter

putrescible: liable to become putrid

Putrescible

Anaerobic Digestion: Biochemistry

Anaerobic Digestion: Reactors

Sludge Drying Beds

Belt Filter

Centrifuge

Multiple Hearth Furnace

Land Application

The Madison Metropolitan Sewerage District provides wastewater treatment to villages towns and cities surrounding the Madison area lakes. Biosolids produced at the MMSD Nine Springs Wastewater Treatment Plant are recycled to agricultural land as a fertilizer and soil conditioner. Biosolids recycling practices are regulated by both USEPA and Wisconsin DNR to ensure that human and animal health are protected.

http://www.madsewer.org/EMS-start-3.htmhttp://www.stdnet.com/company/?category_number=4&subcategory_number=3

Recycling

The Milwaukee Metropolitan Sewerage District has been marketing its biosolids as Milorganite, a fertilizer and soil conditioner, for over 80 years. Today, 55,000 tons of Milorganite are sold annually. Milorganite is produced by place dewatered sludge cake in massive dryers with a temperature gradient of 800-1200 °F at the inlet and 180-210 °F at the outlet. This effectively inactivates viral and bacterial pathogens.

http://members.cox.net/matthewhill_agrilawn/agrilawn1.htmhttp://www.lowes.com/lowes/lkn?action=productDetail&productId=97821-1321-97821&lpage=none

http://www.biosolids.org/docs/source/MilWI.pdf

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

Polymer A

dded

Feadded

Feadded

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

Polymer A

dded

Feadded

Feadded

Lagoons or Oxidation Ponds

Septic Tanks

Septic Tanks