Figure by MIT OCW.

Adapted from: G. Tchobanoglous, F. L. Burton, and H. D. Stensel. Wastewater Engineering: Treatment

and Reuse. 4th ed. Metcalf & Eddy Inc., New York, NY: McGraw-Hill, 2003, p. 617.

Organic Nitrogen(proteins; urea)

Ammonia Nitrogen Nitrate (NO2) Nitrate (NO3)

Organic Nitrogen(bacterial cells)

Organic Nitrogen(net growth)

Nitrogen Gas (N2)

Denitrification

O2 O2

Nitrification

Lysis and AutooxidationAssimilation

- -

Bacterial Decompositionany hydrolysis

Organic Carbon

Cell wall

Short-chain

fatty acids

Facultative bacteria

Substrate

Fermentation Products

Phosphorus removing bacteria

Soluble COD

PHB

Carbon

storage

Carbon

storage

CO2 + H2O

Ener

gy

P

P

New cell production

O2

PHB

ANAEROBIC AEROBIC

Removal mechanisms for excess biological phosphorus (COD = chemical oxygen demand, PHB = poly--hydroxybuty-rate).

+

Energy

Figure by MIT OCW.

Adapted from: Rittman, Bruce E., and Perry L. McCarty. Environmental Biotechnology: Principals

and Applications. New York, NY: McGraw-Hill, 2001.

Figure by MIT OCW.

Adapted from: Rittman, Bruce E., and Perry L. McCarty. Environmental Biotechnology: Principals

and Applications. New York, NY: McGraw-Hill, 2001.

15

10

10

20

30

40

50

5

1

0 05 10 15 20

Ortho Phosphorus

ADP + PO4

Bacteria absorb BOD byreleasing phosphorusATP ADP + PO4 + energy

Soluble BOD

Solu

ble

BO

D, m

g/L

Influent ortho phosphorusconcentration

Bacteria store phosphorusduring growth to competefor BOD when they getback to anaerobic zone

ATPenergy

First Anoxic Aerobic SecondAnoxic

Reaeration

Stored phosphorus in bacteria is removed in waste sludge

Anaerobic

Typical profile of soluble phosphorus concentrations in a biological nutrient removal process (ATP = adenosine triphosphate, ADP = adenosine diphosphate).

Nom

inal

ort

ho p

hosp

horu

s co

ncen

trat

ion,

mg/

L a

s P

Nominal Hydraulic Retention Time, Hours (Based on Influent Flow only)

Anaerobic Aerobic

OrthophosphorusSoluble BOD

TIME

CO

NC

EN

TR

AT

ION

Fate of soluble BOD and phosphorus in nutrient removal reactor.

Figure by MIT OCW.

Adapted from: G. Tchobanoglous, F. L. Burton, and H. D. Stensel. Wastewater Engineering: Treatment

and Reuse. 4th ed. Metcalf & Eddy Inc., New York, NY: McGraw-Hill, 2003, p. 626.

Chemical

Inorganic Chemicals Used Most Commonly for Coagulation and Precipitation Processes in Wastewater Treatment

Formula Molecular WeightEquivalent Weight Form Percent

Alum

594.4 114

Liquid

Lump

Liquid

Lump

8.5 (Al2O3)

17 (Al2O3)

8.5 (Al2O3)

17 (Al2O3)

63-73 as CaO

85-99

15-20

20 (Fe)

20 (Fe)

Al2(SO4)3.18H2O#

Aluminum Chloride

Calcium Hydroxide(lime)

Ferric Chloride

133.3

56.1 as CaO

162.2

44

40

91

Liquid

Lump

Powder

Slurry

Liquid

Lump

AlCl3

Ca(OH)2

FeCl3

18.5 (Fe)Ferric Sulfate 400 51.5 GranularFe2(SO4)3

20 (Fe)Ferrous Sulfate(copperas)

278.1 139 GranularFeSO4.7H2O

46 (Al2O3)Sodium Aluminate

# Number of bound water molecules will typically vary from 14 to 18

163.9

666.5

100 FlakeNa2Al2O4

Al2(SO4)3.14H2O#

AVAILABILITY

Figure by MIT OCW.

Adapted from : Metcalf, and Eddy. 2003

00

% C

OD

Rem

oval

20Ferric Chloride Sulfate Concentration (mg/l)

(no polymer)

North Budapest Wastewater Treatment PlantComparison of Influent vs. Pre-aeration Raw Water

Topolcany Wastewater Treatment PlantBOD and COD % Removal vs. Ferric Chloride Concentration

40 60 80 100

20

40

COD Influent Conc. = 515 mg/lCOD Pre-aeration Conc. = 594 mg/l

60

80

100

00

% R

emov

al

20Ferric Chloride Concentration (mg/l)

(no polymer)

40 30 40 50 60

20

10

30

40

50

60

70

Jar Test - Influent

Jar Test - Pre-aeration

Primary Effluent: Cin = 515 mg/l

Primary Effluent: Cin = 594 mg/l

BOD % Removal

COD % Removal

Figure by MIT OCW.

Adapted from: Murcott, and Hurleman. 1994, p. 24

Low dose

Fe/Al

Cationic

Polymer

Anionic

Polyme

r

High dose

Fe/Al

Possibly

Anionic

Polymer

a. Existing primary treatment plant

b. CEPT (left) and primary precipitation (right)

Fe/Al

c. Preprecipitation (or CEPT) followed by ASP

Fe/Al

Carbon

source

DD

d. Preprecipitation with ASP and postdenitrification

Multi-stage upgrading of an existing

primary treatment plant

Grit

chamber

Grit

chamber

Grit

chamber

Grit

chamber

Primary

Clarifier

Primary

Clarifier

Primary

ClarifierPrimary

Clarifier

Primary

Clarifier

Grit

chamber

Secondary

Clarifier

Secondary

Clarifier

AST

Aeration

AST

AerationMixer

Mixer

Optional

Mixer

Denitrification

020

40

6080

100Without Chemical Addition

0

Susp

ende

d So

lid R

emov

al (%

)

20

40

6080

100Ferric Chloride Addition

050

Overflow Rate

Overflow Rate Verses TSS Removal for Sarnia Treatment Plant

100150 cu m/sq.m/d

20

40

6080

100Ferric Chloride Plus Polymer Addition

Figure by MIT OCW.

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