EB_12

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Environmental Biotechnology

Seven-sessions organized by

Bruce E. Rittmann

Professor and Director

Center for Environmental Biotechnology

Biodesign Institute at Arizona State University

Tempe, Arizona 85287-5701

www.biodesign.asu.edu

Much of the material is taken from

Environmental Biotechnology: Principles

and Applications by B. E. Rittmann and P. L.

McCarty, McGraw-Hill Book Co., New York

(2001)

Center for Environmental Biotechnology

Vision Document, at www.biodesign.asu.edu

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EB1 -- Introduction to

Environmental Biotechnology

Environmental Biotechnologies Provide

Valuable Services to Society

Treating industrial and municipal wastewaters toprotect water resources, ecosystems, and humanhealth

Restoring sites contaminated with hazardous

materials Reclaiming impaired water resources

Capturing renewable resources, particularlyenergy

Producing environmentally benign products

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Science and Technology

Foundation for Environmental

Biotechnology

1 Metabolic Basis--The bacterias food is our pollutant

2 Microbial Ecology and Its Control--Create theconditions to select for the right microorganisms

3 Biomass Retention--Develop systems to takeadvantage of natural aggregation as flocs and biofilms

1 Metabolic Basis

The principle: a pollutant to us is some microorganismssubstrate.

Substrate means a material involved in generating energyto grow and sustain the microorganisms. It is like foodor fuel.

Substrate, fuel, or food involves sending electrons from anelectron donor to an electron acceptor.

On the one hand, virtually every pollutant is an electron-donor or an electron-acceptor for some group ofmicroorganisms.

On the other hand, a substrate can be a true fuel, or asource of energy that we can capture.

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Treatment Examples

Pollutant/Role

Biodegradable organic

matter (BOD)/donor

Ammonium/donor

Nitrate/acceptor

TCE/acceptor

What We Add

Acceptor: e.g., O2

Acceptor: O2

Donor: organic compound

or H2

Donor: H2 or organic H2source

Energy-Capture Examples

Pollutant/Role


matter (BOD)/donor


matter (BOD)/donor


matter (BOD)/donor

Energy Outlet

Methane (CH4)

Biohydrogen (H2)

Electricity (i)

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2 Microbial Ecology and Its Control

We deal with large, open systems.

Microorganisms continually enter most processes.

We have only partial control of the type andconcentration of pollutants (fuels) that are input.

Pure culture is not a relevant concept in practice.We deal with mixed cultures that often change.

Therefore, the game is microbial ecology andsteering it towards the types of microorganisms

that do the job we want done.

Microbial Ecology as Science

As a scientific discipline, microbial ecology tries to

answer these questions:

Who is there? (Community structure)

What could they do? (Community potential) What are they doing? (Community function)

What are their interactions with each other and

their environment? (Community interactions)

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The Players in Microbial Ecology

The main players are from the Bacteria and

Archaea domains, which comprise theprotista or

prokaryotes, which are single-celled organisms

roughly 1 m is size

We are just beginning to quantify and appreciate the

phylogenetic diversity among those two Domains.

Prof. Hausner will tell you about this aspect inEB3 and 4.

QuickTime and aTIFF (Uncompressed) decompressor

areneeded tosee thispicture.

Bacteria have many differentshapes (coccus, rod/bacillus,

spirillum, and filaments/chains

of cells of different shapes).

But, all of them are small,in the

order of 1 m for an individual

cell.


areneeded to seethispicture.

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Biomass Retention

Flocs typically are a few 100 m is size.

They are slightly heavier than water and can

be removed from the water stream by

settling and retained in the system. They

also can be retained by filtration.

Biofilms can be up to a few 100 m thick

and are retained by being attached to a large

amount of surface area in the process.

Dramatic photomicrographs of a floc and

a biofilm on a membrane

30 m

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Biomass Retention

The many different types of processes used in

environmental biotechnology reflect, first

and foremost, how to retain the

microorganisms.

The retention approach must be consistent

with the means to supply the other

substrate, as well as constraints imposed by

economics, space, and operating skill.

EB2

Microorganisms and

Metabolism

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Chemical Composition ofChemical Composition of

Prokaryotic CellsProkaryotic Cells (R&M pg14)(R&M pg14)

1.5g1.5gSOSO33

1.0g1.0gCaOCaO

0.9g0.9gMgOMgO

1.0g1.0gNaNa22OO

0.7g0.7gKK22OO

(2.2g)(2.2g)(as P)(as P)

5.0g5.0gPP22OO55

10g10gInorganic MatterInorganic Matter

8 to 13g8 to 13gNitrogenNitrogen

4.5 to 6.3g4.5 to 6.3gHydrogenHydrogen

19.8 to 25.2g19.8 to 25.2gOxygenOxygen

40.5 to 49.5g40.5 to 49.5gCarbonCarbon

90g90gOrganic MaterOrganic Mater100g100gDryDry MatterMatter

300g300gWaterWater

400g400gBiomass TotalBiomass Total

TSS VSSCOD

(BODL) at fd

XXinin

Fixed, Mineral SS

Prokaryotic and

Eukaryotic Cell

Structures

The eukaryote cell is

much larger and

differentiated.

QuickTime and aTIFF (Uncompressed) decompressorareneeded to seethispicture.

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Differentiating Cell Types


are needed to see this picture.

The metabolic type of a microorganism is mainly determined

by it electron donor and acceptor

QuickTime andaTIFF (Uncompressed) decompressor

areneededto seethis picture.

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Basic electron and energy flows for

microorganisms -- overview

Electron Donor

(S, Substrate)

Active Biomass

(Xa)

Reaction End

Products

Cell Residual,Inert Biomass

(Xi)Growth

Cell Synthesis

feo

fso

fso

+ feo

= 1Energy Production

fm

C,N

Acceptor, SO

fs= fso - fm

fe= feo + fm

Acceptor, SO

The donor is oxidized, with the electrons (fe) transferred to

the acceptor.

This yields energy captured as ATP.

Electron Donor(S, Substrate)

Active Biomass

(Xa)

Reaction End

Products

Cell Residual,

Inert Biomass

(Xi)Growth

Cell Synthesis

feo

fso

fso + fe

o = 1

Energy Production

fm

C,N

Acceptor, SO

fs= fso - fm

fe= feo + fm

Acceptor, SO

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The energy and more electrons from the donor (fs) are

invested to synthesize new active biomass.

Electron Donor

(S, Substrate)

Active Biomass

(Xa)

Reaction End

Products


(Xi)Growth

Cell Synthesis

feo

fso

fso

+ feo


fm

C,N

Acceptor, SO

fs= fso - fm

fe= feo + fm

Acceptor, SO

The synthesis of new biomass consumes elemental nutrients,

like C, N, and P.


Active Biomass

(Xa)

Reaction End

Products

Cell Residual,

Inert Biomass

(Xi)Growth

Cell Synthesis

feo

fso

fso + fe

o = 1

Energy Production

fm

C,N

Acceptor, SO

fs= fso - fm

fe= feo + fm

Acceptor, SO

P

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Active biomass slowly decays (sort of like dying).

Decay consumes more acceptor, as the biomass gains

maintenance energy by oxidizing itself.

Electron Donor

(S, Substrate)

Active Biomass

(Xa)

Reaction End

Products


(Xi)Growth

Cell Synthesis

feo

fso

fso

+ feo


fm

C,N

Acceptor, SO

fs= fso - fm

fe= feo + fm

Acceptor, SO

Decay

Decay also generates residual, inert biomass (sort of like dead

cell bodies), which accumulates suspended solids that are not

metabolically active.


Active Biomass

(Xa)

Reaction End

Products

Cell Residual,

Inert Biomass

(Xi)Growth

Cell Synthesis

feo

fso

fso + fe

o = 1

Energy Production

fm

C,N

Acceptor, SO

fs= fso - fm

fe= feo + fm

Acceptor, SO

Decay

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Solids Retention Time (SRT)

SRT is the master variable for most

environmental biotechnologies.

It has units of time (e.g., days) and is the averagetime that active biomass is in the system.

SRT = (total active biomass)/(net rate of active-

biomass production)

SRT = 1/(specific growth rate) = 1/

We will define SRT more quantitatively in EB5.

The SRT cannot be too short: The active biomass washes

out, and no substrate is removed.

SRTmin

[SRT min]lim

Smin

So

Xio

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22

SRT (d)

S(mg/L)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

Xa,

Xi,Xv(mg/L)

S

Xv

Xi

Xa

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A long SRT increases substrate removal, but also enriches the

total biomass in inert biomass. For a long SRT, much of the

biomass can be inert, which removes no substrate.

SRTmin

[SRT min]lim

Smin

So

Xio

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20 22

SRT (d)

S(mg/L)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

Xa,

Xi,Xv(mg/L)

S

Xv

Xi

Xa

The metabolic type of a microorganism is mainly determined

by it electron donor and acceptor

QuickTime andaTIFF (Uncompressed) decompressor

areneededto seethis picture.

EB_12

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