CEE 697K ENVIRONMENTAL REACTION KINETICS Lecture #19 Chloramines - - PDF document

11/19/2013 1

CEE 697K

ENVIRONMENTAL REACTION KINETICS

Introduction

David A. Reckhow

CEE 679 Kinetics Lecture #19 1

Updated: 19 November 2013

Print version

Lecture #19

Chloramines Cont: Primary Literature Enzyme Kinetics: basics

Brezonik, pp. 419-450

Conclusions

 “Overall the model calculations suggest that

biodegradation is…..not likely to play a major role in most water distribution systems”

 “the conditions needed for significant HAA removals in a

distribution system (i.e., total biomass densities > 105 cells/cm2 over long distances of pipe) are unlikely in the US water distribution systems where total chlorine residuals typically are high and thus inhibit the development of biofilm

• n pipe walls”

But this seems to contradict their introductory conclusion – how to reconcile?

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CEE 679 Kinetics Lecture #19

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CEE 679 Kinetics Lecture #19

What could they have concluded?

 Variability vs diurnal demand

5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Q/Qavg u (ft/s) t (hr) C (ug/L) David A. Reckhow

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Objective/hypothesis

 Not really stated, but they did end the intro with:  “In this work, computer simulations were performed to predict

the fate of three HAAs (MCAA, DCAA, and TCAA) along a distribution system and within a biologically active filter. Sensitivity analyses were performed to investigate the effects

• f physical parameters (e.g., fluid velocity) and biological

parameters (e.g., biodegradation kinetics, biomass density) on HAA removal”

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What could they have said?

 To determined if observed HAA loss could be

attributed to biodegradation on pipe walls given known physical and microbial characteristics of distribution systems

 To estimate spatial and temporal variability of HAA

concentrations based on a rational physical model

• f biodegradation in distribution systems

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CEE 679 Kinetics Lecture #19

What could they have done?

 Find some direct evidence for biodegradation of

HAAs in distribution systems

 A product of the enzymatic reaction?  Chlorohydroxyacetate?  Evidence of abiotic reactions?  Increase in MCAA?

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What else?

 Consider mass

transfer resistance within biofilm

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CEE 679 Kinetics Lecture #19

What should be done next?

 Experimental Work  In-situ controlled study of flow velocity vs DCAA loss in

a pipe segment?

 Effect of biocide in above segment?  Model Refinement  Account for internal mass transfer resistance  Combine with growth model for HAA degraders

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SANCHO Model

 B1: biologically fixed bacteria  B2: adsorbed bacteria 9

B1 B2 H1

H2

S CO2

Cl2 Mortality

B3

Cl2 Cl2

Mortality

BDOC

Fixed Bacteria

Free Bacteria

Input (H1, H2, B3) Output Internal Processes

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CEE 679 Kinetics Lecture #19

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Effect of Zn on HAAs

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 Effect of Zinc on the Transformation of HAAs in

Drinking Water

 Wei Wang and Lizhong Zhu  Journal of Hazardous Materials 174:40-46.

Enzymatic Reactions

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 Many ways of illustrating the steps  Substrate(s) bond to active site  Product(s) form via transition state  Product(s) are released

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Basic Enzyme Kinetics

David A. Reckhow

CEE 679 Kinetics Lecture #19

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 Irreversible  Single intermediate  The overall rate is determined by the RLS, k2  But we don’t know [ES], so we can get it by the SS mass

balance

 Again, we only know [Eo] or [Etot], not free [E], so:

] [ ] [ ] ][ [ ] [

2 1 1

ES k ES k S E k dt ES d    



E + S ES  E + P → ←

k1 k-1 k2

] [ ] [ ] [

2 ES

k dt P d dt S d r    

 

] [ ] [ ] [ ] [ ] [

2 1 1

ES k ES k S ES E k

• 

  

 Note that some references use k2 for k-1, and k3 for k2

Reactants, products and Intermediates

David A. Reckhow

CEE 679 Kinetics Lecture #19

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 Simple Progression of

components for simple single intermediate enzyme reaction

 Shaded block shows steady

state intermediates

 Assumes [S]>>[E]t  From Segel, 1975; Enzyme

Kinetics

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Basic Enzyme Kinetics II

David A. Reckhow

CEE 679 Kinetics Lecture #19

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 And solving for [ES],

] ][ [ ] [ ] [ ] ][ [

1 2 1 1

S E k ES k ES k S ES k

• 

 

 2 1 1 1

] [ ] ][ [ ] [ k k S k S E k ES

• 

 



1 2 1

] [ ] ][ [ ] [

k k k

• S

S E ES





 

Michaelis-Menten

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CEE 679 Kinetics Lecture #19

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 Irreversible  Single intermediate

] [ ] [ ] [ ] ][ [ ] [

max 2

1 2 1

S K S r S S E k dt P d r

s k k k

• 

   





E + S ES  E + P → ←

k1 k-1 k2

] [ ] [

2 ES

k dt P d r  

1 2 1

] [ ] ][ [ ] [

k k k

• S

S E ES





 

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Michaelis Menten Kinetics

David A. Reckhow

CEE 679 Kinetics Lecture #19

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Substrate Concentration

20 40 60 80 100 120

Reaction Rate

20 40 60 80 100

rmax

0.5rmax

Ks

 Classical substrate plot

] [ ] [ ] [

max

S K S r dt P d r

s 

 

Substrate and growth

David A. Reckhow

CEE 679 Kinetics Lecture #19

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 If we consider Y  We can define a microorganism-specific substrate

utilization rate, U

 And the maximum rates are then

] [ ] [ ] [ 1

max

S K S dt X d X

s 

    dt dX Y dt S d dt P d r 1 ] [ ] [    

Y YX dt dX X r U     Y k U

max max

  

] [ ] [ ] [ 1 S K S k dt S d X U

s 

 

and

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Linearizations

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CEE 679 Kinetics Lecture #19

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 Lineweaver-Burke  Double reciprocal plot Wikipedia version Voet & Voet version

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CEE 679 Kinetics Lecture #19

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 das

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 Lineweaver Burk  Hanes  Eadie-Hofstee

3 types Compare predictions

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 ad

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Multi-step

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 Double intermediate  Also gives:  But now:  Note what happens when: k3 >> k2

] [ ] [ ] [

max

S K S r dt P d r

s 

 

E + S ES  EP2  2E + P2 → ←

k1 k-1 k2

3 2 3 2 max

] [ k k E k k r

• 



P1

k3

    1

3 2 2 1 3

k k k k k k Ks   



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CEE 679 Kinetics Lecture #19

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 To next lecture

11/19/2013 14

Enzymatic Reactions

David A. Reckhow

CEE 679 Kinetics Lecture #19

27

 Many ways of illustrating the steps  Substrate(s) bond to active site  Product(s) form via transition state  Product(s) are released

Basic Enzyme Kinetics

David A. Reckhow

CEE 679 Kinetics Lecture #19

28

 Irreversible  Single intermediate  The overall rate is determined by the RLS, k2  But we don’t know [ES], so we can get it by the SS mass

balance

 Again, we only know [Eo] or [Etot], not free [E], so:

] [ ] [ ] ][ [ ] [

2 1 1

ES k ES k S E k dt ES d    



E + S ES  E + P → ←

k1 k-1 k2

] [ ] [ ] [

2 ES

k dt P d dt S d r    

 

] [ ] [ ] [ ] [ ] [

2 1 1

ES k ES k S ES E k

• 

  

 Note that some references use k2 for k-1, and k3 for k2

11/19/2013 15

Reactants, products and Intermediates

David A. Reckhow

CEE 679 Kinetics Lecture #19

29

 Simple Progression of

components for simple single intermediate enzyme reaction

 Shaded block shows steady

state intermediates

 Assumes [S]>>[E]t  From Segel, 1975; Enzyme

Kinetics

Basic Enzyme Kinetics II

David A. Reckhow

CEE 679 Kinetics Lecture #19

30

 And solving for [ES],

] ][ [ ] [ ] [ ] ][ [

1 2 1 1

S E k ES k ES k S ES k

• 

 

 2 1 1 1

] [ ] ][ [ ] [ k k S k S E k ES

• 

 



1 2 1

] [ ] ][ [ ] [

k k k

• S

S E ES





 

11/19/2013 16

Michaelis-Menten

David A. Reckhow

CEE 679 Kinetics Lecture #19

31

 Irreversible  Single intermediate

] [ ] [ ] [ ] ][ [ ] [

max 2

1 2 1

S K S r S S E k dt P d r

s k k k

• 

   





E + S ES  E + P → ←

k1 k-1 k2

] [ ] [

2 ES

k dt P d r  

1 2 1

] [ ] ][ [ ] [

k k k

• S

S E ES





 

Michaelis Menten Kinetics

David A. Reckhow

CEE 679 Kinetics Lecture #19

32

Substrate Concentration

20 40 60 80 100 120

Reaction Rate

20 40 60 80 100

rmax

0.5rmax

Ks

 Classical substrate plot

] [ ] [ ] [

max

S K S r dt P d r

s 

 

11/19/2013 17

Substrate and growth

David A. Reckhow

CEE 679 Kinetics Lecture #19

33

 If we consider Y  We can define a microorganism-specific substrate

utilization rate, U

 And the maximum rates are then

] [ ] [ ] [ 1

max

S K S dt X d X

s 

    dt dX Y dt S d dt P d r 1 ] [ ] [    

Y YX dt dX X r U     Y k U

max max

  

] [ ] [ ] [ 1 S K S k dt S d X U

s 

 

and

Linearizations

David A. Reckhow

CEE 679 Kinetics Lecture #19

34

 Lineweaver-Burke  Double reciprocal plot Wikipedia version Voet & Voet version

11/19/2013 18

David A. Reckhow

CEE 679 Kinetics Lecture #19

35

 das

David A. Reckhow

CEE 679 Kinetics Lecture #19

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 Lineweaver Burk  Hanes  Eadie-Hofstee

3 types

11/19/2013 19

Compare predictions

David A. Reckhow

CEE 679 Kinetics Lecture #19

37

 ad

Multi-step

David A. Reckhow

CEE 679 Kinetics Lecture #19

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 Double intermediate  Also gives:  But now:  Note what happens when: k3 >> k2

] [ ] [ ] [

max

S K S r dt P d r

s 

 

E + S ES  EP2  2E + P2 → ←

k1 k-1 k2

3 2 3 2 max

] [ k k E k k r

• 



P1

k3

    1

3 2 2 1 3

k k k k k k Ks   



11/19/2013 20

David A. Reckhow

CEE 679 Kinetics Lecture #19

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 To next lecture