1666.pdf

A

bstr a ct

S

a r a

h L

ot h

m

a n, P.E.

C

o

m

_pa r is o n of

O

x_{y g}e n T r a n s

f

e r

B

etw e e n a n In te_gr ate

d F

ix e

d

-

F

_{i l}

m A

_{ct iv ate}

d

S l_u d

_g

e

(

I F

A S

₎

P

r o c e s s a n d a

C

o n v e nt io n a

l A

ct

i

v ate

d S

lu

d

_ge Pr o c e s s

(

A

SP

)

Un de r t he

d

ir e ct

i

o n o

f D

r. D

ie

go

R

o s s o a n d

D

r .

M

i

c

h

a el

A

i t ke n

T h

e

T

.Z .

O

s

b

o

rn

e

(

T Z O

) W

ate r R e c

l

a

m

at

i

o n Fa c

i l i

ty

(W

R

F

)

l

o c ate

d i

n

G

r e e n s

b

o r o ,

N C i

s a 4 0

m

i l l i

o n _ga

l l

o n _pe r

_d

a_y

_(M

G D

₎

w

a ste

w

ate r tr e at

m

e nt _p

l

a nt t

h

at

i

n c

l

u

d

e s

b i

o

lo

_g

i

c a

l

n utr

i

e nt

r e

m

o v a

l w i

t

h

s u r

fa c e

-wate r

d is c

h

a r_ge. Se v e r a

l

pr o c e s s a

l

te rn at

iv e s

a r e

b

e

i

ng e v a

lu a

te

d

a s

str ate_g

i

e s to

m

e et

f

o rt

h

c o

m i

n_g n utr

i

e nt

l i

m

i

ts. Integr ate

d fi

x e

d fi l m

a ct

i

v ate

d

s

l

u

d

ge

(

I F

A S

)

i

s

o n e o

f

t

h

e a

lt

e r n at

i

v e s

b

e

i

n

_g

c o n s

i d

e r e

d f

o r

i m p l

e

m

e ntat

i

o n . D u e to t

h

e

l i

m

i

te

d

n u

m b

e r o

f fi

i

U

-s c a

le

o_pe r at

in

_{g I}

F A S

tr e at

m

e nt

f

a c

i l

it

i

e s

i

n t

h

e

U

n

i

_te

d St

ate s a n

d

t

h

e

C i

t

_y

o

f G

r e e n s

b

o r o 's

d

e s

ir e

to e x _pe r

ie n c e

o

_p

e r at

i

n_g t

h

e _pr o c e s s, a t

h

o r o u g

h

ye a r -

l

o n_g stu

d

_y

w

a s c o n

d

u cte

d

to

q

u a nt

i f

_y t

h

e n

i

tr

i f

i c at

i

o n

k i

n et

ic s

, a e r at

i

o n r equ

i

r e

m

e nts, pr o c e s s pe r

f

o r

m

a n c e, an

d

pote nt

i

a

l

o_pe r at

io n a

l i

s s u e s. A s pa rt of the ful l

-_{s ca}l_{e e v a}l_{u a}ti_{o n}

, a n of f

-ga s te st was _perfo rmed in a c c o r

d

a n c e

w ith the A meric a n So ciet_y of C iv i l En_{g i}n e e r s '

(

A SC E

₎

Pr oto c ol. Pr ev io u sl y

, o nl y o n e of f

-ga s te st had

be e n _perfo rmed, a nd it wa s c o ndu cted b y a n other I F A S ma n ufa ctu r e r. To o u r kn ow led ge, the te sting

de s c r ibed in th is r e_po rt is the f ir st inde_pe nde nt of f

-ga s te st o n a n I F A S s_ystem to date Re sults of the

te stin_{g i}nd ic ate that the I F A S pr o c e s s ha s h i g he r air f lu x a nd air u s e _pe r u nit lo ad tre ated c om pared to

the a ctivated slu_{d g}e _proce ss

(

A S P

)

, l ikel y du e to elev ated m ixin g requir ements a nd h i g h d iss olv ed

o x_{y g}e n

(

D O

)

s_pe ci fi ed b y the _pro c e ss manufacturer, w ith a s s o ciated lower o xy ge n tr a nsfer ef fi cie n cy.

T he r elativ e air u s e of the I F A S pr o c e s s is _in the r a n_ge of 1.3 to o v e r 3.0 ti me s that of the A S P, a nd the

T

A

B L E

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C

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_, an d

R

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R E F E R E N C

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L I S T O F

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A SP

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D i

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I F A S Inte_gr ate

d

F

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m

A

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d

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l

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d

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M

O

D

M

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a

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O T E

O

x_{y g}e n Tr a n s

f

e r E

f f

i c

ie n c

_y

O T

R

O

x _{y g}e n Tr a n s

f

e r Rate

O U R

Ox_{y g}e n

U

_pta

k

e Rate

S O T E

St

a n

d

a r

d

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f

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f f

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S ta n

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T

r a n s

f

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R

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L I S

T O

F T

A

B L

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S

T

a

b le

1

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a nt

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C

o n

_{d it}

i

o n s

D

u r

in

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in

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2 8

T

a

b le

2

S

C A

D

A

Data

f

r o

m T

e st

in

_g

Da_y 2

9

Tab le 3 Su

m m

a r_y o

f Ja n

ua r_{y R}e s ults fo r Tan

k

1 1

3 0

T

a

b l

e 4

S

u

m m

a r_y o

f

Ja n u a r_{y R}e s u

lt

s

f

o r T a n

k

1 2

3

1

T

a

b l

e

5

Su

m

m

a r_y o

f Ju

n e

R

e s u

lt

s

f

o r Ta n

k 1

1

3

2

T

a

b l

e

6

Su

m m

a r_y o

f

Jun e Re su

lt

s

f

o r Ta n

k

1 2

3 3

L I S T O F F I G

U

R E

S

F i

_gu r e 1

O f f

-ga s te st

i

n

_{g l}

a_yo ut 2

3

F

_{i g}

u r e 2 T e st

i

n_g

H

o o

d P

o s

i

t

io n s

2 6

F

i

_gu r e 3 D

i

s s olv e

d

o x_{y g}e n _pr o

f i l

e s

f

o r t

h

e

A S

P an

d I

F

A S

_pr o c e s s

i

n t

h

e

J

a n u a r_y te st .

34

F

i

_gu r e 4 D

i

s s o

l

v e

d

o x_{y g}e n _pr o

fi l

e s

f

o r t

h

e

A S

P a n

d

I F

A S

_pr o c e s s

i

n t

h

e

Ju n e

te st

34

F i

_gu r e

5

O T E p

r o

f

i

le s

f

o r t

h

e

A S P

a n

d I

F

A S p

r o c e s s

i

n t

h

e Ja n u a r_{y t}e st

3 5

F

i

_gu r e

6

O T E pr o

fi l

e s

_f

o r t

h

e

A S

P an

d I F A S

_pr o c e s s

i

n t

h

e Ju n e te st 3 5

F i

_gu r e

7

a

S O T E

_pr o

fi

l

e s

f

o r t

h

e

A SP

a n

d I F A S

_pr o c e s s

in

t

h

e

Ja n u a r

_y

test

36

F i g

u r e

8

a

SO T E p

r o

fi

l

es

f

o r t

h

e

A SP

a n

d I F A S p

r o c e s s

in

_t

h

e

Ju n e

te st

3 7

F i

_gur e

9

R

e

l

at

i

ve a

SO T

E pr o

fi l

e s

f

o r t

h

e

A

S P an

d

I F

_{A S p}

r o c e s s

i

n t

h

e Jan ua r_y te st ...

3 8

F

i

_gu r e 1

0

Re

l

at

i

v e a

S

O

T E

_pr o

fi le s

f

o r t

h

e

A SP

a n

d

I

F A S

_pr o c e s s

i

n t

h

e

J

u n e te st

3 9

F

i

_gu r e

1

1

O U

R

_p

r o

fi l

e s

f

o r t

h

e

A SP

a n

d I F A S

_pr o c e s s

i

n t

h

e

J

a n u a r_{y t}e st 4

0

F

i

_gu r e 1 2 O U R

p

r o

fi l

e s

f

o r the

A SP

a n

d

I F A

S

_pr o c e s s

i

n t

h

e

J

u n e te st 4

0

F

_{i g}

u r e 1

3

Re

l

at

i

v e

O U R p

r o

fi l

e s

f

o r the

A SP

a n

d IF A S

_pr o c e s s

in

the

Ja n u a r

_{y t}e st

4 1

F i

_gu r e 1 4 Re

l

at

i

v e O U R pr o

fi l

e s

f

o r t

h

e

_{A SP}

an

d

IF A S _pr o c e s s

in

t

h

e Ju n e te st 4

1

F i

_gu r e 1 5

A i

r

fl

u x

_p

r o

fi l

e s

f

o r t

h

e

A S

P a n

d

I

F A S

_pr o c e_{s s}

in

the Ja n u a r_y te st 4

2

F i

_gu r e 1

6

A i

r

fl

u x _pr o

fi l

e s

f

o r t

h

e

A S

P a n

d

I F

A S

_pr o c e s s

i

n t

h

e Ju n e te st 4

3

F i

_gu r e

17

Re

la

t

iv e

a

i

r

fl

u x o r a

i

r

fl

o

w

r ate

_p

r o

fi

le s

f

o r t

h

e

A

S P an

d

I F

A

_{S p}r o c e s s

in

the

_{Ja n u a r}

_{y t}e st

4 3

F

i

_gu r e 1

8

R

e

la

t

iv e

a

i

r

fl

u x o r a

i

r

fl

o

w

r ate _pr o

fi l

e s

f

o r t

h

e

A SP

a n

d

I F

A

S

_p

r o c e s s

in

t

h

e

Ju n e

te st 4

4

F

i

_gu r e 2 0

A i

r u s e _pr o

f

i

l

e s

f

o r the

A

S P a n

d

I F

A

_{S p}r o c e s s

i

n t

h

e Ju n e te st 4 5

F

i

_gu r e 2 1 Re

l

at

i

v e a

i

r u s e

_p

r o

fi l

e s

f

o r t

h

e A

S

P a n

d

I F A

_{S p}

r o c e s s

i

n t

h

e

J

a n u a r

_y

te st

4 6

F

i

_gu r e 2 2 Re

l

at

i

v e a

i

r u s e _pr o

fi l

e s

f

o r t

h

e

A SP

a n

d

I F

A S p

r o c e s s

i

n t

h

e

J

u n e te st 4

6

F

i

_gu r e

2 3

A m

m

o niu

m

-

N

P_{r o}

fi l

_{e o}

f

t

h

_e J_{a n u a r}

y te st 4 7

F i gu r e 2 4

A

m m

o n iu

m

-

N

P

r o

fi l

e o

f

t

h

e Ju n e te st 4

8

F i gu r e 2 5

N i

tr ate-

N

P

r ofi le o

f

the

J

a n u a r_y te st 4

8

F i

_gu r e 2

6

N i

tr ate-

N

P_{r o}

fi l

_{e o}

f

t

h

_e

J

_{u n e} t_{e s}t 4

9

F

i

_gu r e 2 7

N i

tr

i

te-

N

Pr o

fi l

e o

f

t

h

e

J

a n u a r_y te st 4

9

F

i

_gu r e 2

8

N i

tr

i

te-

N P

_{r o}

fi l

_{e o}

f

th_e

J

_{u n e te st}

50

F i

_gu r e

2 9

O

rt

h

o_p

h

o s

_{p h}

ate

-P -Pr o

fi l

e o

f

t

h

e

J

a n u a r_y te st

5 0

F i gu r e 3

0

O

rt

h

o_p

h

o s_p

h

ate-P P_{r o}

fi l

_{e o}

f

th_e J_{u n e} t_{e s}t 5 1

F

i

_gu r e 3 1

A i

r

fl

u x _pr o

fi l

e s

f

o r t

h

e

A SP

(

Ta n

k

1 1

)

i

n t

h

e Ja n u a r_y te st

5

2

F i

_gu r e

3 2

A i

r

fl

u x

_p

r o

fi l

e s

f

o r t

h

e

A SP

₍

T

a n

k 1 1

₎

i

n the

J

u n e te st

5 2

F

i

_gu r e 3 3

A i

r

fl

u x _pr o

fi l

e s

f

o r t

h

e I F

A S

₍

Ta n

k

1 2

₎

i

n t

h

e Ja n u a r_y te st 5

3

F

i

_gu r e

3 4

A i

r

fl

u x _pr o

fi l

e s

f

o r the

I F A S

(

T

a n

k

12

)

i

n the

J

u n e te st 5

3

F

i

_gu r e

3

5

A i

r u s e _pr o

fi l

e s

f

o r t

h

e

A SP

(

T

a n

k

1 1

₎

i

n t

h

e

J

a n u a r_y te st

5

4

F i

_gu r e

3 6

A i

r u s e _pr o

fi l

e s

f

o r the

A SP

(

T

a n

k 1

1

₎

i

n t

h

e

J

u n e te st 54

F

i

_gu r e

3

7

A i

r u s e _pr o

fi l

e s

f

o r the

I F A S

(

T a n

k

1 2

₎

i

n t

h

e Ja n u a r _{y t}e st

5 5

F

i

_gu r e 3 8

A i

r u s e _pr o

fi l

e s

f

o r t

h

e I F

A S

(

Ta n

k

1 2

)

i

n t

h

e Ju n e te st 5 5

F

i

_gu r e

3 9

N

et

m

i

x

i

n _g a

i

r

fl

u x

i

n t

h

e

J

a n u a r_{y t}e st

56

F

i

_gu r e 4

0

N

et

m i

x

i

n_g air fl u x

i

n t

h

e Ju n e te st 5 6

F

i

_gu r e 4 1

N

et

m i

x

i

n

_g

a

i

r u s e in t

h

e

J

anu a r_y te st 5 7

A C K N O

W

L E D

G

E

M

E

N

T S

T

h i

s _pr o

j

e ct c o u

l d

n ot

h

a v e

b

e e n c o

m p l

ete

d w i

tho ut t

h

e

C i

t y o

f G

r e e n s

b

o r o,

N

o rt

h C

a r o

l i

n a.

I

a

m

_g

r ate

f

u

l

to t

h

e

C i

t y

'

s s

h

a r

_p

an

d

_g

i

v

i

n_g sta

f f

,

D

on

H

o

w

a r

d

,

M

i k

e

A d

c o c

k

,

W

a

l l y K l i

n

g

, a n

d

M

i k

e Bu c

k

.

T h

a n

k

yo u a

l

s o to Dr. D

i

ego R o s s o,

A

s s

i

sta nt Pr o

f

e s s o r at

U C

-_I

r v

i

n e,

f

o r

b

e

i

ng a n

e n o r

m

o u s r e s o u r c e a n

d m

e nto r a n

d

H a z e n a n

d S

a

w

_ye r, P.

C

.

f

o r e n c o u r ag

i

n g a n

d

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i

ng

m

e

C h

a

_p

t

er

1

I

n

t

r o

du c

t

i

o n

T

h

e T .Z . Os

b

o r n e

(

T

Z O

) W

ate r Re c

la

m

at

i

o n Fa c

i l i

ty

(W

RP

)

l

o c ate

d i

n Gr e e n s

b

o r o,

N

C

i

s a

4 0

m

i l l io n _gal lo n _pe r da_y

_(M

G

D

₎

w

a ste

w

ate r tr e at

m

e nt _{p l}a nt that in clude s

b

iolo_{g i}c al n utrie nt

r e

m

o v a

l w i

t

h

su r

f

a c e-

w

ate r

d i

s c

h

a r_ge. Se v e r a

l

pr o c e s s a

l

te r n at

i

v e s a r e

b

e

in

g e v a

l

u ate

d

a s

str ate_g

ie s

to

m

e et

f

o rt

h

c o

m in

_g n utr

i

e nt

l i

m

i

ts. Inte

g

r ate

d f

i xe

d fi l m

a ct

i

v ate

d

s

lu

d g

e

(

I F

A S

)

i

s

o n e o

f

t

h

e a

l

te r n at

iv e s

b

e

in

_g

c o n s

i d

e r e

d f

o r

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_p

l

e

m

entat

i

o n. Du e to t

h

e

l i m i

te

d

n u

m b

e r o

f f

u

l l

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l

e o

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n

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e nt

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t

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n

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d

t

h

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t_y o

f G

r e e n s

b

o r o '

s

d

e s

i

r e to e x_pe r

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i

n_g the _pr o c e s s, a t

h

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ye a r -

l

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d

to

qu a nt

i f

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it

r

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c at

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p

r o c e s s

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e r

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pote nt

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s te c

h

no

l

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u cte

d

a s a c o o

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m

e

f f

o rt

b

et

w

e e n

H

a z e n a n

d S

a

w

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D

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, a n

d

t

h

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C i

ty o

f G

r e e n s

b

o r o . An o

f f

-ga s te st

w

a s _pe r

f

o r

m

e

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i

n a c c o r

d

a n c e

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t

h

t

h

e

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m

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n

_{g i}

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l i

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o n to

t

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m

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l in

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d

a n a

l

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i

s.

T h

e o

f f

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i

n _g

w

a s c o n

d

u cte

d

at

T

Z

O

o n Ja n u a r_y 1 8, 2 0

10

a n

d Ju n e

1

6

-

17

,

2 0

1

0

pe r

A S C E S

ta n

d

a r

d 18

-

9 6

,

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ta n

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a r

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u

i d

e

l i

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f

o r

I

n

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O

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y ge n Tr a n s

f

e r Te st

in

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19 9 7

)

.

T h

e _go a

l

o

f

t

h

e

i

n

i

t

i

a

l Ja n u a r

_{y t}e st

w

a s to

d

ete r

m i

n e t

h

e c o

m p

a r at

iv e

o x_y

_g

e n tr a n s

f

e r e

f fi

c

i

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o

f

t

h

e a ct

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te

d

s

lu

d

_ge _pr o c e s s

(

A S

P

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an

d

t

h

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nte_gr ate

d fi

x e

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-

fi l m

_{a c}t

i

_{v a}t_e

d

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l

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d

ge

(

I F

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)

pr o c e s s. T

h

e

J

u n e te st

w

a s a r e

pet

i

t

i

o n o

f

t

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d i

n

J

a n u a r_{y 2 0}

10

to c o n

fi

r

m

t

h

e r e s u

lt

s

d

u r

i

n _g t

h

e

w

a r

m

s e a s o n .

T h

e p

la n

t

h

a s

12

a e r at

i

o n ta n

k

s

, a

l l

o

f w h i

c

h

a r e e

q

u

i

p

p

e

d

w i

t

h fi

n e

-b

u

b

b le

d i f f

u s e r s . T

h

e I F

A S

pr o c e s s

i

s ope r ate

d i

n

T

a n

k 1

2, s

i d

e -

b

y

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i d

e to t

h

e

A SP i

n Ta n

k 1

1.

O f f

-g

a s te st

i

n_g o

f

t

h

e I F

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a n

d A S

P

b

a s

i

n s

w

a s _pe r

f

o r

m

e

d i

n o r

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e r to

b

et te r u n

d

e r sta n

d

t

h

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i

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l

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i m

_{p l}

i

c at

i

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f

e a c

h

te c

h

n o

l

o_{g y}, to a

i d

t

h

e C i t y o

f

Gr e e n s

b

o r o

i

n s ele ct

i

ng a

p

r o c e s s to

h

e

l

_{p t}

h

e

m m

e et t

h

e

i

r

f

utu r e n utr

i

e nt

l i m i

ts.

1

.1 Pu r

p

o s e o

f

t

h

e

S

tu

d

y

T h

e I F

A S

m

anu

f

a ctu r e r,

A

n o x

K

a

l d

n e s, r equ

i

r e

d

that a c o a r s e

-

b

_u

b b l

_e

d i ff

ii s e r _s

yste

m

b

e

i

n stal le

d i

n _{t h}e I F

A S

c e

l

ls. T he

d

e si gn o

f

the c o a r s e

-

b

_u

b b

l_e

d i f f

u s e r _gr

_{i d f}

o r t

h

e I F

A

S r e a cto r

c e

l l

s

w

a s

_p

e r

f

o r

m

e

d b

_y t

h

e

m

a n u

f

a ctu r e r. T

h

e

m

a n u

f

a ctu r e r a

l

s o spe c

i f i

e

d

t

h

at t

h

e syste

m

s

h

o u

l d

o

_p

e r ate

w i

t

h

a n

i

n c r e a s e

d d i

s s o

l

v e

d

o x_{y g}e n

(

D

O

)

c o n c e ntr at

i

o n r e

l

at

i

v e to t

h

e a ctiv ate

d

s

l

u

d g

e

b

a s

i

n s, to

f

a c

i l i

tate a

b

u

l k

-

l i

qu

i d D O d i f f

us

i

o n

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r a

d i

e nt thr o u

_{g h}

t

h

e

b i

o

f i l m

s u c

h

t

h

at the

b i

o

f

i

l m i

s

f

u

l l

_y a e r o

b i

c.

T h

e

i d

e a t

h

at t

h

e I

F A S m

e

d i

a s e r v e s to sp

l i

t a

p

a rt t

h

e c o a r s e

b

u

b b l

e s

i

nto

fi

n e

b

u

b b l

e s a n

d i

n c r e a s e s o x_{y g}e n tr a n s

f

e r

i

n t

h

e s_yste

m h

a s

b

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h

_{y p}ot

h

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i

z e

d b

_{y t}

h

e

m

a n u

f

a ctu r e r s

b

ut

h

a s n ot

b

e e n _pr o v e n.

F

u rt

h

e r

m

o r e, t

h

e e

f f

e cts o

f

o

p

e r at

i

n g a n

I

F

A S

syste

m

at

var

i

o u s

d i

s s o

l

v e

d

o x

_y

_ge n c o n c e ntr at

i

o n s

h

a s n ot

b

e e n stu

d i

e

d

.

T h

e pu r

p

o s e o

f

t

h i

s stu

d

y

w

a s to

b

e t

h

e

fi

r st

i

n

d

e_pe n

d

e nt

i

n v e st

i

_gat

i

o n to

i d

e nt

i f

_y o x_{y g}e n tr a n s

f

e r e

f fi

c

i

e n c _y, a

i

r u s e, a n

d

o xy ge n

u_pta

k

e o

f

a n I F

A S b

a s

i

n r e

l

at

i

v e to a n a

d

_j

o

i

n

i

n_g a ct

i

v ate

d

s

l

u

d

_ge

b

a s

i

n. Pr e v

i

o u s

l

y , o n e o

f f

-ga s

te st

w

a s

_p

e r

f

o r

m

e

d b

_y a n ot

h

e r I

F

A

S m

a n u

f

a ctu r e r, In

fi l

c o

D

egr e

m

o nt

(

V i

s

w

a n at

h

a n,

2

0

0 8

)

.

T

o

o u r

k

no

w l

e

d

_ge, t

h i

s

i

s the o n

l

y pr e c e

d

e nt t

h

at

i

s pu

b l i

s

h

e

d i

n

l i

te r atu r e.

O

u r te st

i

s t

h

e

fi

r st

i

n

d

e

_p

en

d

e n t o

f f

-g

a s te st o n an I F

A S

s_yste

m

to

d

ate.

T h

e o n e

-ye a r te c

hn

o

l

o

_g

_y

d

e

m

o n str at

i

o n, c o n

d

u cte

d

a s pa rt o

f

t

h

e o n

g

o

i

n

g

M

a ste r P

l

a n ,

n o

in

f

o r

m

at

io n

is

c u r r e nt

l

_y

k

no

w

n a

b

o ut

i

ts o x _{y g}e n tr a n sfe r e

f

fi c ie n c

_y

in c o

m

_p

a ris o n to t

h

e

c o n v e nt

i

o n a

l

a ct

iv a

te

d

s

l

u

d g

e

_p

r o c e s s. En e rg y u s e

is

a gr o

w i

ng c o n c e r n at

w

a ste

w

ate r

tr e at

m

e nt

f

a c

i l i

t

i

e s a n

d

a e r at

io n

h

a s

b

e e n

i d

e nt

i f

i e

d

a s o n e o

f

t

h

e

m

o st e n e r

_g

_y

in

te n s

i

v e

pr o c e s s e s o n site

₍

R

o s s o a n

d

Ste n str o

m

, 2

0

0 5

)

. Fu rt

h

e r

m

o r e,

i

n the c a s e o

f T

Z

O

, a e r at

io n

e n e r_{g y}

m

a_{y b}e the de ci

d

in_g

f

a cto r in cho o sin _g

b

et

w

e e n I F

A S

o r e x_pa n s

io n

o

f

the e x

i

st

i

n_g

A S P

w h

e n the _p

l

an t

i

s u_{p g}r a

d

e

d

. It

i

s t

h

e r e

f

o r e c r

i

t

ic a

l

to c

h

a r a cte r

i

z e t

h

e c u r r e nt syste

m

e

f f

i c

i

e n cy

a n

d

e v a

l

u ate t

h

e _pote nt

i

a

l

to o

_p

t

i m iz e

a e r at

i

o n

i

n a t te

m

_{p t}s to

m

a x

i m i

z e e n e r_g

_y

c o n s e r v atio n

an

d m in

i m i

z e o_pe r at

io n a

l

c o sts. T

h

e o v e r a

l l

go a

l

o

f

t

h

e te st

i

n _g

is

to

i

n c r e a s e ou r u n

d

e r sta n

d i

n_g

o

f

o x _{y g}e n tr a n s

f

e r r ate s

i

n _{I F}

_{A S}

s_yste

m

s a n

d

u

l

t

i m

at e

l

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h

e

k

n o

w l

e

d

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i

n e

d i

n t

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e

d

e c

i

s

i

o n

m

a

k in

_{g p}r o c e s s

f

o r

f

u

l l

- _{s c a}

l

_{e I F}

A S i m

C h

a

_p

t

e r

2

B

a c

k g

r o u n

d

2

.

1

I F A S

T e chno

l

o

g

y

T

h

e c o n c e_pt o

f

inte_gr at

i

n_g

i m

m

ob

i l

iz ed b

i

o

m

a s s in s u s_pe n

d

e

d b

io

l

o_{g i}c al r e a cto r s date s a s e a rl y

a s t

h

e 1

9

4

0

'

s

(

M

etc a

l f

a n

d E d d

_y,

2

0

0 3

)

.

O

n e o

f

t

h

e

m

o r e r e c e nt ap p

l i

cat

io n s o

f

t

h i

s

i d

e a

i

s t

h

e

i

nte_gr ate

d f

i x e

d fi l m

a ct

i

v ate

d

s

lu

d

_ge

₍

I F

A

S

_{) (}

Se n

et a

l

_, 19

9

4 ;

R

a n

d

a

l l

a n

d S

e n,

19 9 6

)

. I F

A S

i

n v o

lv e s

t

h

e a

d d i

t

i

o n o

f fi

x e

d

o r

f

r e e-

f l

o at

i

n _g

m

e

d i

a, e

i

t

h

e r p

la s

t

i

c o r

f

a

b

r

i

c, to a n a ct

iv a

te

d

s

l

u

d

_ge

b

as

i

n. T

h

e

I F A S p

r o c e s s

i m p

r o v e s u

p

o n t

h

e a ct

i

v ate

d

s

l

u

d

ge pr o c e s s

b

y

p

r o v

i d i

ng a

la r

_g

e r

b i

o

m

a s s

in v e n

to r_y

i

n t

h

e a e r at

i

on tan

k b

_y

f

a c

i l i

tat

i

n_g

b i

o

fi l m

_gr o

w

t

h

o n t

h

e

m

e

d i

a

in

a

d d i

t

i

on to s u s_pe n

d

e

d

s o

l i d

s

w h i

c

h

a r e

_p

r e s e nt

in

t

h

e a ct

iv a

te

d

s

l

u

d g

e

_p

r o c e s s.

T h

e

h i

g

h

e r

b

io

m

a s s

i

n v e nto r_y

i

nc r e a s e s tr e at

m

e nt c a

_p

a c

i

t_y.

T h

e e n

h

a n c e

d

r e

m

o v a

l

o

f

c

h

e

m i

c a

l

o x

y g

e n

d

e

m

an

d

(

C O D

)

a n

d

n utr

i

e nts

h

a s

b

e e n

d

e

m

o n str ate

d i

n

I F A S

a

_p

_p

l i

c at

io n s

₍

Ra n

d

a

l

l et al.

,

19 9 6

₎

.

A

s c o n

d i

t

io

ns a

l l

o

w

, atta c

h

e

d b i

o

m

a s s

g

r o

w

s a s a

b i

o

fi l m

o n t

h

e s u r

f

a c e o

f

t

h

e

m

e

d i

a

s

i

m

u

l

ta n e ous

l

_y

w

it

h

s u s_pe n

d

e

d b

io

m

a s s

(

m ix e

d

l

i

_qu o r

)

i

n t

h

e a ct

i

v ate

d

s

l

u

d g

e

b

a s

in

. T he

a

m

o u nt o

f b i

o

m

a s s t

h

at

is

d

e v e

l

o_pe

d

o n t

h

e

m

e

d i

a

d

e_pe n

d

s o n a

h

o st o

f f

a cto r s,

i

n c

lu

d i

n

g

l

o a

d i

n

_g

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d i

s so

l

v e

d

o xy

g

e n c onc entr at

i

on, te

m

pe r atur e,

m i

x

i

ng en erg

y

, s u s

p

e n

d

e

d

-p

h

a s e

b i

o

m

a s s c o n c e ntr at

i

o n , a n

d

s o

l i d

s r eten t

i

o n t

i m

e. B

io

m

a s s a c c u

m

u

la

te s o n t

h

e

m

e

d i

a u nt

i l

a n

a

_{p p}

r o x

i

m

ate

b

a

l

an ce

₍

ste a

d y

state

)

i

s r e ac

h

e

d b

et

w

e e n

b i

o

fi l

m

_g

r o

w

t

h

r ate a n

d

t

h

e r ate at

w h i

c

_h

s o

l i d

s a r e

d

eta c

h

e

d f

r o

m

t

h

e

b i

o

fi l m

D eta c

h

m

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s

h i

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h l

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d

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d

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m

ix

in

_{g t}u r

b

u

l

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a n

d

a

b

r a s

i

o n

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h

e r

m

e

d i

a.

I f b i

o

fi l m

s o

l i d

s

g

r o

w

m

o r e s

lo

w l

y t

h

a n t

h

e

d

eta c

h

m

e nt r ate, t

h

e

at ta c

h

e

d b i

o

m

a s s

w i l l d

e c r e a s e. I

f b i

o

fi l

m

s o

l i d

s gr o

w m

o r e r ap

i d l y

t

h

a n t

h

e

y

a r e

d

eta c

h

e

d

, t

h

e

In a

d d i

t

i

o n to t

h

e atta c

h

e

d

_gr o

w

t

h

o n t

h

e

m

e

d i

a_,

b i

o

m

a s s

w i l l

a

l

s o

d

e v e

l

o_p

i

n t

h

e s u s_pe n

d

e

d

p h

a s e

(

m i

x e

d l i

_qu o r

)

, s

i m i l

a r to c o n v e nt

i

o n a

l

s u spe n

d

e

d

gr o

w

t

h

sy ste

m

s. Be c a u s e a

po rt

i

o n o

f

t

h

e tota

l b i

o

m

a s s

i

s atta c

h

e

d

_gr o

w

t

h

a n

d

r etain e

d i

n t

h

e a e r at

i

o n

b

a s

i

n, o n

l

y t

h

e

m i

x e

d l i

qu o r

s u s_pe nded s o l i ds r e a ch the f

i

n al cla ri fi e r s. T

h

e r efo r e, the total b

i

o

m

a s s c o n c e ntr atio n a ch ie v e

d

i

n a n

I

F

A S

s_yste

m w i l l

e x c e e

d

t

h

e e

f f

e ct

i

v e

b i

o

m

a s s c o n c e ntr at

i

o n a c

h i

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b l

e

b

_y s u s_pe n

d

e

d

p h

a s e o n

l

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d i

n c r e a s e t

h

e c a_pac

i

t y o

f

t

h

e s_yste

m

i

n t

h

e sa

m

e r e a cto r v o

l

u

m

e.

I F A S s_yste

m

s c o

m

e

w i

t

h

s e v e r a

l

_p

h

_ys

i

c a

l

r e_qu

i

r e

m

e nts t

h

at

m

u st

b

e a c c o un te

d f

o r

i

n t

h

e

s_y ste

m

:

•

M

i

x

i

n

_g

-

A d

e

_q

u ate

m

i

x

i

n_g

m

u st

b

e

_p

r o v

i d

e

d f

o r

f

r e e-

f l

_{o at}

i

_n

g s_yste

m

s to e n s u r e t

h

at t

h

e

m

e

d i

a r e

m

a

i

n s u n

i f

o r

m l y d i

str

i b

ute

d

t

h

r o u_g

h

o u_t t

h

e r e a cto r a n

d d

o n ot _ga_t

h

e r o r

c o n c e ntr ate at t

h

e e

f f l

u e nt e n

d

o

f

_p

l

u

_{g f l}

o

w

ta n

k

s.

A d d i

t

i

o n a

l l

y ,

fr

ee

-

f l

_{o at}

i

_n

g

m

e

d i

a

i

s

s

_{l i}

_g

_h

_t

l

_y

_l

e s s

d

e n s e t

h

an

w

ate r, r e s u

l

t

i

n

g i

n

f l

otat

i

o n

w h

e n a e r at

i

o n syste

m

s a r e tu r n e

d

o

ff

.

M

i

x

i

ng e n e rg y

m

u st

b

e a

d

equ ate to r e

d i

str

i b

ute t

h

e

f l

o at

i

ng

m

e

d i

a upo n sta rtup.

T h

e

m i

x

i

n_g r e_qu

i

r e

m

e nt a_p

_{p l i}

e s

m

a

i

n

l

_{y t}o

f

r e e-

fl

_{o at}

i

_n

g

m

e

d i

a.

• _Tu r

b

u

l

e n c e

/

s

l

ou

_{gh i}

n

_g

e n e r

_g

_y -

I

n

f

r e e-

fl

_{o at}

i

_n

g

m

e

d i

a s_y ste

m

s

l i k

e t

h

e o n e at t

h

e T .

Z

.

O

s

b

o r n e

W

R F, t

h

e

m

i

x

i

ng a n

d

a e r at

i

o n pr o v

i d

e

d b

y t

h

e a e r at

i

o n syste

m i

s u s u a

l l

y

a

d

e_qu ate

f

o r t

h

e s

l

ou

_{g h i}

n_g o

f b i

o

l

o_g

i

c a

l m

ate r

i

a

l f

r o

m

t

h

e

b i

o

m

a s s a n

d f

o r

m

a

i

nta

i

n

i

n

_g

a t

h i

n, v

i

a

b l

e

b i

o

fi l m

.

•

_A

_{e r at}

_i

_{o n} -

_{T h}

_e

_b

_u

_{i l d}

_u

_p

_o

_{f b i}

_o

_m

_{a s s o n t}

_h

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_{a re}

_q

_u

_i

_{r e s a}

_{h i}

g

h

e r

d i

s s o

l

v e

d

o x_{y g}e n

c o n c e ntr at

i

o n

i

n t

h

e s u s

_p

e n

d

e

d

_p

h

a s e to e n s u r e t

h

at t

h

e

b i

o

f

i

l m i

s ae r o

b i

c t

h

r o u

_{g h}

o ut

i

ts

the

m

e

d i

a _pe r

f

o r

m

t

h

e

m

a

j

or

i

t_y of n itri fi c atio n in an I F

A

S s_yste

m

. I F

A

S

m

e

d i

a

m

a n u

fa c

tu r e r s

h

a v e

i d

e nt

i f

i e

d

ta r_get

d i

s s o

l

v e

d

o x_{y g}e n c o n c e ntr at

io n s o

f

a

m i

n

i m

u

m

o

f

3 m g /

L a n

d

a

_p

r e

f

e r a

b l

e ta r_get o

_{f 4}

m

_{g / L}

.

•

_{E f fl}

_{u e nt s c r e e n s} -

_F

_{o r}

_f

_{r e e}-

fl

_{o a}t

i

_n

g s_yste

m

s, e

f fl

u e nt s c r e e n s

m

u st

b

e

in s

ta

l le

d

to

c o ntain

m

e_{d i}a

w

ith in the r e a cto r s. Fo r a e r o

b

ic sy ste

m

s, t

h i

s

is u s u a

l

l y in the

f

o r

m

o

f

s u

b

m

e r_ge

d

, cy

l i

n

d

r

i

c a

l

s c r e e n s. Fo r a n o x

ic s

yste

m

s

, t

h i

s

i

s u s u a

l l

y v e rtic a

l w

e

d

ge -

w i

_{r e}

s c r e e n s. T

h

e s e e

f fl

u ent s c r e e n s a r e

d

e s

i g

n e

d f

o r

m in

i

m

a

l h

e a

d lo

s s.

•

F

_{o a}

m

r e

m

o v a

l /

a c c u

m

u

la

t

i

o n - B e c a u s e o

f

t

h

e n ee

d

to r eta

in

t

h

e

m

e

d i

a

w i

th in the

I F A

S

c e

l l

s, a c c u

m

u

la

t

io

n o

f f

o a

m i

n s

it

u at

io n s

w h

e r e

f

o a

m

c a n o c c u r

i

s a c o

m

m

o n

i

s s u e

w i

th

I F A S

s_y ste

m

s

d

u e to t

h

e

d

e c r e a s e

d

a

b i l i

t

_y

to c o

l l

e ct a n

d w

a ste

f

o a

m

-_{c a u s}

in

g

b

a cte r

ia

.

M

o st o

f te

n, c

h l

o r

i

nate

d w

ate r spr ays a r e u s e

d

to r e

d

u c e a n

d

c o ntr o

l fo a

m

.

T h

e u s e o

f

s c r e e n sto r eta

i

n t

h

e

m

e

d i

a c a n a

l lo

w

t

h

e

m

a

j

o r

i

t_y o

f

the

fo a

m

to _pa s s t

h

r o u_g

h

to

d

o

w

n str e a

m

c e

l ls a n

d

o n to t

h

e

fi

n a

l

c

l

a r

i fi

e r s,

w h

e r e

i

t c a n

b

e r e

m

o v e

d f

r o

m

the

s_yste

_m

.

2

.

2

N

o

m

e n clatu r e a n

d N

otat

i

on

T

he

f

o

l l

o

w i

n

_{g d}

e

f

i n

i

tio n s a n

d

s_pe c

i

a

l

te r

m

s a r e u s e

d i

n th is r e

_p

o rt:

T h

e

i

r u s e

is c o

ns

i

ste nt

w i

t

h

t

h

e

A

m

e r

ic a

n So c

i

et_y o

f C i

v

i l

En_g

in e e r s

₍

A

S

CE

)

Sta n

d

a r

d

₍

A S

C E, 2 0 0 7

)

.

•

D O

~ D

i

_{s s o}

l

_{v e}

d

_{o x}

_{y g}

_{e n c o n c e nt}r atio n

in

m

_g

/L

.

•

O T E

=

O

x

_y

_ge n tr a n s

f

e r e

f f

i c

i

e n c_y

i

n

_p

e r c e nt.

T h i

s

is

t

h

e pe r c e nta

g

e o

f

t

h

e o xy ge n

m

a s s

tr an s

f

e r r e

d f

r o

m

t

h

e

_g

a s _p

h

a s e to the

l i

_qu

i d p h

a s e

f

r o

m

t

h

e r

i

s

i

n_g a

i

r

b

u

b b l

e s.

I

t

i

s

te

m

_pe r a_tu r e,

b

a r o

m

etr

i

c pr e s s u r e, s a

l

t c o n c e ntr at

i

o n , a n

d

othe r c o n stitu e nts in the

w

a ste

w

ate r.

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s tr a n s

f

e r e

ffi

c

i

e n cy

i

s

w h

at

i

s a ctu a

l l

y

m

e a s u r e

d i

n a n of

f

-ga s te st.

•

S O T E

=

St

an

d

a r

d

o x_{y g}e n tr a n s

f

e r e

f fi

c

i

e n c_y

i

n

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s

i

s t

h

e pe r c e nta

g

e o

f

the

o x_{y g}e n

m

a s s tr a n s

f

e r r e

d f

r o

m

t

h

e _ga s _p

h

a s e to t

h

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i q

u

i d

_p

h

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f

r o

m

t

h

e r

i

s

i

n_g a

i

r

bub

b

le s at sta n

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a r

d

c o n

d

it

i

o n s

f

o r d

i

s s olv e

d

o x_{y g}e n

₍

_{D O}

₎

c o n c e ntr a_t

i

o n , te

m

pe r atu r e,

b

a r o

m

etr

i

c

_p

r e ssu re, s a

l

t c o n c e ntr at

i

o n , a n

d

c

l

e a n

w

ate r.

O

n e n e v e r o

b

ta

i

n s t

h

e

SO T E i

n

a ctu a

l

_pr o c e s s o_pe r at

i

o n .

S O T

E

i

s

d

ete r

m i

n e

d b

y a c

l

e a n

w

ate r te st, a s

d

e s c r

i b

e

d b

y

A SC E

₍

2 0 0 7

₎

.

• O T R =

O

x_{y g}e n tr a n s

f

e r r ate

i

n _po u n

d

s o

f

o x_{y g}e n

_p

e r

h

o u r.

T

h

i

s is t

h

e r ate o

f

tr ans

f

e r o

f

o x_{y g}e n

m

a s s

f

r o

m

the _ga s

_{p h}

a s e to t

h

e

l i q

u

i d p h

a s e. It

d

e

p

e n

d

s upo n t

h

e pr o c e s s

c o n

d i

t

i

ons, suc

h

a s

d i

s s o

l

v e

d

o xy ge n

(

D O

)

c onc en tr at

i

o n, te

m p

e r atu r e,

b

a r o

m

etr

i

c

p

r e s s u r e, s a

lt

c o n c e ntr at

i

o n, a n

d

ot

h

e r

w

a ste

w

ate r c o n st

i

tu e nts. T

h i

s tr a n s

f

e r r ate c a n

b

e

c a

l

c u

l

ate

d f

r o

m

the

O T E

a n

d

_t

h

e a

i

r

fl

o

w

r ate,

w h i

c

h i

s n o r

m

a

l l y m

e a s u r e

d i

n an o

f f

-gas

te st.

•

S O

T

R

= Sta n

d

a r

d

o x_{y g}e n tr a n sfe r r ate in _po u nds o

f

o x_{y g}e n _pe r

h

o u r. T

h i

s

i

s the r ate o

f

tr a n s

f

e r o

f

o x

_{y g}

e n

m

a s s

f

r o

m

the _ga s _p

h

a s e to t

h

e

l i

_qu

i d p h

a s e at sta n

d

a r

d

c o n

d i

t

i

o n s

f

o r

d i

s s o

l

v e

d

o x_{y g}e n

₍

D O

₎

c o n c e ntr at

i

o n , te

m p

e r atu r e,

b

a r o

m

etr

i

c

p

res s u r e, s a

l

t

c o n c e ntr at

i

o n , a n

d

c

l

e a n

w

ate r.

O

n e n e v e r o

b

ta

i

n s t

h

e

S O T R

i

n a ctu a

l

pr o c e s s

o_pe r at

i

o n. S

O

T

R i

s

d

ete r

m

in e

d b

y a c

l

e a n

w

ate r te st, a s

d

e s c r

i b

e

d b

y A

SC E

(

2 0 0 7

)

.

•

K

_{t a} =

V

o

l

u

m

etr

i

c

m

a s s tr ans

f

e r c o e

f f

i c

i

e nt

i

n u n

i

ts o

f h

o u r s

'

^

T h i

s

i

s a

m

at

h

e

m

at

i

c a

l

p

a r a

m

ete r c a

l

c u

l

ate

d f

r o

m

tr a n s

f

e r

d

ata to

_d

e s c r

i b

e t

h

e r ate o

f

o x_{y g}e n tr a_n s

f

e r

f

r o

m

the

ga s _p

h

a s e to t

h

e a

_q

u e o u s _p

h

a s e.

T h

e

SO T E

c an

b

e c a

l

c u

l

ate

d f

r o

m

the v a

l

u e o

f K

t a a n

d

v i c e-_{v e r s a}

•

Q

c o * = _E

q

u

i l i b

r

i

u

m

D

O

c o n c en tr atio n. T h is is the D O c o n c e ntr at

i

o n that

i

s a c

h

ie v ed in

c

l

e a n

w

ate r a

ft

e r

b

e

i

n_g a e r ate

d f

o r a v e r_y

l

o n _g t

i m

e

i

n o r

d

e r

f

o r the s_yste

m

to r e a c

h

e

_q

u

i l i b

r

i

u

m

(

n o c

h

a n

_g

es

i

n co n

d i

t

i

o n s o v e r t

i m

e

)

.

I

t

i

s t y

p i

c a

l l y l

a r

g

e r t

h

a n t

h

e

s atu r at

i

o n c o n c e ntr at

i

o n

l i

ste

d i

n

h

a n

db

o o

k

s,

w h i

c

h

r e su

l

ts

b

e c a u s e o

f

the

i

n c r e a s e

d

h y dr o static _pr e s s u r e of the

w

ate r c olu

m

n o n the risin_g

b

ub b le s,

a

f

a cto r o r a F

f

a cto r =

T h

e a

f

a cto r

i

s t

h

e r at

i

o o

f

t

h

e v a

l

u e o

f K

t a

m

e a s u r e

d i

n

p

r o c e s s

w

ate r to the

K

_{t a}

m

e a s u r e

d i

n c

l

e an

w

ate r. T

h

e s

m

al

l

e r the v a

l

u e o

f

t

h

e a

f

a cto r t

h

e

_g

r e ate r t

h

e r e

d

u ct

i

o n

i

n tr a n s

f

e r r ate

d

u e to c o n ta

m

i

n a nts

i

n t

h

e

_p

r o c e s s

w

ate r.

W

h

e n the te r

m

a F

i

s u s e

d

,

i

t r e

f

e r s to

di f f

u s e r s t

h

at

h

a v e

b

e en

i

n s e r v

i

c e

f

o r a pe r

i

o

d

o

f

t

i m

e,

w h i

c

h

u su a

l l

y

h

a v e a

d d i

t

i

o n a

l

r e

d

u ct

i

o n

i

n tr ans

f

e r e

f f

i c

i

e n cy

d

u e to

b i

o

f

o u

l i

n

g

o r

c

h

a n _ge s

i

n

d i f f

ii s e r

m

ate r

i

a

l

_pr o_pe rt

i

e s, s u c

h

a s

m

e

m

b

r a n e

h

a r

d

e n

i

n

g

o r s o

ft

e n

i

ng.

a

S O

T

E

o r a F

SO

T E =

O

x _{y g}e n tr a n s

f

e r e

f fi

c

i

e n c_y

(

O T

E

)

c o r r e cte

d f

o r al

l

_pr o c e s s

c o n

d i

t

i

o n s s u c

h

a s D

O

, s a

l i

n

i

t y,

b

a r o

m

etr

i

c

p

r e s s u r e, etc._, e x c e

p

t

f

o r t

h

e a

f

a cto r.

T h i

s

i

s the s

in

_{g l}

e

m

o st u s e

f

u_{l p}a r a

m

ete r to

d

e s c r

i b

e the _pe r

f

o r

m

a n c e o

f

a n a e r at

i

o n s_yste

m

u n

d

e r

_p

r o c e s s c o n

d it

i

o n s. T

h

e a

S

O T E

d i

v i

d

e

d b

y t

h

e S

O

T E

i

s equ a

l

to t

h

e a

f

a cto r .

A

_ga

i

n,

w h

e n a F

i

s u s e

d

,

it

r e

f

e r s to u s e

d d i f f

u s e r s.

•

_p

= s a

l i

n

it

_y cor r e ct

i

on

f

a ctor.

2

.

3

T

e c

h

n

ic a

l

D

e s c r

i p

t ion

O

n e o

f

t

h

e c

h

a

l l

e n

_g

e s

w

it

h

a e r o

b ic

w

a ste

w

ate r tr e at

m

e nt

_p

r o c e s s

d

e s

i

_gn

i

s t

h

e c o r r e ct

s_pe c

i fi

c at

i

o n o

f

a e r at

io n

c a_pa c

i

t_y. A v a r

i

ety o

f

te c

h

n

i

qu e s e x

i

st

f

o r e st

i m

at

i

n g t

h

e o xy ge n

tr a n s

f

e r c a_pa c

i

t_y o

f

a n a e r at

i

o n s_yste

m

.

M

etho

d

s

f

o r e st

i m

at

in

g tr a n sfe r c a n ge n e r a

l

l y

b

e

d i

v

i de

d i

nto t

h

r e e c ate_go r

ie s :

•

C l

e a n

w

ate r te st

i

n_g a n

d

c o n v e r s

i

o n to

f

i e

l d

r ate s

w i

t

h

a

l

_{p h}a,

b

eta, a n

d

t

h

eta c o n v e r s

i

o n

f

a cto r s.

•

T

e st

i

n

_g

u n

d

e r a ctu a

l fi

e

l d

c o n

d i

t

i

ons

(

"

d ir

_{t y}

w

ate r" te st

i

n_g

)

us

in

_g

m

et

h

o

d

s _to a c c o un t

f

o r the

b i

o

l

o_g

ic a

l

c o n s u

m

_{p t}

i

o n o

f

o x_{y g}e n

d

u r

i

n

_g

t

h

e tr a n s

f

e r te st.

•

M

ate r

i

a

l b

a

l

a n c e

m

et

h

o

d

s

w h i

c

h

at te

m

_{p t} to

d

ete r

m

i

n e

d i f f

e r e n c e s

b

et

w

e e n

i

n

_p

uts a n

d

out

_p

uts o

f

o x

_y

_ge n-_{c o n s u}

m

i

_n

g m

ate r

i

a

l

.

A l l

o

f

t

h

e s e

m

et

h

o

d

s

h

a v e a

d

v a nta_ge s a n

d d

is a

d

v a nta_ge s.

W

h

e n u sin

g c

l

e a n

w

ate r te st r e s u

l

ts

i

t

is v e r

_y

d i f fi

c u

l

t to a c c u r ate

l

_y e st

im

ate t

h

e al p

h

a

f

a cto r

(

r at

io

o

f

m

a s s tr a n s

f

e r c o e

f fi

c

i

e nt

i

n

d i

r_{t y}

w

ate r to

i

ts v a

lu e

i

n c

l

e a n

w

ate r

₎

.

D i

rty

-

w

_{ate r te st}

i

_n

g r e_qu

ir e s a c c u r a

te e st

i m

at

i

o n o

f

t

h

e

o x_y

_g

e n c o n s u

m p

t

i

o n r ate,

w h i

c

h i

s o

ft

e n v e ry

d i f fi

c u

l

t, e spe c

i

a

l l

y

i

n o x y ge n

-

l im

i

t

in

g

c o n

d i

t

i

o n s,

w h i

c

h

o cc ur

in

o v e r

lo a

de

d

tr e at

m

e nt

p l

a nts.

M

ate r

i

a

l

-

b

_a

l

a n c e

m

et

h

o

d

sr e

_q

u

i

r e

l

o n _g-t_{e r}

m k

_{n o}

w l

_e

d

s u s c e_pti

b l

e to e r r o r fr o

m

slud ge s et tl

i

n_{g i}n t

h

e a e r at

i

o n

b

a s

i

n o r str

i

_{p p}

i

n_g of v olat

i

le o x_{y g}e n

-c o n s u

m

i

n

_g

c o

m

_po u n

d

s.

A

te c

h

n

_{i q}

u e

w h i

c

h h

a s n o n e o

f

the a

b

o v e s

h

o rtc o

m

in

_g

s

i

s o

f f

-ga s a n a

l

_y s

i

s. T

h i

s

m

et

h

o

d

r e_qu

i

r e s t

h

e c a_ptu r e o

f

a r e_pr e s en tat

i

v e s a

m

_p

l

e o

f

t

h

e _ga s

w h i

c

h

e x

i

ts t

h

e a e r atio n

b

as

i

n s u r

f

a c e,

t_y

_{p i}

c a

l l

_y u s

i

n_g a

f l

o at

i

n

_g

"

h

o o

d

"

that

_p

r o v

i d

e s a s e a

l b

et

w

e e n t

h

e

l i q

u

i d

s u r

f

a c e a n

d

t

h

e

h

e a

d

s_pa c e. T

h

e o

f f

-ga s

i

s anal yz e

d f

o r o x_{y g}e n , c a r

b

o n

d i

o x

i d

e, a n

d w

ate r v apo r c o nte nt. B y

k

n o

w i

n

_g

t

h

e

f l

o

w

r ate s o

f g

a s e nte r

i

n_g a n

d

e x

i

t

i

n

_g

t

h

e

l i

_qu

i d

,

m

a s s tr a n s

f

e r e

f fi

c

i

e n c

y

c a n

b

e

c a

l

c u

l

ate

d

. I

f f l

o

w

r ate s a r e n ot

k

no

w

n

, t

h

e

m

a s s tr a n s

f

e r e

f f

i c

i

e n cy c a n st

i l l b

e

d

ete r

m i

n e

d b

y

k

no

w i

n

_g

t

h

e _pa rt

i

a

l

v o

l

u

m

e s o

f

the r e a ct

i

n _g o r c

h

a n_g

i

n_{g g}a s c o n st

it

u e n ts

(

o x_{y g}e n, c a r

b

o n

d i

o x

i d

e, a n

d w

ate r v apo r

)

a n

d

a s su

m

i

ng t

h

at t

h

e

i

n e rt ga s c onst

i

t ue nts

(

n

i

tr oge n, a rgo n

)

r e

m

a

i

n

c o n sta nt. It

m

u st

b

e

f

u rt

h

e r a s s u

m

e

d

t

h

at t

h

e tr a n s

f

e r at t

h

e

f l

u

i d

s u r

f

a c e a n

d

t

h

e at

m

o sp

h

e r e

i

s

n e_g

l i

_g

i b l

e

w h

en c o

m

_pa r e

d

to t

h

e tr a n s

f

e r c a u s e

d b

_{y t}

h

e a e r at

i

o n s_yste

m

, a n

d

t

h

at ste a

d

y

-state

c o n

d i

t

i

o n s e x

i

st

d

u r

i

n _{g t}

h

e te st. Bot

h

a s s u

m

pt

i

o n s a r e v e r

y g

o o

d f

o r

w

a ste

w

ate r tr e at

m

e nt

s_yste

m

s, e s

p

e c

i

a

l l

y o v e r t

h

e s

h

o rt

d

u r at

i

o n o

f

o

f f

-ga s te st

i

n_g.

T h

e c o n c e_pt o

f

o

f f

-ga s a n a

l

_ys

i

s

i

s n ot n e

w

a n

d w

a s o r

i

_g

i

n a

l l y d

e s c r

i b

e

d i

n 1

9

3

9 b

_y

S

a

w

_ye r a n

d

N i

c

h

o

l

s

(

1

9 3 9

)

.

A

n u

m b

e r o

f l

ate r

i

n v e st

i

gato r s cont

i

n u e

d

t

h

e

d

e v e

l

op

m

e nt o

f

o

f f

-ga s an a

l

_ys

i

s,

i

n c

l

u

d i

n_g

H

o v e r et. a

l

.

(

1

9 54

)

,

P

a u

l i

n g et a

l

(

19 6 8

)

,

P

r

i

t a n

d C

a

l l

o

w

(

19 5 8

)

a n

d

Do

w

n

i

ng

(

19 6 0

₎

.

C

o n

w

ay a n

d K

u

m k

e

(

1

9 6 6

)

an

d

L e a ry et al.

(

1 9

6 8

)

h

a v e a

l

s o u s e

d

o

f f

-ga s a n a

l

_y s

i

s.

T

h

e

A S

C E

/

E P

A

s u

b

c o

m

m

i

tte e o n o x _{y g}e n tr a n s

f

e r te st

i

n

_g

a s

k

e

d E w i

n

_{g E}

n_g

i

n e e r

i

n

_g

(

Re

d m

on

et a

l

.,

19 8 3

)

to

f

u rt

h

e r

d

e v e

l

o

p

t

h

e te c

h

n

i

qu e. T

h

e

i

r r e s u

lt

s r e

p

o rte

d

at t

h

e 1983 m e et

i

ng o

f

t

h

e

o

f f

-g

a s tec

h

n

i

_qu e

i

s a n a c c u r ate a n

d

_pr e c

i

s e

w

a_y o

f

e st

i m

atin

_g

a e r atio n e

f f

i c

i

e n c_y u n

d

e r _pr o c e s s

c o n

d i

t

i

o n s.

N

e

w d

e v e

l

op

m

e nts

w h i

c

h m

a

k

e t

h i

s

m

et

h

o

d m

o r e

p

r e c

i

s e a r e a

d

v a n c e s

i

n o xy

g

e n

a n a

l y

z e r s, an

d

t

h

e u s e o

f

la rge o

f f

-ga s c o

l l

e ct

i

o n

h

o o

d

s

w h i

c

h

c a_ptu r e

m

o r e r e_pr e s e ntat

i

v e

s a

m

_p

l

e s.

O f f g

a s a n a

l

_y s

i

s c a n

b

e u s e

d f

o r a n_y su

b

s u r

f

a c e a e r at

i

o n s_yste

m

r e

_g

a r

d l

e ss o

f

t

h

e o x_y

_g

e n

u_pta

k

e r ate a n

d

_pr o c e s s c o n

d i

t

i

o n s.

E f f

i c

i

e n c

i

e s o

f

o xy ge n

-

l

i

m

i

_t

e

d

s_yste

m

s c a n a

l

s o

b

e

d

ete r

m i

n ed, a

l

t

h

o ug

h

t

h

e tr a n s

f

e r r ate

m

ay

b

e

d i f f

e r e nt t

h

a n t

h

e tr a n s

f

e r r ate u n

d

e r n o r

m

a

l

o_pe r at

i

o n . It

h

a s

b

e e n

d

o c u

m

e nte

d

t

h

at a

l

p

h

a

f

a cto r s c a n v a ry gr e at

l

y

(

S

tenstr o

m

a n

d G i l b

e rt

,

19 8 1

₎

.

2.

3

.1

A

nal ysis

T

he o ry

T o

d

ete r

m i

n e o x_y

_g

e n tr a n s

f

e r e

f fi

c

i

e n c _y u s

i

n

_g

o

f f

-ga s a n a

l

_ysis, a

m

a s s

b

a

l

a n c e

m

u st

b

e

per

f

o r

m

e

d

o n t

h

e _ga s e nte r

i

n

_g

an

d

e x

i

t

i

n

_g

the

l i q

u

i d

. T

h

e

f

o

l l

o

w i

n

g d

e s c r

i p

t

i

o n

i

s pr o v

i d

e

d

, a n

d

i

s

b

a s e

d l

a r_ge

l

_y o n t

h

e a n a

l

_ys

i

s

b

_{y R}e

d m

o n et a

l

.

(

1 9 8

3

)

. I

f

t

h

e

f l

o

w

r ate s o

f

ga s e nte r

i

n g a n

d

e x

i

t

i

n

_g

t

h

e

f l

u

i d

a r e

k

n o

w

n , t

h

e n t

h

e

f

o

l l

o

w i

ng

m

a s s

b

a

l

a n c e c a n

b

e

m

a

d

e :

V

_a

_P

^

=

p

i

q

,

Y

,

-q

J

J

-

K

, a

(

C

:

-

C

)

V

(

1

)

p

d

e n s

i

t_y o

f

o x_{y g}e n at te

m

_pe r atu r e a n

d

_pr e s s u r e o

f g

a s

f l

o

w

,

q i,q_Q

= _tota

_l

_{v o}

_l

_u

_m

_etr

_i

_c

ga s

fl

o

w

r ate s o

f i

n

l

et a n

d

o ut

l

et _ga s s e s,

Y r ,Y_o

g

=

_m

_o

_l

_e

_f

_{r a ct}

_i

_{o n s}

₍

_e

qu

i

v a

l

e nt to v o

l

u

m

etr

i

c

f

r a ct

i

o n s

)

o

f

o x_y

_g

e n

i

n

t

h

e

i

n

l

et

(

R , r e

f

e r e n c e

)

a n

d

e x

i

t

g

a s s e s

(

o

g

, o

f f

-g

a s

)

,

K

La = v o

l

u

m

etr

i

c o x _{y g}e n tr a n s

f

e r c o e

f f

i c

i

e nt.

*

C_oo "= _e

qu

i l i b

r

i

u

m d i

s s o

l

v e

d

o x_{y g}e n c o n c e ntr at

i

o n

i

n t

h

e te st

l i q

u

i d

at t

h

e

_{g i}

v e n c o n

d i

t

i

o n s,

C

=

_{d i}

_{s s olv e}

_d

_{o x}

y ge n c o n c e ntr at

i

o n ,

V

=

_{l i q}

_u

_{i d}

_{v o}

_l

u

m

e, a n

d

V q = ga s

h

o

l d

-_u

p v o

l

u

m

e.

A

t ste a

d

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h

e e

_q

u at

i

on r e

d

u ce s to :

p

(

q

,

Y

,

-

_q

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^

)

=

_K

, a

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C

:

-

_C