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SPECIALIZED ENGLISH – SEMESTER 5MANAGEMENT Chapter 26 FUNDAMENTALS OF BIOLOGICAL Dr.. 2011 WASTEWATER TREATMENT Modeling suspended growth treatment process Purpose The complete The com

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SPECIALIZED ENGLISH – SEMESTER 5

MANAGEMENT

Chapter 26 FUNDAMENTALS OF BIOLOGICAL

Dr Tran Thi My Dieu

Sep 2011

WASTEWATER TREATMENT

Modeling suspended growth

treatment process

Purpose

The complete The complete mix reactor without recycle mix reactor without recycle

The complete The complete mix reactor with recycle mix reactor with recycle

PURPOSES Purpose of modeling suspended growth

treatment processes?

To assess treatability of wastewater

To obtain model kinetic coefficient

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITHOUT RECYCLE

V, X, S

SS 00

COMPLETE

COMPLETE MIX REACTOR MIX REACTOR

WITHOUT RECYCLE

Trang 2

WITHOUT RECYCLE

Biomass mass balance

Rate of

accumulation of

Rate of flow of

microorganism

i h

= -microorganism Rate of flow of

f h

+microorganism Net growth of

i hi h

microorganism

within the system

boundary

into the system

boundary

out of the system boundary

within the boundary

Accumulation = inflow – outflow + net growth

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITHOUT RECYCLE Biomass mass balance

Symbolic representation

' 0

V QX QX Vrg dt

dX/dt = rate of change of biomass concentration in reactor measured as g VSS/m 3 d

V = reactor volume, m 3

Q = influent flow-rate, m 3 /d

Xo= concentration of biomass in influent, g VSS/m 3

X = concentration of biomass in the reactor, g VSS/m 3

r’g= net rate of biomass production, g VSS/m 3 d

COMPLETE

WITHOUT RECYCLE

' 0

V QX QX Vrg

dt

Assumed X o ~ 0























S K

SX V

S m



0

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITHOUT RECYCLE Biomass mass balance























S K

SX V

S m



0 0



 S

d S

S K





1

COMPLETE

WITHOUT RECYCLE

d

S K





1



1 1

1













d

d S

d m

d S

k Yk

k K

k

k K

S







COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITHOUT RECYCLE Substrate mass balance

Accumulation = inflow – outflow – utilization

su Vr QS

QS

V dt

dS





Trang 3

WITHOUT RECYCLE

Substrate mass balance

su

Vr QS QS V

dt

dS























S K

kSX V QS QS

s

0

WITHOUT RECYCLE Substrate mass balance



















S K

kSX V QS QS

s

0 0



 s

















S K

kSX V

S S Q

s

0

COMPLETE

WITHOUT RECYCLE

Substrate mass balance

















S K

kSX V

S

Q

s

0



 s

S K

kSX S

S

S 







0

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITHOUT RECYCLE Substrate mass balance

S

S K S S kS

S K S S X

m

S S



















S Y



d

k

S S Y k

S S Y X















1 1

0

COMPLETE

WITHOUT RECYCLE

Determine model kinetic coefficient

kS

S K S S

X S

K

kSX

S













k S k

K S S

0











COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITHOUT RECYCLE Determine model kinetic coefficient

S S

X



0



k K

tg  S

S

1

k

1

Trang 4

WITHOUT RECYCLE

Determine Y and k d from modeling of the

complete-mix reactor without recycle



d

k

S S Y X





 1

0

Y Y

k X

S

So  d  1  1



COMPLETE

WITHOUT RECYCLE

Y

k d

X

S

S o





tg

Y

1



1

ASSIGNMENT 3

(mg/L)

 (ngày) X (mg

VSS/L)

Determine k and K s

COMPLETE

WITH RECYCLE

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE

Trang 5

WITH RECYCLE HRT

Q

V





Q

V





WITH RECYCLE SRT

VX





r W e e c

X Q X



X Q X Q

VX W e e



COMPLETE

WITH RECYCLE

In case of no return sludge

SRT = HRT

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Biomass mass balance

 Q Q  X Q X r V QX

V dt

dX

g R W e W

COMPLETE

WITH RECYCLE Biomass mass balance

 Q Q  X Q X r V QX

V

dt

dX

g R W e W

Assumed X o ~ 0

(Q – QW)Xe+ QwXR= rgV

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Biomass mass balance

(Q – QW)Xe+ QwXR= rgV

S

d S

m r

W e

S K

S VX

X Q X





Q Q WX e Q W X R

VX SRT







Trang 6

WITH RECYCLE Biomass mass balance

d S

m r

W

e

S K

S VX

X

Q

X





d S

m

c

k S

K

S





 



1

1 1

1













d c

c d S

d m

c

c d S

k Yk

k K k

k K

S







COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Substrate mass balance

Accumulation = inflow – outflow + generation

Q S Q V dt

Q V dt

dS

.

COMPLETE

WITH RECYCLE Substrate mass balance

V r QS QS

V

dt

dS

su



dt































S K

kXS Q

V S

S

s o

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Substrate mass balance































S K

kXS Q

V S

So



 Q Ks S

S K

kSX S

S

s 





 0

COMPLETE

WITH RECYCLE Substrate mass balance

S K

kSX S

S

s





 0

S

c d

c

k

S S Y X











1

0





S S Y k

S S S

Y

S

K

X

d c m













1 1

D t i ki ti ffi i t f

Determine kinetic coefficients from modeling of the complete-mix reactor

with recycle

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WITH RECYCLE

c d

c

k

S S Y X











1

0

Y

k Y

X

S

c



1 1

WITH RECYCLE

Y

k d





tg

X

S

S o





Y

1

c

 1

COMPLETE

WITH RECYCLE Design and operating parameters

Food to microorganism (F/M) ratio

Total applied substrate rate QS o

F/M = - =

-Total microbial biomass VX

F/M = food to biomass ratio, g BOD or bsCOD/g VSS.d

Q = influent wastewater flow-rate, m 3 /d

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Design and operating parameters

Organic volumetric loading rate

QS

kg g V

QS

org

/

103





L org = volumetric organic loading, kg BOD/m 3 d

Q = influent wastewater flow-rate, m 3 /d

S o = influent BOD concentration, g/m 3

V = aeration tank volume, m 3

COMPLETE

WITH RECYCLE Oxygen requirement

Oxygen used = bCOD removed – COD of waste sludge

R o = Q(S o – S) – 1.42 P x,bio

Ro= oxygen required, kg/d

Px,bio = biomass as VSS wasted per day, kg/d

Mixed liquor solids concentration and solids production

SRT

V X

VSS

X T, 

SRT

XT= total MLVSS concentration in aeration tank, g VSS/m

V = volume of rector, m 3

SRT = solid retention time, d

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WITH RECYCLE Mixed liquor solids concentration

biomass

concentration

nbVSS concentration

X T = X + X i

nbVSS inf nbVSS waste per day From cell decay Affected by

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Mixed liquor solids concentration

X T = X + X i Accumulation = inflow – outflow + generation

V r SRT

V X QX V dt

dX

i x i i o i

,















X o,i = nbVSS concentration in influent, g/m 3

X i = nbVSS concentration in aeration tank, g/m 3

r X,i = rate of nbVSS production from cell debris, g/m 3 d

COMPLETE

WITH RECYCLE Mixed liquor solids concentration

V r SRT

V X QX V

dt

dX

i x i i o i

,















At steady state dX i /dt = 0

V r SRT

V X

i

SRT X k f SRT X

X i  o i  d d 

 ,

COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Mixed liquor solids concentration

X T = X + X i

SRT X k f S S Y SRT













d









1

Heterotrophic biomass

Cell debris

nbVSS inf

COMPLETE

WITH RECYCLE Solid production

S S X SRT Y

SRT

V

X

VSS

X T, 

 



SRT X

SRT X k f SRT k

S S Y

SRT

d

o T

















1

i o d

d d

o VSS

SRT k

S S QY









COMPLETE COMPLETE MIX REACTOR MIX REACTOR WITH RECYCLE Solid production

i o d

d d

o VSS

SRT k

S S QY































SRT k S S Y SRT X

d o

1



i o d

o d d d

o VSS

SRT k SRT S S YQ k f SRT k S S QY

1











Heterotrophic biomass

Cell debris

nbVSS inf

Trang 9

WITH RECYCLE Solid production

i o d

o d d d

o

VSS

SRT k SRT S S YQ k f SRT

k

S S

QY

1











Heterotrophic

biomass

Cell debris

nbVSS inf

TSS

P     

85 0 85

0

,

net waste activated sludge produced each day, measured in terms of TSS, kg/d

WITH RECYCLE Solid production Mass of MLVSS = X VSS V = P X,VSS SRT

Mass of MLSS = X TSS V = P X,TSS SRT

COMPLETE

WITH RECYCLE Observed yield

i o d

o d d d

o

VSS

SRT k SRT S S YQ k f SRT k

S S

QY

1











Q(So-S)

S S

X SRT k

SRT Y k f SRT k

Y

o

i o d

d d d









1 1

Yobs = g VSS/g substrate removed

Assignment 4

k and Ks ?

Comments on lab-data

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