11
501 HWAHAK KONGHAK Vol. 39, No. 4, August, 2001, pp. 501-511 (Journal of the Korean Institute of Chemical Engineers) (2001 3 29 , 2001 6 1 ) Modeling and Simulation of the Simultaneous Wastewater Nitrification and Organics Oxidation in Airlift Biofilm Reactors Il-Soon Suh Department of Chemical Engineering, Konkuk University, Seoul 143-701, Korea Received 29 March 2001; accepted 1 June 2001) . , - - , . . , , , , . , . . . Abstract - A reactor model was developed for the simultaneous nitrification and organic oxidation of wastewater in airlift reactors with bioparticles. The diffusion and reaction in the biofilm of bioparticles, liquid-solid mass transfer, and gas-liquid oxy- gen transfer were taken into account together with the consideration of the nitrification and organic oxidation by the biomass sus- pended in the liquid phase of the reactor. Double Monod-type kinetics was employed for representing the reactions of the nitrification and the organic oxidation. Using the numerical simulation, it was discussed how the nitrification and the organic oxi- dation of the wastewater were influenced in the airlift reactor by effective diffusivity in the biofilm, bioparticle media size, air velocity and reactor operation pressure, flow rate and organic concentration of the feed, and maximum organic oxidation rate in the biofilm. The oxidation rate of ammonia and nitrite increased at the given conditions of the air velocity, the media amount and the biofilm thickness, as decreasing the media size. It was demonstrated in the simultaneous nitrification and organic oxidation of wastewater that the nitrite oxidation was first affected by the reactor liquid-phase concentration of dissolved oxygen and the organic oxidation was influenced by the biomass suspended in the liquid phase of reactor. As increasing the organic concentra- tion of the feed, the organic oxidation rate increased but the oxidation rates of ammonia and nitrite decreased. Key words: Nitrification, Organic Oxidation, Airlift Biofilm Suspension Reactor, Biofilm Model, Gas-Liquid Mass Transfer, Liquid-Solid Mass Transfer E-mail: [email protected] 1. ( ), ( ). . ( ). , , .

Modeling and Simulation of the Simultaneous … −A reactor model was developed for the simultaneous nitrification and organic oxidation of wastewater in airlift reactors with bioparticles

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HWAHAK KONGHAK Vol. 39, No. 4, August, 2001, pp. 501-511(Journal of the Korean Institute of Chemical Engineers)

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Modeling and Simulation of the Simultaneous Wastewater Nitrificationand Organics Oxidation in Airlift Biofilm Reactors

Il-Soon Suh

Department of Chemical Engineering, Konkuk University, Seoul 143-701, Korea�Received 29 March 2001; accepted 1 June 2001)

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Abstract − A reactor model was developed for the simultaneous nitrification and organic oxidation of wastewater in airlift

reactors with bioparticles. The diffusion and reaction in the biofilm of bioparticles, liquid-solid mass transfer, and gas-liquid oxy-

gen transfer were taken into account together with the consideration of the nitrification and organic oxidation by the biomass sus-

pended in the liquid phase of the reactor. Double Monod-type kinetics was employed for representing the reactions of the

nitrification and the organic oxidation. Using the numerical simulation, it was discussed how the nitrification and the organic oxi-

dation of the wastewater were influenced in the airlift reactor by effective diffusivity in the biofilm, bioparticle media size, air

velocity and reactor operation pressure, flow rate and organic concentration of the feed, and maximum organic oxidation rate in

the biofilm. The oxidation rate of ammonia and nitrite increased at the given conditions of the air velocity, the media amount and

the biofilm thickness, as decreasing the media size. It was demonstrated in the simultaneous nitrification and organic oxidation of

wastewater that the nitrite oxidation was first affected by the reactor liquid-phase concentration of dissolved oxygen and the

organic oxidation was influenced by the biomass suspended in the liquid phase of reactor. As increasing the organic concentra-tion of the feed, the organic oxidation rate increased but the oxidation rates of ammonia and nitrite decreased.

Key words: Nitrification, Organic Oxidation, Airlift Biofilm Suspension Reactor, Biofilm Model, Gas-Liquid Mass Transfer,

Liquid-Solid Mass Transfer

†E-mail: [email protected]

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+,

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=

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NH4+

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++---------------------------

O2

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----------------------------

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–+

----------------------------

O2

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----------------------------

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rr

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NH4R+

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----- O2

O2

O2R

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βNH4+

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NH4R+

-------------= βNO2 –

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NO2R –

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SR

------=, ,

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O2R

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O2R

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---------------=,=,=

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+

NH4R+

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SR

----- O2S

O2S

O2R

---------=,=,=,=

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+–( )µm NH4

+,YX N⁄ NH4

+,--------------------

NH4R+

KNH4+ NH4R

++------------------------------

O2R

KO2NH4+ O2R+

------------------------------

–=

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+, a'p NH4R+ NH4S

+–( )–

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NO2R –

–( )µm NH4

+,YX N⁄ NH4

+,--------------------

NH4R+

KNH4+ NH4R

++------------------------------

O2R

KO2NH4+ O2R+

------------------------------

+=

XNH4R+

µm NO2 –,

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--------------------NO2R

KNO2 – NO2R

–+

------------------------------- O2R

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------------------------------

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ks NO2

–, a'p– NO2R – N– O2S

–( )

0 F VL⁄( ) SF SR–( )µm het,

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SR

KS SR+-----------------

O2R

KO2 het, O2R+------------------------------

XhetR–=

ks S, a'p SR SS–( )–

0 F VL⁄( ) O2F O2R–( )µm het,

YX O2 het,⁄--------------------

SR

KS SR+-----------------

O2R

KO2 het, O2R+------------------------------

XhetR–=

Table 1. Typical values of Monod constants for nitrifying bacteria[10]

Constant Nitrosomonas NitrobacterHeterotrophs(a)

Cell yield 0.03-0.13 0.02-0.08 0.37-0.79[wt cells/wt energy substrate]

µmax[d−1] 0.46-2.2 0.28-1.44 7.2-17.0

K[mg/L]Energy substrate 0.06-5.6 0.06-8.4 <1-181Electron acceptor 0.3-1.3 0.25-1.3 0.0007-0.1

(a)from activated sludge with glucose substrate.

HWAHAK KONGHAK Vol. 39, No. 4, August, 2001

504 � � �

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��� !"� ´����, DE� !" #34(aerobic) ̧ ¹

�7 �� #�� cM�� �#(anoxic) 34¸¹�7 Q�

�[6� cM�*� �6��*. 3�� ¸¹ ��7 �� #� +

��� cM� _`ç. <¥# J2Þ �� '

@<�M ³@���, æ# ¸¹�7 Q��� cM� _`ç�

J2Þ �� ' _`EW«� H<��*. S#�

,-(HCO3−)|W� c� �èé ä1 @<�M pH �§1 ����

*. vz, ���7� ���� #�AB' 8d _`� åEAB�

�6���, Q���7 �#oíAB� &�#oíAB' ´��

0 ¨µ*.

Ø ×´� _`� ��5 ��Y > ASM3 !d �0 °� Ö�� �

��� �# ̧ ¹ ��7� Q��[61 ����I�, _`� qK

5 Û��Ê0 @,� �8r + Û��Ê0 k ��# ÍÎ1 æF

� _`� qK N�!d� �� _`ç© ��� ��,*. vz, ��

[6�7� &�# #�AB' ���0 ̈ µ� >ñ� � { _`��

7 9" c½$ &�#� _`� k ¼H1 ³@Y � Ô*[4, 6, 7, 17].

3. �� � �

� { ��� c� 2À �ì K��6äç� ��PÀ� �

1 H<��I= , �5 ��$ �ì 6äç5 _`� ���

NO ��$ �ì 6äç� � global method� ́ ��*[18].

�Þ�@� Ö�� �� + �� #� _`� _`EW« �Ó��

µm NH4

+,

YX O2⁄ NH4+,

---------------------NH4R

+

KNH4+ NH4R

++------------------------------

O2R

KO2NH4+ O2R+

------------------------------

XNH4+

R–

µm NO2

–,

YX O⁄ 2 NO2 –,

----------------------NO2R

KNO2 – NO2R

–+

------------------------------- O2R

KO2NO2 – O2R+

------------------------------

XNO2R ––

Ks O2, a'p O2R O2S–( ) kLa' O2* O2R–( )+–

ks NH4+, a'p NH4R

+ NH4S+

–( ) DNH4+ f, a'p

NH4R+

rp δ+-------------

dNH4

+

dr--------------

r 1=

⋅=

ks NO2 –, a'p NO2R

– NO2S –

–( ) DNO2 – f, a'p

NO2R –

rp δ+-------------

dNO2

dr--------------

r 1=

⋅=

ks S, a'p SR Ss–( ) DS f, a'pSR

rp δ+------------

dSdr------

r 1=

⋅=

ks O2, a'p O2R O2S–( ) DO2 f, a'pO2R

rp δ+------------

dO2

dr---------

r 1=

⋅=

0 F VL⁄( ) XNH4F+ XNH4R

+–( ) µm NH4+,

NH4R+

KNH4+ NH4R

++------------------------------

O2R

KO2NH4+ O2R+

------------------------------

+=

XNH4R+ YX N⁄ NH4

+, ks NH4+, a'p NH4R

+ N– H4s+( )+

0 F VL⁄( ) XNO2F – XNO2R

––( ) µm NO2 –,

NO2R –

KNO2 – NO2R

–+

------------------------------- O2R

KO2NO2 – O2R+

------------------------------

+=

XNO2R – YX N⁄ NO2

–, {k s NH4+, a'p NH4R

+ NH4s+

–( )+

+ks NO2 –, a'p NO2R

– NO2s –

–( )}

0 F VL⁄( ) XhetF XhetR–( ) µm het,SR

KS SR+-----------------

O2R

KO2 het, O2R+------------------------------

XhetR+=

YX S⁄ ks S, a'p SR SS–( )+

εG

1 εG–( )4-------------------- 0.25

gDc2ρL

σ---------------

1 8⁄

gDc3

νL2

--------- 1 12⁄

uG

gDc

------------- =

kLa 0.73 1 Φs

0.58----------–

uG0.67=

Φs

ksdp

D---------- 2 0.545

νL

D-----

1 3⁄ εdp

4

νL3

-------- 0.264

+=

ε uGg=

O2RKo O2R

+( )⁄

Ko Ko O2R+( )⁄

���� �39� �4� 2001� 8�

����� � � ���� �� �� � �� ����� �� ���� ��� 505

� � { v�1 Table 2�, _`� + � a9 �d� v�1 Table

3� �Š6\��*.

3-1. ��� �������� ��

Fig. 1. � { �� ��#B�� _`� qK <¥#, ����

�� + &�#�� |W� �Þ �§1 �jú*. � a9 �

d ~�. 0.30 mm, �a� �e. 200 L/d, �a� ������ |

W 260 mg N/L, [� �E. 3.0 cm/s,*. ���� + &�# #

�EW� Å 0.050 mm � { ÜÕ£0 � {I� ¥Ì� !d

e� �� �6$� 0.050 mm ,K� ÜÕ�7 � { k <¥#

|W� �� }: �§1 ?*. � { �� ��#B�� ¤��

 ¡ � { k <¥# ÿ!|W ¤�*. ���� #�EW

"%à _`� ·8¸¹�7 0.9Dw� 0.5Dw� � � { k ���

��� |W� �� �§1 ?� 0.1Dw� 0.2Dw� � � { k

<¥# |W� �� P�C*.

Ø ×´�7 H<� &�#� � { k G¢#�EW� ���� G

¢#�EWg* �. i1 g,�� � { k ���� #�EW� <

¥# + ������ |W� �� P�$0 ¨1 > � { Ü

Õ� ����  ¡ &�#�� qK|W� ���*. � { k �

��� + &�# G¢#�EW � { k !d|W� �� �§1

?*[20]. � { k ���� #�EW� ������� �� �

Í P�C ó�W � { k &�#��|W M8z h. i1 g

,�� &�# #�EW � � |W� �� P�$0 ¨� � {

ÜÕ� ����  ¡ ���M &�#��� _`� qK|W ¤

�M � { ÜÕ� ¢�M G¢Þ' gê*. � { ÜÕ� 0�7

0.200 mm£0 ����  ¡ _`� k � a9 dÃe. 0.028�7

0.347£0 ��� þI� �-q # �8rB� 0.075�7 0.043

s−1� ¤� þI� B#C*.  ¡7 Å 0.175 mm ,K� � {

ÜÕ�7 � { k &�# #�EW� <¥# |W� �� P�$

% � { ÜÕ� ����  ¡ &�# #�EW ¤�M &�#

�� _`� qK|W *F ���� F;�*.

� { k ��# ÍÎ1 �, ? �� ��#B�� 0.1Dw�

0.2Dwê � , � { k ���� + &�# #�EW <¥# |

W� �� P�C*. � { ÜÕ� ����  ¡ �-q �8rB�

Table 2. Kinetic parameters and physical properties of the biofilm usedin the simulation(a)

Parameter Value Reference

0.048� 10−6 m2/min0.048� 10−6 m2/min0.04810−6 m2/min

DS, f 0.048� 10−6 m2/min7.540 mg/l

20.8 mg -N/l � min Denac et al.[6]12.6 mg -N/l � min Denac et al.[6]

νs 121.8 mg COD/l � min Chen et al.[19]5.0 mg -N/l Denac et al.[6]2.8 mg -N/l Denac et al.[6]0.2 mg O2/l Chen et al.[19]0.5 mg O2/l Denac et al.[6]0.25 mg O2/l Denac et al.[6]

Ks 20.0 mg COD/l Chen et al.[19]3.50 mg O2/mg -N Denac et al.[6]1.14 mg O2/mg -N Denac et al.[6]

ss 0.56 mg O2/mg COD Chen et al.[19]1.33 d−1 Sharma and Ahlert[10]0.86 d−1 Sharma and Ahlert[10]

µmax, het 12.1 d−1 Sharma and Ahlert[10]0.278 mg cell/mg -N Huag and McCarty[9]0.0954 mg cell/mg O2 Huag and McCarty[9]0.0841 mg cell/mg -N Huag and McCarty[9]0.0821 mg cell/mg O2 Huag and McCarty[9]

YX/S, het 0.31 mg cell/mg COD Chen et al.[19]0.55 mg cell/mg O2 Chen et al.[19]

(a) unless stated otherwise.

DNH4

+f,

DNO2

–f,

DO2 f,

O2*

νNH4+ NH4

+

νNO2

– NO2 –

KNH4

+ NH4+

KNO2

– NO2 –

KO2 het,

KO2 NH4+,

KO2 NO2

–,

sNH4

+ NH4+

sNO2

– NO2 –

µmax NH4

+,

µmax NO2

–,

YX N⁄ NH4+, NH4

+

YX O2⁄ NH4+,

YX N⁄ NO2

–, NO2 –

YX O2⁄ NO2 –,

YX O2⁄ het,

Fig. 1. Influences of effective diffusivity in biofilm on the reactor con-centrations of (a) dissolved oxygen, (b) ammonium, and (c) nitritein the pure nitrification with the feed flow rate of 200 L/d, thefeed ammonium concentration of 260 mg-N/L, and the air veloc-ity of 3.0 cm/s.

Table 3. Reactor and media characteristics

Reactor diameter 0.14 mReactor volume 18 LMedia particle

Mass 600 gDiameter 0.30 mm(a)

Density 1.22 g/cm3

(a)unless stated otherwise.

HWAHAK KONGHAK Vol. 39, No. 4, August, 2001

506 � � �

¤�� q-� �8r ��H. ���M #�EW ���*.

� { !de� �� #�EW� �6$ � � ��Y > � {

ÜÕ ���  m #�EW ��å, ÑÍz ;ª1 � � Z*. �

{ k ���� + &�# #�EW� <¥# |W� �� ±F� P

�$��, _`� qK &�#�� |W � { ÜÕ� ����

 ¡ G¢Þ' f�: g,0 ¨*.

3-2. �� �� ��

Fig. 2 � a9 �d }�� _`� qK <¥#, ������

+ &�#�� |W� �Þ �§1 �jú*. [��E. 3.0

cm/s,�, � { �� ��#B� qK ��#B�� 50%� �

6��*. "%à �d�e + � { ÜÕ�7 �d}�� ¤��

 ¡ � {I� ¥Ì� !de + � a9� ��H. ���*.

� { k <¥#� æÀí |W�V �d}�� (� � 1 ?

0 ¨I= Å 0.110 mm ,K� � { ÜÕ�7 <¥#� N�º�

� F;C*. <¥# ô8º� ���7 ���� + &�# #�

EW <¥# |W� (� �§1 ?0 ¨�, � { !de� �§

1 ?&7 "%à � { ÜÕ�7 ���� + &�# #�EW �

d_�, ¤��  ¡ ���*. <¥# N�º� ���7 ��

�� + &�# #�EW _`� qK <¥# |W� � a9 �

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a9 ��H� �§, _`� qK <¥#� �§g* �1 � �

Z*. �d_� 0.100 mm + 0.150 mm� � ���� #�EW

ÁÁ 0.060 mm + 0.090 mm ,K� � { ÜÕ�7 ������

|W� �� �§1 ?� F;�M _`� &�#�� |W �

{ ÜÕ� ¢� G¢Þ' �jú*. &�# #�EW� <¥#|W�

�� P�?� F;�� &�# #�EW �-q #8rEW� ��

�6C*. �-q #8rB� � { ÜÕ� ����  ¡ _`�

�dK dÃe ��� ê�M ¤�*.  ¡7 &�# #�EW� <

¥#� �� P�$% � { ÜÕ� ����  ¡ ¤�� _`

� &�#�� |W *F ���*.

3-3. ���� � ��� � !" ��

Fig. 3. [� �E, _`� qK <¥#, ������ + &�

#�� |W� _`� A2N» X ���� + &�#� #�EW

Fig. 2. Influences of the media radius on the reactor concentrations of(a) dissolved oxygen, (b) ammonium, and (c) nitrite in the purenitrification with the feed flow rate of 200 L/d, the feed ammo-nium concentration of 260 mg-N/L, the effective diffusivity inbiofilm of 0.5 DW, and the air velocity of 3.0 cm/s.

Fig. 3. Influences of the air velocity on the reactor concentrations of (a)dissolved oxygen, (b) ammonium, and (c) nitrite and (d) the vol-umetric oxidation rates of ammonium (close symbols) and nitrite(open symbols) in the pure nitrification with the feed flow rateof 200 L/d, the feed ammonium concentration of 260 mg-N/L,and the effective diffusivity in biofilm of 0.5 DW.

���� �39� �4� 2001� 8�

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� �Þ �§1 �jú*. � a9 �d� ~�. 0.30 mm,*. [

� �E1 ��FÇ�  ¡ �-q �8rB�� ���M "%à �

{ ÜÕ�7 h. _`� <¥# |W� �j�*.  ¡7 � {

A2N» X ���� + &�# #�EW ���*. Å 0.070 mm

,K� � { ÜÕ�7 �j� [��E� �§. ���� #�E

W� �� &�# #�EW� }: �j�� �. x2� �E�7 }

: �j�*. � { k ���� #�EW &�# #�EWg* h

� >ñ� ���� #� "� h. <¥#|W' �jk �

a9 �� ���7 �%� _� &�# #� �. <¥#|W

' �jk � { k Ï. ���7W BE àá$%� �*.  ¡7

&�# #�EW _`� qK <¥#|W � [��E� ����

#�EW g* �� �¤�: �§1 ?*.

Fig. 4 _`� ·8ÝÂ Ú �V �� #�Ý, _`� qK <

¥#, ������ + &�#�� |W� _`� A2N» X

���� + &�#� #�EW� �Þ �§1 �jú*. [��E.

1.0 cm/s,*. �_HI� _`� ÝÂ1 ��FÇ�  ¡ �ù� [�

�V� p�$% ÝÂ��� �� V�<¥#|W �� ��W �-q

# 8r��H ��� �p$% �-q # 8rEW� ��C*. Ø

�Þ�@�7 ·8Ý ��� �� �-q # 8r��H� ��

���0 ¨� V�<¥#|W� ��© ����*.  ¡7 , �

n# @<� �� �V k #�Ý� ��' �� V�<¥#

|W ��� � � �@�*. "%à _`� ·8¸¹�7 ����

+ &�# #�EW 2 �Ý ,K� _`� ·8Ý ¸¹�7 <¥

# |W� (� �§1 ?0 ¨�, 1 �Ý + 1.5 �Ý� Ý ¸¹�

7 <¥# |W� �§1 ? � { ÜÕ� ¥Ì�*.

3-4. �#� ��� ��

Fig. 5 ��� �� #�� ±F� àá$ _`B�7 �a�

�e, (a) ������, &�#��, �� + <¥# |W, (b)

N�!d |W, É\� (c) _`� A2N» X ������, &�#

�� + �� P(EW� �Þ �§1 �jú*. � { ÜÕ

0.100 mm, [��E. 3 cm/s, �a� ������ + �� |W

ÁÁ 260 mg N/L� 1,500 mg COD/L, É\� � {�7� G¢

�� P(EW 121.8 mg COD/L min� i1 �6��*. �a�

Fig. 4. Influences of the reactor pressure on the reactor concentrationsof (a) dissolved oxygen, (b) ammonium, and (c) nitrite and (d)the volumetric oxidation rates of ammonium (close symbols) andnitrite (open symbols) in the pure nitrification with the feed flowrate of 200 L/d, the feed ammonium concentration of 260 mg-N/L, the effective diffusivity in biofilm of 0.5 DW, and the air veloc-ity of 1.0 cm/s.

Fig. 5. Effects of feed flow rate on (a) effluent concentrations of ammo-nium, nitrite, organic substance and dissolved oxygen, (b) sus-pended biomass concentrations, and (c) volumetric oxidation ratesof ammonium, nitrite, and organic substance in the simultaneousnitrification and organic oxidation (biofilm thickness of 0.100mm, air velocity of 3 cm/s, influent concentrations of ammo-nium and organic substance of 260 mg N/L and 1,500 mg COD/L, respectively, and maximum oxidation rate of organic sub-stance in biofilm of 121.8 mg COD/L min).

HWAHAK KONGHAK Vol. 39, No. 4, August, 2001

508 � � �

�e, ����  ¡, _`� &�#��, ������, ��

|W nI� ��z �����, N�!d|W �. ��EW' g,

&�# + ���� #�!" É\� h. ��EW' g, ��

#�!"� nI� ��z ¤�*. �� #�!"� N�|W�

���� + &�# #�!"� N�|W� �� G 6 � ,K h.

i1 gê*. _`� qK <¥# |W �a� �e1 ��FÇ�

 ¡ ¤�* Å 300 L/d ,K� �a� �e�7 �j� DE�

!" N�|W� ��z ¤� ���7 N� DE� !"� �

� <¥# �� ¤�M *F ���� F;�*.  ¡7 ���

��� + &�#�� P(EW �a� �e, ����  ¡ *

F Å� ���*. _�� ��#� ¢� ÍÎ1 H: ? <¥#

� ,< ��7 �\� N� DE� !"� |W� ¤��  ¡ _

`� <¥# |W� ����W _`� A2N» X �� #�E

W ¤�*. � { _`��7 F/VR� 6�$ �ã�1 !" G

¢ ���EW ,��7 �0�� h. N�!d |W' �0�� �

. � { !d|W' �p�*.  ¡7 van Benthum °[8]. _`�

�ã�1 ��� !"� G¢ ���EW g* }� DE� !"�

G¢ ���EW g* ;. i�7 �0�� � {�7� ��� !

" |W h: DE� !"� |W �: �0Y � Z% � {�

7� �� ��7 �\�*� g���*. ÉÊ� Ø �Þ�@ �5 _

`� �ã�1 DE� !"� G¢ ���EW g* }: �0�� D

E� !"� N�|W' �: qK <¥#|W' h: �0Y � Z

% � { ��� !"� a��7 �\� �W Zª1 � � Z*.

Fig. 5� �Þ�@�7 �j� � { k <¥#, �� , ����

�� + &�#�� |W�V' Fig. 6� Á �a� �e� ¢�7

�jk�*. �a� �e1 ��FÇ�  ¡ �� , ������ +

&�#��� _`� qK|W� ¢� æÀí|W ����, � {

k <¥# æÀí|W ¤�*. �a� �e1 �. x2�7 �

�F� �� , ������ + &�#��� � { k |W

���  m P(EW� �� �5� � { k <¥#|W ¤�

 m P(EW� ¤ �5 g* ­7 P(EW ���: C*. _�

� �a� �e1 h. x2�7 ��F� �� , ������

+ &�#��� � { k |W ���  m P(EW� �� �5

� � { k <¥#|W ¤�  m P(EW� ¤ �5 g* ;

&7 P(EW ¤�: C*. �a� �e ���  m � { k æ

Àí|W� �� &�#��, ������ + �� nI� �

B� Wr�: C*.  ¡7 �a� �e ���  m P(EW ¤�

�W &�#��, ������ É\� �� � nI� h. �e

�7 F;C*(Fig. 5). <¥#� �� � {, N�HI� º�â

> � { ���7� <¥#|W _`� qK <¥#|W� �

� �� �. i1 gê*. , � { k ��# ÍÎ, _`EW

' P�Y > qd-� a9 �8rEW� 8d _`EW' �6�

� æF Y �Y1 �1 ���*. Ø ×´�7 q-� �8rB�

#�� H<� ä (34) ñ!� g�C *m ä ç� �� h. i1

¬��*[21].

Fig. 7. n� �#� _`B�7 �a� �e, (a) _`� qK �

�����, &�#�� + <¥# |W, (b) N�!d |W, É

\� (c) _`� A2N» X ������ + &�#�� #�E

W� �Þ �§1 �jú*. � { ÜÕ 0.100 mm, [��E. 3

cm/s, �a� ������ |W 260 mg N/L� i1 �6��*.

�a� �e, ����  ¡ &�#�� |W� ��z ��� ó

������ |W� ��� �§1 g,� _`� <¥# |W

¤� ó 190 L/d ,K� �a� �e�7 �6� i1 gê*. �

��� + &�#� #�EW �a� �e, ����  ¡ ���

* �6� i1 g,= G¢#�EW <¥# |W� �� (� P

�$0 ¨� � {I� ¥Ì� !de� �� P�C*. � � {

. ����, &�# + <¥#� �� ô8z º�$� �a� �e

1 ����  ¡ ������ + &�#��� � { k|W�

���M G¢ P(EW' g� >£0 æÀí |W ���*. ��

#�_`, ±F� àá$ Fig. 5� � �a� �e, ���

�  ¡ ���� + &�#� #�EW ���* <¥#� �

{ ÜÕ� �� �. _`� qK |W + �. � { k |W� ��

P�C ó ¤�*. �� #�� �� <¥# � >ñ� �. q

K + � { k |W� �j�*. �� #�EW <¥# |W�

¤��W "´�� �a� �e, ����  ¡ �� |W� �

��M BE ��� ó �� �. <¥# |W�7 <¥# |W�

�� P�C � ,*.

Ø ×´�7 � { k !�� !d|W�V' �6��I� �

{ !d|W _`� ·8¸¹ + � { k 2Þ�  ¡7 �Y �

Z*[20, 22]. Fig. 8. � { !d|W� �¥� � {�7� ��

G¢ #�EW� _`� (a) <¥# + �� |W, (b) ����

�� + &�#�� |W, (c) N�!d |W, É\� (d) A2N»

X ����, &�# + �� � #�EW� �Þ �§1 �jú*.

� { ÜÕ 0.100 mm, [��E. 3 cm/s, �a� ������

|W 260 mg N/L, �a� �e. 200 L/d,*. � { k �� G

¢ #�EW 24.36 mg COD/L min� 121.8 mg COD/L min� i1

�6��*. _`� qK <¥# |W � { k G¢ �� #�

Fig. 6. Dimensionless concentration profiles of ammonia, nitrite, organ-ics and dissolved oxygen in the biofilm with 0.100 mm thicknessrelative to the reactor concentrations which are observed at thegiven feed flow rates in the operations represented in Fig. 5.

���� �39� �4� 2001� 8�

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EW� (� �§1 ?0 ¨µI=, h. G¢ �� #�EW' g�

> �. _`� qK �� |W, h. _`� qK ������ |

W + �. _`� qK &�#��|W' �jú*. , DE�

!"� ��� !" @,� [� � �ê <¥#� ¢�M �ß,

Zª1 ���*. � { k G¢ �� #�EW� h. i1 g� >

� {�7� DE� !" ��EW h. i1 g,� ���

!"� ��EW �. i1 gM h. DE� !" N�|W + �

. ��� !" N�|W' �p�*. �a� �� |W� ����

 ¡ _`� qK �� |W + ������ |W ���� _

`� A2N» X �� #�EW ���= ���� + &�# #

�EW ¤�*.

4. � �

� { �� ��#B�� # i1 g� > � { k ���� +

&�# #�EW _`� qK <¥#|W� �� (� P�$0 ̈

� � { ÜÕ� ����  ¡ � { k ���� #�EW _`

� qK ������ |W� �§1 ?� F;�M (� �6� i

1 g,� &�# #�EW ���M _`� qK &�#�� |

W ¤�� F;�= G¢Þ' f�: �jú*. _�� � { �

� ��#B�� ;. i1 g� > ���� + &�# #�EW�

±F� _`� qK <¥#|W� �� P�$�� � { ÜÕ� �

���  ¡ _`� qK &�#�� |W� G¢Þ� f�: �j

�0 ¨*. "%à �de, � { ÜÕ + [��E�7 �d}��

¤�� � a9� !de + ��H, ���M ���� + &�

# #�EW ��7 �\�*. [��E Ú _`� ·8Ý � _`

Fig. 8. Influence of maximum organic oxidation rate in biofilm on (a)dissolved oxygen and organic concentrations of the reactor liq-uid-phase, (b) ammonium and nitrite concentrations, (c) sus-pended biomass concentrations of ammonium oxidizer, nitriteoxidizer, and heterotroph, and (d) volumetric oxidation rates ofammonium, nitrite, and organic substance; biofilm thickness of0.100 mm, air velocity of 3 cm/s, feed flow rate of 200 L/d, andinfluent ammonium concentration of 260 mg-N/L (open symbol,24.36 mg-COD/L min; close symbol, 121.8 mg-COD/L min).

Fig. 7. Effect of feed flow rate on (a) effluent concentrations of ammo-nium, nitrite, and dissolved oxygen, (b) suspended biomass con-centrations, and (c) volumetric oxidation rates of ammonium andnitrite in the pure nitrification (biofilm thickness of 0.100 mm,air velocity of 3 cm/s, influent ammonium concentration of 260mg-N/L, and maximum organic oxidation rate in biofilm of121.8 mg-COD/L min).

HWAHAK KONGHAK Vol. 39, No. 4, August, 2001

510 � � �

g-

h

h

D]

]

]

-

� qK <¥#|W ���� #�EW g* &�# #�EW� }

: �§1 �¯*.

�� + �� #�� ±F� àá$ B�7 �a� �e1 �

�FÇ�  ¡ � { k ������, &�#�� + �� |

W ����I= � { <¥#|W ¤��*. �a� �e1

��FÇ�  ¡ &�#, ���� É\� �� nI� #�EW

���M G¢Þ' gê ó ¤��*. vz �a� �e1 �� #

�!"� N�!d |W' �: �p� h. ���7 ��F� _

`� A2N» X �� #�EW ¤� _� _`� qK <¥

#|W ���M ������ + &�#��� P(EW *

F ���� F;�*. �6� �a� �e1 �0��7 �a� ��

|W' ��FÇ�  ¡ �� #�EW ���� _`� qK

<¥#|W, ���� + &�# #�EW ¤��*. � { k

G¢ �� #�EW� �� _`� qK <¥#|W� (� �

§1 �Þ0 ¨µI= _`� A2N» X �� #�EW� �� É

\� ���� + &�# #�EW� ¤' �p�*.

This work is dedicated to Professor Wolf-Dieter Deckwer on the

occasion of his 60th birthday.

���

a : surface area of air bubbles referred to reactor volume [m2/m3]

a' : surface area of air bubbles referred to liquid volume [m2/m3]

ap : surface area of bioparticles referred to reactor volume [m2/m3]

ap' : surface area of bioparticles referred to liquid volume [m2/m3]

dp : bioparticle diameter [m]

D : molecular diffusivity [m2/min]

Dc : column diameter [m]

: molecular diffusivity of NH4+ [m2/min]

: molecular diffusivity of [m2/min]

: molecular diffusivity of dissolved oxygen [m2/min]

DS : molecular diffusivity of organic substrate [m2/min]

: effective diffusivity of in biofilm [m2/min]

: effective diffusivity of in biofilm [m2/min]

: effective diffusivity of dissolved oxygen in biofilm [m2/min]

: effective diffusivity of organic substrate in biofilm [m2/min]

Dw : molecular diffusivity in water, 0.096$10−6 m2/min

F : feed flow rate [L/min]

g : gravity acceleration [m/s2]

kL : gas-liquid mass transfer coefficient [m/s]

ks : liquid-solid mass transfer coefficient [m/s]

: saturation coefficient for -N in the nitritification [mg-N/l]

: saturation coefficient for -N in the nitratification [mg-N/l]

KO : constant in the dissolved oxygen switching functions of Activated

Sludge Model [mg-O2/l]

: saturation coefficient for dissolved oxygen of the heterotroph

[mg-O2/l]

: saturation coefficient for dissolved oxygen in the nitratification

[mg-O2/l]

: saturation coefficient for dissolved oxygen in the nitritification

[mg-O2/l]

Ks : saturation coefficient for COD of the heterotroph [mg-COD/l]

: ammonium-N concentration [mg-N/l]

: nitrite-N concentration [mg-N/l]

O2 : dissolved oxygen concentration [mg/l]

: saturation dissolved oxygen concentration [mg/l]

r : radial distance of bioparticle [mm]

rp : media radius of bioparticle [mm]

S : organic substrate concentration [mg-COD/l]

: oxygen stoichiometric coefficient for -N [mg-O2/mg-N]

: oxygen stoichiometric coefficient for -N [mg-O2/mg-N]

ss : oxygen stoichiometric coefficient for organic substrate [m

O2/mg-COD]

uG : superficial air velocity [m/s]

VL : reactor liquid volume [L]

VR : reactor volume [L]

Xhet : biomass concentration of heterotroph [mg/l]

: biomass concentration of nitritification autotroph [mg/l]

: biomass concentration of nitratification autotroph [mg/l]

: biomass yield for -N of nitritification autotroph [g cell/

g -N]

: biomass yield for -N of nitratification autotroph [g cell/

g -N]

: biomass yield for dissolved oxygen of heterotroph [g cell/g O2]

: biomass yield for dissolved oxygen of nitritification autotrop

[g cell/g O2]

: biomass yield for dissolved oxygen of nitratification autotrop

[g cell/g O2]

: biomass yield for organic substrate of heterotroph [g cell/g CO

$%&' ()

: dimensionless saturation coefficient for [-]

: dimensionless saturation coefficient for [-]

: dimensionless saturation coefficient for [-]

: dimensionless saturation coefficient for [-]

: dimensionless saturation coefficient for [-]

βs : dimensionless saturation coefficient for Ks [-]

δ : biofilm thickness [mm]

ε : energy dissipation rate per unit mass of liquid [m2/s3]

εG : gas holdup [-]

εS : solid holdup [-]

µmax, het : maximum specific growth rate of heterotroph [1/d]

: maximum specific growth rate of nitritification autotroph [1/d

: maximum specific growth rate of nitratification autotroph [1/d

νL : kinematic viscosity of liquid [m2/s]

: maximum removal rate of -N in biofilm [mg-N/l$min]

: maximum removal rate of -N in biofilm [mg-N/l$min]

νs : maximum removal rate of organic substrate in biofilm [mg

COD/l$min]

ρL : liquid density [kg/m3]

σ : surface tension

Φs : solid fraction in the suspension, εs/(1−εG) [-]

*+)

F : feed

R : reactor

s : bioparticle surface

DNH4+

DNO2 – NO2

DO2

DNH4+

f, NH4+

DNO2 – f, NO2

DO2 f,

DS f,

KNH4+ NH4

+

KNO2 – NO2

KO2 het,

KO2 NH4+,

KO2 NO2 –,

NH4+

NO2 –

O2*

sNH4+ NH4

+

sNO2 – NO2

XNH4+

XNO2 –

YX N NH4+,⁄ NH4

+

NH4+

YX N⁄ NO2 –, NO2

NO2 –

YX O2⁄ het,

YX O2 NH4+,⁄

YX O⁄ 2 NO2 –,

YX S⁄ het,

βNH4+ KNH4

+

βNO2 – KNO2

βO2 het, KO2 het,

βO2 NH4+, KO2 NH4

+,

βO2 NO2 –, KO2 NO2

–,

µmax NH4+,

µmax NO2 –,

νNH4+ NH4

+

νNO2 – NO2

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.:

P.:

-

nd

����

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HWAHAK KONGHAK Vol. 39, No. 4, August, 2001