Oxygen Transfer Characterization in Aeration Tank for Oxidation Treatment of Water Pollutants

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1 HWAHAK KONGHAK Vol. 40, No. 3, June, 2002, pp ( , ) Oxygen Transfer Characterization in Aeration Tank for Oxidation Treatment of Water Pollutants Hyun Chang Baek, Eun Duk Lee, Geun Bum Kim and Yeong Seong Park Department of Environmental Engineering, Daejeon University, Daejeon , Korea (Received 30 July 2001; accepted 4 February 2002).!"( l/min), #$%& (0-1,000 rpm), '()(1-3), *+,&(20-40 o C) -. /01.!", #$%&, *+,& :;, <!"= #$%& 329 >>?" 32@ AB CD -* EFG / 32H IJ 678 KL MN 9 O: PQR '() STU 32V W:;, #$%&2 X Y 678 Z[ '() MN. \] ^_J`9 O: PQR. a[ 6789 '(),!", *+,&, #$%& - bh cz[ +de: PQf g1. Abstract The oxygen transfer characteristics has been investigated in a designed aeration tank for oxidation treatment of pollutants. As operating variables, air flow rate( l/min), rotation speed(0-1,000 rpm), number of impeller(1-3), and liquid temperature(20-40 o C) were applied. The experimental results showed that overall mass transfer coefficient was increased with increasing air flow rate, rotation speed, and liquid temperature. Especially, air flow rate and rotation speed exhibited m uch distinct effect due to an increase of gas holdup and air-liquid contact area by bubble break. It was also found that overall mass transfer coefficient changes in proportion to number of impeller and the intensity of the effect is largely dependent on rotation speed. The correlational equation of overall mass transfer coefficient was obtained in terms of the operating variables such as impeller number, air flow rate, temperature, and rotation speed. Key words: Oxygen Transfer, Aeration Tank, Mass Transfer Coefficient, Impeller 1.,!"#$% &'$ () *+!,'$-.* /, 01&+, 23, /:; < 9[1-5]. # - =>% % 2EFG HI: EBJKL M IN OPQ, RS 2EL TUVK WX *?@AYF Z [L \] ^N _` 9. Ya, % M I Zbc de f g&h RS i m, no% %pcn qr skt!"#$% &'$ Z uv \]N ypt 2EL uv\]% ^ zi:9[6]. To whom correspondence should be addressed. yspark@dju.ac.kr { %, D1} ~ -=>% ( )- ƒ42-8 -=>% *?@ABC _ v G.U _t ˆ PQ[1-3, 7-10], *?@ABC v G # L\Š & Œ Ž*?@AK, Nz W Št *? N[2, 3, 11-14], =7 ~ < `{ 8[4, 5, 15-21] # N l Š o n ša ` 9. Ya =7 r %. :; zœ -= ƒ4g Nz žm Ÿ S =7% 1 &t L: -= ƒ42-c Nzœ P t ˆ, 9/ =7 % ` : 2E Pt N G : r 5I %. `N j Pt L9. RS, [ ` &'$ {% u@- VK s ª«L \] Cd:\ i}, BC, #,, =7 C r 9/ y±, ³:, Š y±, R² Ž*?@AK,% 7sG 1C:

$Fig. 1. Schematic diagram of experimental apparatus. 2. [ y± µ y±tu Fig. 1-, {, ~?, p (Dissolved Oxygen Meter), t `F¹9. { ºµ»¼ ¼½% Ÿ ¾? 12 } 3l, À % dead space ÁÂ -= ƒ4 :CÃ ÄÅ¹PQ, {% : 9F ^0 U¹9.$ $5 cm lò VUŒ z> R² pêc : 9. 3 % blade Ó Ôt #¼ #N Õ¹PQ, bladeö 2.1 cm 9. # {% À Ø Wt 5cm lò Ù 4cm > ÚPt VU: Û #% Ü, & ¹PQ, BC Ý Z 1,000 rpm Þl {Í: 9. [ y±% _ y±l\% {3{ ßr i}(0.5-3.$

2 Fig. 1. Schematic diagram of experimental apparatus. 2. [ y± µ y±tu Fig. 1-, {, ~?, p (Dissolved Oxygen Meter), t `F¹9. { ºµ»¼ ¼½% Ÿ ¾? 12 } 3l, À % dead space ÁÂ -= ƒ4 :CÃ ÄÅ¹PQ, {% : 9F ^0 U¹9. { % =7 C Æ :; 1l: W: { Ç,{ WU:CÃ : 9. =7Pt È,N µ ¹,?NÉ %X { % =7 ÊC 0.1 mg/l :t ËŒlCÃ purgezìpq, air pump iœ air flow meter 1} {ÍŒ {% : V U 9F ^0G X =7 ÎŒÏŒÐ9. p YSIµ% model 58 µ ¹, =7%, ŸÑt 2.5 cm lò VUŒ z> R² pêc : 9. 3 % blade Ó Ôt #¼ #N Õ¹PQ, bladeö 2.1 cm 9. # {% À Ø Wt 5cm lò Ù 4cm > ÚPt VU: Û #% Ü, & ¹PQ, BC Ý Z 1,000 rpm Þl {Í: 9. [ y±% _ y±l\% {3{ ßr i}( l/min), BC(0-1,000 rpm), #,(1-3), =7 C(20-40 o C)9. =Dà% Ä9 N âè {ß: NÉ7Pt Ù =D7Pt% 9ã , Fig. 2 BC i} R² Ž*?@AK,(K L a)% & ïðñ 9. =7 C 20 o C PQ, {% À Ø W t 5cm lò # 1 N ¹9. òó ô, Œõ BC Œ i} Nö,Ã % *?@AK, N: M G Û, i} Nö,Ã Ž*?@A K,N N: r 9² `\Š %XC PQ [1, 3, 11, 19], i}% N R² F}% Nt L: DDÈ}- -=>% ƒ4 N:, { % âè Nt L l øbc% N Nˆ År ù % eddyš O ¼F -=>% ƒ4úc 2E 7¹ Pt û, 9[19]. Ya, BCN ür ýw i} R² Ž*?@A Fig. 2. Effect of air flow rate on K L a in agitated aeration tank. dc = K dt L ac ( s C) (1) (1)G : 9ã- 9. C s C s C t C o ln = K L at C: z> t% K L a: Ž*?@AK,(t 1 ) C s : äf C, åæ, cc% & C o : z> t=o% C t : z> t% (2) Ž*?@AK, K L a Æ L z±ç yä { % & *% (77½ è %X : 9[22]. éá {?NÉ ÎŒÏŒ p Äw 9ã p% ê ÊC(C o ) ë, 9z { Æz> ÎŒÏŒ z> R² pêc(c t ) 9ã (2) p ÊC z>-% sk linear regressionìptí îg, 9. Fig. 3. Effect of rotation speed on K L a in agitated aeration tank. HWAHAK KONGHAK Vol. 40, No. 3, June, 2002

3 342! Fig. 4. Effect of liquid temperature on K L a in non-agitated aeration tank. K,% &/7 þÿ l Pt ïðû # 7r ür BC F ša ll : Pt J 9. Fig. 3r Æ i} {ß: { % =7% BC N Ž*?@AK,.U v G ïðñ Q, { % =7 C 30 o C, z {% À Ø Wt 5cmlÒ # N ¹9. òó ô ZDt BCN Nì R S Ž*?@AK, N: M G,» B C Œ i} R² Ž*?@AK,% N w% Æ :; ïð Ptí i}% ská % *?@ A õ2- w% Æ,fPt Å : G 9. { % =7 R² Ž*?@AK,% N2-7ï 6 7{ 1µ {ßG : y± 9² `\Š %X ¹Û[15-18], # =7 2- =7% 1 & 1: % 4õzœ -= ƒ4- ƒ42eg Nz, N dead space Á ¹ Ž*?@ AK,N N Pt L9. Fig. 4 =7 Á 7½ { % =7 CN v G ïðñ 9. òó ô, {ß =7 CN Nì RS Ž*?@AK, N: Û. =7 CN qÿ?,ã =7 p% ^BCN N Ž*?@AK,% N Nˆb Pt û, 9[23] Fig. 5 BCN 250 rpm =7 CN 20 o CL {ß #, A$ö i} R² *?@AK,% & ïðñ 9. {ß Ž*?@AK,N N: Pï #, ; v G l Û, # - Fig. 2 i ô, 250 rpm- r ür BC # % N O ÆŒïl Pt #, NzœC *?@A7% 4õ 2-5I Å Pt û, 9. Fig. 6r BCN 750 rpm =7 CN 20 o CL {ß Ž *?@AK,% & ïðñ 9. òó ô, #,N L MI ( ö #,N L MI *?@AK,% þÿ Fig. 5. Effect of impeller number on K L a in agitated aeration tank(rotation speed: 250 rpm, liquid temp.: 20 o C). Fig. 6. Effect of impeller number on K L a in agitated aeration tank(rotation speed: 750 rpm, liquid temp.: 20 o C). N7G 9. #N L MI, #,N L MI ( X *?@AK,N { N: r #% > Ú 4cmt r t N # % 2-N Å Pt > 9. ò#ï # Õö gcn Œï 7: # µ% >Ú 8cmï ËŒˆ Œ 7: D % 2-N?, Œ -= ƒ 4% N ÎŒ *?@A ; 4õ Pt µ] 9. ' %X F % Å G X D% *?@ AG 4õz BCN ŒC 500 rpm7 1lŒ : # >Ú p% 4cm9 ; _ìg, 9. Ya, #% v Œ #, #>Ú z Œ :Q, #% >Ú ; Å 7½ #,

4 343 Fig. 7. Effect of rotation speed on K L a in agitated aeration tank as a function of impeller number. N Nj MI Ž*?@AK,% Z&N N ö Pt J 9. Fig. 7r i} 1.0 L/min, =7 CN 20 o CL MI #, BC R² Ž*?@AK,% & ïðñ 9. BCN Nö,Ã Ž*?@AK,N N:lm #,N 3 L MI BC R² Ž*?@AK,% NEr!9. #,N 1 L MI ( ö #,N 3 L MI BC N 500 rpm Ž*?@AK, 20%C Nï BCN 1,000 rpm Ž*?@AK, 70%C N¹9. # - t Ù Æ i} :C BC #, z &z 5I 9" *?@A 72- îg, ãg, 9. Fig. 8-9 Æ i}(1.0 L/min)% {ß: =7 C Fig. 9. Effect of liquid temperature on K L a in agitated aeration tank as a function of impeller number(rotation speed: 750 rpm). R² Ž*?@AK,% & #,% ì,t ïðñ 9. = 7 C R² Ž*?@AK,% N7r BCN q #,N OG,Ã # þÿ: 9. $, BCN 750 rpmæ =7 C 20 o C 40 o Ct Nz Ž*?@AK, #N 1 L MI % 30% N:ï #N 3 L MI % 50% N: [ y± îr Ž*?@AK, =7 BC(N: 250-1,000 rpm), i}(qg: l/min), =7 C(T: o C) ~ #,(S: 1-3) Fig. 8. Effect of liquid temperature on K L a in agitated aeration tank as a function of impeller number(rotation speed: 250 rpm). Fig. 10. Comparison of calculated overall mass transfer coefficient with measured one. HWAHAK KONGHAK Vol. 40, No. 3, June, 2002

5 344! Z 7sPt äzö MI (3)- ïð&, ¹9. K L a=0.5081n Qg T S (3), (3)Pt Ù îœõ KU y±u ( - Fig Û, KU y±u>% 7sK, 0.937¹9. RS # 7sr 1µ {ß {% VK ~ {3 s ê \] î Û 1 :; š j, G Pt J 9. 4.,?bc*?% &'$ {% ' y±g X îœõ (r 9ã- 9. (1) &'$ { i}, BC, =7 CN Nö,Ã % Ž*?@AK, N: PQ, Ya i}- BC% N DDÈ} N 2- R² -= ƒ4 % N X Ž*?@AK, 9" v G G, ¹9. (2) { % #,N Nö,Ã Ž*?@AK, N:lm #% G Z&: WX BCN 500 rpm 7Pt 1l # >Ú )a ; _ì G, ¹9. (3) &'$ { Œ i}, BC, #,, = 7 C r _ y±, Z Ž*?@AK, 9ã- r 7sPt äz¹9. K L a=0.5081n Qg T S Woo, K. J., Cho, Y. J., Kim, K. I., Kang, Y. and Kim, S. D.: HWA- HAK KONGHAK, 36, 937(1998). 2. Park, C. J.: J. of KSEE, 20, 621(1998). 3. Kang, Y., Min, B. T., Nah, J. B. and Kim, S. D.: HWAHAK KONG- HAK, 28, 560(1990). 4. Han, S. W., Choi, I. G., Yun, Y. W. and Kim, S. Y.: HWAHAK KONG- HAK, 31, 521(1993). 5. Kang, Y. S., Kim, J. W. and Lee, W. K.: HWAHAK KONGHAK, 24, 371(1986). 6. Park, Y. S., Lee, E. D., Kim, G. B. and Lee, H. K.: Energy Engg. J., 9, 123(2000). 7. Park, C. J.: J. of KSEE, 18, 725(1996). 8. Kim, J. O. and Kim, S. D.: Particulate Sci. and Technol., 5, 309(1987). 9. Koh, J. C., Kim, B. S., Kim, C. L., Lee, J. M. and Lee, B. S.: HWA- HAK KONGHAK, 30, 106(1992). 10. Yun, Y. W., Kim, S. Y. and Kim, D. Y.: J. of KSEE, 16, 365(1994). 11. Lee, K. H. and Doh, D. S.: HWAHAK KONGHAK, 31, 395(1993). 12. Kwon, H. M. and Doh, D. S.: HWAHAK KONGHAK, 23, 19(1985). 13. Lee, D. H., Kim, J. O., Han, J. H. and Kim, S. D.: HWAHAK KONG- HAK, 31, 118(1993). 14. Choi, I. G., Baek, J. H., Han, S. W. and Kim, S. Y.: HWAHAK KONG- HAK, 35, 225(1997). 15. Lu, W. M., Wu, H. Z. and Chou, C. Y.: Effect of Impeller Blade Number on K L a in the Mechanically Agitated Vessels, Proceedings of the 6th Asian Conference on Fluidized-Bed and Three-Phase Reactors, 167(1998). 16. Do, J. H., Thakur, N. N., Chang, H. N. and Lee, S. Y.: Theories and Applications of Chemical Engineering, 6, 1265(2000). 17. Kang, J. H., Lee, C. H., Haam, S. J. and Moon, H. M.: Theories and Applications of Chemical Engineering, 6, 1877(2000). 18. Lee, M. S., Kang, J. H. and Haam, S. J.: Theories and Applications of Chemical Engineering, 5, 1701(1999). 19. Choi, K. H., Han, H. H. and Lee, W. K.: HWAHAK KONGHAK, 28, 220(1990). 20. Joung, O. J., Han, S. W. and Kim, S. Y.: Theories and Applications of Chemical Engineering, 5, 4169(1998). 21. Han, S. W., Choi, I. G. and Kim, S. Y.: Theories and Applications of Chemical Engineering, 5, 2441(1996). 22. Kim, D. J.: Measurement of K L a in Bubble Column Formentation with Oxygen Enriched Air, Korea Advanced Institute of Science and Technology, Master Thesis(1996). 23. Bird, R. B., Stewart, W. E. and Lighfood, E. N.: Transport Phenomena, John Wiley & Son, Inc., New York, 503(1960)

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