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1 w y wz 10«( 1y) 47~52, 2007 J. of the Korean Society for Environmental Analysis œ w t y ½ xá Á x Á½ Á x* Ÿ œ, * w œw Optimization of Coagulation In The Conventional Water Treatment Plant Jun-Hyun Kim, Lee-Seuk O, Hyun-Gu Shin, Mi-Kyeong Kim, and Doo-Hyun Park* Gongchon Water Treatment Plant, Seogu Gongchon-dong San 100, Incheon, , Korea *Dept. of Biological Engineering, Seokyeong University, 16-1 Jungneung-dong Sungbuk-gu, Seoul, Korea ph increase of raw water may cause an excess use of coagulation agent. As a result residual aluminium concentration in treated water can be be increased. Accordingly, ph of raw water is required to be suitably controlled for optimal coagulation condition. In this research, ph of raw water source was controlled by addition of carbon dioxide and the effect of ph control on the coagulation efficiency and NOM removal was compared with that before controlled. In the result of ph control 1 ppm, dosage of coagulation agent was decreased, and so as 26 % of residual aluminium, 11% of KMnO 4, 16% of UV254 and 58% of THMs. However, TOC, DOC and turbidity were not influenced by the ph control. Mean value of SUVA was 2.12 and 2.06 after the treatment of water source with carbon dioxide, which was exactly corresponded to the criterion (2-4) of USEPA. On the basis of these results, NOM is presumably composed of soluble humic compounds, non-humic organic compounds, hydrophobic organic compounds and hydrophilic organic compounds. Key words : Optimized coagulation, trihalomethanes (THMs), non organic materials (NOM), total oxygen carbon (TOC), residual aluminium 1. ú y y œ s, yw, w w y ƒ š w ü œ wš., ƒ y» y x w š ph ƒ z w t ƒ jš» ƒ g ƒ ƒ œ ü THMs j š. w»z ùy w y š ph ƒwš w š» w. œ w k ù 1) y» ƒ w» w /y k, š y (AOPs), (Membrane) š» w» w ƒ w š 2)., ü NOM(Natural Organic Matter) w THMsx j» w w» w w û ph k Áe j» w» w 3,4). w w w» w y w ƒ ww ph j 5) w w k NOM w g To whom correspondence should be addressed. baak@skuniv.ac.kr

2 48 ½ xá Á x Á½ Á x š yw (DBPs : Disinfection By-Pruducts) jš w g ƒ w Áœ wš w. 2. x 2.1. tû w w q w NH 3 -N ƒ p š. œ ƒ jš w THMs ƒ š ('06 q NH 3 -N s³ : 0.03 ppm, tû ƒ q 57% ). 06 tû s³ ph 7.8 e ùküš v w ph ƒ, ph š ph ƒ z w š» (PACS) n š. x» (PACS) œ w w, ( 99.9%) œ w g. x w w ƒƒ œ w œ x w x Optimized Coagulation w ph range w Jar-Test w w. x w Flocculator2000(Kemira Kemwater) w 1 (120 rpm), 10 (40 rpm) z 30 e k 50ml k (HACH 2100N) ph meter(thermo Orion 720A ) + w d w. 0.04N Á w y ( : 98%) w ph 5.5 l 8.0¾ w z Jar-Test x mw 1 ph range wš, w 1 ph range ü x mw Optimized Coagulation ph range w. x Sweep Coaculation w ph range w e tn ü y kj 6»(20Kg*6) wš»y» l mw Gas w ew. w ( ) ù ƒ w, w w» w n Á œ w. w, Gas û w p š w 1.5 m w. Gas n w z 24 yy ph y w w, x» w œ w yy ph d» mw w z wš 20 z Jar-Test x mw w, œ w z w z 9 z, yy,, e,, ƒƒ w xw w. w, w 07 Sampling z ƒƒ w y w. 5, 2z Jar-Test w w š, d»(tuf7-0-b11yfy201a01, DKK) w Áz k y l w. œ œ [ :8~9, : 50~55, e :5, : 120 m/day( 20 ), 1.6, : 8 ] š w ( ) z 9 w z s³, z z 9 w z s³ ƒƒ w. 3. š 3.1. Fig. 1 ph 5.5 l 8.0¾ 0.5 w z Jar-Test x mw ph range d w 7.5 z ƒ ùkû šx e z w ph 7.5 ƒ ùkû.

3 œ w t y 49 Fig. 1. Determination of ph for optimal inorganic coagulation of raw water 3.2. Áz (PACS) y w z w yy ƒƒ Jar-Testw w, n w Fig. 2 n 1 ppm w ùkû. w ü w Fig. 3 5 s³ 23%. n mw v w ph range w, ƒ w. Fig. 3. The variation in residual aluminium Áz e k e Fig. 4 5 Áz k e j y, w Fig. 6 TOC j. v w ph 7.5±1 w w e ƒ w ùkû. k NOM z w j z 1) w ph y g w. k NOM wš, NOM k w ùkû, 8). Fig. 2. The variation in dosage rates of inorganic coagulation agent (PACS). Fig. 4. Effect of carbon dioxide treatment on turbidity of treated water.

4 50 ½ xá Á x Á½ Á x. w e TOC ph v œ w ƒ ù z Áe œ w œ mw ƒ z. Fig. 5. Effect of carbon dioxide treatment on alkalinity variation of treated water. k NOM š š ph w t ywš k NOM z w TOC UV254 œ s³ TOC z w, s³ 26%ƒ š, z 29% ƒ 10% w.» s³, e TOC Fig. 6 ùkù. 3.3 k w TOC k š ƒw 3.5. SUVA xy ph z UV254 n s³ 53%, n z s³ 63%» n n zƒ s³ 16% w. x» SUVA s³ 2.12, z 2.06 ù kü ü NOM { {» yw e» w œ wš. USEPA NOM p DOC 2 w» { e» š ³ wš. Áz SUVA ƒ ƒ 2.12, w w» e j š ƒw. 3.6 KMnO 4 n z e KMnO 4 n s³ 11%ƒ w ƒ ù. KMnO 4 w y», e œ, œ mw 11% w (THMs) n w e THMsƒ 4 20 wš w, n w Table 1 s³ 17% w. w e s³ xy, s³ 41% œ e THMs s³ 58% w. Fig. 6. Effect of carbon dioxide treatment on TOC removal in settling water n w ƒ ù Table 2 j y ùkü. w e ph, TDS,, e, e,

5 Table 1. n Áz THM xy e e Section s³ (%) s³ (%) Before ( ) After ( ) Decreasing rate ( - )/ w w w ùkü, p, j w e ph y w w. p ph y z e phƒ 7.1±1 y. ph w ph û ƒ -2.0 wz ƒ mw š w k NOM ƒ û û ph wš w ph y» ph š 8.9, 8.1, s³ 8.6 š ph w. yy ph l w w. ph y Fig. 7 w w, phƒ w š Fig. 7. Corelation with ph and dosage rate. Table 2. n Áz (LSI) t Before After œ w t y 51 ƒw.» y w y ¾ w t y w v w ph w š ph n ƒ w. 4. ƒ w k y w phƒ 9 w ph 7.5~7.8 ù š, g/ Cm 3 m 2.6 g/cm 3 w {» e w.» (PACS) w» w ( ) w» ph range w t THMs y w» œ z w jš w, w w œ ( ) n f«z s ƒ w w. 1. ( ) n z ph 7.5±1 w z w» (PACS) s³ 1 ppm w. w k w w. n ph w y. 2. TOC DOC ph Áz j, ph z s³ 26% ph w g. TOC, DOC ph w w š, ph ƒ n ph ƒ š w. k TOC DOC w LSI š w z ph w v ƒ. date 4/17 4/18 4/19 4/20 4/21 raw water clean water raw water clean water

6 52 ½ xá Á x Á½ Á x 3. œ UV254 s³ 16% w š, KMnO 4 w y ƒ w» Áe mw 11% œ mw ƒ. 4. ph w z KMnO 4 UV254 ƒw THMs. THMs 1 ph w w û 6). 5. DOC UV254 l SUVA Áz ƒƒ s³ 2.12, 2.06 USEPA w 2~4 w w NOM { {» yw, e» w œ wš š w. p 2 w w» e š ƒw. 6. wz yy ph meter w w n» e w œ w v ƒ. š x 1. Seugn-Hyun Kim, Enhanced Coagulation : Determination Of Controlling Criteria And An Effect On Turbidity Removal, Environ. Eng. Res. Vol. 10, No. 3. pp. 105~111 (2005). 2. Kimberlyk, A. B. and Mortza A., Enhanced and Optimazied Coagulation for removal of Particulate and Microbial Contaminants, in Proceedings of the 1996 AWWA Annual Conference, New York (1996). 3. Douglas, M. O., Gary, L. A., and Zaid, K. C., Characterization of Natural Organic Matter and Its Relationship to Treatability. AWWA Research Foundation (1993). 4. Á Á Á½, Water Treatment Techniques Coping with High ph-containing Raw Water, '06, Ÿ, ¼z,» w, y, 2005, xá½ Á, x x THMs d w, wy œwz, Vol. 19. No. 6. pp. 709~ y Á, œ w w, wy œwz Vol. 20. No. 10 pp. 1435~1447, x, w, 97» z t, , , THMs, 97» z t, , Tai il Yoon, Chang Gyun Kim, and Jung Soo Park, Advanced Treatment For Drinking Water Resource By The Ultra Rapid Coagulation, Environ. Eng. Res. Vol. 8, No. 1, pp. 15~21(2003) Process(Korea). 11. yá{ yáx Á, Removal of heavy metals and natural organic matters by chemical treatment in drinking water, w ywœw 12. Á x Á k, y m w œ { e sƒ, wy œwz. Vol. 24. No. 9. pp. 1623~1631, Á Á½ Á Á Á½, ù w z w y, wy œwz. Vol. 22. No. 11. pp. 2059~2065, Á Á k, š e (URC)œ w y y NOM, wy œwz, Vol. 24. No. 3, pp. 421~433, Á, Residual Aluminum Variation in Conventional Water Treatment Plant using Aluminum containing Coagulants, wy œwz, w tz, Á,» œ THMs p w, wy œwz, w tz, 1994.