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1 Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006, pp ms o i m m Š y mkç mqçm o e r r 65 ( o 31p r, o 19p }ˆ) The Characteristic Floc Growth in Coagulation and Flocculation Processes Jae-Yong Heo, Ik-Joong Kang and Sang-Wha Lee Department of Chemical and Bioengineering, Kyungwon University, San 65, Bokjung-dong, Soojung-gu, Seongnam-shi, Kyunggi-do , Korea (Received 31 October 2005; accepted 19 January 2005) k l p rp pv rl p p e l PACCp pv p m. p o ˆv pqp rˆro ph 8~9l mp m p mll TDSm r r p ˆ tl. m p r lp, ˆ p r l pl p q p 95.1 sec 1 l p r pp ˆ l. l 3~5 µmp qp pq lp p p pq l. m p v 3~5 µmp qp pqp m 7~21 µmp t p pq v p ˆ tl. 23 µm pqp n p 95.1 sec -1 l q p l, 3~5 µmp qp pqp nl p sec 1 l q p l. h Abstract The characteristic floc growth of Al-based coagulants was investigated in the aspect of mixing intensity and visualization of generated flocs during coagulation and flocculation processes. Zeta potential of turbid particles in the artificial water nearly approached to zero at phg8-9, in which TDS and conductivity were minimized. The removal rate of turbidity and phosphate was maximized at the optimal mixing intensity of rapid and slow mixing stages. After the rapid mixing stage of coagulation process, small particles (3-5 µm) were abruptly generated, and higher mixing intensity made more numbers of flocs. With the progress of slow mixing stage, the number of small particles were decreased with the simultaneous increase of intermediate particles (7-21 µm). The number of large particles (>23 µm) were maximized at the lowest rapid mixing intensity of 95.1 sec -1, whereas small particles (<5 µm) were maximized at the highest rapid mixing intensity of sec 1. Key words: PACC, Floc Growth, Flocculation, Visualization, Mixing Intensity 1. ql l sq p k, p dm p p o v rš, rš p pq v p. } l pl pv/p r p p pq r rp n r r l l o p pr p p pq kr e ƒ p p [1]. l v m pp p p s o vp e vmmp ppˆ, m s o vp pvrm l n k p To whom correspondence should be addressed. lswha@kyungwon.ac.kr p pvr Œp k r p [2]. } l n pvr pq p p p rr r l p ~ rp. p rp p vr r l pq q, p l pq p p v l o p pq kr v. p pv l o pvr rr kp Œp lk pvsp pl p eˆ p n [3]. o t l sq p r pv} rp pp v e ˆ o pvrp s, ~, m, l r pq (, Œlvr)l l p v pp o tl mm p n k l errp 207

2 208 qnë ptëp rnp l n erp [4]. pv pl p p l 1 pqp (aggregation) o~p r l p (breakup) p l p ov. l m p pq p r pq (pvrp s, pvr Œl, ph, m, pqp ) r s (, ~ e ) p [5]. Francois(1988) p 4 v q rk p [6]. ~ w l p p t l p kr 1 pqp l p, w l 1 pqm p ~ pvl p p qp v. w l 1 pq p l p qp v, p rp p pv. v l p (aging) rp v p pvp p pl. p q m l p vv k q p p n [7,8]. k pvrp nl p ph(ph<3) s l Al 3+ m kpm p rp p sq 1 pq p l p p qp p lv. l ph t l n n k p p p 1 p q k l p p qp p lv [9]. p l q p pvm p p p ~rp p p ep s p ˆ [10, 11]. d G 1 2 P, where G = (1) µv p d p v, G (sec 1 ), P l v, µ o~p r (kg/m-sec), V ps ~r(m )p ˆ t 3 [12]. e (1)l v p v p p ˆ v rp p p. Pp p (2)ep pn l m. l C D paddlep f 1.2~1.5 p v A n l v p Ž p r(m 2 ), ρ o~p V p p p r (rpm)l k p ep tlv [13]. 3 C D A ρ V p P = , where V (2) 2 p 0.70 π 0.06 rpm l l pr p t sr nkp rs l phl Al q pvrp pv p m, m p ( Ë e )l ˆ pp r pl m. p rp r } r l r l rp r p pv l p p e p pv pq r m. 2. e l n PACC(Polyaluminium calcium chloride, (t)o ) 10 wtí Al 2 O 3 p q pvr f m 70Í p. phl o ˆvpqp rˆro Zeta-Plus n l r m. pvr tpe p pv o44 o k Fig. 1. Schematic diagram of mini-flocculator (Jar-Tester). PC(particle counter) pn l pq r m. p v pl p p m (MotionScope 2000, Redlake Imaging Co.) n l p v ll. MotionScope 2000p 2,000qp mp f q- d p ˆl p p v lp pl., Conductivity Meter n l o p conductivity, TDS, resistivity r m. pp p s l PO 4 3 m Ammonium Molybdate, k ek pe molybdeum blue p eˆ 530 nm Žq l p Molybdeum p UV/Vis r p f ppm op pp p p. Fig. 1l m re p sr p pv (Flocculator 2000, KEMIRA ) ˆ p. q- d p p rp t s p 400 rpm( sec )l 1 30, m 40 rpm(24.05 sec )l p r 1 e p ~ pv pp v m. p s p 100~400 rpm(95.1~760.7 sec )p s l 30 m 1 m p s p 20~99 rpm(8.5~93.6 sec 1 ), 10~30 minp s l rp m. } p kp 1.0 L p 5cm k l m e p ml v m. 3. y 3-1. oo m ms l PACC pn pve l pr p ov o l HACH p formazinp } ˆ nkp l o n m [14]. Fig. 2(a)l o p ph l r r TDS p ˆ l. e l n Conductivity Meter q~ ep pn l r conductivity TDS p n o ˆ. ph 8~9 mll r r m TDS p p lt, p r ns pq p rp r sq p ˆ t. Fig. 2(b) l sr p ˆ 20 NTU, p 10 mg/l, k 10 mg/l, m mp ov o p ph 4~11l PACC(m 70Í)p pv pp m. l m p ph 8~9 l q p ˆ p r pp ˆ tl. PACCp ˆ

3 pv r l p q 209 Fig. 2. The characteristic measurements of artificial water with the variation of ph (initial conditions: 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO 3, PACC dosage=30 ppm): (a) Conductivity, TDS, and resistivity, (b) Removal rate and Zeta-potential. Fig. 3. The effect of slow mixing intensity, Gt, on the coagulation efficacy of PACC (initial conditions: ph8, 12 NTU, 10 mg/l PO 4 3, 20 mg/l of CaCO 3, 15 ppm dosage, rapid mixing=100 rpm & 30 sec): (a) residual turbidity, (b) residual phosphate. r pp ˆ p pp r pp rp ˆ., rˆro p ph 8~9 pl 0p r pp pv pp q sp rr ph Ž [15] i ms l Fig. 3l o p ˆ 12 NTU, p 10 mg/l, k 20 ppm/l, PACC tp p 15 ppmp l m p l ˆ m pp r k. p m p s p 8.5~93.6 sec 1, 10~30 minp s l rp m. p 95.1 sec 1, 30 secp m p Gt p 40,000 p l ˆ m pp pv q s ˆ. Fig. 4l p sec 1, 30 secp nl rr Gt p 20,000~40,000l ˆ m pp r r s p sq p ˆ. Fig. 5l p sec 1, 30 sec p nl m p pv pl ˆ v kk. rp ˆ pp r l pl pr s l (494.1 sec 1, 30 sec) m p r r ˆ p, r~rp p p r 100 rpm(95.1 sec 1 )p nl pv pp q s ˆ. Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006

4 210 qnë ptëp Fig. 4. The effect of slow mixing intensity, Gt, on the coagulation efficacy of PACC (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO 3, 15 ppm dosage, rapid mixing=300 rpm & 30 sec): (a) residual turbidity, (b) residual phosphate. Fig. 5. The effect of slow mixing intensity, Gt, on the coagulation efficacy of PACC (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO 3, 15 ppm dosage, rapid mixing=400 rpm & 30 sec): (a) residual turbidity, (b) residual phosphate ms o m pvr tpl p tp ˆv pq p l p pq p l ˆ (floc)p. p p p pv pp v rp erp ˆ p l pv pp p l n tn. o p ˆ 12 NTU, p 10 mg/l, k 10 mg/l, ph 8, PACCp tp 17 ppmp s l 300 rpm & 30 sec, m 30 rpm & 20 minp l motion scope 2000p n l 2 p p p o44 o k v ll. Fig. 6l m p v l p m v p k pl, 16 p l p ˆ v kk. p p p pq p l p l p l p pr ov p [4]. Fig. 7l r e l p 5 p m m r e p p p ˆ t p. p p t p pv q p.

conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO 3, PACC dosage=17 ppm). Fig. 7.

5 pv r l p q 211 Fig. 6. Floc images captured by Motion Scope 2000 during slow mixing stage of 40 rpm & 20 min (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO 3, PACC dosage=17 ppm). Fig. 7. Floc images captured by Motion Scope 2000 during sedimentation (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO 3, 17 ppm of PACC dosage). Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006

212 qnë ptëp Fig. 8. Particle size distribution after rapid mixing (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO3, 17 ppm of PACC dosage). 3-4.

6 212 qnë ptëp Fig. 8. Particle size distribution after rapid mixing (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO3, 17 ppm of PACC dosage) ms m pv pe p m p o e } l PC(particle counter) pn l r m. p o p ˆ 12 NTU, p 10 mg/l, ph 8p s l PACC tp p 17 ppmp r m. v r pq Fig. 8l ˆ p p 100 rpm 300, 400 rpmp nl 3µm~5 µmp qp pq p p k pl. Fig. 9 pv pq p ˆ p. v pqp 3~7 µml p ˆ p 9µm p p pq p v kk. v 3µm pqp nl 95.1 sec 1 l 494.1~760.7 sec 1 p p 2 p l 5~7 µmp pqp nl 400 rpmp n q ˆ. 7 µm p p pq m v l p p k p l., 400 rpmp nl 7~13 µmp pq p 100 rpm, 300 rpml rp ˆ p, 15~21 µmp pq p p rpml p ˆ v kk. rp v pq t 3~5 µml m v 10 µm p p pq m p rpmp v p ˆ tl. Fig. 9. Particle size distribution after rapid mixing, slow mixing, and stationary stages (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO 3, 17 ppm dosage of PACC). o44 o k

pv r l p q 213 Fig. 10. Particle size variation (9-21 µm) during jar test time (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO3, 17 ppm dosage of PACC). 3-5. i m Fig.

7 pv r l p q 213 Fig. 10. Particle size variation (9-21 µm) during jar test time (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO3, 17 ppm dosage of PACC) i m Fig. 10p m p v l pq(7~21 µm)p p v p ˆ p. p 300 rpm, 400 rpm p v pqp v mp m p m er v p pr ov l. l 100 rpmp l 7~13 µmp pq p nl pre p v q v p ˆ l. m p v l 15~21 µmp pq p lag timep r rp v p ˆ tlp p rpml pq p p ˆ v kk. m k 21 µm p pqp nl p rpml lp pqp p p m. v pq t 1 p q l p, m p v l ƒ pq p 1 pqm p p ~ pvl p q. ƒ pq(> 21 µm)p nl p pv v pq p ˆ tl. Fig. 11p pqp 23 µm~47.5 µml nl l p p ˆ. q p 100 rpmp nl p p v v ƒ p p p k pl. p p pv p r m p, p l v p Ž [16]. 4. k pvrp PACC(polyaluminium calcium chloride, m =70Í) tpe p p e m ˆ m pp pv p m. r pvp rr ph 8~9 ol rˆro mp m r r m TDS p ˆ tl. ( Ë e ) PACC pvrp p l m, ˆ r pp q p 100 rpm p l q ˆ. p 300 rpmp nl m p rr ˆ, p p q pv pl tn m p p ˆ t. m p v l p p v m, m p s l p pv pr ov l. p pq p l p p l p l p p qp p p p. v pq 3~5 µmp pv n ˆ p pqp v m. m p Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006

214 qnë ptëp Fig. 11. Particle size variation (23-47.5 µm) during jar test time (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO3, 17 ppm dosage of PACC).

8 214 qnë ptëp Fig. 11. Particle size variation ( µm) during jar test time (initial conditions: ph8, 12 NTU, 10 mg/l of PO 4 3, 20 mg/l of CaCO3, 17 ppm dosage of PACC). v 3~5 µmp qp pq m 7~21 µm p p p q v p ˆ tl. q p 100 rpmp l 23~47.5 µmp pq q ˆ. v, p l ƒ pvp p rp p p ˆ tl. r rp m p v l p pvm lag timep v p ˆ tl. y o44 o k 1. Kemira, K., Handbook on Water Treatment, Helsingburg, Sweden(1993). 2. Lee, C. H., Lee, S. H. and Okada, M., Removal Algae and Cryptoporidium on Drinking Water Treatment by Polysilicato- Iron Coagulant, J. of KSEE, 26, (2004). 3. Rossini, M., Garrido, J. G. and Galluzzo, M., Optimization of the Coagulation-Flocculation Treatment: Influence of Rapid Mix Parameters, Wat. Res., 33, (1999). 4. Kang, L. S., Han, S. W. and Jun, C. W., Synthesis and Characterization of Polymeric Inorganic Coagulants for Water Treatment, Korean J. Chem. Eng., 18(6), (2001). 5. Bouyer, D., Coufort, C., Line, A. and Do-Quang, Z., Experimental Analysis of Floc Size Distribution in a 1-L jar under Different Hydrodynamics and Physicochemical Conditions, Journal of Colloid and Interface Science, 292(2), (2005). 6. Francois, R. J., Growth Kinetics of Hydroxide Flocs, Journal AWWA, 80(6), 92-96(1988). 7. (a) Dharmappa, H. B., Verink, J., Fujiwara, O. and Vigneswaran, S., Optimal Design of a Flocculator, Water Research, 27, (1993), (b) Han, M. and Lawler, D. F., The (Relative) Insignificance of G in Flocculation, Journal of AWWA, 84, (1992). 8. Jeong, J. K., Yoon, T. I., Seo, H. J. and Kim, J. Y., Influence of Mixing Intensity on the Biological Wastewater Treatment, J. of KSEE, 5, 67-83(1983). 9. Kwak, J. W., Physico-chemical Principle and Practice of Water Treatment, Yeigigak(1998). 10. Tambo, N. and Hozumi, H., Physical Characteristics of Flocs- II. Strength of Flocs, Water Res., 13, (1979). 11. Wiesner, M. R., Kinetics of Aggregate Formation in Rapid Mic, Water Res., 26(3), (1992). 12. Reynolds, T. D. and Richards, P., Unit Operations and Processes in Environmental Engineering, Boston, PWS Publishing Company(1995). 13. Han, S. W., Lee, C. W. and Kang, L. S., Physical Effect on Syn-

9 pv r l p q 215 thesis of Al(III) Polymeric Inorganic Coagulants for Water Treatment, Korean Chem. Eng. Res., 40(5), (2004). 14. Lee, K. S. and Lee, S. W., Removal of Phosphorus and Turbidity in Settling-Aggregation Basin using Solid-type Polymeric Coagulants, J. of KSEE, 26(6), (2004). 15. Lee, S. W., Lee, K. S., Haam, S. J. and Kwak, J. W., Phosphorous Removal by Al(III) and Fe(III) Coagulants and Visualization of Flocs, J. Korean Ind. Eng. Chem., 16(1), 74-80(2005). 16. Kim, J. P., Han, I. S. and Chung, C. B., Monte Carlo Simulations of Colloidal Particle Coagulation and Breakup under Turbulent Shear, Korean J. Chem. Eng., 20(3), (2003). Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006

44(3)-16.fm

44(3)-16.fm Korean Chem. Eng. Res., Vol. 44, No. 3, June, 2006, pp. 270-276 지능형헬스케어욕조시스템개발을위한온수온도변화 r ~r l o l l e l 561-756 r rte v v 1 664-14 (2006 3o 9p r, 2006 6o 20p }ˆ) Change of the Warm Water emperature for