전산화 공정에 의한 microcystin 용출 및 고도처리에 의한 제거 특성 = Release of Microcystin from Microcystis sp. by Pre-Oxidation and Removal of Microcystin by Advanced Drinking Water Treatment

국문 초록 (Abstract)

목적 : 하절기 고농도의 Microcystis sp. 함유 원수가 정수장으로 유입시에 전산화 공정에서의 microcystin (MCs) 용출과 후단의 고도 정수처리 공정에서 용출된 MCs의 제거 가능성 평가가 목적이다.
방법 : 고농도 Microcystis sp. 함유원수(400,000 cells/mL)를 이용하여 전염소와 전오존 처리에 의한 MCs 용출 특성을 평가하였으며, 후단의 고도 정수처리 공정인 O3, O3/H2O2, UV/H2O2 및 BAC 공정에서의 전산화 처리에 의해용출된 MCs 제거 특성을 평가하였다.
결과 및 토의 : 전염소 투입농도가 증가할수록 수중으로 용출된 MCs 농도는 급격히 증가하다가 염소 투입농도 5 mg/L 이상에서는 감소하였고, 용출된 MCs의 대부분은 MC-RR (57∼86%)과 MC–LR (11∼29%)이 차지하였다. 전염소 처리 이후 전오존 처리공정에서 오존 투입농도가 증가할수록 수중의 MCs 농도는 처리 전에 비해 수∼수십배 정도 증가하였으나, 전염소를 3 mg/L 이상으로 처리한 경우에는 오존 투입농도가 증가할수록 MCs가 급격히제거되었다. 전산화 처리 후, 응집-침전 처리수 중의 MCs 농도가 처리 전에 비하여 2배 이상 급격히 증가였으며, 침전공정 동안 산화제에 손상된 Microcystis 조체에서 MCs가 지속적으로 유출되었다. 후산화 공정에서는 O3과O3/H2O2 공정이 UV/H2O2 공정에 비해 MCs 제거에 효과적이었고, O3과 O3/H2O2 공정에서 1 mg/L 이상으로 O3을투입한 경우 MCs가 100% 제거되었다. BAC 공정에서는 MCs 유입농도가 각각 0.8 μg/L와 2.8 μg/L일 때 EBCT 15분에서 각각 100%와 93% 제거되었으며, MC-RR에 비해 MC-LR의 생물분해 제거능이 낮았다. 고농도의 MCs가유입되거나 MC–LR의 구성비율이 높을 경우에는 BAC 공정의 EBCT를 증가시켜 운전할 필요가 있었다.
결론 : 고농도 Microcystis sp. 함유 원수를 전산화 처리하면 고농도의 MCs이 용출되었으나 후단의 O3, O3/H2O2, UV/H2O2 및 BAC 공정과 같은 고도 정수처리 공정에서 제거가 가능하였다. 특히, UV-AOP 공정에 비해 O3 공정에의한 MCs 제거율이 높았으며, BAC 공정에서도 EBCT 15분의 조건에서는 93∼99%의 MCs가 제거되었다. Microcystis sp.가 번성하는 시기에 응집/침전 공정의 효율 증진을 위해 전산화 공정을 적용하는 정수장에서는 후단에 O3/BAC 공정을 적용할 경우 MCs 제거에 매우 효과적으로 나타났다.

다국어 초록 (Multilingual Abstract)

Objectives : The objectives of this study were to evaluate the characteristics of microcystins (MCs) release form Microcystis sp. in surface water during pre-oxidation process using chlorine and ozone and it’s removal by advanced water treatment process as post process when raw water containing high Microcystis sp. is introduced into the water treatment plant.
Methods : Raw water which had contained over 400,000 cells/mL of Microcystis sp. were used to evaluate the characteristics of MCs released from Microcyctis sp. and chlorination (Cl2) and ozonation (O3) were used as pre-oxidation process and O3, O3/H2O2, UV/H2O2 and biological activated carbon (BAC) were used as post oxidation process.
Results and Discussion : As the concentration of chlorine increased, the concentration of released MCs in the water increased, but decreased when higher than 5 mg/L of chlorine dosage. Released MCs were consisted of almost MC-RR (57∼86%) and MC–LR (11∼29%). In the ozone treatment after prechlorination process, the MCs concentration was increased by several fold to dozen fold to compare before ozonation. However, when chlorine dosage was over 3 mg/L, MCs were rapidly removed as the ozone concentration increased. The MCs concentration of flocculation/sedimentation treated sample after the pre-oxidation was increased more than two times before treatment, the MCs was continuously released during the coagulation/sedimentation process from the damaged Microcystis sp. due to the prior oxidation process. In the post-oxidation process, O3 and O3/H2O2 processes were more effective for removing MCs than the UV/H2O2 process, and O3 and O3/H2O2 processes removed 100% of the MCs when O3 was added above 1 mg/L. 100% and 93% were removed respectively at 15 minutes of EBCT (empty bed contact time) in the BAC process, when the MCs concentrations of influent were 0.8 μg/L and 2.8 μg/L. The biodegradability of MC-LR was lower than that of MC-RR. It was necessary to increase the EBCT of the BAC process when the concentrations of MCs or the ratio of MC-LR were high.
Conclusions : Although, pre-oxidation treatment to the raw water containing high concentration of Microcystis release higher MCs concentration in the oxidized water, that can be removed by post O3, O3/H2O2, UV/H2O2 and BAC processes. The removal rate of MCs by O3 process was higher than that of UV-AOP process, and 93∼99% of MCs removed with 15 min of EBCT in BAC process. In the drinking water treatment plant where the pre-oxidation process is applied to improve the efficiency of the flocculation/sedimentation process during the blooming season of Microcystis sp., O3/BAC process after the flocculation/sedimentation process is recommendable to MCs remove.

참고문헌 (Reference)

1 손희종, "생물활성탄 공정에서 Geosmin과 MIB의 제거 특성 : 생물분해와 흡착" 대한환경공학회 39 (39): 318-324, 2017

2 손희종, "낙동강 하류지역의 식물플랑크톤 우점종 군집 변화: 2002년~2012년" 대한환경공학회 35 (35): 289-293, 2013

3 손희종, "낙동강 하류지역에서 식물 플랑크톤 생체량 및 수질의 장기변동 특성" 대한환경공학회 35 (35): 263-267, 2013

4 이정규, "낙동강 하류의 정수처리 공정에서 pH, 오존 및 응집이 트리할로메탄 생성에 미치는 영향" 대한환경공학회 39 (39): 105-111, 2017

5 X. He, "Toxic cyanobacteria and drinking water: impacts, detection, and treatment" 54 : 174-193, 2016

6 WHO, "Toxic Cyanobacteria in Water: A Guide to their Public Health Consequences, Monitoring and Management"

7 A. Ando, "Removal of musty-odorous compounds in water and retained in algal cells through water purification processes" 25 (25): 299-306, 1992

8 A. B. Sengül, "Removal of intra- and extracellular microcystin by submerged ultrafiltration (UF) membrane combined with coagulation/flocculation and powdered activated carbon (PAC) adsorption" 343 : 29-35, 2018

9 S. Zhou, "Removal of Microcystis aeruginosa by potassium ferrate(VI): impacts on cells integrity, intracellular organic matter release and disinfection by-products formation" 251 : 304-309, 2014

10 J. Sun, "Removal of Microcystis aeruginosa by UV/chlorine process: inactivation mechanism and microcystins degradation" 349 : 408-415, 2018

11 Z. Wang, "Removal of Microcystis aeruginosa by UV-activated persulfate: performance and characteristics" 300 : 245-253, 2016

12 G. Joh, "Problematic algae in the sedimentation and filtration process of water treatment plants" 60 (60): 219-230, 2011

13 S. Canonica, "Phototransformation of selected pharmaceuticals during UV treatment of drinking water" 42 : 121-128, 2008

14 L. A. Coral, "Oxidation of Microcystis aeruginosa and Anabaena flos-aquae by ozone: impacts on cell integrity and chlorination by-product formation" 47 : 2983-2994, 2013

15 손희종, "Microcystis sp.로 수화된 상수원수에 전염소 및 폴리아민 투입이 정수처리에 미치는 영향 : 입자상 물질 분포" 대한환경공학회 39 (39): 556-560, 2017

16 R. Nishiwaki-Matsushima, "Liver tumor promotion by the cyanobacterial cyclic peptide toxin microcystin-LR" 118 : 420-424, 1992

17 J. Puddick, "High levels of structural diversity observed in microcystins from Microcystis CAWBG11 and characterization of six new microcystin congeners" 12 : 5372-5395, 2014

18 J. R. Bolton, "Fundamental photochemical approach to the concepts of fluence (UV dose) and electrical energy efficiency in photochemical degradation reactions" 28 (28): 857-870, 2002

19 G. Wen, "Formation of assimilable organic carbon during the oxidation of water containing Microcystis aeruginosa by ozone and advanced oxidation process using ozone/hydrogen peroxise" 307 : 364-371, 2017

20 L. Ho, "Fate of cyanobacteria and their metabolites during water treatment sludge management processes" 424 : 232-238, 2012

21 H. B. Jun, "Effectiveness of coagulants and coagulant aids for the removal of filter-clogging Synedra" 50 (50): 135-148, 2001

22 H. Zhang, "Effect of oxidant demand on the release and degradation of microcystin-LR from Microcystis aeruginosa during oxidation" 181 : 562-568, 2017

23 J. Ma, "Effect of algae species population structure on their removal by coagulation and filtration process-a case study" 56 (56): 41-54, 2007

24 US EPA, "Drinking Water Health Advisory for the Cyanobacterial Microcystins Toxins"

25 G. A. Codd, "Cyanobacterial toxins: risk management for health protection" 203 : 264-272, 2005

26 C. MacKintosh, "Cyanobacterial microcystin-LR is a potent and specific inhibitor of protein phophatases 1 and 2A from both mammals and higher plants" 264 (264): 187-192, 1990

27 P. Xie, "Comparison of permanganate preoxidation and preozonation on algae containing water: cell integrity, characteristics, and chlorinated disinfection byproduct formation" 47 : 14051-14061, 2013

28 X. He, "Colonial cell disaggregation and intracellular microcystin release following chlorination of naturally occurring Microcystis" 101 : 10-16, 2016

29 M. Ma, "Chlorination of Microcystis aeruginosa suspension: cell lysis, toxin release and degradation" 217 : 279-285, 2012

30 S. Zhou, "Characterization of algal organic matters of Microcystis aeruginosa: biodegradability, DBP formation and membrane fouling potential" 52 : 199-207, 2014

31 L. E. Fleming, "Blue green algal (cyanobacterial) toxins, surface drinking water, and liver cancer in Florida" 1 : 157-168, 2002

32 L. Chen, "A review of reproductive toxicity of microcystins" 301 : 381-399, 2016