Destruction of Cyanotoxin Microcystin-LR by UV/Chlorine Process OAWWA 78 th Annual Conference Cincinnati, Ohio, September 15, 2016 Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, Ohio 45221-0012, USA Email: [email protected]Xiaodi Duan Advisor: Dionysios D. Dionysiou
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Destruction of Cyanotoxin Microcystin-LR
by UV/Chlorine Process
OAWWA 78th Annual Conference Cincinnati, Ohio, September 15, 2016
Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, Ohio 45221-0012, USA
Harmful algal blooms occur in all types of waters, but those with great concernoccur in fresh waters, such as drinking water reservoirs or recreational waters;
In November 2015, USEPA submitted Algal Toxin Risk Assessment and ManagementStrategic Plan for Drinking Water to Congress;
Cyanobacterial harmful algal blooms can produce cyanotoxins, includingneurotoxins and hepatotoxins.
Cyanobacterial Harmful Algal Blooms
Algae bloom viewed from space, responsible for toxic drinking water in Toledo, Ohio on August 2 2014. Photo: NOAA
In Clermont County, OH, HABs on HarshaLake in June 2014 led to public healthadvisories warning against swimming in thelake. In June 2016, around 5 µg/L of MC-LRwas detected.
Oliver and Carey, 1977, Environ. Sci. Technol., 11: 893-895.Feng, Smith, and Bolton, 2007, J. Environ, Eng. Sci., 6: 277-284.
45
67
O
cyclo
Only consider Adda group:
HN
COHO
N
O CH2
O
NH
NH
O
CH3
CH3
NH
O
COH
O
CNH
O
O
NH
CHN NH2
O
NH
OCH3
MC-LRC49H74N10O12m/ z =
995.5
6. iso-Glutamic Acid
Glu
7. methyl dehydroalanineMdha
1. AlanineAla
2. LeucineLeu
3. Methyl Aspartic
Acid
MeAsp4. ArginineArg
5. Adda
Radical Attack on Aromatic Ring
Cl• is reactive toward benzene (k = 6×109 M-1 s-1 to1.2×1010 M-1 s-1), benzoic acid and phenol.
m/z =1029.5 has also been detected in chlorination ofMC-LR.
The first hydroxylation or chlorination increases theelectron-density of the benzoic ring therefore thesecond one occurs more easily.
Alegre et al, 2000, J. Phys. Chem., 104: 3117-3125. Tsuji et al, 1997, Toxicon, 35:1033-1041. Antoniou et al., 2008, Environ. Sci. Technol, 42: 8877 -8883.
O
45
67
cyclo
Cl
O
45
67 cyclo
HO
HO
O
45
67cyclo
HO
OHOH
m/z 1029.5
m/z 1027.5
m/z 1045.5
45
67
MC-LR
O
m/z 995.5
O
45
67
cyclo
HO
m/z 1011.5
O
45
67 cyclo
Cl
Cl
m/z 1063.5
cyclo
m/z 1047.5
O
45
67 cyclo
OHCl
Radical Attack on Diene Bonds
Gilbert et al., 1988, J. Chem Soc., Faraday Trans., 84(10): 3319-3330. Antoniou et al., 2008, Environ. Sci. Technol, 42: 8877 -8883.
O
45
67 cyclo
m/ z 1029.5
O
45
67cyclo
OHOH
m/z 1029.5
O
45
67 cyclo
m/ z 1013.5
O
m/ z 1011.5
OH
cyclo
45
67
MC-LR
O
m/z 995.5
cyclo
O cyclo O cyclo
m/z 835.5 m/ z 795.5
O
m/z 1011.5
O
cyclo
Tautomers
O
45
67
cyclo
m/ z 1029.5
OHOH
Cl OH
Summary
UV/chlorine lowers the energy and chemical consumption forMC-LR removal, and is still effective at high pH range and inthe presence of NOM;
UV/Chlorine generates high amount of HO•;
MC-LR degradation rate by UV/Chlorine dramaticallydecreases in source water; the conventional water treatmentprocesses and GAC significantly improved the efficiency;
UV-LED is a promising technology for algal toxin removal;
Diene bonds and aromatic ring of the Adda amino acid in MC-LR are the most susceptible groups to radical attack.
Advisor: Dionysios D. Dionysiou
Collaborators: Heath Mash, Toby Sanan, and Joel Allen fromEPA; Maria Meyer and Jeff Swertfeger from GCWW
The project was supported by a Harmful Algal BloomResearch Initiative grant from the Ohio Department of HigherEducation.
Grants-in-Aid of Research from Sigma Xi Society University ofCincinnati Chapter; Summer Research Fellowship, Richard C.Wigger Scholarship, and John David Eye Scholarship fromUniversity of Cincinnati.
Acknowledgement
Sandusky Bay, Erie County, Ohio. The two largest algal blooms ever recorded on Lake Erie occurred in the past five years. Image courtesy Ohio Sea Grant and Stone Laboratory.