Small scale electrochemical disinfection system
with specially coated electrodes
C. Sousa, K.M. Śmiech, A. W. Jeremiasse, L.L.F. Agostinho​​
Athens, September 2016
1
Outlook
•
•
•
•
•
Background:
 (Electrochemical) water disinfection
Methods
Experimental setup
Results:
 Disinfection efficiency
 Produced disinfectants
 Disinfection byproducts and heavy metals
Summing up
2
Water disinfection
Important for preventing the spreading of waterborne diseases
Methods1:
• Chemical  e.g. Cl2, ClO, O3
• Physical  e.g. UV
• Physical-chemical  e.g. electrochemical
Electrochemical disinfection efficiency:
• Electrolyte
• Current (density)
• Electrode material
• BDD
• MMO
1Martinez-Huitle, C.,
& Brillas, E. (2008) Electrochemical
alternatives for drinking water disinfection. Angewandte Chemie
International Edition 47 (11), 2-10
3
Methods
•
•
•
•
•
•
•
2 electrochemical cells
2 MMO types (Ru, Ir, Ti)
 ON2012
 ON2038
Total flowrate = 4 m3 h-1
Cl- concentration = 49 mg L-1
Disinfection efficiency for 3 bacteria and 1 virus
 E.coli
 S. epidermidis
 R. terrigena
 bacteriophage MS2
Analysis for THM
Analysis for heavy metals
4
Experimental setup
5
Disinfection efficiency
Bacteria*: > log 6 disinfection
Virus**: log 3 – log 5 disinfection
20
14
18
12
6,36
6,43
6,22
14
Log(PFU/mL)
Log (CFU/mL)
16
12
10
8
6,39
6,19
6,01
6
4
2
6,22
6,19
0
IN
0
OUT
0 min
30E.min.
coli
6,16
0
OUT
IN
IN
30 min
S. epidermidis
R. terrigena
10
8
6
4
2
0
OUT
60 min
6,31
5,69
5,62
5,78
2,69
5,78
5,72
2,27
1,16
0
IN
OUT
2,54
0,00
OUT
0,78
IN
0 min
OUT
30 min
MS2 cell 2038
IN
60 min
MS2 cell 2012
* Method: Heterotrophic plate count. Standard Methods for the Examination of Water and Wastewater (APHA).
** Method: ISO 10705-1:1995 Detection and enumeration of bacteriophages. Part 1: enumeration of F-specific RNA bacteriophages.
6
Produced disinfectants
IN
OUT 2012
OUT 2038
range
Free Cl (mg L-1)*
0
0,37
1,38
0,5 – 3
O3 (mg L-1)**
0
0,33
0,36
0,1 – 0,8
Active chlorine production: > 90% Coulombic efficiency
*Method: ISO 7393/1:1998 Water quality -- Determination of free chlorine and total chlorine -- Part 1: Titrimetric method using N,N-diethyl1,4-phenylenediamine.
**Method: H. Bader & J. Hoigné (1981) Determination of ozone in water by the indigo method. Water Research 15(4), 449-456
7
Disinfection byproducts and heavy metals
•
Total THM ~0,6 μg L-1 as AOX
•
<< 60 μg L-1 WHO guideline
•
Including BDCM ~0,16 μg L-1
•
Heavy metals (Ti, Ir, Ru) < 10 μg L-1 (max. advisable level for drinking water)
 safe water produced
8
Summing up
•
Small scale (2 x 2 m3 h-1) electrochemical disinfection system with specially
coated electrodes (MMO with Ru and Ir)
•
Treatment of waters with low Cl- content (49 mg L-1) without salt addition
•
Disinfection efficiency:
•
•
•
bacteria: > log 6
virus: log3 – log 5
Produced disinfectants included:
•
•
Free Cl: 0,5 – 3 mg L-1
O3: 0,1 – 0,8 mg L-1
•
THM: ~0,6 μg L-1 as AOX, i.e. << 60 μg L-1 WHO guideline
•
Heavy metals (Ir, Ru, Ti) < 10 μg L-1
9
Acknowledgements
10
Thank you very much!
Questions?
[email protected]
11