Small scale electrochemical disinfection system with specially - - PowerPoint PPT Presentation

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

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Water disinfection

Important for preventing the spreading of waterborne diseases

1Martinez-Huitle, C., & Brillas, E. (2008) Electrochemical

alternatives for drinking water disinfection. Angewandte Chemie International Edition 47 (11), 2-10

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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

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

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Experimental setup

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6,19 6,22 6,16 6,01 6,19 6,39 6,22 6,43 6,36 2 4 6 8 10 12 14 16 18 20 IN OUT IN OUT IN OUT

Log (CFU/mL)

• E. coli
• S. epidermidis
• R. terrigena

30 min.

60 min 0 min 30 min

Disinfection efficiency

Bacteria*: > log 6 disinfection

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Virus**: log 3 – log 5 disinfection

* 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.

5,78 1,16 5,78 0,78 5,72 0,00 5,62 2,69 5,69 2,27 6,31 2,54 2 4 6 8 10 12 14 IN OUT IN OUT IN OUT

Log(PFU/mL)

MS2 cell 2038 MS2 cell 2012

0 min 30 min 60 min

Produced disinfectants

*Method: ISO 7393/1:1998 Water quality -- Determination of free chlorine and total chlorine -- Part 1: Titrimetric method using N,N-diethyl- 1,4-phenylenediamine. **Method: H. Bader & J. Hoigné (1981) Determination of ozone in water by the indigo method. Water Research 15(4), 449-456

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IN OUT 2012 OUT 2038 range Free Cl (mg L-1)* 0,37 1,38 0,5 – 3 O3 (mg L-1)** 0,33 0,36 0,1 – 0,8 Active chlorine production: > 90% Coulombic efficiency

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

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• Heavy metals (Ti, Ir, Ru) < 10 μg L-1 (max. advisable level for drinking water)

 safe water produced

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

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• 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

Acknowledgements

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Thank you very much!

Questions?

karolina.smiech@hvhl.nl

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