Enhancing solar disinfection of water for application in developing regions J.A. Byrne

(1)

Enhancing solar disinfection of

water for application in developing

regions

J.A. Byrne

Nanotechnology and Integrated BioEngineering Centre

www.nibec.ulster.ac.uk

(2)

Care

International

Cambodia

ICROSS

(Kenya)

CSIR

(S. Africa)

IWSD

(Zimbabwe)

USC

PSA

(Spain)

University of Ulster

University of Leicester

(U.K.)

EAWAG

(Switzerland)

RCSI

(Ireland)

SODISWATER

FP6 INCO-DEV

www.rcsi.ie/sodis

(3)

• 1.1 Billion people without access to safe water.

• 4 Billion cases of diarrhoea (88% due to unsafe water).

• 1.8 Million die each year (majority under 5 yrs).

(4)

Household Water Treatment

Intervention Options

• Boiling

• Filtration

• Chlorination

• Solar Disinfection

(5)

(6)

In use by more than 2 million people and in more than 28

countries around the globe

(7)

0

5

10

15

20

25 Adults

6 - 16 yrs

under 6yrs

Solar Disinfection

Control

Cho

lera Infecti

on

Ra

te (

%

)

Only children under age 6 used the SODIS technique. They

were 7 times less likely than non-SODIS users to contract

(8)

Positives for SODIS

Effective against a wide range of pathogens

Low cost (effectively zero)

Simple to use

Negatives for SODIS

Some pathogens are resistant to SODIS

Rate of kill depends upon environmental factors

No quality assurance

Cultural/societical/political factors

Education is required

(9)

Enhancing Solar Disinfection of Water



Continuous flow SODIS reactor with add on CPC



Continuous flow photocatalytic SODIS reactor



Batch photocatalytic SODIS reactor:



UV dosimeter for batch SODIS

(10)

h

+

e

-h

= 3.2 eV

OH



OH

O

₂

O

₂



-,

H

2 O

2

(11)

1. Continuous flow photocatalytic SODIS reactor with add on CPC.

TiO

₂

coated borosilicate glass tubes (0.4 mg/cm

2 _{) were incorporated into the CPC-SODIS}

reactors used at PSA and used as a 7L re-circulating batch system using

E. coli

K12 in

saline (1x10

6 _{CFU/mL) as a model test organism.}

(12)

1. Continuous flow photocatalytic SODIS reactor with add on CPC.

Uncoated external

Uncoated external,

uncoated internal

TiO

₂

coated external

TiO

2 coated external,

uncoated internal

Uncoated external,

TiO

₂

coated internal

TiO

₂

coated external,

TiO

₂

coated internal

(13)

1. Continuous flow photocatalytic SODIS reactor with add on CPC.

0 10 20 30 40 50 60 70 101 102 103 104 105 106 10:30 11:15 12:00 12:45 13:30 14:15 15:00 15:45 15 20 25 30 35 40 45 50 15 20 25 30 35 40 45 50 15 20 25 30 35 40 45 50 01-04-08, Uncoated external uncoated internal 07-05-08, Coated external coated internal

Normalized time (min)

101

102 103 104 105

106 07-05-08, Coated external coated internal 29-04-08, Coated external uncoated internal

E.c

oli

concentration (C

FU/mL)

101 102 103 104 105 106

07-05-08, Coated external coated internal 29-04-08, Coated internal uncoated external

UV Data 29-04-08 UV Data 07-05-08

Local time (HH:MM)

UV Data 29-04-08 UV Data 07-05-08

UV Irradian

ce

(

W/m

2 )

UV Data 01-04-08 UV Data 07-05-08 0 10 20 30 40 50 60 70 101 102 103 104 105 106 10:30 11:15 12:00 12:45 13:30 14:15 15:00 15:45 15 20 25 30 35 40 45 50 15 20 25 30 35 40 45 50 15 20 25 30 35 40 45 50 01-04-08, Uncoated external uncoated internal 07-05-08, Coated external coated internal

Normalized time (min)

101

102 103 104 105

E.c

oli

concentration (C

FU/mL)

101 102 103 104 105 106

UV Data 29-04-08 UV Data 07-05-08

Local time (HH:MM)

UV Data 29-04-08 UV Data 07-05-08

UV Irradian

ce

(

W/m

2 )

Normalized time (min)

101

102 103 104 105

E.c

oli

concentration (C

FU/mL)

101 102 103 104 105 106

UV Data 29-04-08 UV Data 07-05-08

Local time (HH:MM)

UV Data 29-04-08 UV Data 07-05-08

UV Irradian

ce

(

W/m

2 )

Normalized time (min)

101

102 103 104 105

E.c

oli

concentration (C

FU/mL)

101 102 103 104 105

106 07-05-08, Coated external coated internal 29-04-08, Coated internal uncoated external

UV Data 29-04-08 UV Data 07-05-08

Local time (HH:MM)

UV Data 29-04-08 UV Data 07-05-08

UV Irradian

ce

(

W/m

2 )

Normalized time (min)

101

102 103 104 105

E.c

oli

concentration (C

FU/mL)

101 102 103 104 105 106

UV Data 29-04-08 UV Data 07-05-08

Local time (HH:MM)

UV Data 29-04-08 UV Data 07-05-08

UV Irradian

ce

(

W/m

2 )

UV Data 01-04-08 UV Data 07-05-08

E

.

c

oli

c

once

nt

ra

tion (

CFU

/m

L)

UV

A

ra

dia

tion (

W

/m

2

)

(14)

1. Continuous flow photocatalytic SODIS reactor with

add on CPC.

(15)

U

V

Irr

adi

ance

(W/

m

22-04-08, uncoated internal uncoated external

22-04-08, coated internal uncoated external

10-04-08, coated external uncoated internal

Typical UV data

2

E. col

i

concentr

at

ion

(CF

U

/mL)

10

1

10

2

10

3

10

4

10

5

10

6

10:30

11:15

12:00

12:45

13:30

14:15

15:00

10

15

20

25

30

35

40

45

50

55 )

Local time (HH:MM)

(16)

2a. Static batch photocatalytic SODIS reactor

(17)

Summary of Results

(18)

3. UV-sensor and control

Experiments using

E. coli

in natural well water (1x10

6 _{CFU/mL) were carried out to assess}

the total treatment time required for sequential batch SODIS. Effect of UVA dose on total

treatment time investigated using 20, 30, 40, 60, 70 and 80 Wh m

2 _.

(19)

3. UV-sensor and control

Accumulated UVA dose =

33.7 W·h/m

2 Total treatment time 2.5 hours … water must be kept in SODIS reactor!

11:30 12:00 12:30 13:00 13:30 14:00 14:30 15:00 15:30

10

0

10

1

10

2

10

3

10

4

10

5

10

6

10

7

0

5

10

15

20

25

30

35

40

45

50 Bac

terial

c

onc

ent

rat

ion

(C

F

U

/m

L)

Local Time (HH:mm)

Tube 1. Treated water discharged

(samples stored in lab)

Tube 2. Treated water kept in reactor

(samples taken from reactor)

U

V

A

(W

/m

2

)

T

em

perat

ur

e

(ºC)

Temperature tube 2

Temperature tube 1

UV Irradiance

Exposure

Dark

DL

(20)

3. UV-sensor and control

Accumulated UVA dose =

68.0 W·h/m

2 Total treatment time 1.0 hour … in SODIS reactor

12:00

13:00

14:00

15:00

16:00

10

0

10

1

10

2

10

3

10

4

10

5

10

6

10

7

0

5

10

15

20

25

30

35

40

45

50 Bac

terial

c

onc

ent

rat

ion

(C

F

U

/m

l)

Local Time (HH:mm)

U

V

A

(W

/m

2

)

T

emper

at

ur

e

(º

C)

Temperature tube 2

Temperature tube 1

UV Irradiance

DL

Tube 1. Treated water discharged

(samples stored in lab)

Tube 2. Treated water kept in reactor

(samples taken from reactor)

(21)

4. Static batch photocatalytic/SODIS reactor

SODIS enhancement technologies tested:

Polymer bags were made from FEP, PET, PVC and LDPE (500mL and 1500mL).

Photocatalytic polymer bags were prepared in LDPE. Bags used as static batch

system with

E. coli

K12 in distilled water (1x10

6 _{CFU/mL) as a model test organism.}

(22)

4. Static batch photocatalytic SODIS reactor

No dramatic increase in disinfection with use of expensive polymers (500mL bags), however

material choice will effect usable lifetime the SODIS bags.

(23)

4. Static batch photocatalytic SODIS reactor

(24)

4. Static batch photocatalytic SODIS reactor

(25)

4. Static batch photocatalytic SODIS reactor

Low cost (25p)

Large surface area:volume ratio

Easy to fill

(26)

Additional work: Low cost UVA dosimeter

SODIS enhancement technologies

Dosimetric sensors ensure

“lethal solar radiation dose” has been received,

confirming water is safe for consumption.

Time 0

before exposure

Time x

Following receipt of

“lethal dose”

(27)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0

5

10

15

20 Time (min)

A

bso

rban

ce at

660 nm

Additional work: Low cost UVA dosimeter

Single use and repeat use dosimetric sensors made for 30, 45, 60 and 80 Wh.m

2 Incident UVA intensity = 30 Wm

2 Time taken for colour change = 5 min

(28)

Summary

Solar disinfection is a simple, user friendly approach to

reducing mortality where access to safe drinking water supplies

is lacking

Nanotechnology (photocatalysis and sensor technology) can

enhance the efficiency and provide some quality assurance

to the end user

Work is ongoing to evaluate photocatalytically enhancement

against SODIS resistant pathogens

Cost based analysis will be undertaken to determine which

technologies will be deployed for pilot testing in Africa

Just a thought! If we inactivate the microorganisms, but

they remain in the water, would they act as an oral dose

vaccine?

(29)

Acknowledgements

Royal College of Surgeons in Ireland (RCSI), Ireland

University of Ulster (UU), United Kingdom

CSIR Environmentek, South Africa

EAWAG, Switzerland

The Institute of Water and Sanitation Development (IWSD), Zimbabwe

Plataforma Solar de Almería (CIEMAT-PSA), Spain

University of Leicester (UL), United Kingdom

The International Commission for the Relief of Suffering & Starvation

(ICROSS), Kenya

University of Santiago de Compostela (USC), Spain

(30)