M.T. Amin, M.Y. Han

M.T. Amin, M.Y. Han

Socially and economically acceptable drinking water supply from rooftop rainwater and improved solar disinfection

6th World Water Forum

SNU RRC

KSU RFA

Contents

1 Introduction

2

3

4

Materials and Methods

Results and Discussion

Conclusions

Introduction

Background

• Lots of countries have water shortage problems over the world• Rainwater harvesting (RWH) can be alternative water resource to these countries• Because RWH system is simple to install and manage, this system has been spread

to water shortage areas.

< Tailand > < Uganda >

Sited from “ELLIAS SAIDIN and AMINUDDIN BAKI, RAINWATER HARVESTING: POTENTIAL ALTERNATIVE WATER RESOURCES IN MALAYSIA, WATER MALAYSIA 2009”


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What is rainwater harvesting system?

Gardening

Cleaning

Emergency

Drinking


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Rainwater as drinking water ?

-At least one-third of the population in developing countries has no access to safe drinking water

- Rainwater can be used as drinking water if microbial contamination is controlled.

Simple disinfection method can make and supplysafe drinking water by rainwater


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Solar Disinfection (SODIS)• Inactivation of microorganisms by UV-A-radiation and thermal treatment• Suited for providing safe drinking water in rural and semi-urban communities

in developing countries• Promoted by the World Health Organization (WHO)

Solar and LongwaveRadiation

Reflection andBack-Radiation

Conduction

AttenuationBy Plastic?

UVDO/pH

Infrared

Cellular Breakdown

Pasteurization

Temp.Used PET bottle


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Developing Solar Disinfectiona. SODIS

b. W-SODIS c. SOCODIS

d. W-SOCODIS e. I-SOCODIS


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Limitation of SODIS• Few scientific and engineering data for rainwater disinfection• Only strong sunlight radiation for about 6~8 h daily is adequate for the

complete disinfection

SOCO-DIS (Solar Collector Disinfection) system

• Improving SODIS to achieve more con-centrated sunlight radiation

W-SODIS (Wrapping Solar Disinfection) system

• Improving SODIS to achieve more concentrated temperature effects


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Limitation of SOCO-DIS• Sunlight radiation for about 6~8 h daily is not adequate for the complete

disinfection in the weak weather

I-SOCO-DIS (Improved Solar Collector Disinfection) system

• Improving SOCO-DIS to achieve more high pH

W-SOCO-DIS (Wrapping Solar Collector Disinfection) system

• Improving SOCO-DIS to achieve more concentrated temperature effects and sunlight radiation


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Materials and Methods

Sample collection siteCompletion date 2005.10

Roof area 3,892 ㎡Green roof area 935 ㎡

residence about 1,000 per-sons

RWH

Beginning date 2006. 4

A kind of catchment

concrete, ter-race, green roof

Catchment area 3,652㎡

Tank vol-ume 250 ton

Consumed 60~90 ton/dayUses toilet

* RWH : Rainwater harvesting system


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Outline of experiment

Seoul, Republic od Korea, Seoul University Engineering Building (37° N, 126° E)

Rain Water Tank

a. SODIS

b. W-SODIS

c. SOCODIS

d. W-SOCODIS

e. I-SOCODIS


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The quality of rainwater samples

PHYSIOCHEMICAL PARAMETERS MICROBIAL PARAMETERS

Initial Temp. 0C pH ECμS/cm

DOmg/l

TurbidityNTU

TCCFU/100ml

E-ColiCFU/100ml

23-25 7-9 150-500 5-9 1-5 880-1100 200-250

Main target• Samples were always collected from the same outlet point, about 1.35 m from

the base of the tank• The reason for the different initial values of all the parameters is the effect of

the season and residential time in the tank• These are used as the standard initial values for the rainwater samples in this

study.


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Weather conditions

• Weather is categorized into three different types, depending upon weak, moderate sunlight radiations.

• The temperature difference is about 2~10 0C, with the great temperature rise in the SOCO-DIS & W-SOCO-DIS system.

Weak Weather Moderate Weather

Radiation Temperature Radiation Temperature


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Results and Discussion

The effects of weather condition• In case of SODIS, No parameter met the potable guideline values• The difference of disinfection efficiency of SOCO-DIS & W- SOCO-DIS system is

about 20-40% with that of simple SODIS mostly because of the enhanced effects of concentrated radiations and heat.

Weak Weather Moderate Weather

• Rainwater using lemon and vinegar as catalysts(for acidic pH) offered best disinfection efficiency for SOCO-DIS system for all microbial parameters without any exception.

• Overall disinfection efficiency increased from 10 to 20% by decreasing pH values from basic to neutral and then acidic states, respectively.

The effects of initial pH

SODIS SOCODIS

Conclusions

Conclusions• Disinfection efficiency of the W-SOCO-DIS or I-SOCO-DIS

is 20~40 % better than SODIS and it managed complete disinfection under moderate weather condition

• Developed SODIS system- SOCODIS : disinfection efficiency of SOCODIS system is better than SODIS about 20-40% because of the enhanced effects of concentrated radiations. - W-SOCODIS : The maximum temperature increase due to wrapping with plastic bags was about 4-7 C°, which enhanced the disinfection efficiency by about 5-8%.- I-SOCODIS : using lemon and vinegar as catalysts makes low pH improving the efficiency from 10 to 20 %


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Conclusions

• this method can be easily applied to any place to gain acceptable water in the world, especially where the centralized water supply system is not affordable in a short time period, eventually contribute to achieve the MDGs.


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Thank you

M.T. Amin, M.Y. Han

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