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M.T. Amin, M.Y. Han
Socially and economically acceptable drinking water supply
from rooftop rainwater and improved solar disinfection
Contents
1
Introduction
2
Materials and Methods
3
Results and Discussion
4
Conclusions
Background
< Tailand >
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< Uganda >
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.
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?
Drinking
Emergency
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Cleaning
Gardening
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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 supply
safe drinking water by rainwater
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Solar Disinfection (SODIS)
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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 Longwave
Radiation
UV
DO/pH
Attenuation
By Plastic?
Cellular
Breakdown
Infrared
Reflection and
Temp. Back-Radiation
Used
PET
bottle
Pasteurization
Conduction
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Developing Solar Disinfection
a. SODIS
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b. W-SODIS
c. SOCODIS
d. W-SOCODIS
e. I-SOCODIS
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Limitation of SODIS
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Few scientific and engineering data for rainwater disinfection
Only strong sunlight radiation for about 6~8 h daily is adequate for the
complete disinfection
W-SODIS (Wrapping Solar
Disinfection) system
SOCO-DIS (Solar Collector
Disinfection) system
• Improving SODIS to achieve more concentrated
temperature effects
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• Improving SODIS to achieve more
concentrated sunlight radiation
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Limitation of SOCO-DIS
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Sunlight radiation for about 6~8 h daily is not adequate for the complete
disinfection in the weak weather
W-SOCO-DIS (Wrapping Solar
Collector Disinfection) system
• Improving SOCO-DIS to achieve more concentrated
temperature effects and sunlight radiation
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I-SOCO-DIS (Improved Solar
Collector Disinfection) system
• Improving SOCO-DIS to achieve more
high pH
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Sample collection site
Completion date
2005.10
Roof area
3,892 ㎡
Green roof area
935 ㎡
residence
about 1,000
persons
RWH
Beginning
date
2006. 4
A kind of
catchment
concrete, terrace,
green roof
Catchment
area
3,652㎡
Tank
volume
250 ton
Consumed
60~90 ton/day
Uses
toilet
* RWH : Rainwater harvesting system
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Outline of experiment
a. SODIS
b. W-SODIS
Seoul, Republic od Korea,
Seoul University Engineering Building
(37° N, 126° E)
c. SOCODIS
d. W-SOCODIS
e. I-SOCODIS
Rain Water Tank
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The quality of rainwater samples
PHYSIOCHEMICAL PARAMETERS
MICROBIAL PARAMETERS
Initial Temp. 0C
pH
EC
μS/cm
DO
mg/l
Turbidity
NTU
TC
CFU/100ml
E-Coli
CFU/100ml
23-25
7-9
150-500
5-9
1-5
880-1100
200-250
Main target
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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
Weak Weather
Radiation
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Moderate Weather
Temperature
Radiation
Temperature
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.
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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
The effects of initial pH
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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.
SODIS
SOCODIS
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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