SDG6. CLEAN WATER AND SANITAION / GROUP 3
19. SEP. 2022
SDG6: CLEAN WATER AND SANITATION -SOLAR DISINFECTION (SODIS)
The best clean water method in India - Advanced SODIS General level Water Supply in India In India, people usually have two ways to obtain drinking water, one is through the government to build water pipes to deliver drinking water, and the other is to build their own wells to obtain water. Because of the lack of government funding, the small number of professionals and the difficulty of construction in rural areas have resulted in a lack of infrastructure, which has led to many rural villages in India only having to build their own wells to obtain drinking water. However, the quality of water obtained from wells is not up to the standard of drinking water and as a result, diseases such as cholera and diarrhea are prevalent in many rural areas of this country due to the drinking of well water.
Drinkable water is rarely an urgent problem in India so far. From the technical aspect, this article will introduce an advanced water treatment for India.
2. Why SODIS is a good choice for India?
Common household water treatment method are the Chlorination, Flocculant/Disinfectant Powder, Solar-disinfection, ceramic Filtration and Slow Sand Filtration. That could be summed up as the need to add chemicals and filter. Selecting the most appropriate treatment method for India Why SODIS is suitable for circumstances is often a complex decision. The most appropriate option for India depends on existing India? water and sanitation conditions, water quality, 1.What is SODIS? cultural acceptability, implementation feasibility, Solar Disinfection (SODIS) is a availability of technology, and other local household water treatment. Users conditions. need to fill 0.3-2.0-liter plastic soda bottles with low-turbidity water, Considering the plastic bottles are things that can be shake them to oxygenate, and place recycled without funding and the simplicity of use the bottles on a roof or rack for 6 and acceptability. In addition, recontamination is hours (if sunny) or 2 days (if cloudy). low because water is served and stored in the small The combined effects of ultra-violet narrow necked bottles. So, the SODIS is the light (UV)-induced DNA damage, appropriate household water treatment for India. thermal inactivation, and photooxidative destruction inactivate disease-causing organisms It was developed in the 1980s to inexpensively disinfect water used for oral rehydration solutions. Over 2 million people in 28 developing countries use SODIS for daily drinking water treatment. The CBO Kenya Water for Health Organization external icon promotes SODIS in the Kibera slums of Nairobi, Kenya. Over 250,000
The water supply frequency to this area is from two sources, bore wells which provide 24-hour water supply and municipal taps which supply water for 1–2 hours at variable intervals of time ranging from alternate days to once in 3–4 weeks. The municipal supply is used for drinking water, while the bore well water is used for bathing and cleaning. In all seasons, there is a people are reached by trained shortage of drinking water, and water is promoters using social marketing to stored in households in a few containers, mainly wide mouthed metal, or plastic disseminate knowledge about SODIS. containers, with a capacity of 10–12 liters.
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SDG6. CLEAN WATER AND SANITAION / GROUP 3
19. SEP. 2022
Specific level SPECIFIC CHALLENGE (The problems when India using SODIS)
Low level of economic development In a developing country such as India, it is difficult to install water-related infrastructure in a short period of time. Even if water facilities are installed in the long term, there is a shortage of experts who can continuously maintain them.
Let’s see what happened in India GENERAL CHALLENGE
GENERAL SOLUTIONS
(Problems for all countries using SODIS)
On Cold or Cloudy Weather
On cloudy and rainy days?
SODIS is a technology that purifies water by attacking bacteria by the UV rays of the sun. If the temperature drops or if there is not enough sunlight due to clouds, the sterilization effect can be greatly reduced.
48 hours preserve in cloudy days and no use in rainy days
The Fear of Leaching in Plastic Bottles Because SODIS exposes plastic bottles to sunlight, there is a risk of leaching of chemicals in the plastic into the water.
Long-standing habits Residents who lack a sense of hygiene tend to drink the polluted water around them without purifying them. It can also cause water-borne diseases. Long time to purify SODIS is undoubtedly an economical and easy way to purify water. However, depending on the climate, it takes a long time to purify the water. This is also a fatal flaw of SODIS.
The fear of leaching in plastic bottles? From numerous experiments, scholars claim that the level of the plastic bottles they choose are food level. There are no toxic substances in plastic Water Turbidity? Make
Water Turbidity Highly turbid water reduces the efficiency of the SODIS. Community Acceptance Ignorance of the causes of diarrheal disease, unwillingness to produce water, and the lack of a nearby water source are problems.
sure the sunshine could pass through the bottle. Using minerals like Alum (potassium sulphate) and the seeds of plants like Moringa oleifera Community Acceptance? If
people do not believe SODIS could kill or inactive the bacteria, they will not use it. In such circumstance, government or local communities could give some speeches, figures, and evidence to show SODIS is feasible and useful
In some countries with poor energy conditions, using natural energy such as SODIS is more advantageous than pumped water systems.
Evaluation of SODIS bottle used in the SODIS process is one of 3. In addition, if you want to promote this them, it needs to be replaced every six technology in rural areas, it is also a major months. challenge if you want to make it acceptable 2. In addition, once the government wishes to the public. First of all, the local people as to roll it out on a large scale throughout the well as adapted to the traditional way of life, country, it will be necessary to organize even if they are physically sick, they will not specialized technical staff to train the blame the problem on drinking dirty water, public in the standardization process. The and they are even less likely to accept the government will also need to set standards government-organized training on new for the size of water bottles, the duration of drinking water technologies that require money and time in a short time, which will purification and the intensity of sunlight. This is a complex task that requires not be a major obstacle in the process of only the coordination and cooperation of implementing the SODIS technology. In 1. Even as a virtually zero-cost various departments, but also financial addition, the purification process of SODIS technology, the SODIS water purification support, which is not possible in rural takes 6-8 hours, which is too long, especially in the hot summer months, and skill still has some materials need to keep areas where water is scarce. people are not willing to wait for this, which replacing, the bottle used in the SODIS is also an issue that needs to be considered process is one of them, it needs to be in the implementation of SODIS. replaced every six months.
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SDG6. CLEAN WATER AND SANITAION / GROUP 3
19. SEP. 2022
A map of the World indicating the 55 countries where, in 2009 [144], SODIS was in daily use by more than 4.5 million people. (Solar water disinfection (SODIS): A review from bench-top to roof-top, Kevin G. McGuigan et al, 2012)
Specific Solutions Photocatalyst
ADVANTAGES OF PHOTOCATALYSTS
CHALLENGES In the map above, the red areas indicate countries using SODIS. Some countries that use SODIS need to supplement SODIS due to high turbidity or the influence of climate. The photocatalyst would be the alternative method to compensate for SODIS. This method just puts the catalysis like beads coated catalysis into the bottle. That is a way to utilize photocatalysts for SODIS. The following picture shows the photocatalyst. Photocatalysts can be used in various forms, such as beads and films. Recently, it has been used for various purposes such as air purification and water treatment. You can see the white beads in the next photo. This titanium dioxide is a kind of photocatalyst. It is used by coating the catalyst on the beads. Put these catalysts in a water bottle and expose them to sunlight. This purifies the water as the catalyst changes color over time.
The graph shows the effect of photocatalysis. The horizontal axis represents the sun shining time, and the vertical axis represents the number of E. coli. As you can see, the irradiance remained almost constant. Water with SODIS and photocatalyst appears to decrease the number of E. coli over time. What is important here is that the E. coli in the water containing the photocatalyst was getting down quickly. In terms of efficiency, the sterilizing power of water with a photocatalyst is much higher than SODIS. This method suggests that the photocatalytic process is an excellent complement to SODIS in rural areas with many unfavorable conditions.
In the future
This economical and efficient methods do help millions of people receive access to clean water and avoid many diseases due to drinking dirty water.
Although there are some weaknesses like the time of cleaning, solar conditions and so on, could be improved in the using of photocatalyst in solar disinfect. the solar disinfection is still the first choice in many rural areas. Appears to decrease the number of E. coli over time.
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In the future, it would be better that we decrease the time and the cost of using SODIS. In addition, the more important thing is that the public should improve the awareness of drinking clean water and the government should invest the infrastructure in rural areas. Only relying on the distinct efforts, we made, more available accesses to clean water for public in rural areas, can the drinking water issue be solved. Finally, all of us wish the better future is coming soon!
SDG6. CLEAN WATER AND SANITAION / GROUP 3
19. SEP. 2022
REFERENCE Conroy, R. M., Meegan, M. E., Joyce, T., McGuigan, K., & Barnes, J. (1999). Solar disinfection of water reduces diarrhoeal disease: an update. Archives of disease in childhood, 81(4), 337-338. Acra, A., Raffoul, Z., & Karahagopian, Y. (1984). Solar disinfection of drinking water and oral rehydration solutions. Rose, A., Roy, S., Abraham, V., Holmgren, G., George, K., Balraj, V., ... & Kang, G. (2006). Solar disinfection of water for diarrhoeal prevention in southern India. Archives of disease in childhood, 91(2), 139-141. McGuigan, K. G., Joyce, T. M., & Conroy, R. M. (1999). Solar disinfection: use of sunlight to decontaminate drinking water in developing countries. Journal of Medical Microbiology, 48(9), 785-787. Conroy, R. M., Elmore-Meegan, M., Joyce, T., McGuigan, K. G., & Barnes, J. (1996). Solar disinfection of drinking water and diarrhoea in Maasai children: a controlled field trial. The Lancet, 348(9043), 1695-1697. Oates, P. M., Shanahan, P., & Polz, M. F. (2003). Solar disinfection (SODIS): simulation of solar radiation for global assessment and application for point-of-use water treatment in Haiti. Water research, 37(1), 4754. Chaúque, B. J. M., & Rott, M. B. (2021). Solar disinfection (SODIS) technologies as alternative for largescale public drinking water supply: Advances and challenges. Chemosphere, 281, 130754. Porley, V., Chatzisymeon, E., Meikap, B. C., Ghosal, S., & Robertson, N. (2020). Field testing of low-cost titania-based photocatalysts for enhanced solar disinfection (SODIS) in rural India. Environmental Science: Water Research & Technology, 6(3), 809-816. Conroy, R. M., Meegan, M. E., Joyce, T., McGuigan, K., & Barnes, J. (1999). Solar disinfection of water reduces diarrhoeal disease: an update. Archives of disease in childhood, 81(4), 337-338. Acra, A., Raffoul, Z., & Karahagopian, Y. (1984). Solar disinfection of drinking water and oral rehydration solutions. Rose, A., Roy, S., Abraham, V., Holmgren, G., George, K., Balraj, V., ... & Kang, G. (2006). Solar disinfection of water for diarrhoeal prevention in southern India. Archives of disease in childhood, 91(2), 139-141. McGuigan, K. G., Joyce, T. M., & Conroy, R. M. (1999). Solar disinfection: use of sunlight to decontaminate drinking water in developing countries. Journal of Medical Microbiology, 48(9), 785-787. Conroy, R. M., Elmore-Meegan, M., Joyce, T., McGuigan, K. G., & Barnes, J. (1996). Solar disinfection of drinking water and diarrhoea in Maasai children: a controlled field trial. The Lancet, 348(9043), 1695-1697. Oates, P. M., Shanahan, P., & Polz, M. F. (2003). Solar disinfection (SODIS): simulation of solar radiation for global assessment and application for point-of-use water treatment in Haiti. Water research, 37(1), 4754. Chaúque, B. J. M., & Rott, M. B. (2021). Solar disinfection (SODIS) technologies as alternative for largescale public drinking water supply: Advances and challenges. Chemosphere, 281, 130754. Porley, V., Chatzisymeon, E., Meikap, B. C., Ghosal, S., & Robertson, N. (2020). Field testing of low-cost titania-based photocatalysts for enhanced solar disinfection (SODIS) in rural India. Environmental Science: Water Research & Technology, 6(3), 809-816
TEAM MEMBER LUKE YUAN KEMING ZHANG WEIWUA LI BONGSOO KIM
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