Support for technology[edit | edit source]

Support from the WHO[edit | edit source]

Sobsey, M. Managing Water in the Home: Accelerated Health Gains from Improved Water Supply. (Department of Protection of the Human Environment, World Health Organization. WHO/SDE/WSH/02.07: 2002)

  • Solar disinfection is an appropriate technology for disinfection of household water due to its simplicity, low cost, and need for only beverage bottles and sunlight.
  • UV radiation simple and highly effective for inactiviating microbes, and does not introduce harmful by-products or chemicals.
  • Exposing water to sunlight and heating to 55 C in transparent bottles for several hours has been shown to dramatically reduce bacteria as well as many viruses and parasites.
  • Allows water to be stored in the same container in which it has been treated, thereby reducing risk of recontamination.
  • "One of the technically simplest and most practical and economical [systems] is the SODIS system developed by scientists at the Swiss Federal Agency for Environmental Science and Technology (EAWAG). SODIS consists of: (1) removing solids from highly turbid (>30 ntu) water; (2) placing low turbidity (<30 ntu) water in clear plastic bottles of 1-2 litre volume; (3) aerating water by vigorous shaking in contact with air; and (4) exposing to full sunlight for about 5 hours (longer if only partial sunlight).
  • System is suitable for treating small volumes (<10 L) of water, particularly if low turbidity.
  • Polyethylene terephthalate (PET) bottles preferred to polyvinylchloride (PVC) as they are lightweight, less likely to leach harmful consitutents into water, chrmically stable, not likely to impart tastes or odors. Need to be replaced periodically as they can become scratched, and deformed if temperaturs >65 C.
  • Important that temperatures of 55 or higher, for several hours, is reached.
  • "One of the most promising and extensively tested methods for disinfection of household water stored in a container".
  • Field-tested in many different countries: South America (Columbia, Bolivia); Africa (Burkina Faso, Togo); Asia (China); Southeast Asia (Indonesia, Thailand).
  • Introduced and disseminated by governments and NGOs, subjected to economic analysis based on actual cost (estimated: 3 USD per year for household of 5).
  • Acceptance rate reported at >80% when accompanied by adequate educational, socio-cultural, and community involvement activities.

Bactericidal effect under real sunlight conditions[edit | edit source]

Boyle, M. et al. "Bactericidal effect of solar water disinfection under real sunlight conditions". Appl. Environ. Microbiol 74, 2997-3001 (2008).

Abstract:

Batch solar disinfection (SODIS) inactivation kinetics are reported for suspensions in water of Campylobacter jejuni, Yersinia enterocolitica, enteropathogenic Escherichia coli, Staphylococcus epidermidis, and endospores of Bacillus subtilis, exposed to strong natural sunlight in Spain and Bolivia. The exposure time required for complete inactivation (at least 4-log-unit reduction and below the limit of detection, 17 CFU/ml) under conditions of strong natural sunlight (maximum global irradiance, approximately 1,050 W m(-2) +/- 10 W m(-2)) was as follows: C. jejuni, 20 min; S. epidermidis, 45 min; enteropathogenic E. coli, 90 min; Y. enterocolitica, 150 min. Following incomplete inactivation of B. subtilis endospores after the first day, reexposure of these samples on the following day found that 4% (standard error, 3%) of the endospores remained viable after a cumulative exposure time of 16 h of strong natural sunlight. SODIS is shown to be effective against the vegetative cells of a number of emerging waterborne pathogens; however, bacterial species which are spore forming may survive this intervention process.

URL: http://www.ncbi.nlm.nih.gov/pubmed/18359829

Inactivation of fecal bacteria in drinking water by solar heating[edit | edit source]

Joyce, T., McGuigan, K., Elmo, M. & Conroy, R. "Inactivation of fecal bacteria in drinking water by solar heating". Applied and Environmental Microbiology 62, 399-402 (1996).

Abstract:

We report simulations of the thermal effect of strong equatorial sunshine on water samples contaminated with high populations of fecal coliforms. Water samples, heavily contaminated with a wild-type strain of Escherichia coli (starting population 􏰪 20 􏰩 105 CFU/ml), are heated to those temperatures recorded for 2-liter samples stored in transparent plastic bottles and exposed to full Kenyan sunshine (maximum water temperature, 55C). The samples are completely disinfected within 7 h, and no viable E. coli organisms are detected at either the end of the experiment or a further 12 h later, showing that no bacterial recovery has occurred. The feasibility of employing solar disinfection for highly turbid, fecally contaminated water is discussed.

URL: http://aem.asm.org.proxy.queensu.ca/cgi/content/abstract/62/2/399

Solar disinfection of poliovirus and cysts in water using simulated sunlight[edit | edit source]

Heaselgrave, W., Patel, N., Kilvington, S., Kehoe, S. & McGuigan, K. Solar disinfection of poliovirus and Acanthamoeba polyphaga cysts in water – a laboratory study using simulated sunlight. Lett Appl Microbiol 43, 125-130 (2006).

Abstract:

Aims: To determine the efficacy of solar disinfection (SODIS) in disinfecting water contaminated with poliovirus and Acanthamoeba polyphaga cysts. Methods and Results: Organisms were subjected to a simulated global solar irradiance of 850 Wm(-2) in water temperatures between 25 and 55 degrees C. SODIS at 25 degrees C totally inactivated poliovirus after 6-h exposure (reduction of 4.4 log units). No SODIS-induced reduction in A. polyphaga cyst viability was observed for sample temperatures below 45 degrees C. Total cyst inactivation was only observed after 6-h SODIS exposure at 50 degrees C (3.6 log unit reduction) and after 4 h at 55 degrees C (3.3 log unit reduction). Conclusions: SODIS is an effective means of disinfecting water contaminated with poliovirus and A. polyphaga cysts, provided water temperatures of 50-55 degrees C are attained in the latter case. Significance and Impact of the Study: This research presents the first SODIS inactivation curve for poliovirus and provides further evidence that batch SODIS provides effective protection against waterborne protozoan cysts.

Disinfection of drinking water contaminated with Cryptosporidium under natural sunlight[edit | edit source]

Méndez-Hermida, F. et al. "Disinfection of drinking water contaminated with Cryptosporidium parvum oocysts under natural sunlight and using the photocatalyst TiO2". J. Photochem. Photobiol. B, Biol 88, 105-111 (2007).

Abstract:

The results of a batch-process solar disinfection (SODIS) and solar photocatalytic disinfection (SPCDIS) on drinking water contaminated with Cryptosporidium are reported. Cryptosporidium parvum oocyst suspensions were exposed to natural sunlight in Southern Spain and the oocyst viability was evaluated using two vital dyes [4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI)]. SODIS exposures (strong sunlight) of 8 and 12h reduced oocyst viability from 98% (+/-1.3%) to 11.7% (+/-0.9%) and 0.3% (+/-0.33%), respectively. SODIS reactors fitted with flexible plastic inserts coated with TiO2 powder (SPCDIS) were found to be more effective than those which were not. After 8 and 16 h of overcast and cloudy solar irradiance conditions, SPCDIS reduced oocyst viability from 98.3% (+/-0.3%) to 37.7% (+/-2.6%) and 11.7% (+/-0.7%), respectively, versus to that achieved using SODIS of 81.3% (+/-1.6%) and 36.0% (+/-1.0%), respectively. These results confirm that solar disinfection of drinking water can be an effective household intervention against Cryptosporidium contamination.

URL: http://www.ncbi.nlm.nih.gov/pubmed/17624798

Efficacy of SODIS in turbid waters under real field conditions[edit | edit source]

Gómez-Couso, H., Fontán-Saínz, M., Sichel, C., Fernández-Ibáñez, P. & Ares-Mazás, E. "Efficacy of the solar water disinfection method in turbid waters experimentally contaminated with Cryptosporidium parvum oocysts under real field conditions". Trop. Med. Int. Health 14, 620-627 (2009).

Abstract:

OBJECTIVE: To investigate the efficacy of the solar water disinfection (SODIS) method for inactivating Cryptosporidium parvum oocysts in turbid waters using 1.5 l polyethylene terephthalate (PET) bottles under natural sunlight. METHODS: All experiments were performed at the Plataforma Solar de Almería, located in the Tabernas Desert (Southern Spain) in July and October 2007. Turbid water samples [5, 100 and 300 nephelometric turbidity units (NTU)] were prepared by addition of red soil to distilled water, and then spiked with purified C. parvum oocysts. PET bottles containing the contaminated turbid waters were exposed to full sunlight for 4, 8 and 12 h. The samples were then concentrated by filtration and the oocyst viability was determined by inclusion/exclusion of the fluorogenic vital dye propidium iodide. Results After an exposure time of 12 h (cumulative global dose of 28.28 MJ/m(2); cumulative UV dose of 1037.06 kJ/m(2)) the oocyst viabilities were 11.54%, 25.96%, 41.50% and 52.80% for turbidity levels of 0, 5, 100 and 300 NTU, respectively, being significantly lower than the viability of the initial isolate (P < 0.01). CONCLUSIONS: SODIS method significantly reduced the potential viability of C. parvum oocysts on increasing the percentage of oocysts that took up the dye PI (indicator of cell wall integrity), although longer exposure periods appear to be required than those established for the bacterial pathogens usually tested in SODIS assays.

URL: http://www.ncbi.nlm.nih.gov/pubmed/19570059

Effect of SODIS on model microorganisms under improved and field SODIS conditions[edit | edit source]

Dejung, S. et al. "Effect of solar water disinfection (SODIS) on model microorganisms under improved and field SODIS conditions". Journal of Water Supply: Research and Technology—AQUA 56, 245 (2007).

Abstract:

SODIS is a solar water disinfection process which works by exposing untreated water to the sun in plastic bottles. Field experiments were carried out in Cochabamba, Bolivia, to obtain standard UV-A (320–405 nm) dose values required to inactivate non-spore forming bacteria, spores of Bacillus subtilis, and wild type coliphages. Inactivation kinetics for non-spore forming bacteria are similar under SODIS conditions, exhibiting dose values ranging between 15 and 30 Wh m-2 for 1 log10 (90%) inactivation, 45 to 90 Wh m-2 for 3 log10 (99.9%), and 90 to 180 Wh m-2 for 6 log10 (99.9999%) inactivation. Pseudomonas aeruginosa was found to be the most resistant and Salmonella typhi, the most sensitive of the non-sporulating organisms studied here. Phages and spores serve as model organisms for viruses and parasite cysts. A UV-A dose of 85 to 210 Wh m-2 accumulated during one to two days was enough to inactivate 1 log10 (90%) of these strong biological structures. The process of SODIS depended mainly on the radiation dose [Wh m-2] an organism was exposed to. An irradiation intensity exceeding some 12 Wm-2 did not increase the inactivation constant. A synergistic effect of water temperatures below 50°C was not observed. Data plotting from various experiments on a single graph proved to be a reliable alternative method for analysis. Inactivation rates determined by this method were revealed to be within the same range as individual analysis.

URL: http://web.archive.org/web/20140407031058/http://www.iwaponline.com/jws/056/jws0560245.htm

SODIS and diarrhoea in Maasai children - controlled field trail[edit | edit source]

Conroy, R.M., Elmore-Meegan, M., Joyce, T., McGuigan, K.G. & Barnes, J. "Solar disinfection of drinking water and diarrhoea in Maasai children: a controlled field trial". Lancet 348, 1695-1697 (1996).

Abstract:

BACKGROUND: Solar radiation reduces the bacterial content of water, and may therefore offer a method for disinfection of drinking water that requires few resources and no expertise. METHODS: We distributed plastic water bottles to 206 Maasai children aged 5-16 years whose drinking water was contaminated with faecal coliform bacteria. Children were instructed to fill the bottle with water and leave it in full sunlight on the roof of the hut (solar group), or to keep their filled bottles indoors in the shade (control group). A Maasai-speaking fieldworker who lived in the community interviewed the mother of each child once every 2 weeks for 12 weeks. Occurrence and severity of diarrhoea was recorded at each follow-up visit. FINDINGS: Among the 108 children in households allocated solar treatment, diarrhoea was reported in 439 of the 2-week reporting periods during the 12-week trial (average 4.1 [SD 1.2] per child). By comparison, the 98 children in the control households reported diarrhoea during 444 2-week reporting periods (average 4.5 [1.2] per child). Diarrhoea severe enough to prevent performance of duties occurred during 186 reporting periods in the solar group and during 222 periods in the control group (average 1.7 [1.2] vs 2.3 [1.4]). After adjustment for age, solar treatment of drinking water was associated with a reduction in all diarrhoea episodes (odds ratio 0.66 [0.50-0.87]) and in episodes of severe diarrhoea (0.65 [0.50-0.86]). INTERPRETATION: Our findings suggest that solar disinfection of water may significantly reduce morbidity in communities with no other means of disinfection of drinking water, because of lack of resources or in the event of a disaster.

PIP: During December 1995-March 1996 in Kajiado Province, Kenya, 206 Maasai children, 5-16 years old, whose drinking water was contaminated with fecal coliform bacteria, were assigned 1.5 liter plastic bottles in which to store their drinking water. These bottles were re-used commercial table water bottles. The families of the children had only community sources for drinking water: 2 open water-holes and 1 tank fed from a piped supply. These water sources were not suited to chlorination. Scarce fuel and indoor air pollution precluded boiling water inside the hut. In the presence of their mothers, 108 children (the solar group) were told to fill the bottles with water at dawn, leave them in full sunlight on the roofs of their homes, and wait until midday before drinking from the bottles. The remaining 98 children (the control group) were told to leave the bottles in their homes. The purpose of the study was to evaluate the effect of solar disinfection on diarrheal disease in these Maasai children. Over a 12-week period, children in the solar group suffered fewer diarrhea episodes than those in the control group (4.1 vs. 4.5; adjusted odds ratio [AOR] = 0.66). They also were less likely to have diarrhea episodes severe enough to prevent them from doing their chores (1.7 vs. 2.3; AOR = 0.65). These findings suggest that solar disinfection of water may reduce diarrhea in communities with no access to other means of disinfection.

URL: http://www.ncbi.nlm.nih.gov/pubmed/8973432

NOTES:

  • Question raised: is 4.1 vs. 4.5 (adjusted odds ratio, AOR of 0.66) significant?

SODIS protects against cholera in children under 6 years of age[edit | edit source]

Conroy, R.M., Meegan, M.E., Joyce, T., McGuigan, K. & Barnes, J. "Solar disinfection of drinking water protects against cholera in children under 6 years of age". Arch. Dis. Child 85, 293-295 (2001).

Abstract:

BACKGROUND AND AIMS: We have previously reported a reduction in risk of diarrhoeal disease in children who used solar disinfected drinking water. A cholera epidemic, occurring in an area of Kenya in which a controlled trial of solar disinfection and diarrhoeal disease in children aged under 6 had recently finished, offered an opportunity to examine the protection offered by solar disinfection against cholera. METHODS: In the original trial, all children aged under 6 in a Maasai community were randomised by household: in the solar disinfection arm, children drank water disinfected by leaving it on the roof in a clear plastic bottle, while controls drank water kept indoors. We revisited all households which had participated in the original trial. RESULTS: There were 131 households in the trial area, of which 67 had been randomised to solar disinfection (a further 19 households had migrated as a result of severe drought). There was no significant difference in the risk of cholera in adults or in older children in households randomised to solar disinfection; however, there were only three cases of cholera in the 155 children aged under 6 years drinking solar disinfected water compared with 20 of 144 controls. CONCLUSIONS: Results confirm the usefulness of solar disinfection in reducing risk of water borne disease in children. Point of consumption solar disinfection can be done with minimal resources, which are readily available, and may be an important first line response to cholera outbreaks. Its potential in chorine resistant cholera merits further investigation.

URL: http://www.ncbi.nlm.nih.gov/pubmed/11567937

SODIS for diarrhoeal prevention in southern India[edit | edit source]

Rose, A. et al. "Solar disinfection of water for diarrhoeal prevention in southern India". Arch. Dis. Child 91, 139-141 (2006).

Abstract:

AIMS: To evaluate the efficacy and acceptability of solar irradiation in the prevention of diarrhoeal morbidity in children under 5 years of age, in an urban slum in Vellore, Tamil Nadu. METHODS: A total of 100 children were assigned to receive drinking water that had been subjected to solar disinfection in polyethylene terephthalate bottles. One hundred age and sex matched controls were also selected. Both groups were followed by weekly home visits for a period of six months for any diarrhoeal morbidity. At the end of the follow up period, the acceptability of the intervention was assessed by interviews, questionnaires, and focus group discussions. RESULTS: There was significant reduction in the incidence, duration, and severity of diarrhoea in children receiving solar disinfected water, despite 86% of the children drinking water other than that treated by the intervention. The incidence of diarrhoea in the intervention group was 1.7 per child-year, and among controls 2.7 per child-year, with an incidence rate ratio of 0.64 (95% CI -0.48 to 0.86). The risk of diarrhoea was reduced by 40% by using solar disinfection. In qualitative evaluation of acceptability, most women felt that solar disinfection was a feasible and sustainable method of disinfecting water. CONCLUSIONS: Solar disinfection of water is an inexpensive, effective, and acceptable method of increasing water safety in a resource limited environment, and can significantly decrease diarrhoeal morbidity in children.

URL: http://www.ncbi.nlm.nih.gov/pubmed/16403847

NOTES:

  • Good support for application of SODIS as prevention of diarrhea in children.

SODIS improves drinking water quality to prevent diarrhea in children under five[edit | edit source]

Rai, B., Pal, R., Kar, S. & Tsering, D.C. "Solar disinfection improves drinking water quality to prevent diarrhea in under-five children in sikkim, India". J Glob Infect Dis 2, 221-225 (2010).

Abstract:

BACKGROUND: Solar radiations improve the microbiological quality of water and offer a method for disinfection of drinking water that requires few resources and no expertise and may reduce the prevalence of diarrhea among under-five children. AIMS AND OBJECTIVES: To find out the reduction in the prevalence of diarrhea in the under-five children after consumption of potable water treated with solar disinfection method. MATERIALS AND METHODS: This was a population-based interventional prospective study in the urban slum area of Mazegoan, Jorethang, south Sikkim, during the period 1(st) May 2007 to 30(th) November 2007 on 136 children in the under-five age group in 102 households selected by random sampling. Main outcome measure was the assessment of the reduction of the prevalence of diarrhea among under-five children after consumption of potable water treated with solar disinfection method practiced by the caregivers in the intervention group keeping water in polyethylene terephthalate (PET) bottles as directed by the investigators. The data were collected by the interview method using a pre-tested questionnaire prepared on the basis of socio-demographics and prevalence of diarrhea. The data were subjected to percentages and chi-square tests, which were used to find the significance. RESULTS: After four weeks of intervention among the study group, the diarrhea prevalence was 7.69% among solar disinfection (SODIS) users, while 31.82% prevalence was observed among non-users in that period; the reduction in prevalence of diarrhea was 75.83%. After eight weeks of intervention, the prevalence of diarrhea was 7.58% among SODIS users and 31.43% among non-users; the reduction in diarrhea was 75.88% in the study group. The findings were found to be statistically significant. CONCLUSIONS: In our study, we observed that the prevalence of diarrhea decreased significantly after solar disinfection of water was practiced by the caregivers keeping potable water in PET bottles in the intervention group.

URL: http://www.ncbi.nlm.nih.gov/pubmed/20927281

Health gains from SODIS: evaluation of intervention on Cameroon[edit | edit source]

Graf, J. et al. "Health gains from solar water disinfection (SODIS): evaluation of a water quality intervention in Yaoundé, Cameroon". J Water Health 8, 779-796 (2010).

Abstract:

In developing countries, the burden of diarrhoea is still enormous. One way to reduce transmission of pathogens is by water quality interventions. Solar water disinfection (SODIS) is a low-cost and simple method to improve drinking water quality on household level. This paper evaluates the implementation of SODIS in slum areas of Yaoundé, Cameroon. Promoters trained 2,911 households in the use of SODIS. Two surveys with randomly selected households were conducted before (N = 2,193) and after (N = 783) the intervention. Using a questionnaire, interviewers collected information on the health status of children under five, on liquid consumption, hygiene and other issues. Prior to the intervention, diarrhoea prevalence amounted to 34.3% among children. After the intervention, it remained stable in the control group (31.8%) but dropped to 22.8% in the intervention group. Households fully complying with the intervention exhibited even less diarrhoea prevalence (18.3%) and diarrhoea risk could be reduced by 42.5%. Multivariate analyses revealed that the intervention effects are also observed when other diarrhoea risk factors, such as hygiene and cleanliness of household surroundings, are considered. According to the data, adoption of the method was associated with marital status. Findings suggest health benefits from SODIS use. Further promotional activities in low-income settings are recommended.

URL: http://www.ncbi.nlm.nih.gov/pubmed/20705988

Establishing SODIS at household level[edit | edit source]

Meierhofer, R. "Establishing solar water disinfection as a water treatment at household level". Madagascar Conservation & Development 1, 25-30 (2006).

Abstract:

  1. 1 billion People worldwide do not have access to safe drinking water and therefore are exposed to a high risk for diarrhoeal diseases. As a consequence, about 6,000 children die each day of dehydration due to diarrhoea. Adequate water treatment methods and safe storage of drinking water, combined with hygiene promotion, are required to prevent the population without access to safe drinking water from illness and death. Solar water disinfection (SODIS) is a new water treatment to be applied at household level with a great potential to reduce diarrhoea incidence of users. The method is very simple and the only resources required for its application are transparent PET plastic bottles (or glass bottles) and sufficient sunlight: microbiologically contaminated water is filled into the bottles and exposed to the full sunlight for 6 hours. During solar exposure, the diarrhoea causing pathogens are killed by the UV-A radiation of the sunlight. At present, SODIS is used by about 2 Million users in more than 20 countries of the South. Diarrhoea incidence of users significantly has been reduced by 30 to 70 %. A careful and long-term community education process that involves creating awareness on the importance of treating drinking water and initiates behaviour change is required to establish the sustainable practice of SODIS at community level. In Madagascar, more than 160 children younger than 5 years die each day from malaria, diarrhoea and acute respiratory illnesses. The application of household water treatment methods such as SODIS significantly could contribute to improve their health.

NOTES:

  • Good general overview of need for clean water, SODIS method, supporting studies, application. Good source of related articles.

URL: www.mwc-info.net/en/services/Journal_PDF's/Issue1/Sodis.pdf

Factors supporting the sustained use of SODIS[edit | edit source]

Meierhofer, R. & Landolt, G. "Factors supporting the sustained use of solar water disinfection — Experiences from a global promotion and dissemination programme". Desalination 248, 144-151 (2009).

Abstract:

Every year, 1.8 million people, mainly children under the age of five, die of diarrhoea. Point-of-use water treatment methods, such as solar water disinfection (SODIS), reveal a great potential to reduce the global diarrhoea burden. Comprehensive micro- biological research demonstrated the effectiveness of SODIS to destroy diarrhoea-causing pathogens in contaminated drinking water. Since the year 2000, SODIS is being promoted in developing countries through information and awareness campaigns, training and advising of the public sector (government institutions), networking activities, as well as user training at the grassroot level. The method is currently used in 33 countries by more than 2 million people. Several project evaluations and health impact studies reveal that the diarrhoea incidence of SODIS users has dropped by 16–57%. One year after project implementation, 20– 80% of the trained people used SODIS on a regular basis. This paper looks into factors influencing acceptance and sustained use of SODIS on grassroot level, i.e. local availability of bottles, repeated promotion and training programmes, motivation and commit- ment of promoters, educational level of users, social pressure, and institutional aspects.

URL: http://linkinghub.elsevier.com/retrieve/pii/S0011916409005797

Solar disinfection of poliovirus and cysts in water using simulated sunlight[edit | edit source]

Heaselgrave, W., Patel, N., Kilvington, S., Kehoe, S. & McGuigan, K. Solar disinfection of poliovirus and Acanthamoeba polyphaga cysts in water – a laboratory study using simulated sunlight. Letters in Applied Microbioly 43, 125-130 (2006).

Disinfection of drinking water contaminated with Cryptosporidium under natural sunlight[edit | edit source]

Méndez-Hermida, F. et al. "Disinfection of drinking water contaminated with Cryptosporidium parvum oocysts under natural sunlight and using the photocatalyst TiO2". J. Photochem. Photobiol. B, Biol 88, 105-111 (2007).

Abstract:

The results of a batch-process solar disinfection (SODIS) and solar photocatalytic disinfection (SPCDIS) on drinking water contaminated with Cryptosporidium are reported. Cryptosporidium parvum oocyst suspensions were exposed to natural sunlight in Southern Spain and the oocyst viability was evaluated using two vital dyes [4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI)]. SODIS exposures (strong sunlight) of 8 and 12h reduced oocyst viability from 98% (+/-1.3%) to 11.7% (+/-0.9%) and 0.3% (+/-0.33%), respectively. SODIS reactors fitted with flexible plastic inserts coated with TiO2 powder (SPCDIS) were found to be more effective than those which were not. After 8 and 16 h of overcast and cloudy solar irradiance conditions, SPCDIS reduced oocyst viability from 98.3% (+/-0.3%) to 37.7% (+/-2.6%) and 11.7% (+/-0.7%), respectively, versus to that achieved using SODIS of 81.3% (+/-1.6%) and 36.0% (+/-1.0%), respectively. These results confirm that solar disinfection of drinking water can be an effective household intervention against Cryptosporidium contamination.

URL: http://www.ncbi.nlm.nih.gov/pubmed/17624798

Efficacy of SODIS in turbid waters under real field conditions[edit | edit source]

Gómez-Couso, H., Fontán-Saínz, M., Sichel, C., Fernández-Ibáñez, P. & Ares-Mazás, E. "Efficacy of the solar water disinfection method in turbid waters experimentally contaminated with Cryptosporidium parvum oocysts under real field conditions". Trop. Med. Int. Health 14, 620-627 (2009).

Abstract:

OBJECTIVE: To investigate the efficacy of the solar water disinfection (SODIS) method for inactivating Cryptosporidium parvum oocysts in turbid waters using 1.5 l polyethylene terephthalate (PET) bottles under natural sunlight. METHODS: All experiments were performed at the Plataforma Solar de Almería, located in the Tabernas Desert (Southern Spain) in July and October 2007. Turbid water samples [5, 100 and 300 nephelometric turbidity units (NTU)] were prepared by addition of red soil to distilled water, and then spiked with purified C. parvum oocysts. PET bottles containing the contaminated turbid waters were exposed to full sunlight for 4, 8 and 12 h. The samples were then concentrated by filtration and the oocyst viability was determined by inclusion/exclusion of the fluorogenic vital dye propidium iodide. Results After an exposure time of 12 h (cumulative global dose of 28.28 MJ/m(2); cumulative UV dose of 1037.06 kJ/m(2)) the oocyst viabilities were 11.54%, 25.96%, 41.50% and 52.80% for turbidity levels of 0, 5, 100 and 300 NTU, respectively, being significantly lower than the viability of the initial isolate (P < 0.01). CONCLUSIONS: SODIS method significantly reduced the potential viability of C. parvum oocysts on increasing the percentage of oocysts that took up the dye PI (indicator of cell wall integrity), although longer exposure periods appear to be required than those established for the bacterial pathogens usually tested in SODIS assays.

URL: http://www.ncbi.nlm.nih.gov/pubmed/19570059

Effect of SODIS on model microorganisms under improved and field SODIS conditions[edit | edit source]

Dejung, S. et al. "Effect of solar water disinfection (SODIS) on model microorganisms under improved and field SODIS conditions". Journal of Water Supply: Research and Technology—AQUA 56, 245 (2007).

Abstract:

SODIS is a solar water disinfection process which works by exposing untreated water to the sun in plastic bottles. Field experiments were carried out in Cochabamba, Bolivia, to obtain standard UV-A (320–405 nm) dose values required to inactivate non-spore forming bacteria, spores of Bacillus subtilis, and wild type coliphages. Inactivation kinetics for non-spore forming bacteria are similar under SODIS conditions, exhibiting dose values ranging between 15 and 30 Wh m-2 for 1 log10 (90%) inactivation, 45 to 90 Wh m-2 for 3 log10 (99.9%), and 90 to 180 Wh m-2 for 6 log10 (99.9999%) inactivation. Pseudomonas aeruginosa was found to be the most resistant and Salmonella typhi, the most sensitive of the non-sporulating organisms studied here. Phages and spores serve as model organisms for viruses and parasite cysts. A UV-A dose of 85 to 210 Wh m-2 accumulated during one to two days was enough to inactivate 1 log10 (90%) of these strong biological structures. The process of SODIS depended mainly on the radiation dose [Wh m-2] an organism was exposed to. An irradiation intensity exceeding some 12 Wm-2 did not increase the inactivation constant. A synergistic effect of water temperatures below 50°C was not observed. Data plotting from various experiments on a single graph proved to be a reliable alternative method for analysis. Inactivation rates determined by this method were revealed to be within the same range as individual analysis.

URL: http://web.archive.org/web/20140407031058/http://www.iwaponline.com/jws/056/jws0560245.htm

SODIS and diarrhoea in Maasai children - controlled field trail[edit | edit source]

Conroy, R.M., Elmore-Meegan, M., Joyce, T., McGuigan, K.G. & Barnes, J. "Solar disinfection of drinking water and diarrhoea in Maasai children: a controlled field trial". Lancet 348, 1695-1697 (1996).

Abstract:

BACKGROUND: Solar radiation reduces the bacterial content of water, and may therefore offer a method for disinfection of drinking water that requires few resources and no expertise. METHODS: We distributed plastic water bottles to 206 Maasai children aged 5-16 years whose drinking water was contaminated with faecal coliform bacteria. Children were instructed to fill the bottle with water and leave it in full sunlight on the roof of the hut (solar group), or to keep their filled bottles indoors in the shade (control group). A Maasai-speaking fieldworker who lived in the community interviewed the mother of each child once every 2 weeks for 12 weeks. Occurrence and severity of diarrhoea was recorded at each follow-up visit. FINDINGS: Among the 108 children in households allocated solar treatment, diarrhoea was reported in 439 of the 2-week reporting periods during the 12-week trial (average 4.1 [SD 1.2] per child). By comparison, the 98 children in the control households reported diarrhoea during 444 2-week reporting periods (average 4.5 [1.2] per child). Diarrhoea severe enough to prevent performance of duties occurred during 186 reporting periods in the solar group and during 222 periods in the control group (average 1.7 [1.2] vs 2.3 [1.4]). After adjustment for age, solar treatment of drinking water was associated with a reduction in all diarrhoea episodes (odds ratio 0.66 [0.50-0.87]) and in episodes of severe diarrhoea (0.65 [0.50-0.86]). INTERPRETATION: Our findings suggest that solar disinfection of water may significantly reduce morbidity in communities with no other means of disinfection of drinking water, because of lack of resources or in the event of a disaster.

PIP: During December 1995-March 1996 in Kajiado Province, Kenya, 206 Maasai children, 5-16 years old, whose drinking water was contaminated with fecal coliform bacteria, were assigned 1.5 liter plastic bottles in which to store their drinking water. These bottles were re-used commercial table water bottles. The families of the children had only community sources for drinking water: 2 open water-holes and 1 tank fed from a piped supply. These water sources were not suited to chlorination. Scarce fuel and indoor air pollution precluded boiling water inside the hut. In the presence of their mothers, 108 children (the solar group) were told to fill the bottles with water at dawn, leave them in full sunlight on the roofs of their homes, and wait until midday before drinking from the bottles. The remaining 98 children (the control group) were told to leave the bottles in their homes. The purpose of the study was to evaluate the effect of solar disinfection on diarrheal disease in these Maasai children. Over a 12-week period, children in the solar group suffered fewer diarrhea episodes than those in the control group (4.1 vs. 4.5; adjusted odds ratio [AOR] = 0.66). They also were less likely to have diarrhea episodes severe enough to prevent them from doing their chores (1.7 vs. 2.3; AOR = 0.65). These findings suggest that solar disinfection of water may reduce diarrhea in communities with no access to other means of disinfection.

URL: http://www.ncbi.nlm.nih.gov/pubmed/8973432

NOTES:

  • Question raised: is 4.1 vs. 4.5 (adjusted odds ratio, AOR of 0.66) significant?

SODIS protects against cholera in children under 6 years of age[edit | edit source]

Conroy, R.M., Meegan, M.E., Joyce, T., McGuigan, K. & Barnes, J. "Solar disinfection of drinking water protects against cholera in children under 6 years of age". Arch. Dis. Child 85, 293-295 (2001).

Abstract:

BACKGROUND AND AIMS: We have previously reported a reduction in risk of diarrhoeal disease in children who used solar disinfected drinking water. A cholera epidemic, occurring in an area of Kenya in which a controlled trial of solar disinfection and diarrhoeal disease in children aged under 6 had recently finished, offered an opportunity to examine the protection offered by solar disinfection against cholera. METHODS: In the original trial, all children aged under 6 in a Maasai community were randomised by household: in the solar disinfection arm, children drank water disinfected by leaving it on the roof in a clear plastic bottle, while controls drank water kept indoors. We revisited all households which had participated in the original trial. RESULTS: There were 131 households in the trial area, of which 67 had been randomised to solar disinfection (a further 19 households had migrated as a result of severe drought). There was no significant difference in the risk of cholera in adults or in older children in households randomised to solar disinfection; however, there were only three cases of cholera in the 155 children aged under 6 years drinking solar disinfected water compared with 20 of 144 controls. CONCLUSIONS: Results confirm the usefulness of solar disinfection in reducing risk of water borne disease in children. Point of consumption solar disinfection can be done with minimal resources, which are readily available, and may be an important first line response to cholera outbreaks. Its potential in chorine resistant cholera merits further investigation.

URL: http://www.ncbi.nlm.nih.gov/pubmed/11567937

SODIS for diarrhoeal prevention in southern India[edit | edit source]

Rose, A. et al. "Solar disinfection of water for diarrhoeal prevention in southern India". Arch. Dis. Child 91, 139-141 (2006).

Abstract:

AIMS: To evaluate the efficacy and acceptability of solar irradiation in the prevention of diarrhoeal morbidity in children under 5 years of age, in an urban slum in Vellore, Tamil Nadu. METHODS: A total of 100 children were assigned to receive drinking water that had been subjected to solar disinfection in polyethylene terephthalate bottles. One hundred age and sex matched controls were also selected. Both groups were followed by weekly home visits for a period of six months for any diarrhoeal morbidity. At the end of the follow up period, the acceptability of the intervention was assessed by interviews, questionnaires, and focus group discussions. RESULTS: There was significant reduction in the incidence, duration, and severity of diarrhoea in children receiving solar disinfected water, despite 86% of the children drinking water other than that treated by the intervention. The incidence of diarrhoea in the intervention group was 1.7 per child-year, and among controls 2.7 per child-year, with an incidence rate ratio of 0.64 (95% CI -0.48 to 0.86). The risk of diarrhoea was reduced by 40% by using solar disinfection. In qualitative evaluation of acceptability, most women felt that solar disinfection was a feasible and sustainable method of disinfecting water. CONCLUSIONS: Solar disinfection of water is an inexpensive, effective, and acceptable method of increasing water safety in a resource limited environment, and can significantly decrease diarrhoeal morbidity in children.

URL: http://www.ncbi.nlm.nih.gov/pubmed/16403847

NOTES:

  • Good support for application of SODIS as prevention of diarrhea in children.

SODIS improves drinking water quality to prevent diarrhea in children under five[edit | edit source]

Rai, B., Pal, R., Kar, S. & Tsering, D.C. "Solar disinfection improves drinking water quality to prevent diarrhea in under-five children in sikkim, India". J Glob Infect Dis 2, 221-225 (2010).

Abstract:

BACKGROUND: Solar radiations improve the microbiological quality of water and offer a method for disinfection of drinking water that requires few resources and no expertise and may reduce the prevalence of diarrhea among under-five children. AIMS AND OBJECTIVES: To find out the reduction in the prevalence of diarrhea in the under-five children after consumption of potable water treated with solar disinfection method. MATERIALS AND METHODS: This was a population-based interventional prospective study in the urban slum area of Mazegoan, Jorethang, south Sikkim, during the period 1(st) May 2007 to 30(th) November 2007 on 136 children in the under-five age group in 102 households selected by random sampling. Main outcome measure was the assessment of the reduction of the prevalence of diarrhea among under-five children after consumption of potable water treated with solar disinfection method practiced by the caregivers in the intervention group keeping water in polyethylene terephthalate (PET) bottles as directed by the investigators. The data were collected by the interview method using a pre-tested questionnaire prepared on the basis of socio-demographics and prevalence of diarrhea. The data were subjected to percentages and chi-square tests, which were used to find the significance. RESULTS: After four weeks of intervention among the study group, the diarrhea prevalence was 7.69% among solar disinfection (SODIS) users, while 31.82% prevalence was observed among non-users in that period; the reduction in prevalence of diarrhea was 75.83%. After eight weeks of intervention, the prevalence of diarrhea was 7.58% among SODIS users and 31.43% among non-users; the reduction in diarrhea was 75.88% in the study group. The findings were found to be statistically significant. CONCLUSIONS: In our study, we observed that the prevalence of diarrhea decreased significantly after solar disinfection of water was practiced by the caregivers keeping potable water in PET bottles in the intervention group.

URL: http://www.ncbi.nlm.nih.gov/pubmed/20927281

Health gains from SODIS: evaluation of intervention on Cameroon[edit | edit source]

Graf, J. et al. "Health gains from solar water disinfection (SODIS): evaluation of a water quality intervention in Yaoundé, Cameroon". J Water Health 8, 779-796 (2010).

Abstract:

In developing countries, the burden of diarrhoea is still enormous. One way to reduce transmission of pathogens is by water quality interventions. Solar water disinfection (SODIS) is a low-cost and simple method to improve drinking water quality on household level. This paper evaluates the implementation of SODIS in slum areas of Yaoundé, Cameroon. Promoters trained 2,911 households in the use of SODIS. Two surveys with randomly selected households were conducted before (N = 2,193) and after (N = 783) the intervention. Using a questionnaire, interviewers collected information on the health status of children under five, on liquid consumption, hygiene and other issues. Prior to the intervention, diarrhoea prevalence amounted to 34.3% among children. After the intervention, it remained stable in the control group (31.8%) but dropped to 22.8% in the intervention group. Households fully complying with the intervention exhibited even less diarrhoea prevalence (18.3%) and diarrhoea risk could be reduced by 42.5%. Multivariate analyses revealed that the intervention effects are also observed when other diarrhoea risk factors, such as hygiene and cleanliness of household surroundings, are considered. According to the data, adoption of the method was associated with marital status. Findings suggest health benefits from SODIS use. Further promotional activities in low-income settings are recommended.

URL: http://www.ncbi.nlm.nih.gov/pubmed/20705988

Establishing SODIS at household level[edit | edit source]

Meierhofer, R. "Establishing solar water disinfection as a water treatment at household level". Madagascar Conservation & Development 1, 25-30 (2006).

Abstract:

  1. 1 billion People worldwide do not have access to safe drinking water and therefore are exposed to a high risk for diarrhoeal diseases. As a consequence, about 6,000 children die each day of dehydration due to diarrhoea. Adequate water treatment methods and safe storage of drinking water, combined with hygiene promotion, are required to prevent the population without access to safe drinking water from illness and death. Solar water disinfection (SODIS) is a new water treatment to be applied at household level with a great potential to reduce diarrhoea incidence of users. The method is very simple and the only resources required for its application are transparent PET plastic bottles (or glass bottles) and sufficient sunlight: microbiologically contaminated water is filled into the bottles and exposed to the full sunlight for 6 hours. During solar exposure, the diarrhoea causing pathogens are killed by the UV-A radiation of the sunlight. At present, SODIS is used by about 2 Million users in more than 20 countries of the South. Diarrhoea incidence of users significantly has been reduced by 30 to 70 %. A careful and long-term community education process that involves creating awareness on the importance of treating drinking water and initiates behaviour change is required to establish the sustainable practice of SODIS at community level. In Madagascar, more than 160 children younger than 5 years die each day from malaria, diarrhoea and acute respiratory illnesses. The application of household water treatment methods such as SODIS significantly could contribute to improve their health.

NOTES:

  • Good general overview of need for clean water, SODIS method, supporting studies, application. Good source of related articles.

URL: www.mwc-info.net/en/services/Journal_PDF's/Issue1/Sodis.pdf

Factors supporting the sustained use of SODIS[edit | edit source]

Meierhofer, R. & Landolt, G. "Factors supporting the sustained use of solar water disinfection — Experiences from a global promotion and dissemination programme". Desalination 248, 144-151 (2009).

Abstract:

Every year, 1.8 million people, mainly children under the age of five, die of diarrhoea. Point-of-use water treatment methods, such as solar water disinfection (SODIS), reveal a great potential to reduce the global diarrhoea burden. Comprehensive micro- biological research demonstrated the effectiveness of SODIS to destroy diarrhoea-causing pathogens in contaminated drinking water. Since the year 2000, SODIS is being promoted in developing countries through information and awareness campaigns, training and advising of the public sector (government institutions), networking activities, as well as user training at the grassroot level. The method is currently used in 33 countries by more than 2 million people. Several project evaluations and health impact studies reveal that the diarrhoea incidence of SODIS users has dropped by 16–57%. One year after project implementation, 20– 80% of the trained people used SODIS on a regular basis. This paper looks into factors influencing acceptance and sustained use of SODIS on grassroot level, i.e. local availability of bottles, repeated promotion and training programmes, motivation and commit- ment of promoters, educational level of users, social pressure, and institutional aspects.

URL: http://linkinghub.elsevier.com/retrieve/pii/S0011916409005797

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Authors Brittney Dawney
Published 2022
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