Impact of a natural coagulant pretreatment for colour removal on solar water disinfection (SODIS)

Solar water disinfection (SODIS) is the process of treating microbiologically contaminated water in clear plastic bottles through exposure to sunlight. One of the major limiting factors of this treatment is source water quality. This work investigates the impact of source water colour on SODIS efficiency and evaluates a natural coagulant for colour removal. The ability of Moringa oleifera seed emulsion to both clarify and decolourize source waters was investigated as a coagulation pretreatment for SODIS. This coagulant reduced the colour by more than two-thirds and achieved up to 1-log10 bacterial removal (90%). The combined Moringa oleifera coagulation-SODIS treatment sequence was tested in highly coloured natural source water and was found to reduce the sunlight exposure time required by up to 2 hours. However, despite being an effective clarification and decolouring process, the pretreatment may not shorten the overall treatment time because of its own labour and time requirements, potentially decreasing the treatment compliance rates. In addition, while total coliform and heterotrophic bacteria regrowth was observed during overnight storage of the treated water, no Escherichia coli regrowth was found to occur.

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Solar Water Disinfection to Produce Safe Drinking Water: A Review of Parameters, Enhancements, and Modelling Approaches to Make SODIS Faster and Safer

Molecules ◽

10.3390/molecules26113431 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3431

Author(s):

Ángela García-Gil ◽

Rafael A. García-Muñoz ◽

Kevin G. McGuigan ◽

Javier Marugán

Keyword(s):

Drinking Water ◽

Kinetic Models ◽

Critical Role ◽

Water Disinfection ◽

Safe Drinking Water ◽

Reactor Material ◽

Solar Water ◽

Solar Water Disinfection ◽

The Impact ◽

Modelling Approaches

Solar water disinfection (SODIS) is one the cheapest and most suitable treatments to produce safe drinking water at the household level in resource-poor settings. This review introduces the main parameters that influence the SODIS process and how new enhancements and modelling approaches can overcome some of the current drawbacks that limit its widespread adoption. Increasing the container volume can decrease the recontamination risk caused by handling several 2 L bottles. Using container materials other than polyethylene terephthalate (PET) significantly increases the efficiency of inactivation of viruses and protozoa. In addition, an overestimation of the solar exposure time is usually recommended since the process success is often influenced by many factors beyond the control of the SODIS-user. The development of accurate kinetic models is crucial for ensuring the production of safe drinking water. This work attempts to review the relevant knowledge about the impact of the SODIS variables and the techniques used to develop kinetic models described in the literature. In addition to the type and concentration of pathogens in the untreated water, an ideal kinetic model should consider all critical factors affecting the efficiency of the process, such as intensity, spectral distribution of the solar radiation, container-wall transmission spectra, ageing of the SODIS reactor material, and chemical composition of the water, since the substances in the water can play a critical role as radiation attenuators and/or sensitisers triggering the inactivation process.

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SODIS potential: A novel parameter to assess the suitability of solar water disinfection worldwide

Chemical Engineering Journal ◽

10.1016/j.cej.2021.129889 ◽

2021 ◽

Vol 419 ◽

pp. 129889

Author(s):

José Moreno-SanSegundo ◽

Stefanos Giannakis ◽

Sofia Samoili ◽

Giulio Farinelli ◽

Kevin G. McGuigan ◽

...

Keyword(s):

Water Disinfection ◽

Solar Water ◽

Solar Water Disinfection

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Solar water disinfection in high-volume containers: Are naturally occurring substances attenuating factors of radiation?

Chemical Engineering Journal ◽

10.1016/j.cej.2020.125852 ◽

2020 ◽

Vol 399 ◽

pp. 125852 ◽

Cited By ~ 2

Author(s):

Ángela García-Gil ◽

Rafael Valverde ◽

Rafael A. García-Muñoz ◽

Kevin G. McGuigan ◽

Javier Marugán

Keyword(s):

High Volume ◽

Water Disinfection ◽

Solar Water ◽

Naturally Occurring ◽

Solar Water Disinfection

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Excystation ofCryptosporidium parvumat temperatures that are reached during solar water disinfection

Parasitology ◽

10.1017/s0031182009005563 ◽

2009 ◽

Vol 136 (4) ◽

pp. 393-399 ◽

Cited By ~ 11

Author(s):

H. GÓMEZ-COUSO ◽

M. FONTÁN-SAINZ ◽

J. FERNÁNDEZ-ALONSO ◽

E. ARES-MAZÁS

Keyword(s):

Solar Radiation ◽

Cryptosporidium Parvum ◽

Gradual Increase ◽

Water Disinfection ◽

Waterborne Diseases ◽

Pathogenic Microorganisms ◽

Simple Method ◽

Solar Water ◽

Solar Water Disinfection ◽

Notable Increase

SUMMARYSpecies belonging to the generaCryptosporidiumare recognized as waterborne pathogens. Solar water disinfection (SODIS) is a simple method that involves the use of solar radiation to destroy pathogenic microorganisms that cause waterborne diseases. A notable increase in water temperature and the existence of a large number of empty or partially excysted (i.e. unviable) oocysts have been observed in previous SODIS studies with water experimentally contaminated withCryptosporidium parvumoocysts under field conditions. The aim of the present study was to evaluate the effect of the temperatures that can be reached during exposure of water samples to natural sunlight (37–50°C), on the excystation ofC. parvumin the absence of other stimuli. In samples exposed to 40–48°C, a gradual increase in the percentage of excystation was observed as the time of exposure increased and a maximum of 53·81% of excystation was obtained on exposure of the water to a temperature of 46°C for 12 h (versus8·80% initial isolate). Under such conditions, the oocyst infectivity evaluated in a neonatal murine model decreased statistically with respect to the initial isolate (19·38%versus100%). The results demonstrate the important effect of the temperature on the excystation ofC. parvumand therefore on its viability and infectivity.

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In vitro toxicity studies of novel solar water disinfection reactors using the E-screen bioassay and the Ames test

H2Open Journal ◽

10.2166/h2oj.2021.108 ◽

2021 ◽

Author(s):

Paloma Ozores Diez ◽

M. Inmaculada Polo-López ◽

Azahara Martínez-García ◽

Monique Waso ◽

Brandon Reyneke ◽

...

Keyword(s):

Ames Test ◽

Daily Intake ◽

Cost Effective ◽

Water Disinfection ◽

In Vitro Toxicity ◽

Toxic Substances ◽

Solar Water ◽

Point Of Use ◽

Solar Water Disinfection

Abstract Solar water disinfection (SODIS) is a cost-effective point of use method for disinfecting water, usually in a 2 L polyethylene terephthalate (PET) plastic bottle. To increase the volume of water disinfected, three novel transparent reactors were developed using PET in 25 L transparent jerrycans, polymethyl methacrylate (PMMA) in tubular solar reactors capable of delivering >20 L of water and polypropylene (PP) in 20 L buckets. In vitro bioassays were used to investigate any toxic substances leached from the plastic reactors into disinfected water as a result of exposure to sunshine for up to 9 months. The Ames test was used to test for mutagenicity and the E-screen bioassay to test for estrogenicity. No mutagenicity was detected in any sample and no estrogenicity was found in the SODIS treated water produced by the PMMA reactors or the PP buckets. While water disinfected using the PET reactors showed no estrogenicity following exposure to the sun for 3 and 6 months, estrogenicity was detected following 9 months' exposure to sunlight; however levels detected were within the acceptable daily intake for 17β-estradiol (E2) of up to 50 ng/kg body weight/day.

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