Editing Solar energy (section)

===Water treatment===
{{Main|Solar still|Solar water disinfection|Solar desalination|Solar Powered Desalination Unit}}
[[File:Indonesia-sodis-gross.jpg|thumb|[[Solar water disinfection]] in Indonesia]]
Solar distillation can be used to make [[saline water|saline]] or [[brackish water]] potable. The first recorded instance of this was by 16th-century Arab alchemists.<ref name="Tiwari 2003">Tiwari (2003), pp. 368–71</ref> A large-scale solar distillation project was first constructed in 1872 in the [[Chile]]an mining town of Las Salinas.<ref name="Daniels 1964">Daniels (1964), p. 6</ref> The plant, which had solar collection area of {{convert|4700|m2|abbr=on}}, could produce up to {{convert|22700|L|abbr=on}} per day and operate for 40&nbsp;years.<ref name="Daniels 1964"/> Individual [[still]] designs include single-slope, double-slope (or greenhouse type), vertical, conical, inverted absorber, multi-wick, and multiple effect. These stills can operate in passive, active, or hybrid modes. Double-slope stills are the most economical for decentralized domestic purposes, while active multiple effect units are more suitable for large-scale applications.<ref name="Tiwari 2003"/>

Solar water [[disinfection]] (SODIS) involves exposing water-filled plastic [[polyethylene terephthalate]] (PET) bottles to sunlight for several hours.<ref>{{cite web|title=SODIS solar water disinfection|publisher=EAWAG (The Swiss Federal Institute for Environmental Science and Technology)|url=http://www.sodis.ch/index_EN|access-date=2 May 2008}}</ref> Exposure times vary depending on weather and climate from a minimum of six hours to two days during fully overcast conditions.<ref name="SODIS CDC">{{cite web|title=Household Water Treatment Options in Developing Countries: Solar Disinfection (SODIS) |publisher=Centers for Disease Control and Prevention |url=http://www.ehproject.org/PDF/ehkm/cdc-options_sodis.pdf |access-date=13 May 2008 |archive-url=https://web.archive.org/web/20080529090729/http://www.ehproject.org/PDF/ehkm/cdc-options_sodis.pdf |archive-date=29 May 2008 |url-status=dead }}</ref> It is recommended by the [[World Health Organization]] as a viable method for household water treatment and safe storage.<ref>{{cite web|title=Household Water Treatment and Safe Storage|publisher=World Health Organization|url=https://www.who.int/household_water/en/|archive-url=https://web.archive.org/web/20041025024316/http://www.who.int/household_water/en/|url-status=dead|archive-date=October 25, 2004|access-date=2 May 2008}}</ref> Over two million people in developing countries use this method for their daily drinking water.<ref name="SODIS CDC"/>

Solar energy may be used in a water stabilization pond to treat [[waste water]] without chemicals or electricity. A further environmental advantage is that [[algae]] grow in such ponds and consume [[carbon dioxide]] in photosynthesis, although algae may produce toxic chemicals that make the water unusable.<ref>{{cite journal|author1=Shilton A.N. |author2=Powell N. |author3=Mara D.D. |author4=Craggs R. |title=Solar-powered aeration and disinfection, anaerobic co-digestion, biological CO(2) scrubbing and biofuel production: the energy and carbon management opportunities of waste stabilization ponds|journal=Water Sci. Technol.|volume=58|issue=1|pages=253–58|year=2008|pmid=18653962|doi=10.2166/wst.2008.666|doi-access=|bibcode=2008WSTec..58..253S }}</ref><ref>{{cite journal|author1=Tadesse I. |author2=Isoaho S.A. |author3=Green F.B. |author4=Puhakka J.A. |title=Removal of organics and nutrients from tannery effluent by advanced integrated Wastewater Pond Systems technology|journal=Water Sci. Technol.|volume=48|issue=2|pages=307–14|year=2003|pmid=14510225|doi=10.2166/wst.2003.0135 |bibcode=2003WSTec..48..307T }}</ref>