Editing Desalination (section)

==Environmental concerns==
===Intake===
In the United States, cooling water intake structures are regulated by the [[Environmental Protection Agency]] (EPA). These structures can have the same impacts on the environment as desalination facility intakes. According to EPA, water intake structures cause adverse environmental impact by sucking fish and shellfish or their eggs into an industrial system. There, the organisms may be killed or injured by heat, physical stress, or chemicals. Larger organisms may be killed or injured when they become trapped against screens at the front of an intake structure.<ref>[http://water.epa.gov/lawsregs/lawsguidance/cwa/316b/ Water: Cooling Water Intakes (316b)]. water.epa.gov.</ref> Alternative intake types that mitigate these impacts include beach wells, but they require more energy and higher costs.<ref>Cooley, Heather; [[Peter Gleick|Gleick, Peter H.]] and Wolff, Gary (2006) [http://pacinst.org/wp-content/uploads/sites/21/2015/01/desalination-grain-of-salt.pdf ''Desalination, With a Grain of Salt. A California Perspective''], Pacific Institute for Studies in Development, Environment, and Security. {{ISBN|1-893790-13-4}}</ref>

The [[Kwinana Desalination Plant]] opened in the Australian city of [[Perth]], in 2007. Water there and at [[Queensland]]'s [[Gold Coast Desalination Plant]] and [[Sydney]]'s [[Kurnell Desalination Plant]] is withdrawn at {{convert|0.1|m/s|abbr=on}}, which is slow enough to let fish escape. The plant provides nearly {{convert|140000|m3|abbr=on}} of clean water per day.<ref name=npr>Sullivan, Michael (June 18, 2007) [https://www.npr.org/templates/story/story.php?storyId=11134967 "Australia Turns to Desalination Amid Water Shortage"]. NPR.</ref>

===Outflow===
{{More citations needed section|date=January 2012}}
Desalination processes produce large quantities of [[brine]], possibly at above ambient temperature, and contain residues of pretreatment and cleaning chemicals, their reaction byproducts and heavy metals due to corrosion (especially in thermal-based plants).<ref name="PanagopoulosHaralambous2020">{{Cite journal|last1=Panagopoulos|first1=Argyris|last2=Haralambous|first2=Katherine-Joanne|date=2020-10-01|title=Minimal Liquid Discharge (MLD) and Zero Liquid Discharge (ZLD) strategies for wastewater management and resource recovery – Analysis, challenges and prospects|url=http://www.sciencedirect.com/science/article/pii/S2213343720307673|journal=Journal of Environmental Chemical Engineering|language=en|volume=8|issue=5|pages=104418|doi=10.1016/j.jece.2020.104418|s2cid=225309628|issn=2213-3437}}</ref><ref>Greenberg, Joel (March 20, 2014) [http://www.mcclatchydc.com/2014/03/20/221880/israel-no-longer-worried-about.html "Israel no longer worried about its water supply, thanks to desalination plants"] {{Webarchive|url=https://web.archive.org/web/20140324202006/http://www.mcclatchydc.com/2014/03/20/221880/israel-no-longer-worried-about.html |date=March 24, 2014 }}, ''[[The McClatchy Company|McClatchy DC]]''</ref> Chemical pretreatment and cleaning are a necessity in most desalination plants, which typically includes prevention of biofouling, scaling, foaming and corrosion in thermal plants, and of biofouling, suspended solids and scale deposits in membrane plants.<ref>{{cite journal|doi=10.1016/j.desal.2007.03.009 |title=Environmental impact and impact assessment of seawater desalination|year=2008|last1=Lattemann|first1=Sabine|last2=Höpner|first2=Thomas|journal=Desalination|volume=220|issue=1–3|page=1|bibcode=2008Desal.220....1L }}</ref>

To limit the environmental impact of returning the brine to the ocean, it can be diluted with another stream of water entering the ocean, such as the outfall of a [[Sewage treatment|wastewater treatment]] or power plant. With medium to large power plant and desalination plants, the power plant's cooling water flow is likely to be several times larger than that of the desalination plant, reducing the salinity of the combination. Another method to dilute the brine is to mix it via a diffuser in a mixing zone. For example, once a pipeline containing the brine reaches the sea floor, it can split into many branches, each releasing brine gradually through small holes along its length. Mixing can be combined with power plant or wastewater plant dilution. Furthermore, zero liquid discharge systems can be adopted to treat brine before disposal.<ref name="PanagopoulosHaralambous2020" /><ref>Szeptycki, L., E. Hartge, N. Ajami, A. Erickson, W. N. Heady, L. LaFeir, B. Meister, L. Verdone, and J.R. Koseff (2016). Marine and Coastal Impacts on Ocean Desalination in California. Dialogue report compiled by Water in the West, Center for Ocean Solutions, Monterey Bay Aquarium and The Nature Conservancy, Monterey, CA. https://www.scienceforconservation.org/assets/downloads/Desal_Whitepaper_2016.pdf</ref>

Another possibility is making the desalination plant movable, thus avoiding that the brine builds up into a single location (as it keeps being produced by the desalination plant). Some such movable (ship-connected) desalination plants have been constructed.<ref>{{Cite web|url=https://www.theexplorer.no/solutions/waterfountain-innovative-floating-desalination-system/|title=Innovative floating desalination system|website=www.theexplorer.no}}</ref><ref>{{Cite web|url=https://waterfountain.no/|title=Oisann Engineering|website=Oisann Engineering}}</ref>

Brine is denser than seawater and therefore sinks to the ocean bottom and can damage the ecosystem. Brine plumes have been seen to diminish over time to a diluted concentration, to where there was little to no effect on the surrounding environment. However studies have shown the dilution can be misleading due to the depth at which it occurred. If the dilution was observed during the summer season, there is possibility that there could have been a seasonal thermocline event that could have prevented the concentrated brine to sink to sea floor. This has the potential to not disrupt the sea floor ecosystem and instead the waters above it. Brine dispersal from the desalination plants has been seen to travel several kilometers away, meaning that it has the potential to cause harm to ecosystems far away from the plants. Careful reintroduction with appropriate measures and environmental studies can minimize this problem.<ref>{{cite journal |last1=Yolanda Fernández-Torquemada |title=Dispersion of brine discharge from seawater reverse osmosis desalination plants |journal=Desalination and Water Treatment |date=March 16, 2009 |volume=5 |issue=1–3 |pages=137–145 |doi=10.5004/dwt.2009.576 |bibcode=2009DWatT...5..137F |hdl=10045/11309 |hdl-access=free }}</ref><ref>{{Cite journal|last1=Panagopoulos|first1=Argyris|last2=Haralambous|first2=Katherine-Joanne|date=2020-12-01|title=Environmental impacts of desalination and brine treatment – Challenges and mitigation measures|url=http://www.sciencedirect.com/science/article/pii/S0025326X20308912|journal=Marine Pollution Bulletin|language=en|volume=161|issue=Pt B|pages=111773|doi=10.1016/j.marpolbul.2020.111773|pmid=33128985|bibcode=2020MarPB.16111773P |s2cid=226224643|issn=0025-326X}}</ref>

=== Energy use ===
The energy demand for desalination in the Middle East, driven by severe [[water scarcity]], is expected to double by 2030. Currently, this process primarily uses [[fossil fuel]]s, comprising over 95% of its energy source. In 2023, desalination consumed nearly half of the residential sector's energy in the region.<ref>{{Cite web |date=2024-03-22 |title=Energy is vital to a well-functioning water sector – Analysis |url=https://www.iea.org/commentaries/energy-is-vital-to-a-well-functioning-water-sector |access-date=2024-04-19 |website=IEA |language=en-GB}}</ref>

===Other issues===
Due to the nature of the process, there is a need to place the plants on approximately 25 acres of land on or near the shoreline.<ref name="Einav">{{cite journal|last1=Einav|first1=Rachel|last2=Harussi|first2=Kobi|last3=Perry|first3=Dan|date=February 2003|title=The footprint of the desalination processes on the environment|journal=Desalination|volume=152|issue=1–3|pages=141–154|doi=10.1016/S0011-9164(02)01057-3|bibcode=2003Desal.152..141E }}</ref> In the case of a plant built inland, pipes have to be laid into the ground to allow for easy intake and outtake.<ref name=Einav /> However, once the pipes are laid into the ground, they have a possibility of leaking into and contaminating nearby aquifers.<ref name=Einav /> Aside from environmental risks, the noise generated by certain types of desalination plants can be loud.<ref name=Einav />