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https://en.wikipedia.org/wiki/Desalination#Outflow https://en.wikipedia.org/wiki/Desalination#Outflow gives an overview of the environmental problems in desal o

by dalke 10y ago

https://en.wikipedia.org/wiki/Desalination#Outflow https://en.wikipedia.org/wiki/Desalination#Outflow gives an overview of the environmental problems in desal outflow: > 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.[45] 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.[46] > To limit the environmental impact of returning the brine to the ocean, ... > Brine is denser than seawater and therefore sinks to the ocean bottom and can damage the ecosystem. Careful reintroduction can minimize this problem. Typical ocean conditions allow for rapid dilution, thereby minimizing harm. What's an example of not typical? Here's an article which points out that the Arabian Gulf is shallow, with low circulation rates and high evaporation rates which make it naturally saltier. That, combined with the damming of freshwater and increasing number of desal plants places a limit on to how much it can be use as a water source: http://www.thenational.ae/news/uae-news/environment/desalination-threat-to-the-growing-gulf http://www.thenational.ae/news/uae-news/environment/desalina...

ethbro 10y ago
From the article, "chemical-free method." [1] I'm sure the salt concentration isn't great, but it's a lot easier to spread salt around than remove heavy metals and cleaning chemicals. [1] https://www.researchgate.net/profile/Ilana_Berman-Frank/publication/236137883_Bioflocculation_Chemical_free_pre-treatment_technology_for_the_desalination_industry/links/00b4951976edf67426000000.pdf https://www.researchgate.net/profile/Ilana_Berman-Frank/publ...
- dalke 10y ago
  More details at http://www.filtsep.com/view/44376/success-behind-advanced-swro-desalination-plant/ http://www.filtsep.com/view/44376/success-behind-advanced-sw... : > Minimizing the plant's environmental impact: Pipe jacking .... Other measures: the potential impacts of the Sorek Plant's operation on the environment were thoroughly assessed, and appropriate measures were taken to prevent, minimize and mitigate these. The following are some highlights of these measures: > – The feed water pumping station is located far (2,400 meters) from the coastline, and feed water flows by gravity to the on-site pumping station. > – Entrainment and impingement effects at the intake system are minimized, thus minimizing the consumption of electricity and chemicals (especially CO2) and reducing the emission of related greenhouse gases, air pollutants and noise. > – Environmentally-friendly antiscalants, and inorganic and treatable cleaning solutions, are used. > – Brine is discharged back to the sea approximately 2 kilometers offshore, and at a depth of 20 meters through a specially designed outfall system (diffusers) that enhances quick brine dilution to the seawater body. The critical parameters of the brine disposal are monitored online, 24/7. > – The plant is equipped with a special sludge treatment system to treat any effluents generated in the process. This system removes all suspended matter and only clear water is discharged to the sea.
TenOhms 10y ago
Why don't they create a huge "sea" using concrete and just dump the brine there? I'd imagine if they built it large enough, they could dump all the brine they needed to and it would evaporate faster than they could pour it in (leaving behind the salts/chemicals).
- dalke 10y ago
  The evaporation rate is too low. From http://www.ide-tech.com/blog/b_case_study/sorek-project/ http://www.ide-tech.com/blog/b_case_study/sorek-project/ assume 26,000 m³/hour of brine outflow. According to http://www.engineeringtoolbox.com/evaporation-water-surface-d_690.html http://www.engineeringtoolbox.com/evaporation-water-surface-... , 1000 sq. meters of water surface evaporates under 500 kg/hour. 26,000 m³ = 26,000,000 kg => 52,000,000 sq. meters are needed or 52 sq. km. However, as the salinity increases, the evaporation rate decreases. If I read http://www.actis.com.au/evaporation_rate_of_brines.pdf http://www.actis.com.au/evaporation_rate_of_brines.pdf correctly, a saturated saline needs almost 50% more area for the same evaporation rate. So, call it 75 sq. km. for your evaporation pan/sea. Oh, and double it because night-time. And add more safety factor because of rain. Perhaps 200 sq. km will do? That's a huge area. As a quick check, some of the storm waves in the eastern Med. can be 5 meters high - http://www.sciencedirect.com/science/article/pii/0378383985900249 http://www.sciencedirect.com/science/article/pii/03783839859... . So you're talking about some massive walls. To say nothing of redundancy, since you don't want the sea to breach a nearly full basin of salt.

by dalke 10y ago

ethbro 10y ago

From the article, "chemical-free method." [1] I'm sure the salt concentration isn't great, but it's a lot easier to spread salt around than remove heavy metals and cleaning chemicals. [1] https://www.researchgate.net/profile/Ilana_Berman-Frank/publication/236137883_Bioflocculation_Chemical_free_pre-treatment_technology_for_the_desalination_industry/links/00b4951976edf67426000000.pdf https://www.researchgate.net/profile/Ilana_Berman-Frank/publ...

dalke 10y ago
More details at http://www.filtsep.com/view/44376/success-behind-advanced-swro-desalination-plant/ http://www.filtsep.com/view/44376/success-behind-advanced-sw... : > Minimizing the plant's environmental impact: Pipe jacking .... Other measures: the potential impacts of the Sorek Plant's operation on the environment were thoroughly assessed, and appropriate measures were taken to prevent, minimize and mitigate these. The following are some highlights of these measures: > – The feed water pumping station is located far (2,400 meters) from the coastline, and feed water flows by gravity to the on-site pumping station. > – Entrainment and impingement effects at the intake system are minimized, thus minimizing the consumption of electricity and chemicals (especially CO2) and reducing the emission of related greenhouse gases, air pollutants and noise. > – Environmentally-friendly antiscalants, and inorganic and treatable cleaning solutions, are used. > – Brine is discharged back to the sea approximately 2 kilometers offshore, and at a depth of 20 meters through a specially designed outfall system (diffusers) that enhances quick brine dilution to the seawater body. The critical parameters of the brine disposal are monitored online, 24/7. > – The plant is equipped with a special sludge treatment system to treat any effluents generated in the process. This system removes all suspended matter and only clear water is discharged to the sea.

TenOhms 10y ago

Why don't they create a huge "sea" using concrete and just dump the brine there? I'd imagine if they built it large enough, they could dump all the brine they needed to and it would evaporate faster than they could pour it in (leaving behind the salts/chemicals).

dalke 10y ago
The evaporation rate is too low. From http://www.ide-tech.com/blog/b_case_study/sorek-project/ http://www.ide-tech.com/blog/b_case_study/sorek-project/ assume 26,000 m³/hour of brine outflow. According to http://www.engineeringtoolbox.com/evaporation-water-surface-d_690.html http://www.engineeringtoolbox.com/evaporation-water-surface-... , 1000 sq. meters of water surface evaporates under 500 kg/hour. 26,000 m³ = 26,000,000 kg => 52,000,000 sq. meters are needed or 52 sq. km. However, as the salinity increases, the evaporation rate decreases. If I read http://www.actis.com.au/evaporation_rate_of_brines.pdf http://www.actis.com.au/evaporation_rate_of_brines.pdf correctly, a saturated saline needs almost 50% more area for the same evaporation rate. So, call it 75 sq. km. for your evaporation pan/sea. Oh, and double it because night-time. And add more safety factor because of rain. Perhaps 200 sq. km will do? That's a huge area. As a quick check, some of the storm waves in the eastern Med. can be 5 meters high - http://www.sciencedirect.com/science/article/pii/0378383985900249 http://www.sciencedirect.com/science/article/pii/03783839859... . So you're talking about some massive walls. To say nothing of redundancy, since you don't want the sea to breach a nearly full basin of salt.