The high concentration of mixture of inorganic and organic salts present in RAE restrains it from disposal [ 13 , 14 ]. Recovery of salts from RO concentrate is increasing for its environmental safe way to reuse of waste volume of reject. The change of solution temperature either by evaporation and cooling used to extract salts from concentrate has been widely used worldwide. In which, electro-dialysis, ion-exchange, eutectic freezing, and chemical processing are being practiced to recover salts from concentrate.
Further, in advance hybrid systems which consisting of combination of two or more separation process techniques, such as the nanofiltration—reverse osmosis—thermal processes, are being deployed actively to increase the amount of extracted salt and reduce the final volume of reject.
Buckley et al. Chemical conversion of reject to products: chemical conversion of rejects to other reusable salts from waste RO reject. Direct and indirect discharge of concentrated brine by dilution without affecting receiving environment. Stabilization of concentrate to inert material: stabilizing the waste concentrate into chemically stable material. Recovery of valuable salts or minerals can be obtained from RO concentrate or brackish water by altering solution temperature either by evaporation or cooling effect.
There are reports on evaporators are being practiced in brine management, among which multiple effect evaporator MEE are most promising and cost effective. The MEE operate based on the principle of reducing the vapor pressure of solution within the system to permit boiling occurs at low temperature. The multiple effect evaporator feed water is boiled and pumped into tube side in the evaporator in series. The outcome of steam has been condensed over the tube wall of the evaporator and collected as water to reuse.
The excess heat is further used for the boiling of inlet water. In other way, vapor compression distillation VCD is used for the desalination process. In VCD inlet water is boiled through heater to vaporize and discharged through evaporative compressor. The generated vapor has been compressed and used as steam supply for boiling concentrate and the condensate product is obtained after compression process.
Electro-dialysis system consists of anion-exchange and cation-exchange membranes are being arranged alternately in a large cell of compartment between an anode and a cathode. The influence of applied electric field, the various ions could migrate towards the electrodes based on its ionic charge.
The membranes are permeable only to cations or anions, through which the water between the membranes are alternately depleted and enriched with salt ions.
The cation membranes allow only positively charged ions to diffuse through them. Similarly, anion exchange membrane allows only negatively charge ions. Electro-dialysis is being considered used as a pre-treatment or a pre-concentration method for brine management [ 15 , 16 , 17 ].
This method of application significantly reduces the concentration of calcium or sulfate ions from gypsum crystallization during further evaporation [ 15 ]. However, fouling by colloidal material, organics, and bio-growth should be taken care for the effective and sustainable use of the equipment.
The performance of ion exchange processes based on packed bed column resin, which are generally organic resins that contains hydrogen ions and is capable of exchanging positive ions present in the feed water. The ion exchange processes are being studied, investigated, and applied for many desalting process over several decades [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. However, this method of treatment applies only to low concentrations of salts containing brine water and its cost of regeneration is also higher.
In this process, the feed concentrate stream is frozen continuously until it reaches a eutectic temperature. The ice being forming. If the unsaturated concentrate is reaching its freezing point. At the specific eutectic point of crystallization, the brine salt is crystallized out as product.
The energy required for the EFC process are found to be very less than the conventional method of evaporative and cooling crystallization process and its theoretically possible way to complete the conversion of concentrate water into water and solidified solutes. This technique has been used successfully to recover magnesium sulfate from sulfate rich brine, rock forming minerals, and salty lake water [ 31 , 32 , 33 ].
There are many sequential extraction of salts from rejected brine thus which high concentration of dissolved sulfate, potassium, and magnesium salts are being separated through multiple effect evaporator and cooling crystallization method, reactive precipitation methods [ 15 , 28 ]. The use of lime favors selective separation of magnesium hydroxide from concentrate solution and thermal calcination of concentrate having sodium sulfate helps to recover Na 2 SO 4 from wastewater [ 34 ].
The recovery of calcium from RO reject is done to avoid secondary RO scaling [ 36 , 37 , 38 ]. Bond and Veerapaneni [ 36 ] have developed detailed methodology for the recovery of calcium carbonate by chemical precipitation, in particular to separate calcium during desalination. Several other researchers have evaluated fluidized bed crystallizers for the production of calcium carbonate pellets from RO reject [ 36 , 39 ], further studies have been reported on influence of anti-scalants, impurities, metals, and ions on calcium carbonate precipitation [ 40 , 41 , 42 ].
The concentration of calcium ions in seawater and desalination reject is relatively high, through this calcium carbonate pellets has been prepared from brackish water in Southern California [ 39 ]. However, the extraction of calcium sulfate from RO reject has not received significant attention, due to low price of commercial grade gypsum. Also, the mechanisms of calcium sulfate precipitation have been observed to form scaling minimized equipment failure in separation process [ 43 , 44 , 45 , 46 ].
The ion-exchange resin is being used to selectively extract calcium sulfate salts from RO reject by controlling the pH of the mixture of anion and cation regeneration solution. The main unit processes used for the extraction of magnesium is evaporation cum crystallization, precipitation, and ion-exchange. Ohya et al. Drioli et al. In Russia, a large scale extraction plant is also being operated for the recovery of magnesium from seawater using ion-exchange, and extraction of magnesium from RO reject from seawater desalination system.
The main source of potash production is done by conventional shaft mining or deep-well solution mining process techniques. Currently, potassium is being produced from seawater as a byproduct from solar salt evaporation. The extraction of potassium is done using natural zeolite clinoptilolites ion-exchange materials which has high exchange capacity for potassium through a two-step dual-temperature process.
Membrane crystallization MCr is being practiced to produce relatively pure salt crystals from a synthetic NF reject solution having calcium and magnesium [ 66 ]. Offset the lid slightly so that the water that condenses on the inside of the lid will run down the side to be collected in a separate container. You've just made distilled water. When all of the water has boiled off, the salt will remain in the pot.
Evaporation works the same way as distillation, just at a slower rate. Pour the salt water into a shallow pan. As the water evaporates, the salt will remain behind. You can speed up the process by raising the temperature or by blowing dry air over the surface of the liquid.
A variation of this method is to pour the salt water onto a piece of dark construction paper or a coffee filter. This makes recovering the salt crystals easier than scraping them out of the pan. Another way to separate salt from water is to use reverse osmosis. In this process, water is forced through a permeable filter, causing the concentration of salt to increase as the water is pushed out. While this method is effective, reverse osmosis pumps are relatively expensive.
However, they can be used to purify water at home or when camping. Electrodialysis can be used to purify water. Here, a negatively-charged anode and a positively-charged cathode are placed in water and separated by a porous membrane. When an electric current is applied, the anode and cathode attract the positive sodium ions and negative chlorine ions, leaving behind the purified water. Note: this process does not necessarily make the water safe to drink, since uncharged contaminants may remain.
A chemical method of separating salt and water involves adding decanoic acid to salt water. The solution is heated. Upon cooling, salt precipitates out of the solution, falling to the bottom of the container.
When the reaction is complete, the water and salt sit in two completely separate layers, making it easy to remove the water. Use electro-dialysis. Using the power of electricity, it's possible to remove particles like salt from water. This is done by submerging a negatively charged cathode and a positively charged anode in water and separating them with a porous membrane.
The electrical charge of the anode and cathode essentially "pull" dissolved ions like those that make up salt toward them like magnets, leaving relatively pure water.
Recent research has been promising, however, suggesting new techniques that do kill bacteria as part of the process. Did you know you can get expert answers for this article? Unlock expert answers by supporting wikiHow. Meredith Juncker, PhD. Support wikiHow by unlocking this expert answer. Not Helpful 3 Helpful Not Helpful 10 Helpful No, because it is a homogeneous mixture.
You need to use heat and evaporation in order to separate salt from water. Not Helpful 16 Helpful My teacher said distillation is only used for separating two different liquids, not a salt-water mixture, and I got the question on the exam wrong for that. So can distillation really be used in this way? Distillation is how you separate a pure liquid from a mixture, in this case you are removing pure water from salt water.
Sorry to tell you, but teachers are human and not always correct. More likely - whatever the lesson was on, distillation was not a proper response. So sometimes you might not be wrong, but still not have the correct answer.
There are few dangers that come with this method. There is also the danger of electrolysis, which would generate hydrogen and chlorine gas, but that risk is very low. Overall, it's a safe activity to do with kids as long as basic safety precautions are taken. Not Helpful 2 Helpful Immiscible liquids are two liquids that when mixed do not combine together; for example, water and oil. Not Helpful 5 Helpful It's chemistry because the kitchen apparatus apparently has something to do with the relationshop between water, which is boiling and salt.
It's just an object that causes heat, you can use other things instead of it that lead to the same solution. So this specific thing actually doesn't have to do anything with chemistry at all, it's just the salt, water, and heat that are chemistry-related.
Not Helpful 21 Helpful I tried using the electrodialysis method with a 9 volt battery connected to two nails in the salt water. I failed to separate the salt, but separated hydrogen from the water. What did I do wrong? You did nothing wrong, this is simply an oversimplification of electrodialysis. If you carry out this method as described, you'll only succeed to electrolyze the dissolved sodium chloride, resulting in hydrogen gas and chlorine.
Chlorine gas is poisonous, so be careful. Not Helpful 22 Helpful The easiest way is to find the saltiest water possible and distill it. This would leave all the salt behind in the pot and the water would be completely separate, allowing you to do whatever you would like with the two materials. As shown with unusual methods, there are other ways to remove salt from water, such as Reverse Osmosis, Electrodialysis, or Decanoic Acid.
Include your email address to get a message when this question is answered. Don't use seawater unless you have to. In addition to salt, it can also contain minerals, organic matter, and other contaminants that can make it harder to purify completely. Helpful 0 Not Helpful 0. You can also use a solar still which doesn't need a stove at all. All you need is a hole in the ground, some plastic wrap, rocks, and a small bowl or cup.
Be careful whenever you're boiling water on the stove. If you need to touch the hot pot or pan, be sure to use an oven mitt or a towel to protect yourself.
Helpful 10 Not Helpful Don't drink saltwater if you're lost in the wilderness. Our bodies need more water to get rid of the salt than the water actually provides, so salt water can make someone even more dehydrated. Related wikiHows How to.
How to. About This Article. Co-authored by:. Co-authors: Updated: June 2, Categories: Water Experiments. Article Summary X To separate salt from water with a basic evaporation experiment, start by putting a few cups of water in a pan and placing it on a hot burner.
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