Brine is a high-concentration solution of salt (usually sodium
chloride) in water. In different contexts, brine may refer to salt
solutions ranging from about 3.5% (a typical concentration of
seawater, on the lower end of solutions used for brining foods) up to
about 26% (a typical saturated solution, depending on temperature).
Lower levels of concentration are called by different names: fresh
water, brackish water and saline water.
Brine naturally occurs on Earth's surface (salt lakes), crust, and
within brine pools on ocean bottom. High-concentration brine lakes
typically emerge due to evaporation of ground saline water on high
Brine is used for food processing and cooking
(pickling and brining), for de-icing of roads and other structures,
and in a number of technological processes. It is also a by-product of
many industrial processes, such as desalination, and may pose an
environmental risk due to its corrosive and toxic effects, so it
requires wastewater treatment for proper disposal.
1 In nature
2.2 Chlorine production
2.3 Refrigerating fluid
Water softening and purification
4 See also
Main article: Saline water
A NASA technician measures the concentration level of brine using a
hydrometer at a salt evaporation pond in San Francisco.
Saline water with relatively high concentration of salt (usually
sodium chloride) occurs naturally on Earth's surface (salt lakes),
crust, and within brine pools on ocean bottom.
Numerous processes exist which can produce brines in nature.
Modification of seawater via evaporation results in the concentration
of salts in the residual fluid, a characteristic geologic deposit
called an evaporite is formed as different dissolved ions reach the
saturation states of minerals, typically gypsum and halite. A similar
process occurs at high latitudes as seawater freezes resulting in a
fluid termed a cryogenic brine. At the time of formation, these
cryogenic brines are by definition cooler than the freezing
temperature of seawater and can produce a feature called a brinicle
where cool brines descend, freezing the surrounding seawater.
The brine cropping out at the surface as saltwater springs are known
as "licks" or "salines". The contents of dissolved solids in
groundwater vary highly from one location to another on Earth, both in
terms of specific constituents (e.g. halite, anhydrite, carbonates,
gypsum, fluoride-salts, organic halides, and sulfate-salts) and
regarding the concentration level. Using one of several classification
of groundwater based on total dissolved solids (TDS), brine is water
containing more than 100,000 mg/L TDS.
Brine is commonly
produced during well completion operations, particularly after the
hydraulic fracturing of a well.
Main article: Brining
Brine is a common agent in food processing and cooking.
used to preserve or season the food.
Brining can be applied to
vegetables, cheeses and fruit in a process known as pickling.
fish are typically steeped in brine for shorter periods of time, as a
form of marination, enhancing its tenderness and flavor, or to enhance
Main article: Chlorine production
Elemental chlorine can be produced by electrolysis of brine (NaCl
solution). This process also produces sodium hydroxide (NaOH) and
Hydrogen gas (H2). The reaction equations are as follows:
Cathode: 2 H+ (aq) + 2 e− → H2 (g)
Anode: 2 Cl− (aq) → Cl2 (g) + 2 e−
Overall process: 2
NaCl + 2 H2O → Cl2 + H2 + 2 NaOH
Brine is a common fluid used as a secondary refrigerant in large
refrigeration installations for the transport of thermal energy from
place to place. Being inexpensive, most common refrigerant brines are
based on calcium chloride and sodium chloride. It is used because
the addition of salt to water lowers the freezing temperature of the
solution and the heat transport efficiency can be greatly enhanced for
the comparatively low cost of the material. The lowest freezing point
NaCl brine is −21.1 °C (−6.0 °F) at the
concentration of 23.3%
NaCl by weight. This is called the eutectic
Sodium chloride brine spray is used on some fishing vessels to freeze
fish. The brine temperature is generally −5 °F
(−21 °C). Air blast freezing temperatures are −31 °F
(−35 °C) or lower. Given the higher temperature of brine, the
system efficiency over air blast freezing can be higher. High-value
fish usually are frozen at much lower temperatures, below the
practical temperature limit for brine.
Because of the corrosive properties of salt-based brines, glycols such
as polyethylene glycol have become more common for this purpose.
Water softening and purification
Brine is an auxiliary agent in water softening and water purification
systems involving ion exchange technology. The most common example are
household dishwashers, utilizing natrium chloride in form of
Brine is not involved in the purification process
itself, but used for regeneration of ion-exchange resin on cyclical
basis. The water being treated flows through the resin container until
the resin is considered exhausted and water is purified to a desired
level. Resin is then regenerated by sequentially backwashing the resin
bed to remove accumulated solids, flushing removed ions from the resin
with a concentrated solution of replacement ions, and rinsing the
flushing solution from the resin. After treatment, ion-exchange
resin beads saturated with calcium and magnesium ions from the treated
water, are regenerated by soaking in brine containing 6–12% NaCl.
The sodium ions from brine replace the calcium and magnesium ions on
In lower temperatures, a brine solution can be used to de-ice or
reduce freezing temperatures on roads.
Industrial wastewater treatment
Industrial wastewater treatment §
Brine is a byproduct of many industrial processes, such as
desalination for human consumption and irrigation, power plant cooling
towers, produced water from oil and natural gas extraction, acid mine
or acid rock drainage, reverse osmosis reject, chlor-alkali wastewater
treatment, pulp and paper mill effluent, and waste streams from food
and beverage processing. Along with diluted salts, it can contain
residues of pretreatment and cleaning chemicals, their reaction
byproducts and heavy metals due to corrosion.
Wastewater brine can pose a significant environmental hazard, both due
to corrosive and sediment-forming effects of salts and toxicity of
other chemicals diluted in it. It must be properly disposed, which may
require permits and compliance with environmental regulations.
The simplest way to dispose of unpolluted brine from desalination
plants and cooling towers is to return it back to the ocean. To limit
the environmental impact, it can be diluted with another stream of
water, such as the outfall of a wastewater treatment or power plant.
Since brine is heavier than seawater and would accumulate on the ocean
bottom, it requires methods to ensure proper diffusion, such as
installing underwater diffusers in the sewerage. Other methods
include drying in evaporation ponds, injecting to deep wells, and
storing and reusing the brine for irrigation, de-icing or dust control
Technologies for treatment of polluted brine include: membrane
filtration processes, such as reverse osmosis; ion exchange processes
such as electrodialysis or weak acid cation exchange; or evaporation
processes, such as brine concentrators and crystallizers employing
mechanical vapour recompression and steam.
^ "The Scioto Saline-Ohio's Early
Salt Industry" (PDF).
dnr.state.oh.us. Archived from the original (PDF) on 2012-10-07.
^ "Global Overview of Saline
Groundwater Occurrence and Genesis".
^ a b "Secondary
Refrigerant Systems". Cool-Info.com. Retrieved 17
^ Kolbe, Edward; Kramer, Donald (2007). "Planning forSeafood Freezing"
(PDF). Alaska Sea Grant College Program Oregon State University.
ISBN 1566121191. Retrieved 17 July 2017.
Calcium Chloride versus Glycol". accent-refrigeration.com.
Retrieved 17 July 2017.
^ Kemmer, Frank N., ed. (1979). The NALCO
Water Handbook. McGraw-Hill.
pp. 12–7; 12–25.
^ "Hard and soft water". GCSE Bitesize. BBC.
^ Arup K. SenGupta (19 April 2016). Ion Exchange and Solvent
Extraction: A Series of Advances. CRC Press. pp. 125–.
^ "Prewetting with
Brine for More Effective Roadway Deicing".
^ a b "7 Ways to Dispose of
Brine Waste". Desalitech. Retrieved 18
^ "Reverse Osmosis Desalination:
Brine disposal". Lenntech. Retrieved
18 July 2017.
Acid mine drainage
Adsorbable organic halides
Biochemical oxygen demand
Chemical oxygen demand
Total dissolved solids
Total suspended solids
Agricultural wastewater treatment
API oil-water separator
Decentralized wastewater system
Fecal sludge management
Industrial wastewater treatment
Rotating biological contactor
Sewage sludge treatment
Ultraviolet germicidal irradiation
Wastewater treatment plant
Septic drain field