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Solar saltworks are most efficient converters of solar energy into an inorganic commodity. Conversion
rate of solar radiation into removal of water vapour from the brine takes place with 45%
efficiency. Solar salt requires only a fraction of man made energy compared with salt produced
by solution mining and thermal evaporation. Advanced technologies for biological management,
crystallisation, harvesting techniques and salt processing, allow production of solar salt 99.94%
pure, which is comparable with purity of vacuum salt.
Proper biological management of solar saltworks leads to brine containing less organics. Organic
compounds in brine adversely influence the crystal growth habit, which results in inclusions of
impurities inside the salt crystals. Advanced salt purification technology is able to completely remove
impurities from the salt crystals incurring insignificant salt processing losses.
About 60% of salt produced worldwide is consumed by the chemical industry. High quality solar
salt used as feedstock in membrane cell chloralkali plants causes equally low contaminated effluent
discharge from brine treatment as vacuum salt. Trace elements that may cause membrane
damage, such as iodine, or those elements that are critical to chlorine purity, such as bromine,
are present in smaller quantities in solar salt than in many salts originating from rock salt deposits.
Bird watchers driving in jeeps through solar saltworks may not realise that the vast water fields
hosting flamingos are not only beautiful but that they contribute towards the shift in the environmental
balance in the direction of higher overall ecological benefit as well.

The commonly accepted brine concentration practice in most Chinese Northern solar works is
to pump the sea water into salt works and then let it go through a physical changing process of
natural evaporation, condensation and crystallization, during which, weather factor and the soil
nature have to be taken into consideration when determining the technologic parameters such
as brine depth, brine protection area, fresh water drainage rate and so on. Meanwhile, different
methods should be employed according to various weather conditions, for example, brine is
concentrated with decided depth and salinity over periods of stable weather conditions
(Spring); rapid brine concentration by deep storage and lower depth brine should be used
during rainy seasons; and in winters, the amount should be increased to keep the salinity.
However, accompanying this physical changing process of salt production is balancing
process of the amount of multi-biology in brine. Every salt work fosters an ecosystem, which
includes algae, bacteria, protoza, menatoza, artemia, sea weed and fish communities.
The low salinity brine is featured of a myriad of algae, which are able to synthesize and
accumulate pigments, elevate the brine’s absorbency of solar energy and quicken the
evaporation speed; the algae, bacteria, organic and inorganic substances on the salt ponds
floor may form a biological pad, performing the functions of brine purifying, soil improvement
and leakage protection. At the same time, the biological pad can block out large amount of
elements and trace elements in the mud on the salt pond floor and the bacteria can effectively
decompose organic crumbs of the solar salt works ecosystem.
The medium salinity brine is dominated by artemia, who are good at sieving the algae, organic
and inorganic substances in brine so as to purify it. The artemia corpse are sources of protein
for red halobacteria, which are capable of increasing the brine staining ability, purifying brine
and promoting the evaporation amount and the salt quality.
In conclusion, a balanced ecosystem is beneficial to salt industry by :
A. culturing bentic communities, available for seizing nutrition and controlling leakage;
B. staining brine to enhance the absorbency of solar energy and evaporation rate;
C. being able to decompose most of its self-generated organics.
The Bidirectional Brine Concentration Technology is meant supplementing the ordinary brine
concentration with ecosystem management, namely, through the artificial adjustment of the
amount of biology to reach the eco-balance. This is composed of two parts:
A. The bio-management of artemia. Combining the concentrated multiplication with culturing
during the whole production process to adjust the community density to a suitable level
and keep the eco-balance in line with scientific standards. As long as the brine salinity
reaches certain level and the artemia food chain starts loosing balance, we will fish
over-thick community and let the resting artemia die in the high salinity area and their
corpse will be used for the source of protein for halobecteria.
B. Selecting and culturing excellent breed of halobacteria.. Let red halobacteria reproduce in
saturated brine and crystallizers and contact a corresponding scientific surveillance. This
helps heighten the brine transparency, lower the brine stickiness and promote the salt
quality.

The goal of every solar saltworks with seawater intake--continuous and economic production
of high quality salt (sodium chloride) at design capacity—requires ability to simultaneously
manage and coordinate physical systems with biological systems in the concentrating and
crystallizing ponds. This effort requires close control of specified salinities, depths, and brine
transfers, frequent surveillance and adjustments of planktonic and benthic communities and
their key microorganisms, and timely recognition and correction of developing problems. This
report reviews features and concepts that facilitate biological and physical management,
considers causes and effects of common and severe disturbances and their solutions, and
provides information that enable biological systems in the ponds of a solar saltworks aid
rather than harm salt production.

A major solar salt works in Israel is located just north of the town of Eilat and close to the
airport. This solar salt works has been in operation since 1977 and produces about 170,000
tons a year. A three-year study was initiated to examine the temporal and salinity impacts on
the microbial community throughout this saltern. At the time this study was begun in the late
1990's, there were several paradigms about the microbial community:
1. there is greatly reduced diversity as the water reaches saturation;
2. because of the relative stability of the salt concentrations in the various pans, there is little
change in the microbial community; and,
3. halophilic Archaea are not found in ponds with less than 15% salt and halophilic Bacteria
would not be found in pans at saturation.
The first paradigm was developed based on a few studies using one medium and single
observations of various salterns. The second paradigm was an assumption that had not been
systematically tested, and the third paradigm, at least for the Bacteria, was shown in 1980 not
to be true with the discovery of the genus Halomonas.
We examined these paradigms by systematically studying on a seasonal basis the saltern at
Eilat, Israel, as well as the Cargill Solar Salt Plant in Newark, California. Both traditional and
molecular techniques have been used throughout these studies.
Several different approaches were taken: plate counts were made on several different media,
whole community carbon requirements were determined, molecular fingerprinting of the whole
microbial community using the amplicon length heterogeneity approach was performed to
determine the changes in the community composition over time, and partial characterization
of the isolated pure cultures were all performed. Samples were taken at least twice a year
corresponding to the cooler and hotter times of the year.
Based on this extensive study there were significant differences in the plate counts and in the
ratios of the various peaks found during the fingerprinting. It is safe to say now that the
microbial community in the waters of a solar saltern is variable and both domains can be
found throughout the saltworks.