For those who
live or have lived in desert areas such as in Saudi Arabia and surrounding
areas, must have terbesit in our minds, whence the source of water we consume daily
?? While we are aware that the area we live in is mostly desert ... Of course
there is the technology behind it. Let's look at the following article:
WATER CRISIS
In addition due
to the geographical location, limited access to clean water sources has become
a global problem. Clean water crisis has become a threat in almost all parts of
the world. This happens because the natural water sources are no longer able to
meet the growing needs of the high growth rate skyrocketing human population
and the vigorous industrialization in various fields. In this case, the
industry beperan particularly on water pollution source of sewage discharge.
The presence of
water on Earth is apparently not much. In the picture below looks that clean
water are in a very limited portion compared to other sources of water (sea
water). In this number, as well as of the serving of contaminated waste water,
so the water is getting smaller net amount.
From the
picture above, clear sea water into the huge potential if it can be used as raw
material for clean water. With the innovation of technology, the production
process and potable water from sea water can be done by utilizing seawater
desalination technology.
WORTH DRINKING WATER from AIR SEA?
Sea water has
become a raw material for production of clean water since even 60 years ago
through a desalination process. Desalination of sea water is a general term
that describes the allowance of salt and other impurities that are naturally
present in seawater.
Process water
production by desalination method is done through several stages, including:
making sea water, seawater pretreatment, salt separation process, and final
processing.
Intake seawater
The earliest
stages in the process of making seawater desalination is a process feedstock. A
common method is to install pipes seaward to a distance of several kilometers
from the coast. This is done to obtain a good quality of sea water with the
sediment surface to avoid movement that generally occurs in shallow ocean
depths. Flow rate of sea water sampling done slowly to prevent the entry of
marine life into the pipe.
The above
method becomes top choice for ease of system installation. However, in terms of
performance, the technique is very sensitive to changes in sea conditions that
occur along with changes in season and climate. Prevention of marine life to
enter into the system is also not as effective as expected.
Alternative
methods are being crowded discussed is to utilize the local geological
conditions to the coast with the sea water filter systems well (beach wells).
With this method, the sea water is extracted from the subsurface (subsurface)
beach. In addition, the technology being developed is the type of gallery with
a structure resembling a sand filtration mounted beneath the sea surface
(seabed) to obtain high quality raw materials. The methods above are covered in
the subsurface intake system.
initial
processing
Initial
treatment is aimed at conditioning the raw material, in terms of impurity
content, so friendly to the main desalination processes. Usual impurities
contained in sea water include macromolecules (sand and marine life including
fish, algae, etc..) And mikromolekul (the causative agent of sedimentation,
crystallization and fouling). Technique performed generally include
coagulation-flocculation-sedimentation
(coagulation-flocculation-sedimentation), low-pressure membrane (low pressure
membrane), filtration media (filter media) and cartridge filters.
Initial
processing of key importance because it determines the smoothness of the
desalination process stability and process performance with the high quality of
the feed water. From an economic perspective, as of the beginning of the
processing of almost 30% of the overall cost of the process. Cost savings in
the initial processing is feasible with alternative applications making sea
water as described previously. With raw material quality is better when,
pretreatment will be lighter, thereby reducing the consumption of chemicals and
the process of reducing the number of process equipment and ultimately
decreased the operational costs and improve the performance and stability of
the process.
Core process
At this stage,
the raw materials that have undergone initial processing will undergo a process
of elimination to produce salt water. Based on the salt separation techniques,
desalination processes are categorized into two: heat-based and membrane-based.
In the
heat-based process, the raw materials are conditioned boiling at low pressure
to produce water vapor at low temperatures. In this process, only water
evaporation are experiencing, so after collecting and condensing the steam,
will produce clean water without salt and impurities. Multistage flash
distillation and multi-effect distillation desalination technology is an
example of the heat-based.
Unlike the case
in the above process which uses heat energy to separate the salt from sea
water, using energy-pressure membrane technology. Membrane is a general term
for a thin filter which facilitates the separation of selectively - only
certain materials that can be passed and retained by this membrane. Membrane
type used is very dependent on the application. Especially for desalination,
use reverse osmosis (RO) membrane with a non-porous character who is able to
perform separation on ion levels, including salt dengang main composition of
sodium and chloride ions.
RO membrane
filtration is done by pressing the raw material sea water on the membrane
surface so pure pass water on the product side, while holding the salt content
and other impurities into the waste stream. The resulting product is very pure
water with very low ion concentration.
end processing
Conditions of
pure water with a low concentration of ions in the desalination products need
to be adjusted for comfort when consumed and does not damage the distribution
pipes. For consumption, pure water does not taste, the need for the addition of
minerals so it seems according to the quality of drinking water: refreshing
taste of water comes from mineral deposits. Minimum ion content which can lead
to corrosion of the pipe distribution process due to the tendency of the
binding of metal ions to pipe water's chemical balance is reached. At the end
of the addition of mineral phases performed on the product stream to produce a
product water with drinking water quality.
Seawater
desalination process to this day continues to grow around the world to meet the
needs of clean water and alleviate the problem of water crisis. Very intensive
research activities conducted and thorough at every stage of the process to
make this process more environmentally friendly, energy efficient and cheap.
The process is also suitable to be implemented in Indonesia, which is a
maritime country with a long coastline. The study of the energy that led to the
economic viability needs to be done further on the implementation of this
process.
