How do reverse osmosis systems work?
The water on our planet exists in a closed cycle, which means there is a constant amount of it, and nature continues to recycle the amount of water on the planet, however, what meets the human needs of this huge amount of the planet’s water, is the tiny fraction of freshwater without salt and not polluted.
Therefore, it has become necessary to exploit all the available possibilities to treat untapped water by establishing a drinking water treatment plant. This is done with many techniques, including reverse osmosis, and that is what we will present in this article to learn how to treat drinking water with this technology.
First: What is a reverse osmosis system?
Reverse osmosis means the flow of water molecules through a semi-permeable membrane selectively into a solution of lower salt concentration by applying pressure higher than the osmotic pressure to the more concentrated solution, in fact, reverse osmosis is achieved through a membrane that retains the solute on one side and prevents its passage and extracts the pure solvent from, On the other hand, this phenomenon is not spontaneous and requires corresponding mechanical action to be achieved in order to cancel the effect of osmotic pressure.
Second: The purpose of using reverse osmosis technology?
The main purpose of a reverse osmosis filter is to remove microorganisms and dissolved solids present in water. Dissolved solids include the minerals and organic molecules found in water. Among these small molecules, there may be some beneficial trace minerals, but the most often are toxic pollutants.
Reverse osmosis is not only applied in household water filters, but also on a much larger scale in sewage treatment plants, water desalination plants, and plants that extract salt from water, and this method is also used to make seawater drinkable and allows ships at sea to purify water sea for fresh drinking water.
Third: The mechanism of action of the reverse osmosis system:
Setting up such a system is not very simple. Water from building pipes or any other source enters the reverse osmosis machine and passes through a pre-filter, which is a filter placed before the semi-permeable membrane. The function of this pre-filter is to filter out all the large particles, such as sediment, dirt, and rust that may come through the water pipes. This filter is relatively inexpensive and increases the overall life of the reverse osmosis filter.
After passing through the pre-filter, the water reaches the semi-permeable membrane, also known as the reverse osmosis membrane. It is a carefully designed multi-layer membrane, made of polymers such as polyamide and cellulose. Polyamide can be manufactured, or obtained from natural sources, such as wool and silk. Cellulose membranes are the oldest, having been in use since 1955, but polyamide is more efficient.
A pressure pump is used to push water through a reverse osmosis membrane. The pore size of the reverse osmosis membrane is less than 1 nanometer, about 90,000 times less than the width of a human hair! These filters remove all germs in the water, along with other fine chemical compounds that may be present in it.
Some reverse osmosis filters may also contain post-treatment filters, which improve the taste of the water. One of the side effects of reverse osmosis is that the water usually tastes worse compared to the water inside. This is mainly due to the removal of trace minerals and other elements from the water. Natural freshwater usually contains some amount of mineral and organic water, so humans evolved to taste the mixture to cope with this side effect. The after filter may contain mineral balls that selectively regenerate the good minerals lost during the reverse osmosis process.
The final product coming out of the filter is clean, potable drinking water. Besides, waste and dirt leave the filter through another pipeline connection that goes to the drain.
Fourth: Advantages of reverse osmosis system:
Reverse osmosis systems are the best water systems available today, and they are better than other traditional options. Reverse osmosis systems filter bacteria, fungi, and viruses very effectively, many of which are responsible for causing common bowel diseases and other health disorders. These filters are also effective in removing toxic chemical components, such as heavy metals and various solid salts. The water that leaves the reverse osmosis system is free of 97-98% of dissolved ions and 99% of germs and other contaminants. The improved filtration capacity makes reverse osmosis filters far better than standard water filters that use heat, chemicals, or UV rays to treat water.
This technology is also completely environmentally friendly, as it does not leave much pollution, and there is no need to use chemicals in the process.
It is very common for reverse osmosis filters to incorporate additional filtration technologies, such as more efficient or multiple filters. It may include an additional filtration system such as a fixed ultraviolet light. The installed UV lamps emit ultraviolet rays, which kill all microorganisms in the water by damaging their DNA.
Fifth: Disadvantages of reverse osmosis system:
Unfortunately, nothing good is without its drawbacks. The main drawback of reverse osmosis systems is that the reverse osmosis plant is difficult to maintain.
A pump malfunction may cause the water pressure to drop, which means that the flow of water through the reverse osmosis membrane will be very slow. This will increase the time it takes for the reverse osmosis filter to purify the water. If the filters are not cleaned regularly, the reverse osmosis system may become clogged and bacterial biofilms can form inside the device. This brings us to the importance of carrying out the maintenance of the reverse osmosis plant on a regular basis.
Reverse osmosis technology is currently used all over the world to filter wastewater, tap water, and seawater. Research in this field mainly focuses on improving the sustainability of reverse osmosis filters, by reducing energy requirements and improving the durability of reverse osmosis membranes.