Short overview of filtration types: reverse osmosis, filtration, carbon adsorption, UV irradiation, ion exchange and distillation

This article provides a comprehensive overview of different types of water filtration systems, including reverse osmosis, carbon filtration, UV disinfection, ion exchange, and distillation. Each filtration system has its own unique advantages and limitations, making it important to choose based on your specific needs and expectations. This informative article also emphasizes the importance of amalgamating different technologies in a water treatment system to achieve optimal performance and cost-effectiveness.

Reverse osmosis (RO) is one of the most popular water filtration systems, but it's not the only one. In this article, we'll compare RO to other types of filtration systems, including filtration, carbon filtration, UV disinfection, ion exchange and distillation.

Water filtration is a crucial process when it comes to ensuring access to clean and safe water. There are several types of water filtration systems, each with its own unique set of advantages and disadvantages. Among these filtration systems, reverse osmosis has gained in popularity due to its high efficiency in removing impurities. In this article, we'll compare reverse osmosis filtration to other water filtration systems to help you determine which is the best option for your situation.


Reverse Osmosis

Reverse osmosis is a water filtration process that uses a semipermeable membrane to remove impurities from water. The membrane allows water molecules to pass through, but blocks larger molecules such as minerals, bacteria, and dissolved solids. Reverse osmosis is known to be highly effective in removing a range of contaminants, including lead and chemicals. It is also capable of removing salt from salt water, making it a popular choice for desalination plants.

One of the main advantages of reverse osmosis is its ability to remove impurities without the use of harsh chemicals or electricity. It is also known for producing tasty, clean water, making it a popular choice for domestic use. At industrial levels, it is very popular due to its performance and the low costs associated with its use.

 However, reverse osmosis generally requires considerable water pressure to operate properly, which can be a problem in areas where water pressure is low. It also tends to waste a significant amount of water, as the process of forcing water through the membrane produces a large quantity of wastewater. Known as concentrate, this wastewater can, however, be retreated to reduce losses, or it can be reused for specific purposes, such as regenerating the resin in an ion exchanger.

Carbon Adsorption

Activated carbon filtration is another popular method for removing impurities from water. This filtration system involves passing water through a carbon filter, which retains impurities thanks to its adsorptive power, and removes them from the water. Activated carbon filtration is effective in removing a range of contaminants such as chlorine, volatile organic compounds (VOCs) and certain heavy metals.

One of the main advantages of activated carbon filtration is its ability to improve the taste and odour of water. Unlike reverse osmosis, it does not require high water pressure to work properly and does not produce wastewater.

However, activated carbon filtration has certain limitations. It is not capable of removing dissolved solids or micro-organisms, which means it is not a suitable option for areas where the water contains high levels of minerals or bacteria. What's more, where carbon filtration is carried out via filters, the filters have to be changed frequently, which can prove costly. On the other hand, many industries opt for carbon filtration via a carbon bed installed in a tank similar to those of a water softener.



Ultrafiltration is a water filtration system that uses a membrane to remove impurities from water. It is similar to reverse osmosis, but uses larger pores, enabling it only to remove larger particles such as bacteria, viruses and even some small viruses. Ultrafiltration is mainly used for water treatment in areas where bacterial contamination is common.

Ultrafiltration is therefore effective at eliminating bacteria, viruses, and germs, making it an ideal option for areas with high bacterial contamination. It also produces less wastewater than reverse osmosis, making it an environmentally friendly option.

However, ultrafiltration is not effective at removing dissolved solids, chemicals, and minerals, which means it cannot be used for desalination. It also requires a considerable amount of energy to operate properly, making it a more expensive option than other filtration systems.

Without going into the details of the other types of filtrations (microfiltration and nanofiltration), they both work on the same principle as ultrafiltration, the difference being the size of the pores the membranes have. In other words, nanofiltration removes particles from 0.001 to 0.01 um, while microfiltration removes particles from 0.1 to 10 microns. In comparison, ultrafiltration generally removes particles from 0.001 to 0.1 um.



Distillation is the process of boiling water and collecting the resulting steam. The steam is then condensed back into pure, contaminant-free water. Distillation is an effective way of removing impurities from water, such as bacteria, viruses, and minerals.

Effective in producing clean, safe drinking water, distillation is also capable of removing trihalomethanes and chlorine from water. 

However, distillation is less efficient than other filtration systems, as it requires a lot of energy to heat water to boiling point. Nor does it remove volatile organic compounds, which are harmful chemicals commonly found in water. 


UV disinfection:

UV disinfection, or UV irradiation, is a process of purifying water by exposure to ultraviolet light, which kills bacteria, viruses, and other micro-organisms. UV irradiation works because the DNA bases of micro-organisms absorb ultraviolet light. During ultraviolet absorption, changes in chemical bonds occur, affecting the cell's ability to multiply. Since this type of treatment eliminates micro-organisms, but does not extract them, UV disinfection is often used in conjunction with other filtration methods, such as sediment and carbon filters. 

One of the advantages of UV filtration is that it is an effective way of eliminating bacteria and viruses without the use of chemicals or high maintenance. However, it does not remove dissolved solids or other impurities that reverse osmosis can, so it is not optimal for water with a high mineral content or other contaminants.


Ion exchange:

Ion exchange is a process whereby contaminant ions in water are exchanged for non-contaminant ions. For example, water softening removes calcium and magnesium, exchanging them for sodium ions. This process is often used in regions with hard water, which can lead to scaling of equipment and pipes. Other types of ion exchangers include dealkalizers, demineralizers and deionizers.

Whatever the type of ion exchange, the exchange takes place thanks to acid or basic radicals found in the molecular structure of the resin, enabling an exchange between those in the liquid to be treated and those on the resins.

The advantage of ion exchange is that it is highly effective in removing the dissolved minerals responsible for water hardness, but it does not eliminate other impurities, such as bacteria, viruses, or VOCs.



Choosing the best water filtration system depends on your water's contamination levels, your budget and your personal preferences. Reverse osmosis, and all the other types of filtrations discussed above, have their strengths and weaknesses. That's why it's important to choose the type of water treatment technology you need based on your needs and expectations. It's also important to note that in most cases, water treatment systems don't consist of a single technology, but rather an amalgam of technologies that are installed in a precise order to optimize system performance and costs. 


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