How do filters & filtration work?

Why do we need to filter our water?

Water is a part of the very basic needs for survival and water is such that it is amazingly good at dissolving other things. You would see this in action when adding salt to water or as water erodes away shorelines. Water is never gone from the earth and the same water that you are drinking may very well be the same water that dinosaurs drank!

So water may be contaminated from external sources such as pesticides, pollution or even from the corroding of old pipes which will leach particles of iron, copper or others. which is why sometimes the water may taste weird or metallic. Through filtration, we are able to remove all unwanted foreign contamination to ensure the water you drink is clean and healthy.

So how do filters work?

Filters work primarily through 2 means, either physical or chemical filtration.

Physical Filtration

Physical filtration is simply like a sieve, where particles larger than a certain size is removed physically. A basic example of a physical filter is using polypropylene filters or string wound filters. These are considered pre-filters, and their role is to handle the basic filtration to extend the lifespan of the finer filters located after this process. As their purpose is to catch particles, they would be required to be replaced at a much faster rate as compared to the chemical filters, but are also a lot more affordable.

Chemical Filtration

Chemical filtration is through the use of an activated media, to chemically absorb or adsorb the unwanted ions onto the surface of the media. This can be through Activated Carbon, which will absorb chlorine and other chemicals in the water, removing foul taste and odour causing compounds. Activated Carbon filters are usually installed in concurrent with a pre-filter, especially if the water quality is poor. This is enable the Activated Carbon to focus on chemical removal without particles blocking the surface of the filter.

Other forms of filtration methods

Ion Exchange

Ion exchange is most commonly used to ‘soften’ water, where a high presence of certain minerals can cause the water to be ‘hard’. Ion exchange does an exchange of ions within the ion resin and the water, releasing and adsorbing the ions that the resin is meant to be used against.

Reverse Osmosis

Osmosis is the natural phenomenon where if 2 liquids are separated with a semi-permeable membrane and 1 liquid is more concentrated than the other, the less concentrated liquid will flow into the more concentrated liquid to create a balance. Reverse Osmosis is the process of applying pressure to reverse the flow such that all the water in the concentrated solution will be forced out. This process is used especially in desalination or highly contaminated water, where water can be purified by this method.

It is an excellent method of filtration, however, it requires high electricity consumption to generate the pressure, and also wastes a lot of water, due to the rejection of high concentrated salt solution which can be a problem also. Another issue with Reverse Osmosis is that the process will remove all concentrated salts including all essential minerals, leaving the output with a lack of minerals. Having water too pure is not suitable for human consumption

Distillation

Distillation is the process of boiling water, then capturing the steam and condensing it. It is a good method when other treatment are not available, but can waste unnecessary energy and water.