Water filtration process involves the process of water flowing at low speed through sand, granular bed or other suitable media. The use of the media is to retain most solid matter and let the water to pass. Usually, this process is repeated several times until all the unwanted particles inside the water are removed. When it comes to performing the process, there are several methods usually used. The method using sand and is processed at low speed is the oldest filtration method yet is still widely used until today.
Distillation is among the oldest water filtration process. The process requires the water to be boiled first. When the water has started to boil, water vapor will rise and head into a condenser to be condensed with the help of cooling water to lower its temperature. Then, the condensed water vapor is collected and stored. In liquid phase vessels, most of the contaminants stay behind.
In this distilled water, there are usually still some pesticides and herbicides known as carry-overs that can’t be fully removed by being boiled at less than 100 degrees Celsius. Usually these minor particles are concentrated in the water. This is among the disadvantages of distillation process. Apparently, there is also another disadvantage which is related to the cost. This process is more costly as it requires large amount of both water and energy to produce clean water. The possibility for the water to be very acidic is also high yet lack of mineral, oxygen and has flat taste. Therefore, it has to be contained in glass.
- Ion Exchange
This water filtration process involves the process of penetrate water through spherical resin materials that look like bead. Then, the ions inside the water are exchanged for different types of ions that can be fixed to the beads. Usually, deionization and softening are two most common methods for ion exchange.
Softening method comes as pretreatment method that works in reducing water hardness before reversing the osmosis processing. It involves beads that work to exchange 2 sodium ions for each of magnesium or calcium ion that is removed from “softened” water.
The advantages of this water filtration methods method include effective removal of dissolved inorganics, regenerable or service deionization and relatively affordable initial capital investment. Yet, there are also some disadvantages. This method unfortunately cannot effectively remove pyrogens, bacteria and other particles. Another disadvantage is the generating of culture bacteria and resin particles. The third disadvantage is high operation cost for long term.
- Carbon Adsorption
This third water filtration process is a common method widely used at home water filter treatment. It is often used because it can improve the water and remove any disagreeable odors and tastes including any objectionable chlorine. It can happen due to the activate carbon that effectively removes any gases and chemicals. In fact, it can also be an effective method against the microorganism.
Unfortunately, it does have disadvantage. It cannot fully dissolve hardness, heavy and solid metal. Therefore, carbon filter system is required for use in the process. However, not all of the carbon filter systems are certified. Only few that has been certified to remove cysts, asbestos, lead and coliform. Two most common carbon filter systems include solid block carbon and granular activate carbon. These methods work well together with the reverse osmosis system. Similar to other methods, this method of water filtration process does have advantages and disadvantages. Its advantages include long life with high capacity of water filtration and ability to remove chlorine and dissolved organics effectively. Meanwhile, its disadvantage is it generates carbon fines.
- Microporous Basic Filtration
The fourth method of water filtration process consists of three types, the depth, surface and the screen. The screen filters are naturally uniform structure that look like sieve and are able to retain any particles that are even larger compared to the controlled pore size found on their surface. Depth filters are materials like matted fibers compressed until they form matrix that can retain any particles through entrapment and random adsorption. Surface filters on the other hand are multiple layers of media. All the particles larger compared to spaces within matrix for filter are retained when the fluid of water passes through filters. Then, they accumulate on the filter’s surface.
The advantages of this method of water filtration process include its ability to remove most particles including microorganism, collois and pyrogens above their rated size. And it also can produce water in highest quality with the least energy amount. The third advantage is it being regenerable. But there is also disadvantage as it cannot remove dissolved inorganics.
- Reverse Osmosis (RO)
This method of water filtration process is known as the most economical as it can remove up to 99% of all the contaminants. This method has pore structure that is much tighter compared to the UF membranes. This is the reason why it is capable to reject any particles including organics, pyrogens and bacteria with the size of less than 300 daltos molecular weight. Therefore, it is often used by big bottling plants that make great sale.
In this method, the concentrated solution is being applied with hydraulic pressure in order to counteract osmotic pressure. Then, the pure water is driven and collected downstream from the concentrated solution. It requires storage tanks in order to produce pure water in an adequate volume in reasonable time amount. This method also involves the process of ionic exclusion.
The RO method has some advantages including its ability to remove all contaminant types effectively including colloids, microorganism, pyrogens, dissolved inorganics and particles). It is also minimal in maintenance. However, there is a disadvantage where the flow rates are limited to certain amounts of gallons per day. Despite of this disadvantage, it is the most economical with the best result used by big water filtration plant.
From the explanation above, each method of water filtration process has its own advantages and disadvantages. Therefore, choosing the right method means considering the needs and conditions. With the right method, the expected result will be obtained.