What is Reverse Osmosis?
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Reverse Osmosis (RO) is considered as one of the most effective water filtration methods. It helps us in creating clean and great-tasting water. The RO system is widely used. For example, it is used in houses, restaurants and aquariums.
Primarily, in reverse osmosis, contaminants are removed from unfiltered water (feed water). By applying pressure, unfiltered water is forced through a semipermeable membrane. During this process, water flows from the more concentrated side of the RO membrane to the less concentrated side (fewer contaminants), providing clean drinking water. While the fresh water produced is called the permeate, the leftover water (concentrated) is called the brine.
The small pores on the semipermeable membrane block contaminants allowing water molecules to pass through.
During reverse osmosis, If pressure is applied to a volume of salt water, clean water will flow through the membrane, leaving behind salt.
In a reverse osmosis system, sediments and chlorine are removed from water with a pre filter before forcing it through a semipermeable membrane for removing dissolved solids. Then the water passes through a postfilter. After this, the polished drinking water enters into its dedicated faucet.
Stages
In addition to the RO membrane, every reverse osmosis system will contain a sediment filter and a carbon filter.
- A sediment filter reduces particles like dirt, dust, and rust
- A carbon filter is responsible for removing volatile organic compounds, chlorine, and other contaminants which gives water a bad taste or smell
- The semipermeable membrane is responsible for removing 98 percent of the total dissolved salts (TDS)
- Prefiltration happens first as water enters a RO system. It includes a carbon filter and sediment filter for removing sediments and chlorine.
- In the next step, even the minute dissolved particles are removed, as the water passes through the reverse osmosis membrane.
- The filtered water flows into the storage tank. Filtration continues until the storage tank is full.
- A postfilter is attached to polish the drinking water, before it reaches the faucet.
Storage
It takes time to produce fresh drinking water using a reverse osmosis system. It takes at least one minute to produce a minimum of two to three ounces of water. This means that at the actual membrane production rate, it would take at least 5 minutes to fill a glass of water from a faucet! Hence a storage tank is important in an RO system, since it helps your glass fill instantly as you turn on the drinking water faucet!
Filtration
Arsenic and fluoride are filtered out with the help of RO membrane. While the sediment filter removes dirt and debris, the carbon filter helps in removing chlorine and bad taste and odors.
Basically a RO system helps us in filtering out fluoride, salt, sediment, chlorine, arsenic, VOCs, herbicides, pesticides and a slew of other contaminants.
Reverse osmosis system is however not really effective in removing bacteria and viruses from drinking water. UV disinfection method is recommended for removing living organisms and viruses from water.
Benefits of RO system
Using the RO system, we can remove 98 percent of dissolved salts, making water healthier to drink. The RO system is more efficient than a water distiller.
With the use of RO system, harmful dissolved contaminants in water get reduced. Sodium gets reduced. It is easy to install and maintain the RO system. It is environment friendly as well.
Installing a permeate pump, helps in increasing the efficiency of the reverse osmosis system. Using a permeate pump helps in reducing the wastewater from an RO system by 75 to 80%. The RO ‘reject’ water can be used for landscaping or artificial lakes.
Most importantly, the reverse osmosis system helps us provide water as pure as bottled water. Ultimately, it tastes refreshing without taking a toll on the environment!
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Reverse Osmosis system
Sediment filter and Carbon filter