Osmosis is a chemical process where water is passed through a semipermeable membrane to separate the unwanted substances that are dissolved in water. Wilhelm Pfeffer, a German physiologist, first studied the process of osmosis in 1877.
What is Reverse osmosis?
When polluted water is passed through a U-shaped tube where the semipermeable membrane is fixed in the middle, it blocks all the unwanted solvents, only letting out smaller solvents that are less harmful.
Reverse osmosis was introduced to diffuse seawater by separating all the salt particles. To generate osmotic pressure in RO systems, you need to add some external pressure, which will push the salty water to pass through the semipermeable membrane and to let out fresh water.
In this way, several membranes are made to decontaminate the water from harmful solutes like arsenic, fluoride, nitrates, and several other bacteria that are present in water.
Types of Osmosis
There are two types of osmosis:
Endosmosis: When a cell is placed inside a hypotonic solution and water flows from higher concentration to lower concentration performing deplasmolysis is known Endosmosis.
Exosmosis: When a cell is placed inside a hypertonic solution, then the solvents particles flow outside the cell performing plasmolysis is known as Exosmosis.
How is reverse osmosis useful to us?
Reverse osmosis is used in water purifiers to purify water and blocks all the wastes allowing only smaller solutes to pass through. The desalination of water via RO systems started in the 1950s. RO systems were installed in large factories to turn salty sea water into fresh potable drinking water. However, a lot of other filters were also installed like carbon and activated charcoal filter, which removes the organic contaminants like bacteria as well.
What is the disadvantage of the RO system?
Nowadays, almost every household has a water filter due to the increased number of pollutants and harmful diseases. There are a lot of brands that provide filters, but the common thing is the RO system, which is present in almost every filter which blocks all the waste particles but the problem in RO system is it wastes a lot of water; around five times the water is wasted than purified.
Another problem with the RO system is it also filters out the essential salts that our body needs like zinc, magnesium, and calcium. Due to the immense waste of water through RO systems, the environmentalists protested against using RO systems and succeeded in convincing the National Green Tribunal to RO systems in Delhi.
The cost of the RO systems is high, and it cuts down the incentive for the government water distribution systems, and people who are financially ill can’t afford such costly systems.
What is the condition of filtered water that is distributed across the country?
Recently the Department of Consumer affairs checked the quality of water according to the Bureau of Indian Standards; none of the samples that were drawn from all over the country, even from the metropolitan cities like Delhi, Chennai, Kolkata, and Bengaluru didn’t fulfill the requirements of BIS except Mumbai where most of the samples did.
The Prime Minister of India, honorable Narendra Modi, has committed that by 2024 the whole country will get the service of tap water.
