Water treatment is essential & an absolute necessity in today’s times!
Healthy drinking water is the birthright of every living being. The population of humans on earth is multiplying at an unusual rate. We are facing extreme difficulty in managing abundant resources like food & water for survival.
Rapid industrialization & increasing desires of people have forced companies to increase factories & production.
More production means more exploitation of natural resources!
Water is Life & Clean Water Means Health
– Audrey Hepburn (Humanitarian)
People like drinking branded mineral water. Factories have entirely exhausted the underground water resource to cope up with the demand, and followed by more factories that release their untreated wastewater into rivers.
The result was untreated, unhygienic water in infected water bodies.
There is sharp multiplication in permissible limits of heavy metals & dangerous toxins. Making the water completely unfit for drinking & other activities.
Water, Water Everywhere and Not a Drop to Drink
– Samuel Taylor Coleridge
Why Water Treatment is Essential for Survival of life?
Water treatment is an essential process to remove poisonous toxic chemicals from untreated water & drastically improve water quality.
The treatment process initiates before releasing the treated water into rivers for drinking & farming-related activities.
Untreated water may contain uncountable
- Heavy metals
- Non-degradable waste
- Radioactive contaminants
Consuming untreated water can lead to numerous body infections including diarrhea, dysentery, pneumonia, cancer, poisoning & even death.
Here is the Water Treatment process :
Step 1: How water is cleansed ?
Raw water from huge water bodies like rivers or ponds is diverted to a high capacity basin/tank.
At this stage, Alum mixes into water. It forms tiny sticky particles known as flocs when mixed with water.
Flocs attract the smaller particles in raw water to form bigger particles.
Now, how to separate the dirtier floc from water ?
Now comes the sedimentation stage, where floc loaded water flows into a giant basin.
Water is left stagnant in the sedimentation basin for some time. Due to this, floc eventually becomes heavy & settles down at the bottom of the tank due to gravity.
Now water is clear but still not fit for drinking. It has to be filtered & disinfected.
Step 2: Disinfection of water
Filtration in water treatment is essential. Water from the basin flows in for filtration through sand filters and activated Carbon layers.
Sand filters help in the instant removal of dangerous protozoa & filters about 98-99% of bacteria from water.
Activated Carbon controls foul smelling odour & water flavour.
These are macro carbon particles which are very effective in reducing numerous chemicals such as
- Chlorine bi-products
How disinfection of water is done?
Chlorine disinfects drinking water in pre-stage & post-stage filtration process.
It is the most powerful disinfectant to kill disease-causing pathogens. Chlorinated water prevents the spread of diseases like Jaundice, cholera, gastroenteritis & dysentery.
Pre-chlorination is done in the pre-filtration stage. This controls the biological growth of unwanted microbes in the storage tanks.
Water is cleansed by Chlorine which oxidizes heavy metals like iron & manganese. They too can be removed in the disinfection process as they become heavy to settle down in the tank.
Step 3: Post Treatment
The post treatment stage varies from country to country across the world.
In western countries, advanced & costly procedures like Reverse Osmosis(RO), Ozone/UV water treatment used to deal with the grave challenges arising from varying geographic conditions.
How does Reverse Osmosis Water Treatment works ?
We must know about Osmosis first !
Osmosis is a naturally occurring process in which a liquid like water spontaneously passes through a membrane. The membrane acts as a semi-permeable barrier to the liquid from which the majority of salt molecules are unable to pass through it.
Aha ! Now we get pure water minus the salts !!
Usually, the natural flow of water from a membrane is from a less concentrated solution (purified water) to a more concentrated solution (salted water).
What is reverse osmosis ?
Water flow is reversed & pressured to enter the semi-permeable membrane to get purified water. Then this process is known as reverse osmosis.
Which materials are used to make RO membrane ?
They are made up of a thin Polyamide layer deposited on top of Polysulfone & a polyester base at the bottom. RO membranes can be as thin as 0.0001 microns.
These membranes are wrapped like a sheet & sealed inside a cylindrical structure to cater to customized requirements.
Reverse osmosis (RO) use multi-stage systems in industries & municipality which need high water recycling.
Requirement of RO membrane pipes decrease as per the increasing stages.
Example : In case of 4 stage RO system –
Suppose Stage 1 needs 10 pipes
Stage 2 will need 5 pipes
Stage 3 will need 3 pipes
& then Stage 4 will need only 1.
Curious to know why ?
Wastewater pressure at the end of each stage keeps decreasing! So, lesser no of RO cylindrical membranes recover water.
If water recovery needs more improvement, then one needs to install RO motor at each stage to increase water pressure, which is a very costly solution.
How effective is reverse osmosis ?
- 99.99% protection against bacteria & viruses
- Removes excess unwanted salts from water
- Removes harmful toxins like lead & arsenic
- Converts unfit hard water into drinking water
- Preserves taste & quality of water
- Does not adds any chemical to your water
- Required minimum cleaning & maintenance
- Energy requirement is extremely low
Methods for disinfecting water?
Ozone(O3) is an unstable form of O2 which is the most powerful oxidizing agent.
Ozone in water helps :
- Destroy micro-organisms
- Removes many Na, K ions
- Changes the taste of water
- Neutralizing the fertilizers
How Ozone water treatment is done?
Ozone is highly unstable & has to be created on-site due to its poor half life.
To create on-site ozone we need to use :
Water + Electricity + Catalysts
Ultraviolet(UV) Light + Air
Ozone is suggested to be added at the initial stage of water treatment as it helps in coagulation. It helps in making the particles bigger which settle down at the bottom of the tank.
The addition of Ozone disinfects water but it is equally dangerous if not removed from the water. So, ozonated water is filtered with activated carbon to remove ozone.
UltraViolet (UV) Light
How does it works :
Salts needs instant removal from treated water before UV exposure. If water is salted, then it shields micro-organisms present in water.
So, if water transparency is greater ! Greater is the UV exposure which kills the pathogens
That’s the reason; the UV stage comes after reverse osmosis & carbon filter stage, which help in sanitizing water.
Advantages of UV :
- UV can destroy & break the DNA of any micro-organism
- Ensures Sterilization of water
- Get a 100% kill rate of micro-organisms
- Exposure is the key to achieve water purity
So, if simple water is without any heavy metals, then ultraviolet (UV) rays are used to destroy viruses & bacteria.
But if water is loaded with urea, heavy metals & other pathogens, then Ozone is used at this stage.
This effectively breaks up the cells of unwanted components to give pure drinking water. Home & commercial usage of RO water purifier requires both Ozone & UV purification methods for disinfecting water.
I hope we understand as to why water treatment is essential. Its demand is growing at breakneck speed & would continue to grow.
Every nation should aggressively play their roles in preserving natural resources & help spread public awareness against littering water with waste.
We must understand that rivers are not the dumpyard of sewage water & waste!
Consciousness & a little bit of effort can help solve any problem.
Save Water ! Save the Planet !! Save the Human race !!!