Recently, several people left these questions in the comment area:

What is reverse osmosis?

What is reverse osmosis water?

How does reverse osmosis work?

I have worked in the water treatment industry for eight years. Even so, explaining this concept in plain daily words is not as simple as it sounds.

We can easily understand a membrane. It is just a kind of filtering material.

Osmosis is a natural phenomenon, and we can even call it a natural rule. Solutions with low concentration will move toward solutions with high concentration by themselves. This is the inherent property of osmosis. Let me give you a common example from daily life in China: pickling cucumbers.

Cucumbers contain lots of water and very little salt inside.

We spread plenty of salt on the outside, so the salt water there has an extremely high concentration.We do not need any external force. The water inside cucumbers flows out automatically. The cucumbers turn soft little by little, and more water keeps leaking out.

We name osmosis the process where liquid flows from a low-concentration area to a high-concentration area.

Now let us talk about reverse osmosis.The word "reverse" means this process goes against the normal natural rule. In other words, people add external pressure on purpose. This pressure pushes water to flow from the high-concentration side to the low-concentration side, and we call this whole process reverse osmosis.

Why did human beings invent reverse osmosis to counteract natural osmosis, instead of only using natural osmosis to solve practical problems?

Our purpose of filtering is to keep the clean water we need and discharge the unwanted substances. However, if we only depend on natural osmosis, the final result will be completely opposite to our demands.

Here is a typical example:Suppose we have a bucket of seawater, and we want to get fresh water for drinking.

If we only rely on natural osmosis without adding extra pressure, one side of the membrane holds seawater (high concentration), and the other side connects to an empty bucket filled with fresh water. Under this condition, even if we use the membrane to filter seawater, water will keep flowing back to the seawater side. The empty bucket will never collect drinkable fresh water.

But when we use reverse osmosis, we apply strong pressure to the seawater side. This powerful pressure offsets the natural pulling force created by osmosis. Clean water passes through the membrane and enters the empty bucket, while all salt remains in the original bucket. As a result, we get usable fresh water in the empty bucket, and the high-salinity concentrated water left in the original bucket can be discharged directly. This method perfectly finishes the water purification task.

In short, reverse osmosis is a manual control technology based on the natural law of osmosis. People create it to make filtering fit our real practical demands.

That is all for the basic definition of reverse osmosis membrane today. If you still have any confusing points, feel free to leave messages and communicate with XBYMC anytime. I, the monitor, will reply to your messages as soon as I can.