Reverse Osmosis Plants – a Boon in Today’s Times

Introduction

A reverse osmosis plant is actually a plant that deionises water through the principle of reverse osmosis. Many of you might find the term difficult to understand, but the basics of the process are really simple to comprehend. Reverse osmosis utilizes water pressure and semi-permeable membranes to remove contaminants from drinking water and provide pure and clear water.

The principle of osmosis

However, before full understanding the process of reverse osmosis, it is necessary to understand the process of osmosis. This is a naturally occurring phenomenon, wherein a weaker saline solution tends to migrate to a strong saline solution as is in the case of plant roots which absorb water from the soil and human kidneys which absorb water from blood. This is based on the natural principle that a less concentrated solution has a natural tendency to migrate to a solution that has a higher concentration.

Reverse Osmosis

Reverse osmosis is the process of osmosis that happens in reverse. In this case, energy is applied to the more saline solution to allow water to pass through but not dissolved salts, chemicals, bacteria, and other pryogens. Thus, by pushing the water through the reverse osmosis membrane with the help of pressure higher than the natural osmotic pressure, reverse osmosis is achieved.

Reverse Osmosis Plant

A reverse osmosis plant consists of a high pressure pump to increase the pressure on the salt side of the RO membrane and force water across the RO membrane. This leaves behind around 95% to 99% of salts, organic particles, colloids, etc. in the reject stream. If the salt concentration of the feed water is higher, greater pressure will be required to overcome the osmotic pressure. The desalinated water which is demineralised is called the permeate or the product water, while the water that did not pass through the RO membrane is called the reject or concentrate stream.

A reverse osmosis plant actually consists of several components. These include a pre-filter, a post filter, RO membrane, and a storage tank. The pre-filter accepts piped city water or well water and filters out all the sediment and contaminants that can cause harm. However, the membrane does the actual filtering work. This is a semi-permeable membrane, which means that particles above a certain molecular size cannot pass through it. Thus water molecules can pass through the membrane but larger particles such as contaminants and others cannot pass through it. Once the water is filtered by the membrane, it is conveyed to the storage tank that stores the water. Any particles that remain at this stage are filtered out by the post filter. Thus, routine maintenance of the RO plant is necessary.

Reverse Osmosis Benefits

Today, many water sources have become polluted. This pollution is caused due to pollutants like chemicals, fertilizers, industrial waste, and household contaminants that can seep into rivers and other water sources. Clean water can be obtained through various means which require external intervention. For example, one can add chlorine to water for purification, but it leaves a bitter taste in the mouth. However, reverse osmosis does not require the addition of any chemical and is essentially a superior technology than others.