Reverse osmosis equipment has been used for many years to purify drinking water. It is used all over the world to desalinate seawater and bring fresh water to those with limited or no access to it. There are even household versions of reverse osmosis equipment to purify well water before it’s fed into the ice maker, for example. More recently, this technology is being used in industrial facilities to recycle the wastewater from manufacturing processes.
Reverse osmosis equipment facilitates the natural osmosis process in reverse. Osmosis occurs when a less concentrated saline solution is drawn to the higher concentrated saline solution. For example, a flower’s roots absorb water from the ground through osmosis. In reverse osmosis equipment, a semi-permeable membrane separates the higher concentrated water from the lower concentrated water. A little pressure is applied to the higher concentrated water, forcing it to flow through the membrane, where the salts and other particles become trapped. The result on the other side of the membrane is desalinated and filtered water.
The same reverse osmosis equipment has been scaled down for use in industrial facilities. Industrial reverse osmosis equipment uses a much higher pressure than desalination equipment, operating at 800 and 1,200 psi. Desalination equipment operates between 200 and 400psi. Because of the higher pressure, the industrial reverse osmosis equipment can treat water with up to 35,000 ppm of total dissolved solids (TDS) while the desalination equipment treats water with TDS up to 1,500 ppm. This allows the industrial equipment to remove most any dissolved solid found in wastewater, such as heavy metals.
The effluent quality exceeds discharge permit limits and is ideal for reuse. It is being used to recycle industrial wastewater at a rate of 75% to 95%, instead of treating and discharging. The purity of the effluent can even be adjusted, depending upon what the manufacturing process requires. For example, electronics manufacturers require high purity water.
The disadvantage of industrial RO equipment is the rate at which membranes can become fouled. Replacing fouled membranes is expensive and requires the unit to be shut down. That’s where pretreatment comes into play. With the right physical/chemical pretreatment process upstream, the life of the membranes inside the unit will be extended greatly. Cleaning membranes regularly can also extend their life.
It is no longer just a treatment for drinking water. It enables manufacturers to conserve water in innovative ways by recycling their wastewater. A Manufacturer in Texas is using industrial reverse osmosis equipment to recycle both their industrial wastewater and the facility’s sanitary water for reuse in their manufacturing process.