To understand the principle of reverse osmosis, we first have to look at the natural process of osmosis: Osmosis describes the process of equalizing the concentration of two liquids through a semi-permeable membrane. This process always occurs when two aqueous solutions with different ion concentrations are separated by a semipermeable wall. In nature, the osmosis is of the greatest physiological importance if only the solvent but not the dissolved substances are allowed to pass through the semipermeable membranes. Because on the one hand the water balance of the cells can be regulated and on the other hand an internal pressure can be maintained for stability. From a physical point of view, the ion solutions — which are separated from each other by membranes — always strive to achieve a concentration balance. This means that ions from the highly concentrated side want to move to the lower concentration side.

Since the membrane represents a barrier that the ions cannot easily move through due to its molecular size, the smaller water molecules flow from the low-concentration side to the higher-concentration side instead. The water molecules flow until either the ion concentrations on the two sides are balanced or a pressure is built up on the highly concentrated side — the so-called osmotic pressure. The osmotic pressure of a highly diluted solution obeys the laws that apply to ideal gases. It increases in proportion to the concentration of the solution and increases in proportion to the temperature.

How does reverse osmosis work?

In reverse osmosis, raw water is pressed against a synthetic, semipermeable membrane, which is closed for water molecules, but not for impurities in the raw water itself. On the other side of the membrane container is only clean water. The contaminants are washed away and carried into the drain. A water line pressure of 3 bar is sufficient to reach the raw water through the membrane. Reverse osmosis is the only way to get close to 100 % pure drinking water. It removes all pollutants such as uranium, nitrate, nitrite, fungicide, herbicide, residues of interest, hormone, asbestos, germs, bacteria etc. from the water. Since tap water with the substances contained therein flows continuously during operation, the substances retained by the membrane must be continuously removed to prevent the membrane from clogging. As a result, a reverse osmosis system produces not only the pure water but also waste water which contains the undesired substances in an increased concentration and which are washed away. This immediately shows one of the serious differences between reverse osmosis technology and techniques with accumulation filters.

The membrane is the most important part of the reverse osmosis process

The membrane is a complex structure. The average lifespan of the membranes you use is approximately 5 to 7 years. The cleaning performance and the yield of a reverse osmosis membrane depend on many factors. For example, from raw water pressure. Our household systems generally work at a water pressure between 2.8 and 6 bar. If your water supply has less pressure, this is not a problem either, because the market also offers individual solutions. The amount of pure water produced increases with increasing pressure. If, for example, a system at 4 bar and 10 degrees C produces 30 l / day, this system can produce twice the amount of pure water at double pressure. The ratio of concentrate to pure water also changes slightly at different pressures. But in small systems that are operated in the range of 3 m- 6 bar, this slight change in the ratio can be neglected.

 

For more information, contact Vinny’s Jersey Plumbing, located in Wayne, New Jersey.  We also service other towns in New Jersey, such as Parsippany, Wyckoff and Elmwood Park.