When talking about reverse osmosis, one needs to understand what it is a reversed of. Osmosis is basically the movement of water from a high concentration to a low concentration through a semi-permeable membrane. In osmosis the water from a dilute solution will naturally move through a separating membrane to the concentrated side to equalize the concentrations of the both solutions.
However, when pressure is applied to the concentrated side, the natural flow is prevented and what results is the reversal of the process. The water will now flow out of the concentrated solution instead of into it. This is what we refer to as reverse osmosis. This process is more commonly used for a variety of filtering purposes. Reverse osmosis has a number of different types.
As you might already know, reverse osmosis is a pretty common and effective process used for filtering unwanted pollutants or contaminants from the water supply. This ensures that pure and clean water passes through the other side. Aside from the drinking water use, reverse osmosis has become quite a popular process for cleaning up our water but aside from home use, the whole reverse osmosis have become quite useful in laboratories, medical facilities, desalination, pre treatments and other industrial usage.
The differences of the basic types of reverse osmosis systems lies on the number and kinds of membranes or filters used. For instance, the reverse osmosis floor water type utilizes at least nine stages of filtration processes. Each stage removes specific kinds of contaminants. For instance the first stage removes organic contaminants which can cause bad tasting or smelling water. Because of the number of filters, the quality of the water filtered is unquestionable. However, due to the number of filters the process is relatively slow. On an hourly rate, this system can only clean a little above one gallon of water.
Another water filter which utilizes reverse osmosis is the counter top model which is great for home or office use. Depending on the manufacturer, the counter top features from four to nine filtering stages. More often than not, it also features hot and cold power switch. One the average, this filter can provide one and a half gallon of filtered, clean water per hour. A key advantage of a counter top model is being portable.
There are reverse osmosis filter systems that offer a continuous flow of filtered water. This kind does not use any storage facility. It is installed under the sink and features basically the same multi stage filters. Some would include carbon filters in their system which gives the advantage of having reverse osmosis membranes and carbon filtering technology. Since it has no tank, you get purified water only when you open the tap. This is good for areas where water supply is very reliable.
Talking about reverse osmosis membranes, we can still differentiate them from either cellulosic membranes, to fully aromatic polyamide or to thin film composite membranes. Cellulosic membranes are made up of thin dense porous substances which can come in sheets or hollow fibers. Aromatic polyamide membranes, on the other hand, are quite similar to cellulosics but react better to organic materials and generally last longer. The thin film composites meanwhile are made up of thin, dense, solute rejecting surface film which is placed on top of a porous substance.
The different types of reverse osmosis systems are not only based on the system itself but also on the filters or membranes used. When selecting one, it is important to know how much and what kinds of contaminants a system could filter.