What is Reverse Osmosis | Kitchen Judge

The reverse osmosis water filter system of water purification is used especially with patients who have stone problem that needed dialysis to clean their body. The water purified by the reverse osmosis water filters is the safest water to clean the body of a person whose kidneys are no longer working properly.

To have this kind of water purification system is standard operating procedure for most dialysis centers because the use of only tap water in the dialysis machine will contaminate the patient and may even kill the patient in the process.

The membrane of the reverse osmosis system is semi-permeable. It only allows pure water to pass through and rejects the contaminants. After passing through the reverse osmosis water filter, it strains larger molecular composition compounds than water as well as restricts the entry of bacteria and disease causing pathogens. The system is most commonly used in the treatment technology of bottled water as well as in the desalinization process. The desalinization plants also use reverse osmosis water filters in order to produce mineral free water from salt water. With the use of reverse osmosis water filters that has activated carbon, the water is thoroughly purified.

Crossflow is the process used by the reverse osmosis water filter system. It allows the reverse osmosis membrane to continually clean itself. The membrane has very small pores that restrict the entry of organic compounds like salt and natural minerals, which has a much larger molecular structure than water. However, the reverse osmosis membrane can only do so much, without the help of reverse osmosis water filters, which have activated carbon contaminants from chemicals like pesticides, herbicides, and chlorine can still penetrate the semi-permeable material of the membrane since the molecules of these chemicals are much smaller than that of water.

The contaminants strained from the reverse osmosis water filter and the membrane are drained and separated from the water. For every gallon of reverse osmosis purified water two to three gallons of water are wasted because of the process. It is a very slow process of decontaminating water but the safest there is if the need for pure water is in demand.

As the water passes through the reverse osmosis water filter and the membrane a couple of times the harder ions like calcium remain. This strips off minerals that naturally are found in water which are at times helpful to the body. Also these natural minerals adds natural taste to water and if take off makes water tasteless. And also this makes the water hard for drinking especially with the presence of the harder ions so what is usually done is that a water softener is added to the water to replace the harder ions with sodium. In this way water is much easier to drink and will not irritate the esophagus when taken in.

The reverse osmosis system allows water to pass through the reverse osmosis water filter and then to the membranes then is recycled back to the front of the system again for another cycle of purification. On the second pass through the reverse osmosis water filter and the membrane a bleed is taken off and goes straight to the drain. This allows very high system of purification.

Water that runs through the reverse osmosis water filter is devoid of its natural minerals is sometimes harmful to the body since some of the minerals naturally occurring in water are good for the function of the body system.

But to those who needed this kind of water just like the patients whose kidneys are no longer functional it is very beneficial to them. A single contaminant in the water mixed in their dialysis will mean life or death to them. A Reverse osmosis water filter is very important to these people it is their source of prolonged life without which a diagnosis of kidney trouble is a pronouncement of death.

Contents

How a Reverse Osmosis System Works
Basic components of a RO System:
Applications of Reverse Osmosis System in Life
Applications of Reverse Osmosis System in Life

How a Reverse Osmosis System Works

To better understand how a reverse Osmosis system works, you should first have a firm grasp of the basis – what is osmosis and how it works.

To put it in a simply, Osmosis is the movement of water molecules or other solvents from a region of high concentration to a region of low concentration through a semipermeable membrane, from that description, one thing is clear, an RO system makes use of a semi permeable membrane. Semi permeable means that the membrane allows certain molecules to pass through and not others.

The best example that you might be aware of is a furnace air filter. However, unlike the air filters, whose semipermeable membranes separate the contaminants exclusively by size, semi permeable membranes in RO systems separate the contaminants based on size as well as the charge of the molecules. The pores in a semipermeable membrane are designed to let through water molecules only. Paint pigments and smoke particles are way too large to pass through these pores. As a matter of fact particles that are 1/1000th of a micron are too large to pass through the membrane. This is to mean it can block the passage of the tiniest of viruses and ions present in the water.

The reverse osmosis technology to a great extent relies on pressure to push through the water molecules. The water pressure however varies with your source. The city water delivers its water at pressures between 40 and 100 psi. Water from the well has lower pressure than this (between 20 and 60 psi depending on the power of the pump you use). The production rates of the system on the other hand vary depending on the pressure, temperature and the total dissolved solids. And since the production and the flow vary greatly, many of the RO systems have a storage tank of their own, making available pure water at all times when the need arises.

And because the water produced is very pure, bad odors and tastes from the storage tank’s walls and bladder can find their way into the water after a long time in contact. As such, they have to be gotten rid of. It is for this reason that a post filter is important in the whole process. It removes all bad odors and tastes gotten from the storage tank and restores the great taste of purified water.

In the event the pH is too low, the whole house systems make use of a polisher after the post filter stage which adds minerals to the water and further enhances the taste.

Basic components of a RO System:

Cold Water Line Valve: fitting onto the cold water supply line and attaching to the inlet side of the RO pre filter though a tube. This is the water source for the RO system.
Pre-Filter (s): Water from the cold water supply line enters the RO pre-filters first. They are usually sediment filters, which can remove dirt, sand silt and other sediment. Besides, carbon filters may be used to eliminate chlorine.
RO Membrane: This is the heart of the system. There are two selections: the CTA (cellulose tri-acetate), which is chlorine tolerant, or the TFC/TFM (thin film composite/material), which is not chlorine tolerant.
Post filter (s): The product water will go through the post filters after leaving the storage tank and before going to the RO faucet. They are usually carbon (in granular or carbon block form) and have ability to remove odors and bad taste.
Automatic Shut Off Valve: When the storage tank is full, this valve will stop any further water from entering the membrane, therefore stopping water production.
Check Valve: located in the outlet end of the RO membrane housing, preventing the backward flow or product water from the storage tank.
Flow Restrictor: Water flow through the RO membrane is regulated by a flow control. This component maintains the required flow rate to gain the highest quality drinking water. In addition, it helps maintain pressure on the inlet side of the membrane.
Storage Tank: The capacity of the RO storage tank varies from 2.5 gallons up to tens of gallons of water.
Faucet: usually installed on the kitchen sink. Each RO system uses its own faucet.
Drain line: running from the outlet end of the RO membrane housing to the drain, used to get rid of the impurities and contaminants found in the tap water.

Applications of Reverse Osmosis System in Life

In food industry

Besides desalination purposes, Reverse Osmosis System is also an application in filtering food liquids (such as juices) in stead of normal process so far. Researches were conducted on concentration of orange juice and tomato juice. The advantage of RO System includes lower operating costs and the ability of avoiding heat treatment process.

This system is consistent with heat-sensitive substances such as proteins and enzymes in most of food products.

RO System is extensively used in the dairy industry to produce whey protein powder (the remaining liquid from cheese production) and concentration of milk to reduce shipping costs.

Milk will be concentrated by Reverse Osmosis System; the solids total is from 5% up to 18-22% in order to reduce crystallization and lactose powder drying costs.

In wine production industry, Reverse Osmosis System is widespread used. About 60 Reverse Osmosis System machines are in operation in Bordeaux (France) by the end of 2002.

Car wash water treatment

Because of lower mineral content, Reverse Osmosis System is popularly used in car washing for the final phase which prevents water spotting on the vehicle.

RO System is popular in US for conserving and reusing water within the car washing industry.

Especially in areas which are effected by the droughts, water conserving and reusing are incredibly important. It also helps car wash workshop owners to reduce costs of drying vehicles and blowing equipment.

In Syrup production

In 1946, a syrup factory started to use RO System to remove water from tree sap before boiling it to produce syrup. Using RO System allows 40 – 50% of water volume to be removed from tree sap, it helps to reduce energy consumption and limit exposure of the syrup to high temperatures.

In hydro production

For small-scale hydrogen production, RO System is occasionally used for preventing formation of minerals on the surface of the electrode.

In fish cultivation treatment

Many coral reefs and fish lakes are installed a Reverse Osmosis System to make an artificial mixture of seawater. Ordinary tap water may contain too much chlorine, chloramines, copper, nitrogen, phosphate, silicate, and other chemicals which are harmful for sensitive creatures in coral reefs environment.

Pollutants such as nitrogen compounds and phosphates can lead to eutrophication. A great combination of RO System and deionization is quite popular for fish cultivation treatment in coral reefs and lakes. It is ideal for a low ownership costs and minimal operating costs.

Desalination

Reverse Osmosis System does not use heat to operate so it requires less energy than other desalination methods in comparison. The typical desalination system of RO System includes: Pretreatment, high pressure pump, filter installation, chemicals for filter preservation and pH adjustment, disinfection and control panel.

Pretreatment is very important to protect Reverse Osmosis filter and Nano filtration or ultra filtration. This requires high pressure pump. The filter wall must be strong enough to withstand the pressure of the pump. RO filter is made of several constructions of matrix filter; with the two most common structures are spiral and hollow fiber.

Antiseptic

Reverse Osmosis System is an effective barrier to prevent the pathogenic bacteria. However, in some cases of water treatment process, the RO filter may be damaged and water will possibly have recontamination. Antiseptic with a combination of RO System and ultraviolet light are totally safe and sure for completely sterile water.