Water filter with reverse osmosis: how it works, the pros

The most effective and meet the needs of the system time to purify water based on reverse osmosis technology.

How does a water filter with reverse osmosis

What is reverse osmosis?

Using a reverse osmosis technology is that of a more concentrated solution, which is water with dissolved inorganic and organic therein substances, by passing through the semipermeable membrane into the less concentrated under very high pressure, only water molecules pass through the small size then.

Reverse osmosis membranes made from a composite polymer of uneven density, consisting of two layers, interconnected inseparably. The outer barrier layer has a thickness of about 0.00001 inches. It is located on the less dense filter layer 0.005 inch thick, which is permeated with an incredible amount of micropores.

In household and semi reverse osmosis filter elements used roll.

In such an embodiment the semi-permeable membrane is enclosed in a flask with inlet and outlet for connection to water supply, and is a coiled polymer film composed of two layers, the drainage and The water supply.

On installation fed raw water under high pressure, which is being filtered, forming a permeate (filtrate) and concentrate (impurities).

Permeate is collected on the membrane and the drainage layer spirally flows in the central tube. The concentrate is stored at the other end and then drained into the drainage.

The types of membranes used:

• Ultrafiltration - pore size - 0,1-0,002 microns. Capable of retaining the colloidal suspension, bacteria and viruses.
• Nanofiltration - pore size - 0,002-0,001 microns delay suspended and dissolved impurities, including nitrates, nitrites and salts of heavy metals. The difference - the ability to pass dissolved minerals.
• RO - pore size of less than 0.0001 mm, which corresponds to the size of water molecule. This means that the substances which are present in the form of suspensions or solutions, are retained on the membrane. Reverse osmosis technology has been successfully used in medicine and pharmacy. In preparing for drinking purposes requires additional processing on the mineralizer.

Important! Depending on the type of membrane used for filtration plants, should be guided by the number of purification steps and the quality of source water! The pore size of the membrane is directly proportional relationship with the resistance to flow: the smaller the pores, respectively, the higher the pressure necessary for the filtration process.

Filter characteristics for reverse osmosis water

reverse osmosis filter is connected to the water supply, where the installation is supplied source water, and the concentrate obtained after purification is discharged into the sewage system. In contrast to other models, membrane units are connected in the point where potable water is required. As a rule, this is the kitchen with a separate crane equipment.

The quality of treated water, its amount and conditions of the reverse osmosis system depends on the following conditions:

• Pressure. For working performance system pressure should not be lower than 2.8 atm.
• Temperature. For normal operation, the water temperature should be in the range of from +4 to +35 degrees Celsius.
• The quality of the source water. From the initial contamination depends on the performance and lifetime of the membrane. In some types of pollution can increase the productivity increase of the operating pressure. High rates of solid, bicarbonate hardness, calcium and magnesium salts lead to premature contamination of the membrane, and it often requires regeneration.

Plant capacity is measured in gallons (GPD). Household filters may be of the following parameters:

• 36 GPD, which is equal to 132 l / day;
• 45 GPD, which is equal to 170 l / day;
• 50 GPD, which is equal to 189 l / day;
• 75 GPD, which is equal to 283 l / day;
• 100 GPD, which equates to 378 liters / day.

Conventional membrane unit includes 5 to 7 stages.

Basic equipment:

• Preliminary three-stage cleaning (removable cartridges with polypropylene and carbon cartridge);
• RO membrane;
• final cleaning (carbon cartridge).

additionally connected:

• an ultraviolet lamp for biocide treatment;
• cartridge or bioceramic mineralizer.

Priority belongs stage prefilter, which purpose - to provide normal operation of the installation. Typically three filters are used sequentially:

• Mechanical polypropylene with a pore diameter of 5 microns. It is intended for extracting coarse particles, such as rust, sand and other suspended matter;
• carbon pre-filter. It removes up to 95% organic contaminants, including oil, chlorine and organochlorines, including salts of heavy metals, manganese and iron;
• Mechanical polypropylene filter with a pore diameter of 1 .mu.m, delays the slurry and colloidal substances.

In the next stage of processing takes place on the primary reverse osmosis membrane. After that, the permeate is fed to a carbon filter for final cleaning. Separately filtering system with reverse osmosis supplemented UV lamp for bactericidal treatment and special cartridges - mineralizer and texturizers.

Their mission - enriching the purified water minerals and restoring its natural physical structure.

The filtered water is fed into the collecting vessel with a volume that depends on the model, and performance. As you use the system automatically adds a portion of purified water in a container. Storage containers are made of stainless steel plate with enamel coating.

Inside with silicone membrane container is divided into two chambers. The lower pressure air is injected, so that when lowering the water level in the upper chamber, silicone membrane increases in size and compensates for the pressure in the tank to complete draining.

The air chamber mounted nipple with which, if necessary regulated air pressure level in the storage tank.

Exploitation

In membrane plants the most expensive replacement element - RO membrane. In operation period directly affects the quality of water is supplied to the processing: operation block suspended substances, free chlorine, hardness salts. To restore the productivity of labor is carried out by washing.

Regeneration is required if the performance of the membrane has fallen to 20% of the nominal power.

Rinsing is carried out with an acidic solution in the case of inorganic deposits such as calcium and magnesium carbonates, hydroxides of iron and manganese.

Washing is performed with an alkaline solution of pollution with organic matter and colloidal suspensions.

Annually disinfection filtration unit with special disinfectants.

Important! Domestic reverse osmosis system can not be used for the treatment of microbially contaminated water or water of unknown origin! It is necessary to closely monitor the technical parameters of the installation and timely replacement of replaceable elements. Otherwise, the water quality is not guaranteed!

The main parameter that provides high-quality and long-term performance of the filter elements, especially membrane - sufficient pressure. At an operating pressure of 4-6 atmospheres, the unit operates smoothly.

At a pressure lower than 3 atmospheres resource membrane element is greatly reduced, and at a pressure below 1.2 atmosphere filtration ceases. If the system pressure is less than 2.8 atm, it is recommended to install the pump.

When operating the reverse osmosis in terms of increased supply water hardness at the stage of pre-treatment is advisable to install water softeners - filters with ion exchange downloads.

Pros and cons of filters with reverse osmosis

Manufacturers membrane systems offer a wide range of products to meet all needs.

• Number of degrees of purification. In the basic configuration all filters have at least five purification steps, providing the standard quality of water at normal usage. Additional modules are installed on the client.
• The quality of plastic for the manufacture of the filter housing. This parameter is important because module housing must withstand high pressure, not to give "Chemical smell and taste," and have been on the inside walls, so that they were not going to microorganisms. When using low-quality raw cracked housing modules, which can result in a flood.
• The quality of fittings and joints. Not least, than the previous one. Since the system operates under conditions of constant high pressure of the order of 4-5 atmospheres, it is important that the quality mans compounds fittings and key binding sites.
• The quality of the membrane. This is the "heart" of the filtration plant, and it affects not only the normal operation of all components, but also the quality of the treated water, which is then used for drinking.
• Crane for bottling. This filter element, which is always in sight. Aesthetic motives better pick it up in accordance with the interior of the kitchen.

malfunctions

With low pressure, and improper operation of the filtration plant the following problems may arise:

• Reduction of the service life;
• Premature contamination of pre-filters;
• Incomplete filling of the storage tank;
• Insufficient water in the storage tank;
• Lack of issuing the full water storage tank;
• Increasing the amount of drainage of water;
• Accelerated sedimentation filter housings;
• Changing the taste and appearance of water at its boiling scale;
• Problems with the switching on or off of the pump;
• Extraneous sounds when the pump;
• Overheating of the power supply;
• Non-stop discharge into the sewer;
• The increase over the counter flow compared to normal mode.