The problems of poor quality and unstable water composition that flows from the tap are relevant for many Russian cities. According to water experts, the main reasons for this phenomenon lie in the lack of control of sanitary zones around water intakes, insufficient equipment of distribution facilities, and deterioration of water networks. An effective way to solve this problem at the level of a house or an apartment is installing a membrane filter, which operates on the principle of reverse osmosis (OJ). Below, we will look at the basic elements of the technology, household, and industrial water treatment systems.
Reverse osmosis: what it is
Reverse osmosis is a method of water purification in which the solution passes under pressure through a special synthetic membrane, where up to 98% of mineral salts and impurities are delayed. For the first time about the process of reverse osmosis began in the 50s of the 20th century. Today, reverse osmosis is considered to be the most effective method in the field of water treatment. It is in demand, both in industrial enterprises and in private homes. Reverse osmosis permeate is purified water that is supplied to technical and drinking needs.
What is osmosis and reverse osmosis: what are the differences
The phenomenon of osmosis(direct osmosis)is the basis of the metabolic processes of all living organisms at the cellular level. Thanks to it, water-salt exchange, nutrients, withdrawal of life products “work.” The process requires a solution, solvent, and a semi-permeable membrane separating them, which is a barrier to the dissolved substance.
Direct osmosis is a baro-mass-exchange process. It can be described as follows: osmotic pressure appears on the solvent side, which causes its molecules to move to the side of the solution and dilute it. An increase in hydrostatic pressure accompanies an increase in the volume of the solution. The process stops when static and osmotic pressures come into balance.
Importantly! The cell wall plays In-plant and animal organisms the role of a semi-permeable septum. Artificial membranes are made from organic synthetics.
If you apply pressure from the solution, the process will go the other way. This is reverse osmosis. In reverse osmosis, on one side of the membrane increases the concentration of the solution, and on the other – increases the volume of solvent.
What is the reverse osmosis membrane?
Semi-permeable membranes are used for reverse osmosis filters. The membrane of the reverse osmosis consists of:
- selective layer, which is a barrier to impurities;
- arming layer, setting the strength of the membrane.
In the reverse osmosis filter cartridge, the membrane is rolled into a roll. This design allows you to get a large area of active surface and place it in a compact body of standard size.
The membrane for reverse osmosis is the main element in the cleaning system. The following materials are suitable for the manufacture of membranes:
- Cellulose acetate. Cheap and easy-to-make membranes from this material appeared in the 1950s. They are excellent at purifying water from salts with a large molecular mass but “miss” several low-molecular compounds. In addition, they operate in a limited pH range and are prone to biodegradation. Currently, cellulose acetate is superseded by more advanced materials.
- Armed polyamide. The material operates in a wide range of pH and is not a breeding ground for microorganisms. Strong polyamide membranes withstand high working pressures, have good selectivity to NaCl and organics. The main drawback is low resistance to oxidizers. Water with high chlorine content quickly disables polyamide membranes.
- Thin-film composites. The membranes of this material are the most advanced to date. Films from the composite have a high selectivity to all known impurities.
Why filters with reverse osmosis system are needed
Reverse osmosis systems are installations that cope well with the removal of dissolved mineral salts. Reversing water by osmosis is the removal of inorganic compounds from the water from 90 to 98%.
The membranes filter out organic matter, whose molecules are much larger than those of mineral salts. Compounds with a molecular weight above 150 Da are removed from the water 100%. The probability of bacteria and viruses entering through the filter is almost zero. The exception is cartridges with mechanical damage to the membrane. The purified water obtained from a normally functioning plant does not require boiling and dosing of disinfectants.
But what clears the reverse osmosis? Do all substances linger on membranes? Reverse-osmotic membranes freely pass dissolved two-volume gases: oxygen, nitrogen, hydrogen.
Cleaning on EO can be subjected to water with a total mineralization of 3 – 20 g/l with the cloudiness of up to 5 EMF and permanganate oxidation of up to 3 mg2Among the requirements of most membrane manufacturers to the original water can also be identified the absence of strong oxidizers (free chlorine, ozone) and bivalent iron.
What is the essence of reverse osmosis?
The return osmosis of water is a process that gives clean drinking and technical water at the exit. Reverse osmosis installations are used at the following facilities:
- Hydroelectric power plants, nuclear power plants, and other energy companies;
- Housing, for the water supply of facilities of the first category;
- Scientific and research laboratories, including the defense complex;
- individual water supply.
Why you need to install reverse osmosis
The main uses of reverse osmosis plants are water treatment to reduce overall mineralization, desalination of brackish waters. The reverse osmosis filter is one of the stages of pre-training when receiving ultra-clean water for the electronics industry, medicine, heat energy.
Another area of reverse osmosis – the receipt of concentrates – is widely used in the food industry. Condensed milk and concentrated juices are produced by reverse osmosis.
Industrial reverse osmosis: what it is
Commercial and industrial reverse osmosis installations are high-performance water treatment systems with semi-automatic or fully automated control. They include several modules responsible for pre-training and membrane cleaning.
The typical industrial reverse osmosis plant for technical water consists of the following elements:
- The filter is a rough cleaning. A grid with a certain cell size traps insoluble particles.
- A column of deforestation. In it, bivalent iron oxidizes to trivalent and is removed in the form of insoluble sediment.
- Sorbate filter. Active sorbent absorbs free chlorine.
- The membrane of reverse osmosis. Removes dissolved salts and other contaminants. One of the advantages of industrial re-osmosis plants is scalability. You can add the required number of filters to it to increase performance.
Reverse osmosis: how it works
To leak the reverse osmosis, you need high working pressure created by a high-pressure pump. The systems are equipped with sensors, gauges, automatic reset valves, tubular strapping. A TDS meter is installed to control the quality of treated water.
The installation consists of two stages:
- water purification.
- Washing the membrane.
A microcontroller carries out the control. Because the original water varies in composition, the system is individually equipped and set up. Additional stages of pre-training may be required.
Importantly! With the good quality of the original water, it is possible to abandon some pre-filtration stages, simplify, and reduce installation costs.
Household reverse osmosis for water: what it is needed for
The equipment market offers a wide range of modular reverse osmosis systems for private homes and cottages, usually placed in separate rooms. There are also mono-block models for apartments with a centralized water supply. They are distinguished from industrial reverse-osmotic systems by two parameters: productivity and water consumption. But what is reverse osmosis in household filters?
A household system with reverse osmosis is a compact device that works at relatively low pressures (up to 3 atmospheres). They do not often have a boost pump, and filtration is due to the pressure in the water supply. Such installations produce several liters of purified water per day, which is enough for the private consumer. Because of the low working pressure, the household membrane requires rinsing more often than the industrial one.
In household installations after reverse osmosis, install a mineralizer – a post-processing device that enriches water useful for humans minerals in the right concentrations. This water is for drinking only. Mineralization does not affect cooking or hot drinks at all (or has a negative impact).
Importantly! The resource of household and industrial membranes of reverse osmosis of most manufacturers is 1 year. Pre-cleaning cartridges are changed every six months.
Why reverse-osmotic filters are in demand
Reverse osmosis systems have many advantages:
- High water quality at low energy levels.
- Unlimited performance and relatively small dimensions.
- Low operating costs.
- The concentrate does not require recycling and is dumped into the sewer.
Diesel sells industrial and household reverses osmosis systems. Our specialists will offer a ready-made modification or will choose a set of equipment for private customers and businesses. We will find a solution based on the analysis of the original water and the required performance.