With the accelerated development of industrialization and urbanization, water pollution problems have become increasingly serious, and water quality issues have always attracted people's attention. Therefore, as an effective water filtration equipment, reverse osmosis water filtration system has attracted more and more attention and favor.
What is Reverse Osmosis?
Reverse osmosis (RO) is a water purification process that uses a semi-permeable membrane to separate water molecules from other substances. RO applies pressure to overcome osmotic pressure that favors even distributions. RO can remove dissolved or suspended chemical species as well as biological substances (principally bacteria) and is used in industrial processes and the production of potable water. RO retains the solute on the pressurized side of the membrane and the purified solvent passes to the other side. It relies on the relative sizes of the various molecules to decide what passes through. "Selective" membranes reject large molecules while accepting smaller molecules (such as solvent molecules, e.g., water).
RO is most commonly known for its use in drinking water purification from seawater, removing the salt and other effluent materials from the water molecules.
What contaminants does RO remove?
Reverse osmosis (RO) membranes are effective in removing a wide range of contaminants from water, including:
- Ions such as chlorides, sulfates, and nitrates
- Dissolved metals such as lead, mercury, and arsenic
- Pesticides and herbicides
- Bacteria
- Viruses
- Parasites
- Chlorine
- Volatile organic compounds
- Pesticides
- Pharmaceutical residues
- Sediment
- Rust
- Other suspended particles
These are some of the most common contaminants treated by RO membrane systems, but RO systems can remove many other contaminants.
Recommended reading: How to filter pfas from tap water?
How does reverse osmosis (RO) work?
The reverse osmosis membrane is the core component of the reverse osmosis technology. It is an artificial semipermeable membrane with certain characteristics. It is made of polymer materials and simulates biological semipermeable membrane materials.
Reverse osmosis, also known as reverse osmosis, is a membrane separation operation that uses pressure difference as a driving force to separate solvents from aqueous solutions. It is the process of filtering impurities from water. Because it is in the opposite direction of natural osmosis, it is called reverse osmosis.
The technical principle is to apply pressure to one side of the membrane under a pressure higher than the osmotic pressure of the solution. When the pressure exceeds its osmotic pressure, the solvent will penetrate in the opposite direction and separate these substances and water. The solvent obtained on the low-pressure side of the membrane is called permeate; the concentrated solution obtained on the high-pressure side is called concentrate.
Reverse osmosis is a water treatment technology that uses membrane separation and is a physical cross-flow filtration method. Its advantages are as follows:
- Under room temperature conditions, it relies on water pressure as the driving force, and the operating cost is low;
- No large amount of waste acid and alkali liquid is discharged, and it does not pollute the environment;
- The system is simple, easy to operate, and has a high degree of automation;
- It has a wide range of adaptability to the water quality of the plateau water, and the water quality of the outlet is stable;
- The equipment occupies a small area and the workload of inspection and maintenance is small.
Recommended reading: How Does Reverse Osmosis Water Filter Work?
Advantages of reverse osmosis water filtration system
Reverse osmosis (RO) water filtration systems are a popular choice for home and commercial water purification solutions due to their powerful filtration capabilities and many benefits. Here are the main advantages:
1. Excellent pollutant removal ability:
Wide range of removal: RO systems can effectively remove a variety of pollutants in water, including bacteria, viruses, heavy metals (such as lead, arsenic, and mercury), pesticides, chlorine, fluoride, sediments, and more.
High removal rates: Compared to other filtration methods, RO systems can remove up to 99% of dissolved solids and contaminants, providing higher-purity drinking water.
2. Improve the taste and smell of drinking water:
Removing odors: RO systems can remove substances that cause bad odors and tastes in water, such as chlorine, hydrogen sulfide, etc., making your drinking water more refreshing and delicious.
Improve the taste: By removing various impurities and minerals from the water, the RO system can make the water quality closer to pure water and taste better.
3. Convenient and easy to maintain:
Automated operation: Most RO systems have an automatic flushing function, which can clean the filter membrane regularly to ensure normal operation of the system.
Convenient filter element replacement: The filter element replacement process is simple and users can operate it by themselves.
Osmosis
In (forward) osmosis, the solvent moves from an area of low solute concentration (high water potential), through a membrane, to an area of high solute concentration (low water potential). The driving force for the movement of the solvent is the reduction in the Gibbs free energy of the system in which the difference in solvent concentration between the sides of a membrane is reduced. This is called osmotic pressure. It reduces as the solvent moves into the more concentrated solution. Applying an external pressure to reverse the natural flow of pure solvent, thus, is reverse osmosis. The process is similar to other membrane technology applications.
RO differs from filtration in that the mechanism of fluid flow is reversed, as the solvent crosses the membrane, leaving the solute behind. The predominant removal mechanism in membrane filtration is straining, or size exclusion, where the pores are 0.01 micrometers or larger, so the process can theoretically achieve perfect efficiency regardless of parameters such as the solution's pressure and concentration. RO instead involves solvent diffusion across a membrane that is either nonporous or uses nanofiltration with pores 0.001 micrometers in size. The predominant removal mechanism is from differences in solubility or diffusivity, and the process is dependent on pressure, solute concentration, and other conditions.
RO requires pressure between 2–17 bar (30–250 psi) for fresh and brackish water and 40–82 bar (600–1200 psi) for seawater. Seawater has around 27 bar (390 psi) natural osmotic pressure that must be overcome.
Membrane pore sizes vary from 0.1 to 5.000 nm. Particle filtration removes particles of 1 µm or larger. Microfiltration removes particles of 50 nm or larger. Ultrafiltration removes particles of roughly 3 nm or larger. Nanofiltration removes particles of 1 nm or larger. RO is in the final category of membrane filtration, and hyperfiltration, and removes particles larger than 0.1 nm.
Does RO waste water?
Generally, most RO water filtration systems produce about four gallons for every gallon. Different RO water filtration systems have different ratios. The RO system process produces two streams of water, one of which is treated pure water, and the other is concentrated water that has been removed from salts, minerals, and other impurities. This concentrated water is called "wastewater" or "brine" and is usually discharged directly to the sewer.
Of course, this concentrated water can be used to wash water. Therefore, the brine has a purpose and is not wasted. By choosing the right RO water filtration system, taking water conservation measures, and making reasonable use of wastewater, we can minimize the impact of RO systems on the environment.
How to choose the right reverse osmosis water filtration system
There are several factors to consider when choosing the right RO system, here are some key steps:
1. Understand the key parameters, such as water production volume, wastewater ratio, filtration level, and filter element life.
2. Select filter element configuration: usually includes PP cotton filter element, activated carbon filter element, and RO membrane, which can meet basic filtration needs.
3. Brand and after-sales service: Choose a well-known brand of RO system to ensure better quality and more confidence in use. For example, choose the ITEHIL water filtration system, which has been tested and certified by the FDA, CE, EMC, PSE, FCC, and RoSH, and has a high-quality product experience and perfect after-sales service!
The ITEHIL reverse osmosis water filtration system uses PP cotton + activated carbon + reverse osmosis membrane to remove bacteria, viruses, parasites, toxic metals, pesticides, polyvinyl chloride, PFAS, etc., and can easily filter rainwater, spring water, lake water, pond water, and river water, sweat, urine, tap water, coffee, cola, etc. The portable design makes water filtering easier. USB-C charging takes only 2-3 hours to fully charge. Each charge can provide up to 9 gallons of drinking water, which is satisfactory. With the water needs of 13 adults living outdoors for a day, from ponds to rivers to creeks, ITEHIL enables fast and convenient water filtration at the source, portable water filtration has never been easier.
Overall, reverse osmosis water filtration systems are of great significance in modern life and can effectively protect our health and improve our quality of life. Choosing the right reverse osmosis water filtration system can have a positive impact on your family's health and environment.
Recommended reading: What is the best water filtration system? And how to choose?
Precautions for RO system application
During the application of reverse osmosis technology in water treatment, necessary filtration of sewage should be carried out. Filtration is the basis for the function of reverse osmosis technology. The filtration process should be strictly controlled to prevent impurities from mixing in the water and entering the reverse osmosis system, to protect the osmosis membrane and equipment, increase the water output, and reduce the possibility of corrosion.
The reverse osmosis water filtration system device should be regularly flushed, especially for the scale to clean, maintain the good performance of the semipermeable membrane, and extend the service life of the device.
When the reverse osmosis water filtration system device is not in use, it will be affected by the accumulated sewage, thereby breeding microorganisms. Therefore, during the shutdown period of the device, it needs to be flushed and disinfected, and the temperature during the shutdown period should be well set to protect the reverse osmosis membrane.
Operators should strictly abide by the operating procedures and operating specifications, continuously improve their professional quality, and carefully check the device before using it to avoid damage to the device due to operator errors, ensure that the device can operate normally, and smoothly carry out sewage treatment work.
Frequently Asked Questions
What is the difference between a water filtration system and reverse osmosis?
Water filtration systems use various media (activated carbon, sediment, ceramics, etc.) for physical and chemical filtration, which can remove sediment, chlorine, taste, and odor; reverse osmosis (RO) uses a semi-permeable membrane for physical separation, which can remove dissolved salts, heavy metals, nitrates, pesticides, bacteria, viruses, etc.
Is it better to drink tap water or reverse osmosis water?
Usually, it is better to drink reverse osmosis water for a long time. The specific analysis is as follows:
Because reverse osmosis water is generally filtered through RO membranes, most of the impurities, microorganisms, and pollutants are removed, and it is usually closer to a pure state. Therefore, long-term drinking will not have adverse effects on health. Tap water may contain chlorine, heavy metals, residual chemicals, etc., and long-term drinking may have a certain degree of impact on health.
Does reverse osmosis really purify water?
Yes, reverse osmosis (RO) does purify water very effectively. RO systems use a very fine semi-permeable membrane that blocks most contaminants and allows only water molecules to pass through. This process removes more than 95% of contaminants in water, producing very pure drinking water.
Is reverse osmosis better than bottled water?
In general, reverse osmosis water has some advantages over bottled water, including:
Purer water quality: The reverse osmosis process can effectively remove bacteria, heavy metals, harmful chemicals, etc. from water, providing cleaner, healthier drinking water.
Environmentally friendly: Using a reverse osmosis water filtration system can avoid environmental pollution caused by single-use plastic water bottles.
Affordable: Over the long term, it may be more economical than buying bottled water.
Is reverse osmosis water good for you?
Reverse osmosis water filtration systems can remove dissolved contaminants that you cannot see, and drinking reverse osmosis water can reduce health risks caused by pollutants in the water. Therefore, reverse osmosis water is still good for the human body.
