RO Water Treatment Series
Reverse osmosis removes a variety of contaminants from unfiltered water by forcing it through a semi-permeable membrane. The permeate water that passes through is clean, while the concentrate or waste water left over from the process carries the more concentrated contaminants.
RO systems can be used to produce drinking water, industrial water and waste water for treatment and reuse. They can also be used to produce parenteral solutions for use in hospitals and other medical facilities.
1. Removes Contaminants
A RO water treatment series uses the process of reverse osmosis to remove contaminants from water. It works by using a semi-permeable membrane to allow water to flow from a more concentrated side (with contaminants) to a less concentrated side (without contaminants). The water that flows through the membrane is called permeate or product water, while the waste or brine is rejected water that isn’t allowed to pass.
The RO membrane removes contaminants by allowing only certain dissolved salts, organics, particles and other substances to pass through it. It does so by assessing the molecule size and ionic charge of the contaminants.
Some of these substances have a molecular weight that’s greater than 200, while others have a molecular weight that’s lower than 18. Depending on the contaminant’s size and chemical properties, the RO membrane will reject it by a percentage.
Once the dissolved contaminants are removed, they are carried out of the system in a brine or wastewater stream that carries them to a drain. A typical reverse osmosis system sends about 4 gallons of this wastewater to the drain for every gallon of permeate produced, but it’s not exactly wasted water since it is used to carry dissolved contaminants out of the system.
Adding a permeate pump to your RO system increases the efficiency of this process by using the wastewater as energy to send clean water to the storage tank. This is an environmentally friendly and cost-effective way to treat your home’s drinking water.
A reverse osmosis water treatment system is a great option for treating your family’s drinking water. It can help reduce a wide range of contaminants including dissolved solids, arsenic, bacteria and viruses. It’s also an excellent choice if you get your drinking water from a private well.
2. Reduces Hardness
Reverse osmosis systems are designed to remove a wide range of contaminants from water that is high in dissolved solids. They use a multi-stage filtration process that relies on specialized RO membranes and pressure to filter water.
In the first stage, feed water is pumped up against a semi-permeable RO membrane. Depending on the type of weave, only a certain percentage of contaminants can pass through this barrier and leave the water.
Next, the water is pushed through another filter that can reduce contaminants like lead and mercury. This can be done with a simple cartridge or with Culligan’s Total Defense filter that features specialty media to reduce these and other chemicals.
Once the water passes through the final filter, it is sent through the RO membranes again to be treated with the concentrated solution that is left behind. This is called the reject stream.
This concentrate stream is used by other equipment to do tasks that require the most pure water. Some examples include water used for humidification and evaporative cooling applications, as well as drinking water.
In addition, the concentrate is added to a water tank for storage purposes. The amount of concentrate needed depends on the chemistry of the source water and the system design, but the typical recovery rate is 50 to 85%.
It’s important to remember that a reverse osmosis membrane is subject to fouling, scaling and chemical attack if it is not properly pretreated before it begins processing water. These can result in reduced membrane performance, premature failure and more frequent cleaning requirements.
3. Reduces Chlorine
Reverse osmosis (RO) water treatment is a water filtration process that works by removing contaminants from incoming water. RO systems can RO Water treatment series be installed at the point of use, such as a sink under your kitchen faucet, and can reduce pollutants including lead, volatile organic compounds (VOCs), PFAS, arsenic and bacteria.
The feed water that enters the RO system will be pushed against a semi-permeable membrane at high pressure. The water flows through the membrane until the chemicals on either side of the membrane reach an equal concentration. The dissolved molecules of the chemical will pass through the membrane and into the permeate stream and the non-dissolved solids will drain away as concentrate.
Most RO systems run anywhere from 50% to 85% recovery depending on the feed water characteristics and other design considerations. The higher the recovery, the better the permeate will be.
To determine if your RO system is producing the amount of permeate you are expecting, it is important to monitor the normalized flow, pressures and salt rejection data. This will help you determine when it is time to clean or replace your membranes.
Fouling of the membranes is another concern that can result in poor performance of your RO system. Fouling occurs when small, naked to the human eye, harmless contaminants in your feed water build up on the surface of the membrane, effectively plugging it and causing a decrease in the permeate flow and pressure.
Fouling of the membranes is a common problem with municipal feed water and should be addressed by performing pretreatment and cleaning schedules that minimize contaminants in the feed water. It is also important to monitor the normalized flow, pressure and salt rejection of the membranes to determine when they need cleaning or replacement.
4. Reduces Odors
Reverse osmosis (RO) drinking water RO Water treatment series systems have been around for decades and are used in a variety of applications including medical treatment of dialysis patients. These point-of-use (POU) units are often connected to a single faucet in a kitchen or bathroom sink and use the process of RO to remove contaminants from water.
The RO membrane in the system is a semi-permeable filter that is designed to remove a wide variety of aesthetic and health-related contaminants as well as reduce total dissolved solids (TDS). Once the water passes through the RO membrane, it enters a pressurized storage tank where it can be stored.
A pre-filtration stage is usually included in a system to reduce suspended particles that can clog the RO membrane. Typically, this stage will also include a carbon filter to remove chlorine from the water.
An RO membrane must have a high rejection rate to ensure it can effectively reduce all contaminants. For example, if the water supply contains 80 mg/L nitrate, an 85 percent rejection rate will decrease the nitrate level to 12 mg/L.
During the filtration process, the membrane will be cleaned and replaced periodically to maximize its lifespan. In order to prevent premature fouling, RO membranes must be regularly disinfected and inspected for damage.
After the water leaves the RO membrane, it passes through a post-filtration stage that will remove any remaining tastes or odors. Typically, this post-filter is a carbon filter, which will help to “polish” the taste and odor of the water.
5. Reduces Scale
Reverse Osmosis (RO) is an effective filtration process that removes many contaminants from water. The RO membrane has the ability to ionize salts, reduce hardness and chemicals, and make the water safe for use.
The RO membrane’s performance is dependent on a number of factors, including contaminant concentration, the chemical properties of the contaminant and the membrane type. In addition, the membrane’s condition and operation can affect its effectiveness.
In order to keep RO membranes functioning at their highest level, it is important that they are maintained correctly. Some simple steps to take include cleaning them on a regular basis and changing the membranes when they are due for replacement.
Adding a scale inhibitor to feed water before it goes into an RO system can also help to reduce scaling of the membrane. This will allow the RO membrane to operate at its highest level and will increase the recovery rate.
Another way to reduce scale is to install a double pass RO unit. This allows for the permeate to be passed twice through the RO membranes before it is rejected. It also provides the opportunity to remove carbon dioxide from the permeate by injecting caustic between the first and second passes of the RO system.
Scale is caused when certain dissolved inorganic compounds become more concentrated than their solubility limits. They can precipitate on the surface of the RO membrane and cause a higher pressure drop, lower salt passage, less permeate flow and lower quality permeate water.
Scale is a common problem with RO systems and can be solved by installing an antiscalant or scale inhibitor in the feed water before it goes into an RO system. The amount of an antiscalant or scale inhibitor needed will vary depending on the feed water chemistry and the system design.