How does reverse osmosis technology and RO system work?

Reverse osmosis technology, also known as RO, mainly uses the pressure difference existing on both sides of the membrane as the power to achieve membrane separation and filtration, is a very advanced and effective energy-saving membrane separation technology.

RO Basic principles and advantages Reverse osmosis membrane is the core component of reverse osmosis technology. It is an artificial semi-permeable membrane with certain characteristics. It is made of polymer material and simulated biological semi-permeable membrane material.

Reverse osmosis, also known as reverse osmosis, is a membrane separation operation that separates the solvent from the aqueous solution by the pressure difference as the driving force, and is the process of water filtration of impurities. Because it is opposite to the direction of natural penetration, it is called reverse osmosis. The technical principle is that under the action of higher than the osmotic pressure of the solution, the pressure is applied to one side of the membrane, and when the pressure exceeds its osmotic pressure, the solvent will penetrate in the opposite direction, leaving these substances and water. The solvent obtained on the low pressure side of the membrane is called osmotic solution; The concentrated solution obtained at the high pressure side is called the concentrated solution. If seawater is treated by reverse osmosis technology, fresh water is obtained on the low pressure side of the membrane and brine is obtained on the high pressure side. The reverse osmosis pressure can be used to achieve the purpose of separation, extraction, purification and concentration. Reverse osmosis is a water treatment technology using membrane separation, which belongs to the physical method of cross-flow filtration. Its advantages are as follows: at room temperature, relying on water pressure as a driving force, the operating cost is low; No large amount of waste acid lye discharge, does not pollute the environment; The system is simple, easy to operate, high degree of automation; The raw water quality has a large range of adaptation, and the effluent water quality is stable; The equipment covers a small area and the maintenance workload is small.

RO water treatment basic technology

First, one stage treatment process. After the liquid enters the membrane module, the pure water and the concentration liquid are extracted. Compared with other reverse osmosis water treatment processes, the overall process is more convenient and simple to operate, but it has high limitations and can not meet the higher water quality requirements.

Second, a multi-stage treatment process. On the basis of a one-stage treatment process, the liquid was concentrated in multiple steps. Compared with the first-stage treatment process, the process is more complex, can meet the higher water quality requirements, and realize the recycling of water resources.

Third, two-stage one-stage treatment process. In the case that the actual water quality requirements are difficult to achieve using the primary method, the secondary one-stage treatment process can be used. Compared with the above two first-stage processes, the use of the two-stage one-stage treatment process can extend the application life of the reverse osmosis membrane, and does not require too much human operation, and the corresponding treatment cost is also reduced. In the advanced treatment of urban water pollution, reverse osmosis technology can increase the recovery rate of sewage and is widely used. Different materials of reverse osmosis membrane produced by water pollution depth treatment effect is different. Generally speaking, in the advanced treatment of urban water pollution, after the treatment of urban residents' domestic sewage is up to standard, the treatment of water quality is higher (such as water reuse), at this time, cellulose triacetate hollow fiber membrane, spiral rolled polyvinyl alcohol composite membrane can play a better effect. Compared with the reverse osmosis membrane of other materials, the retention rate of the reverse osmosis membrane of the above two materials reaches 100%, the color is not higher than 1 degree, and the penetrant liquid is 1mg/L~2mg/L. At the same time, the reverse osmosis membranes of these two materials have higher water flux and stronger anti-pollution ability.

Industrial wastewater treatment

1) Treatment of heavy metal ions The reverse osmosis water treatment technology is applied to industrial wastewater treatment, and the effect is also very good, in line with the overall design principle of industrial economy and reasonable, which can reduce energy consumption and operating costs as well as the difficulty of operation management. Reverse osmosis devices used for industrial wastewater treatment are generally internal pressure tube or roll type components, the pressure is generally stable at about 218MPa, and the effect is excellent in heavy metal ion recovery. Among them, the operating pressure of the reverse osmosis device based on the internal pressure tube component is stable at 217MPa, at this time, the recovery rate of nickel is above 99%, and the separation rate of nickel is in the range of 97.12%~97.17%.

2) Treatment of oily wastewater In general, the oil content of oily wastewater mainly exists in three forms, including emulsified oil, dispersed oil, and floating oil. In comparison, the treatment method of dispersed oil and floating oil is relatively simple, relying on mechanical separation, precipitation, activated carbon adsorption treatment, can promote the corresponding oil content is greatly reduced. However, for emulsified oil, it contains organic matter, can play the role of surfactant, and the oil content is generally in the size of micron particles, so it has high stability, it is difficult to effectively and quickly realize the separation of water and oil.

With the support of reverse osmosis water treatment technology, concentration separation can be achieved without destroying the emulsion, and then the concentrated liquid is incinerated, and the permeate is recycled or discharged. At this stage, in the treatment of oily wastewater, due to the consideration of the final treatment effect and effluent quality, reverse osmosis water treatment technology is generally used in combination with other treatment methods. The results show that the removal rate of COD in the purified water by demulsification and reverse osmosis is 99.96%, and the oil content is almost undetectable. Desalting brackish water In the process of desalting brackish water, through the introduction of reverse osmosis water treatment technology, can effectively inhibit the inorganic salt ions contained in the brackish water, such as magnesium ions, calcium ions, to achieve the quality of pure water enhancement.

At this stage, people's quality requirements for purified water are improving, and the original treatment method (adding scale inhibitor in salt water) is difficult to meet people's realistic requirements, and reverse osmosis water treatment technology is an inevitable choice. In a brackish water desalination operation using reverse osmosis, it is necessary to test the SDI index regularly, strictly control the recovery rate, pay attention to the pressure difference between the membrane components, and measure the change of water production and desalination rate in real time. In practice, the desalting rate of the reverse osmosis device is stable at more than 96%, and the water quality after desalination meets the standard of drinking water in China.