INTRODUCTION

Ultra-low pressure reverse osmosis membrane elements are high-performance membrane separation elements manufactured using advanced materials and processes. For example, the ESPA series of ultra-low pressure reverse osmosis membranes from Hydranautics in the United States was an energy-saving, ultra-low pressure, high-flux composite reverse osmosis membrane launched in the world in May 1995. Toray's TMH20A - 430 extremely ultra-low pressure reverse osmosis membrane element has an effective membrane area of 430 square feet and is suitable for the desalination and advanced treatment of brackish water with a salinity of about 1000 ppm or less, surface water, and tap water.

These membrane elements have an ultra-thin desalination layer and can operate under ultra-low operating pressures. Compared with conventional low-pressure composite reverse osmosis membranes, the operating pressure is reduced by about 25% - 40%. Meanwhile, while maintaining a high desalination rate, they have a higher water flux, which can significantly save the operating costs of the system.

WORKING PRINCIPLE

The working principle of ultra-low pressure reverse osmosis membrane elements is based on reverse osmosis technology. Reverse osmosis, also known as reverse osmosis, is a membrane separation operation that separates the solvent from the solution with the pressure difference as the driving force.

The pore size of the ultra-low pressure reverse osmosis membrane is as small as the nanometer level. Under a certain pressure, only water molecules can pass through this membrane layer, while other substances in the source water, such as heavy metal ions, bacteria, viruses, and organic substances, cannot pass through. This is because under the action of a pressure higher than the osmotic pressure of the solution, these substances are separated from water according to the fact that they cannot pass through the semi-permeable membrane. Due to its special surface structure, its surface potential is neutral and it has good hydrophilicity. Unlike ordinary reverse osmosis membranes, it is not easy to be blocked by dirt due to the adsorption of surface-active substances, so it can stably play an efficient filtering role.

MAIN PERFORMANCE AND FEATURES

l Low-pressure operation with significant energy savings:Ultra-low pressure reverse osmosis membrane elements can achieve efficient water separation under relatively low operating pressures. For example, Toray's TMH20A - 430 can achieve a relatively high water production volume under a test pressure of 0.69 MPa. Compared with traditional reverse osmosis membranes, it can greatly reduce the energy consumption of equipment such as water pumps and cut down the operating costs.

l High desalination rate and excellent water quality:It has excellent desalination ability. For example, the average desalination rate of Hydranautics' ESPA series membrane elements can reach more than 99%, which can effectively remove various salts and impurities in water and produce high-quality pure water to meet the strict water quality requirements of different industries.

l High water flux and efficient water production:It can still maintain a relatively high water flux under low-pressure conditions, which can quickly realize the separation and purification of water and improve the production efficiency of the water treatment system. For example, the water production volume of the ESPA1 - 4040 type membrane element can reach 9.8 m³/d.

l Strong anti-pollution ability and long service life:Its special surface structure gives it good anti-pollution performance. It is not easy to adsorb pollutants, which can effectively reduce the frequency of membrane cleaning, extend the service life of membrane elements, and reduce maintenance costs and replacement frequency.

l Good chemical stability:It can withstand changes in pH values, temperatures, and other factors within a certain range and maintain stable performance under different water quality conditions, adapting to a variety of complex application environments.

APPLICATION FIELDS AND INDUSTRIES

l Drinking water treatment: It can be used for the advanced treatment of water in tap water plants to remove trace organic substances, heavy metal ions, and bacteria in water, improve the quality of drinking water, and ensure the safety of residents' drinking water. At the same time, it is also widely used in water purification equipment in households and commercial places to provide people with high-quality direct drinking water.

l Industrial pure water preparation: In the electronics industry, ultra-low pressure reverse osmosis membrane elements can be used to produce ultrapure water to meet the extremely high water quality requirements of processes such as chip manufacturing and semiconductor processing. In the pharmaceutical industry, it can also be used to prepare water for injection, pharmaceutical pure water, etc., ensuring the quality and safety of drugs. In addition, it is also applied in the food and beverage industry, such as producing purified water, mineral water, and beverage water, to guarantee the taste and quality of products.

l Wastewater treatment and reuse: For the treatment of industrial wastewater and municipal sewage, ultra-low pressure reverse osmosis membrane elements can further purify the pretreated wastewater to realize the recycling of water resources, reduce the waste of water resources, and lower the water consumption costs of enterprises and the pollution to the environment. For example, in the wastewater treatment of printing and dyeing, electroplating, and other industries, it can effectively remove pollutants and salts in water so that the treated water meets the reuse standards.

l Seawater and brackish water desalination: In coastal areas and some areas with scarce water resources, it can be used for seawater desalination and the desalination of brackish water to provide reliable freshwater supply for local areas. For example, on islands, ships, and offshore oil drilling platforms, by installing ultra-low pressure reverse osmosis membrane seawater desalination equipment, the water demand for life and production can be met.

SUMMARY

Ultra-low pressure reverse osmosis membrane elements, with their outstanding performances such as low-pressure operation, high desalination rate, high flux, and anti-pollution ability, have brought efficient, energy-saving, and environmentally friendly solutions to the water treatment industry. They have broad application prospects in many fields such as drinking water treatment, industrial pure water preparation, wastewater treatment and reuse, and seawater desalination, providing powerful technical support for solving the global problems of water shortage and water pollution. With the continuous progress of science and technology, it is believed that ultra-low pressure reverse osmosis membrane elements will continue to innovate and improve in terms of material research and development and manufacturing processes, further enhancing their performance and cost-effectiveness and making greater contributions to the sustainable utilization and protection of water resources. Choosing ultra-low pressure reverse osmosis membrane elements means choosing a more efficient, more economical, and more environmentally friendly water treatment method, enabling us to better cope with the challenges of water resources and usher in a new era of efficient water purification.