The LP (low pressure) series of aromatic polyamide compound membrane elements developed by Vontron Technology Co., Ltd. has the properties of low-pressure operation, high permeate flow, and excellent desalination and is applicable to the desalination of brackish water. Besides, it is particularly applicable to the fabrication of high-purity water for the electronic industry and electric power industry owing to its excellent performance in removing soluble salts, TOC, SiO₂, etc. Being suitable for desalting such water sources as surface water, underground water, tap water, and municipal water, etc., the LP series is mainly applicable to the treatment of various industrial water such as industrial-purpose pure water, boiler water replenishment in power plants, and can be also applied to such brackish water applications, such as treatment of high-concentration saline wastewater and production of beverage-purpose water.