Misunderstanding and Explanation of Reverse Osmosis Membrane by Hongjie Water

In response to many people's misunderstandings about membranes, this article specifically explains these easily occurring misunderstandings (Hongjie Water, every point is true)

Misunderstanding 1: Membrane water treatment equipment is a highly difficult operating system

The automatic control requirements of the membrane water treatment system are much higher than those of conventional biochemical treatment systems, and many users mistakenly believe that the operation of the membrane system is difficult. In fact, the operation of the membrane water treatment system is highly automated, and operations such as start/stop, dosing, and online flushing are all carried out by the PLC system program control, which can achieve unmanned operation. Only manual scheduled inspection and dispensing, periodic maintenance and cleaning are required, and there is basically no need for additional operating staff. The routine cleaning and maintenance of membranes can be mastered within one day of training, and the difficulty is much lower than that of biochemical systems that require high comprehensive skills from employees.

Misunderstanding 2: Investing too much, unable to afford it

There is a viewpoint that the one-time investment and depreciation replacement cost of membranes are high, and they can be purchased but not used. In fact, with the development of domestic membrane manufacturing enterprises, the price of membranes is constantly decreasing. The use of MBR membrane system can save construction and land costs, reduce sludge volume and disposal costs, and has a high comprehensive cost-effectiveness, making it a good choice; For UF and RO systems, the economic benefits generated by achieving wastewater resource recycling far exceed the investment of the equipment itself. If the MBR membrane with lining or UF and RO membrane are combined for depreciation and replacement, the general depreciation cost of the membrane will not exceed 0.6 yuan/ti for influent water, or even lower than the cost of adding chemicals per ton of influent water in the system.

Misunderstanding 3: The membrane is delicate and easily damaged

Due to lack of experience, some engineering companies have encountered problems with membrane system design and construction, such as membrane breakage and scrapping, leading users to mistakenly believe that membrane products are difficult to maintain. Actually, the main issues arise from two aspects: process design and the membrane itself. Through reasonable pre-treatment design and safety protection design, high-quality lined reinforced PVDF film can be used for more than 5 years, and the replacement cycle of RO film is more than 3 years.

Myth 4: Brand and RO quantity are more important than membrane area and system design

When some enterprises establish membrane systems, they excessively focus on whether the membrane is an imported product and lack awareness of the importance of system design. In fact, the performance of some domestically produced ultrafiltration membranes has approached or even reached international advanced levels, with a cost-effectiveness exceeding that of imported membranes. The problem of membrane system failures mostly comes from engineering design.

Many users pay more attention to the number of RO membranes in membrane reuse systems, rather than the membrane area and system design of lined reinforced PVDF membranes in MBR and ultrafiltration components in pre-treatment. In fact, when using the MBR+RO or UF+RO dual membrane recycling process, the RO system operates well, which is often related to insufficient membrane area and unreasonable design of the pre-treatment MBR or UF, resulting in excessive inlet water quality of the R0 system. In fact, the cost of some membrane products for pre-treatment itself exceeds that of RO membranes, such as MBR flat membrane, which is very high in cost.

Myth 5: Membrane technology is omnipotent

Membrane technology is a unit treatment technology that has characteristics such as low effluent turbidity, decolorization, desalination, and strong softening. However, when treating industrial wastewater, membrane technology usually needs to be combined with traditional physicochemical and biochemical treatment processes to better leverage the advantages of membrane deep treatment. Moreover, membrane water treatment often has the problem of concentrated water discharge, and it also requires supporting other technologies, which is not omnipotent.

Myth 6: The more membranes there are, the better

Within a certain range, increasing the number of membranes can improve the water production safety of the membrane system and reduce operating costs. However, as the number of membranes increases to a certain extent, the amount of water evenly distributed on the unit membrane decreases. The flow rate of cross flow filtration water on the membrane surface is lower than the critical value, and sediment on the membrane surface cannot be taken away, leading to increased fouling and blockage of the membrane, and a decrease in water production performance. Moreover, as the number of membranes increases, the required flushing water volume increases. If the flushing water pump and compressed air volume cannot meet the flushing volume requirements per unit membrane area, it will be difficult to thoroughly flush, exacerbate membrane fouling, and affect its water production performance, which is particularly important for MBR or UF membranes. In addition, as the number of membranes increases, the primary membrane investment and depreciation cost of the system will also increase.

Myth 7: RO membranes must use anti fouling membranes

In theory, anti fouling RO membranes are more suitable for wastewater reuse treatment than conventional RO membranes, but the selection of anti fouling membranes depends on their anti fouling mechanism. There are two types of anti fouling RO membranes: one is that the flow channel of the membrane is wider, less prone to blockage, and anti fouling. This type of membrane is widely applicable; Another method is to modify the surface of the RO membrane to make it negatively charged, positively charged, or electrically neutral. Based on the principle of electrical repulsion, pollutants with specific properties are not easily deposited on the membrane surface, thus achieving anti pollution characteristics. The performance of the latter in terms of pollution resistance largely depends on the characteristics of water quality. Due to the wide variety of additives in printing and dyeing wastewater, it is necessary to choose the appropriate type of anti fouling membrane with appropriate electrical properties based on the inflow characteristics of the R0 system, otherwise it will be counterproductive. In addition, in wastewater reuse, due to the fact that the surface of the RO membrane is quickly covered by a layer of pollutants and homogenized, the electrical properties of the membrane surface itself are not distinct, so its practical anti pollution effect needs to be studied. The price of anti fouling RO membranes is much higher than that of conventional RO membranes, and there are few ultra-low pressure anti fouling membranes, so they do not have significant comprehensive advantages in wastewater reuse.

Shenzhen Hongjie Water Technology Co., Ltd. is an integrated high-tech enterprise specializing in product research and development, production, sales, engineering design, installation and debugging, technical consulting, and sales of supporting materials in the fields of industrial water treatment and drinking water treatment. Our main products include the design, manufacturing, installation, debugging, and maintenance of water treatment equipment, including pure water equipment, ultra pure water equipment, reverse osmosis equipment, GMP purified water equipment, EDI deionized water equipment, domestic sewage equipment, industrial wastewater equipment, softened water equipment, and reclaimed water reuse equipment, all of which are integrated into an environmentally friendly high-tech manufacturer.