There are many misunderstandings about membrane in many people at present,   In particular, these easy misunderstandings are explained here (dry goods, every point is truth)

one point one   Misunderstanding 1: membrane water treatment equipment is a high difficulty operating system

The automatic control requirements of membrane water treatment system are much higher than that of conventional biochemical treatment system, and many users mistakenly think it is difficult to operate membrane process system. In fact, the membrane water treatment system is highly automatic, and the operation of start-up and stop, dosing and online flushing are all performed by PLC system program control, which can be unattended. Only manual and regular inspection and dispensing, periodic maintenance and cleaning are required, and no additional operators are required. The routine cleaning and maintenance of membrane can be mastered in one day, and the difficulty is far lower than the biochemical system with high requirements for comprehensive skills of employees.

one point two   Misunderstanding 2: big investment, can't afford to buy

It is argued that the cost of one-time investment and depreciation replacement of membrane is very high, and can not be bought but can not be used. In fact, with the development of domestic membrane manufacturing enterprises, the price of membrane is falling. MBR membrane system can save civil engineering and land occupation cost, reduce sludge volume and sludge disposal cost, and has high comprehensive cost performance, which is a good choice; For UF and RO system, after the reuse of sewage resources, the economic benefits generated by the system are far higher than the investment of the equipment itself. The depreciation cost of MBR membrane or UF and RO membrane will not exceed 0.6 yuan / t water inflow, or even lower than the dosage cost of system ton water inflow.

one point three   Misunderstanding 3: delicate film is easy to damage

  S-some engineering companies have some problems such as membrane breakage and membrane scrap due to lack of experience. The user mistakenly thinks that membrane products are difficult to maintain. In fact, the main problems come from two aspects: process design and membrane itself. Through the reasonable pretreatment design and safety protection design, the high quality inner lining reinforced PVDF film can be used for more than 5 years, and the replacement period of RO film is more than 3 years.

one point four   Misunderstanding 4: brand and RO quantity are more important than membrane area and system design

Some enterprises have not enough understanding of the importance of system design when they set up membrane system, paying too much attention to whether the membrane is imported. In fact, some domestic ultrafiltration membranes have reached the international advanced level, and the cost performance exceeds the imported membrane. The failure of membrane system is more from engineering design.

Many users pay more attention to the number of RO films in membrane reuse system, rather than the membrane area and system design of membrane reinforced PVDF membrane in MBR and ultrafiltration module. In fact, when mbr+ro or uf+ro double membrane process is used for reuse, RO system is in good operation, which is often related to insufficient membrane area and unreasonable design of MBR or UF, which leads to excessive water quality of RO system. In fact, the cost of some membrane products before treatment is higher than RO film, such as MBR flat film, which is very high.

one point five   Misunderstanding 5: membrane technology is omnipotent

Membrane technology is a unit treatment technology, which has the characteristics of low turbidity, decolorization, desalination and strong softening of effluent. However, when treating industrial wastewater, membrane technology usually needs to be combined with traditional physical and chemical treatment technology, so as to give full play to the advantages of membrane in-depth treatment. Moreover, membrane water treatment usually has the problem of concentrated water discharge, and it also has the need of supporting other technologies, which is not universal.

one point six   Misunderstanding 6: the more the film, the better

In a certain range, increasing the number of membranes can improve the water production safety of the membrane system and reduce the operating cost. However, when the number of films increases to a certain extent, the water amount evenly distributed on the unit membrane decreases. The flow velocity of the flow membrane surface of cross flow filtration is lower than the critical value, and the deposition debris on the membrane surface cannot be taken away, which leads to the aggravation of membrane pollution and blockage and the decline of water production performance. Moreover, after the increase of membrane quantity, the required flushing water quantity increases. If the flushing water pump and compressed air volume cannot meet the flushing volume requirements of unit membrane area, it is difficult to thoroughly wash, aggravate membrane pollution and affect its water production performance, which is particularly important for MBR or UF membrane. In addition, the system's one-time membrane investment and depreciation cost will increase when the number of membranes increases.

one point seven   Misunderstanding 7: RO film must be anti pollution membrane

In theory, the anti pollution RO membrane is more suitable for wastewater reuse than conventional RO membrane, but the anti pollution membrane selection depends on its anti pollution mechanism. RO membrane can be divided into two types: one is that the circulation channel of membrane is wider, and it is not easy to block and anti pollution, which is widely applicable; The other is to make RO film negative, positive or neutral by surface modification of RO film. According to the principle of repelling the same electrical property, pollutants of specific properties are not easy to deposit on the membrane surface, so as to realize the anti pollution characteristics. The latter plays a great role in the anti pollution, which depends on the characteristics of water quality to a large extent. Because of the various kinds of auxiliaries in printing and dyeing wastewater, the suitable electric anti pollution film must be selected according to the inflow characteristics of RO system, otherwise it will be counterproductive. In addition, in wastewater reuse, because RO membrane surface will be covered by a layer of pollutants and homogenized quickly, and the electrical characteristics of membrane surface are not distinct, so its practical effect of anti pollution needs to be studied. The price of anti pollution RO membrane is much higher than that of conventional RO membrane, and there is little ultra-low pressure anti pollution membrane, so it has no significant comprehensive advantage in wastewater reuse.

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