How to clean the membrane of MBR integrated wastewater treatment equipment?

Physical cleaning is a process of removing pollutants from membrane surface and pore by physical mechanical flushing and backwashing. The physical cleaning equipment is simple, but the cleaning effect is limited, which can not completely remove membrane fouling. Physical cleaning mainly includes the following methods:

1. Water backwashing

Backwashing is one of the simple methods to ensure the good water permeability of submerged MBR membrane under various operating conditions. Backwashing is to apply backwashing pressure to reverse the water flow through the membrane at the outlet of the membrane, so that the membrane hole is slightly expanded, and the solid particles attached to the surface of the membrane filament are removed. After water backwashing, the membrane system generally needs to stop for a period of time, and stop control is an alternative to backwashing.

In the stop mode, the water production is stopped. In this process, the solid particles will be taken away by membrane aeration.

The backwashing kept the TMP at a low level and ensured the high permeability of the membrane. At the same time, it can effectively reduce the frequency of maintenance cleaning and recycling cleaning, and reduce the consumption of cleaning agent. Using a small amount of filtered water to backwash the membrane module periodically can significantly improve the membrane flux. In order to avoid the deterioration of effluent quality, backwashing should be carried out under low pressure.

2. Aeration scrubbing

Aeration washing is a physical cleaning method to strengthen water circulation. Aeration can form two-phase flow of water and air, and bubble wake has shear effect on membrane surface. The volume of the bubble wake is proportional to the bubble size. When the gas and liquid flow in the form of large bubbles, the larger bubble wake area is more conducive to inhibiting the development of membrane fouling. Aeration scrubbing is an effective method for membrane cleaning in the early stage of organic pollution.

The study shows that a large number of bubbles pass through the membrane group at high velocity, and the scouring effect makes the membrane surface in a state of intense turbulence on the membrane surface, avoiding thickening of the gel layer and accumulation of material, and prolonging the cleaning cycle of the membrane. At the same time, this turbulence also slows down the concentration polarization phenomenon from two aspects: one is to increase the flow speed through aeration, so that it is in a turbulent state, so that the high concentration can be better mixed with the mainstream concentration on the membrane surface. The two is to clean the membrane surface continuously, eliminating the gel layer that has formed.

3. Ultrasonic cleaning

Ultrasonic cleaning is a process of removing membrane fouling by using the violent turbulence, cavitation and vibration caused by ultrasonic in water. In particular, the conventional cleaning method is difficult to meet the requirements and geometry, the membrane surface viscosity is high, and the conventional physical cleaning effect is poor. Ultrasonic cleaning can restore about 30% of membrane permeability. Due to the killing effect of ultrasound on microorganisms, the effect of ultrasound on microorganisms in activated sludge needs further study. Ultrasonic cleaning membrane is feasible, but the specific operating parameters need to be further discussed.

4. Other methods

Electric cleaning is a method to accelerate the cleaning process by applying voltage to the membrane to make the particles charged. This method is still in the research stage. In addition, the contaminated membrane can be cleaned by mechanical scraping, pulse cleaning and electrodialysis backwashing.

The MBR integrated wastewater treatment equipment adopts the MBR flat membrane with high porosity, good permeability, large flux, high filtration precision, good interception effect and stable effluent quality. Good anti pollution performance, effectively prevent the accumulation of sludge and other impurities, put an end to the hardening of traditional components and other problems, strong anti pollution ability, convenient maintenance and cleaning. The utility model has the advantages of simple aeration structure, low energy consumption, convenient replacement, high mechanical strength, eliminating the disconnection phenomenon of traditional components, long service life, etc.