Advantages and disadvantages of MBR membrane wastewater treatment process
MBR, also known as membrane bioreactor, is a new type of water treatment technology that combines a membrane separation unit and a biological treatment unit. There are many types of membranes, which are classified according to the separation mechanism, including reactive membranes, ion exchange membranes, permeable membranes, etc.; according to the nature of the membranes, there are natural membranes (biological membranes) and synthetic membranes (organic membranes and inorganic membranes); by membrane Structural types are classified into flat type, tubular type, hollow fiber type, etc.
The advantages of the MBR process: 1. The hydraulic retention time is separated from the sludge age. The MBR membrane technology can intercept all microorganisms in the water, realize the separation of the hydraulic retention time and the sludge age, make the operation control more flexible, and make it possible to extend the sludge age. This is conducive to the growth and reproduction of slow-proliferating nitrifying bacteria, and the denitrification efficiency is greatly improved. At the same time, because the system has a long sludge age, the amount of excess sludge produced is very small.
2. The effluent quality is higher than that of traditional biochemical processes. Membrane technology can not only trap microorganisms in the water, but also trap some of the insoluble pollutants of macromolecules, prolong the residence time of pollutants in the reactor, and increase the removal rate of refractory pollutants. At the same time, because the mud age is long, the denitrification effect is good, and the effluent is basically free of SS, the effluent quality of MBR is better than that of the traditional process.
3. Strong impact resistance, MBR sludge load is generally about 0.1~0.2kgCOD/(kgVSS·d), and the volume load can reach about several thousand grams.
4. It can effectively reduce the concentration of pollutants. As a biochemical treatment process, the MBR membrane can convert organic matter into carbon dioxide and water, and nitrogen pollutants can be converted into nitrogen. It can also reduce the conductivity of raw water, which makes the subsequent membrane treatment process load a lot Alleviate, prolong the life of the membrane, increase the water production rate, and reduce the concentration of the concentrated solution.
5. Small footprint. Due to the high rejection rate of the membrane system, the reactor can maintain a high concentration of sludge, which is usually 3-5 times that of the traditional activated sludge method. The high sludge concentration makes the volume of the reactor relatively large. The traditional craft is much smaller, coupled with the high-efficiency deep-water oxygen supply form, the area of the biochemical part is much smaller than that of the traditional craft.
6. The remaining sludge output of this process is low, which reduces the cost of sludge treatment.
7. Convenient operation and management, easy to realize automatic control
Disadvantages of MBR process:
1. The high membrane cost makes the capital investment of membrane-bioreactor higher than traditional sewage treatment technology
2. Membrane fouling is easy to occur, which brings inconvenience to operation and management
3. High energy consumption. First, the MBR mud-water separation process must maintain a certain membrane driving pressure, and secondly, the MLSS concentration in the MBR tank is very high. To maintain sufficient oxygen transfer rate, the aeration intensity must be increased, and in order to increase the membrane To reduce membrane fouling, the flow rate must be increased to flush the membrane surface, which causes the energy consumption of MBR to be higher than that of the traditional biological treatment process.
4. There are many influencing factors. The increase in membrane flux and the extension of membrane life will greatly reduce the operating cost of MBR. Therefore, under the premise of ensuring the quality of the effluent, the membrane flux should be as large as possible, which can reduce the use of membranes. Area, reducing capital construction costs and operating costs. Therefore, controlling membrane fouling and maintaining a high membrane flux are important contents of MBR research. The membrane flux is closely related to factors such as membrane materials, operation methods, and hydraulic conditions.