Membrane bioreactors

Mondo Science Updated on 2024-03-01

Membrane bioreactor (MBR) is a new wastewater treatment system that organically combines membrane separation technology and biological treatment technology. Replacing the secondary sedimentation tank at the end of the traditional biological treatment process with membrane modules maintains a higher activated sludge concentration in the bioreactor, increasing the organic load of the biological treatment, thereby reducing the footprint of the wastewater treatment facility and reducing the remaining effluent by keeping the sludge load low. The amount of mud. It mainly uses membrane separation equipment immersed in aerobic biological pools to intercept activated sludge and macromolecular organic matter in the pool. The activated sludge concentration in the membrane bioreactor system can be increased to 8000 to 10000 mg l. Sludge age (SRT) can be extended to more than 30 days.

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The retention effect of the membrane bioreactor can retain microorganisms with a long generation cycle, so as to achieve deep purification of wastewater. At the same time, nitrifying bacteria can fully multiply in the system, and its nitrification effect is obvious, which provides the possibility of deep phosphorus removal and denitrification.

Sewage treatment: China is a water-scarce country, and sewage treatment and reuse is a measure to develop and utilize water resources. Wastewater reuse is to treat municipal sewage and industrial wastewater through equipment such as membrane bioreactors, and then use it for non-potable purposes such as greening, toilet flushing, and replenishment of ornamental water bodies, while using clean water for drinking and other uses with high water quality requirements. It can take urban sewage and industrial sewage nearby, which can eliminate the need for long-distance water transportation, and realize the full utilization of water resources through nearby treatment. At the same time, treating sewage nearby can also prevent sewage leakage during long-distance transportation and polluting groundwater sources. Wastewater reuse has been widely used in many water-scarce areas around the world and is considered a practical technology for wastewater treatment in the 21st century.

Comparison of inlet and effluent water quality:

The design water quality of general municipal sewage is: BOD5 300mg L. codcr500mg/l。SS > 300 mg of total nitrogen< 45 mg of nitrogen.

Effluent quality: NH4+-N<5mg LCODCR 50mg L. tn5mg/l。tp<0.5 mg l turbidity "5 ntu total coliform count" 1000 l.

Membrane bioreactors (MBRs) are the product of a combination of membrane separation technology and biotreatment technology. Its origin is to use membrane separation technology to replace the secondary sedimentation tank in the activated sludge method for solid-liquid separation. The process not only achieves the purpose of slurry separation, but also has the incomparable advantages of traditional process for sewage treatment

1.Solid-liquid separation. The separation is much better than that of conventional sedimentation tanks. The effluent water quality is good, and the suspended solids and turbidity of the effluent are close to zero, which can be directly reused, and the recycling of sewage is realized.

2.The membrane retention effect enables the microorganisms to be completely trapped in the bioreactor, and the reactor hydraulic retention time (HRT) and mud age (SRT) are completely separated, and the operation control is flexible and stable.

3.Since MBR combines the aeration tank and the secondary sedimentation tank for traditional sewage treatment into one, replacing all the process facilities for ** treatment, it can significantly reduce the footprint and save civil engineering investment.

4.It is conducive to the interception and reproduction of nitrifying bacteria, and the system has high nitrification efficiency. By changing the operation mode, it can also have the functions of deamination and phosphorus removal.

5.Since the mud age can be very long, the degradation efficiency of refractory organic matter is greatly improved.

6.The reactor operates under the conditions of high volumetric load, low sludge load, long sludge age, and the residual sludge production is extremely low. Since the sludge age can be infinitely long, zero sludge discharge can theoretically be achieved.

7.The system realizes PLC control, and the operation and management are convenient.

Technological advantages. Under the conditions of high MLSS and microfiltration membrane filtration, the effluent quality is stable. Under high volumetric loads, short residence times, the MBR process is simpler than conventional systems, has a reduced footprint, and completely replaces sedimentation tanks and sand filter units. Save up to 30% of the floor space compared to traditional methods, and there is no sludge settling problem.

The concentration of MLSS in the reaction tank can reach more than 10000 mg L, which has strong resistance to load impact and can treat high-concentration organic wastewater. Under microfiltration membrane filtration, the separation effect is far better than that of traditional sedimentation tanks and sand filters. The effluent quality is good and stable, and the suspended solids and turbidity are low. Generally speaking, low-pollution urban sewage can be directly used as a secondary waterway after treatment. Use water from on-site resources or recycled water. It is conducive to the retention, growth and reproduction of nitrifying bacteria that proliferate slowly, and can improve the nitrification efficiency of the system. It has a denitrification effect under the AO reaction. The AO and A2O methods can effectively remove ammonia nitrogen and phosphorus, especially in water quality control areas. Internal use. Microfiltration membranes block most bacteria and other microorganisms, reducing the amount of disinfectant dosage and obtaining safe water for reuse. Low energy consumption and low operating costs. Biological retention in the pond can obtain a longer sludge age and a higher sludge age. Under the operation of high sludge age, the amount of sludge is reduced by more than 1 2 due to biological self-lysis. The low amount of waste sludge is lower than that of the traditional activated sludge method, and the sludge discharge cycle is long, and the operation flexibility is high. The biofilm piping system is a filtration system with a high MLSS that easily overcomes wastewater with high variability. The system adopts PLC control design, which is convenient for operation and maintenance, can realize automatic control, and is convenient for the management of high biological sludge operating concentration. MLSS=6000 10000mg L, which can reduce the volume of biological aerobic sludge tank, and can be designed as a closed type, with low pollution, low noise and low odor. Membrane separation technology has greatly improved the treatment efficiency of refractory macromolecules in wastewater. The standard mobile modular design is quick and simple to install, easy to expand in stages, and is suitable for the transformation of old sewage treatment plants, only MBR membrane equipment needs to be installed.

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