As an advanced water treatment technology, the membrane bioreactor (MBR) combines biological treatment technology with membrane filtration technology and is widely used in the treatment of urban wastewater, industrial wastewater, and the purification of drinking water. Its core lies in the use of biological treatment technology to remove organic matter, ammonia nitrogen, phosphorus, and other pollutants from water, and at the same time, effectively remove suspended solids, colloids, and microorganisms through membrane filtration technology to ensure that the effluent water quality meets high standards. The following will introduce in detail the principle of water purification by the membrane bioreactor and how biological treatment is combined with membrane filtration.

Basic principle of the membrane bioreactor

The basic principle of the membrane bioreactor is to combine the traditional activated sludge process with membrane separation technology by adding a membrane module to the biological reactor, achieving efficient biological degradation and solid-liquid separation. The membrane module usually adopts ultrafiltration (UF), microfiltration (MF), or nanofiltration (NF) and other technologies, with pore sizes ranging from 0.001 to 0.1 micrometers, which can effectively retain macromolecular substances such as microorganisms and suspended solids produced during biological treatment.

Combination of biological treatment and membrane filtration

Biological treatment stage: In the membrane bioreactor, microorganisms degrade organic matter, ammonia nitrogen, and other pollutants in wastewater under aerobic, anaerobic, and anaerobic conditions through synergistic action, converting them into harmless substances. In this process, the microbial community removes pollutants in water through adsorption, oxidation-reduction, and other actions.

Membrane filtration stage: After biological treatment, the mixed liquid enters the membrane module and achieves solid-liquid separation by utilizing the selective permeability of the membrane. The membrane module has a high retention capacity for macromolecular substances, microorganisms, and some suspended solids, while water molecules and other small molecular substances can pass through the membrane into the outlet. In this way, on the one hand, most suspended solids and microorganisms can be removed, and on the other hand, the activity of microorganisms in the biological treatment process can be maintained.

Membrane cleaning and regeneration: In order to ensure the long-term stable operation of the membrane module, the membrane module needs to be cleaned and regenerated regularly. The cleaning methods usually include chemical cleaning and physical cleaning, the purpose of which is to remove dirt and sediments on the membrane surface, and restore the permeability of the membrane. The regeneration process involves the chemical or physical treatment of the membrane to restore its structure and performance.

Conclusion

The membrane bioreactor combines biological treatment technology with membrane filtration technology, which not only effectively removes organic matter, ammonia nitrogen, phosphorus and other pollutants from water, but also maintains the activity of microorganisms in the biological treatment process, achieving efficient and stable water treatment effects. In addition, the membrane bioreactor has great potential in water resource recycling and industrial wastewater treatment, and is expected to be widely used in more fields in the future.