Compared to many conventional biological water treatment processes, MBR has the following key advantages.
Due to the high efficiency of the membranes, the separation effect is much better than in traditional sedimentation tanks. The treated water is extremely clear, with near-zero suspended solids and turbidity, and bacteria and viruses are significantly removed, allowing it to be reused directly as non-potable municipal miscellaneous water.
The membrane separation also allows the microorganisms to be completely trapped in the bioreactor, enabling the system to maintain a high concentration of microorganisms, which not only improves the overall efficiency of the reactor in removing pollutants and ensuring good effluent quality, but also makes the reactor very adaptable to changes in influent load (water quality and quantity) and resistant to shock loading, enabling stable and high quality effluent quality to be obtained.
The process can operate at high volumetric loads and low sludge loads, resulting in low residual sludge production (zero sludge discharge is theoretically possible) and reduced sludge treatment costs.
The bioreactor maintains a high concentration of micro-organisms, resulting in a high volumetric load on the treatment unit and a significant saving in floor space; the process is simple, compact and has a small footprint, and is suitable for any occasion, and can be made into a surface, semi-underground or underground type.
As the microorganisms are completely trapped in the bioreactor, it is conducive to the growth of slow-growing microorganisms such as nitrifying bacteria, and the nitrification efficiency of the system can be improved. At the same time, the hydraulic residence time of some difficult to degrade organic matter in the system can be increased, which helps to improve the degradation efficiency of difficult to degrade organic matter.
The process achieves a complete separation of hydraulic retention time (HRT) and sludge retention time (SRT), which makes the operational control more flexible and stable.
The process can be used as a depth treatment unit of the traditional wastewater treatment process and has broad application prospects in areas such as the deep treatment of the effluent from secondary urban wastewater treatment plants (thus realising the reuse of large quantities of urban wastewater).
(1) High membrane cost, making the infrastructure investment of membrane - bioreactor higher than the traditional wastewater treatment process.
(2) Membrane contamination is easy to occur, which brings inconvenience to operation and management.
(3) high energy consumption: firstly, the MBR mud-water separation process must maintain a certain membrane driving pressure; secondly, the MLSS concentration in the MBR pool is very high, to maintain sufficient oxygen transfer rate, the aeration intensity must be increased; and in order to increase the membrane flux and reduce membrane pollution, the flow rate must be increased to scour the membrane surface, resulting in higher energy consumption of the MBR than the traditional biological treatment process.
