Daily inspection of MBR membrane bioreactor

Operation and Management Project     

      The operating performance of membrane components varies with the quality of raw water and the operating conditions. To maintain stable operation, it is recommended that you record the values of various management items to grasp the changes and characteristics of the membrane component performance of your company.

The following are examples of operation and management projects.

1 Aeration volume

2 Air outlet pressure   

3 Permeate water flow rate or membrane filtration flow rate

4 Transmembrane pressure ( TMP )

5 Permeate water quality ( BOD 、 COD Turbidity, T - N 、 T - P etc.)

6 Reaction tank water temperature   

7 Raw water quality ( BOD 、 COD Turbidity, T - N 、 T - P etc.)

8 Excess sludge discharge

9、 DO (Dissolved oxygen concentration)

10 Membrane immersion tank pH

11、 MLSS

12 Sludge viscosity   

13 Sludge settling performance ( SV60 or SVI120 )

      For stable operation of the membrane components, the aeration status and the stability of biological treatment are particularly important. Please carry out the daily inspections shown below.

1 Transmembrane pressure   

      Check the stability of the transmembrane pressure. A sudden increase in transmembrane pressure indicates membrane fouling, which may be caused by abnormal aeration or deterioration of sludge properties. When this happens, check the following parameters and take necessary actions, such as chemical cleaning of the membrane components.

2 Aeration status   

      Check whether the aeration air volume is the standard amount and whether it is uniform aeration. If the aeration air volume is abnormal and there is obvious uneven aeration, please take necessary measures: such as removing scaling from the aeration pipe, checking the installation, checking the blower, and adjusting the aeration.

3 Color and smell of activated sludge   

      The normal color and smell of activated sludge is tea-brown with flocculation and no unpleasant smell. If the appearance and smell are not in this state, please appropriately adjust MLSS Sludge viscosity, DO 、 pH Water temperature, BOD Check the values such as load.

4、 MLSS

        Normal MLSS in 7,000 ~ 18,000mg/L If this condition is not met, the specified performance may not be achieved, so please adjust appropriately. MLSS Range: MLSS If it is too low, measures such as adding seed sludge or stopping sludge discharge can be adopted; MLSS If it is too high, measures such as increasing the amount of sludge discharged to the sludge thickening tank can be taken.

5 Sludge viscosity   

      Normal sludge should be 250mPa*s or less. If this condition is not met, the specified performance may not be achieved, so please adjust to the normal viscosity range: If it is too high, measures such as updating the sludge and increasing the amount of sludge discharged to the sludge thickening tank can be taken.

6、 DO

    Normal DO is uniformly 1mg/L or more in the membrane bioreactor. If this condition is not met, if the maximum aeration amount is not exceeded, necessary measures such as adjusting the aeration conditions can be taken.

7、 pH

      Normal pH is 6 ~ 8 If this condition is not met, the specified performance may not be achieved. Please add acid or alkali to adjust. pH 。

8 Water temperature   

      The normal water temperature is 15 ~ 40 ℃ If this condition is not met, the specified performance may not be achieved. Therefore, if possible, please take necessary measures such as cooling and heat preservation.

9 Water level   

      Please check whether the water level of the membrane bioreactor is within the normal range. If an abnormality occurs, please check the following:

① Check the liquid level gauge

② Check the permeate pump  

③ Check the transmembrane pressure of the membrane element, etc.     

Immersion MBR membrane component operation method

1 Clear water operation

（ 1） Inspection and setting  

Before clear water operation, please carry out the following inspection and preparation work.

（ a) Please reconfirm the correct connection of the air pipe and wastewater pipe.

（ b) Confirm that the membrane element tank is fixed on the aeration tank.   

（ c) Confirm that the reaction pool where the membrane components are placed has been cleaned. Open the protective cover. Dirt and dust may damage the membrane components.   

（ d) Before putting clean water into the pool, open the air vent valve to exhaust the air from the membrane elements.

（ e) Add clean water (tap water or filtered water) to the operating water level.

（ f) After the water has been drained, close the air vent valve.

（ 2) Clean water operation   

Please follow the following instructions for clean water operation.   

（ a) After starting the aeration blower, please confirm the aeration volume and uniformity of aeration.   

Foam may be generated during clean water operation. This phenomenon may be due to insoluble, biodegradable, hydrophilic substances contained in the membrane. This phenomenon can be ignored and operation can continue.   

（ b) When one blower supplies air to multiple membrane components, the air supply to each membrane component should be ensured to be the same. If there are serious differences, please check the pipeline structure (interface pipe thickness, etc.) and the condition of each air supply pipe to ensure consistent air supply.   

（ c) During clean water commissioning, please check the performance of the control equipment.   

（ d) During clean water commissioning, please measure and record the transmembrane pressure difference and water temperature under the design filtration water volume (usually, maximum, and minimum flow rates).   

（ e) During clean water commissioning, after the performance test is completed, please immediately stop filtration and aeration.     

2、 Seed sludge addition   

Seed sludge must be added. If seed sludge is not added and the membrane is used to separate raw water directly, membrane blockage may occur earlier.   

Please follow the following points when adding seed sludge.   

（ 1) Please prepare seed sludge for treating the same type of wastewater. It is recommended to use MLSS concentration at 20,000mg/L or so seed sludge.

（ 2) Start feeding raw water immediately after adding seed sludge. Please feed through a micro-fine screen (gap 5mm or less) etc. to remove impurities.

（ 3) The amount of seed sludge added should be sufficient to make the membrane immersion tank MLSS concentration at 7,000mg/L or more.

Do not use inoculants.     

3、 Operation start   

After the seed sludge is added, aeration is started first, then filtration operation is started, and raw water supply is started simultaneously. When the filtration water volume is stable, please measure and record the transmembrane pressure difference and water temperature under the actual operating filtration water volume.