Troubleshooting of Toray Submerged Membrane Module for MBR(Manual)

May 27, 2021


Most of the troubles in the operation of Toray Submerged Membrane Module for MBR are related to poor membrane scouring aeration, delayed chemical cleaning, and pretreatment upsets. The following table lists some performance losses, their causes and possible remedies.

Table   Troubleshooting
Problem Cause Action
1 The air diffusion flow is below
the required level.
The blower is broken Stop filtration and inspect the blower.
The air diffusers are clogged. Clean the air diffusers.
2 The air diffusion is uneven in
the module or between
The air diffusers are clogged. Clean the air diffusers.
The bottom of the element block is stuck with debris. Check the pretreatment system.
Inspect the module.
Correct operation and maintenance works of the pretreatment system.
3 The filtrate water flow rate has decreased, or the trans-
membrane pressure has
Membrane clogging has got
Conduct chemical cleaning.
Sludge accumulated on the
membrane surface
because of uneven
air diffusion
Inspect the blower and clean the air
diffusers to improve air diffusion.
Conduct chemical cleaning.
Sludge cake removal by external cleaning.
Abnormal properties of
sludge have worsened its
Improve sludge properties.
・    Adjust the excess sludge discharge rate.
・    Prevent entry of abnormal components, such as oils.
・    Adjust the BOD load and oxygen supply.
・    Adjust the raw water quality (add nitrogen, phosphorous, etc.)
Air is accumulated insidz
filtrate piping.
Prime the filtrate piping with water.
Install air removal equipment such as vacuum pump.
Relocate filtrate piping.
4 The concentration of
suspended solids in the filtrate
water has increased.  
Element and/or tube has
been broken.
Seal the element and manifold nozzle*1.
Replace cassette or element according
to the type of module.
Leakage has occurred in
the filtrate water piping.
Inspect the faulty part*2 and correct
the fault.
Germs are generated on the
membrane or the filtrate line.
To clean the filtrated water piping,
inject into it a sodium hypochlorite
solution with an effective chlorine
concentration of 100 to 200 mg/L.

*1:    Even if a cause is found in the tube, there still is the possibility of contamination inside the element. Thus, seal the element and manifold nozzle.
*2:    To check the piping joints and welds for leakage with a pressure being applied, be careful not to apply pressure to the membrane modules.

This content does not intend to guarantee the results of application of the information provided herein or the safety and the compatibility of this product.
Before using this product, the user is asked to check for its safety and compatibility with the intended purpose.
This content is subject to revision from time to time.
Unauthorized use or reproduction of this content is forbidden.

This content is extracted from “Submerged Membrane Module for MBR TORAY “MEMBRAYTM” Instruction Manual”(the Manual).  Please refer to other contents stated in the Manual.
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