Chemical Cleaning for Pressurized Toray UF Membrane Module (Manual)

May 28, 2021

                                   



The chemical cleaning should be carried out to remove foulants accumulated in the membrane pores or sticking to the membrane surface.
 
  • Carry out the chemical cleaning before the trans-membrane pressure rises up to 200 kPa (29.0 PSI), or the module filtration performance could be reduced significantly.
  • Follow the instruction described in this manual when you carry out the chemical cleaning.  If you use the unacceptable chemicals or perform the cleaning altered from the recommended procedure, the membrane could be seriously damaged.
 
  • Pay full attention when handling chemicals and be sure to wear the safety gear such as glasses and gloves.  The chemicals used for the chemical cleaning are harmful to people.  If chemicals directly contact your skin, your eyes or other body parts, take the appropriate treatment as stated in its SDS.
  • Do not mix sodium hypochlorite with acid.  Such mixture generates toxic chlorine gas.
  • Stop operations when any instrumental anomalies occur or any sign of anomalies are observed.




(1)    The flow diagram for cleaning simultaneously both outer surface and inside of hollow fiber membranes is shown in Fig. 1.  The flow diagram can be changed case by case.  Please contact us if you need the information in detail.
(2)    Open the chemical return valve and then open the chemical feed valve.
(3)    Run the chemical feed pump to start the circulation of chemical and then open the chemical permeate valve to have the chemical permeate through the membrane.
(4)    Circulate the chemical for a fixed time.
(5)    Stop the chemical feed pump.
(6)    Drain the chemical and rinse the cleaning line and the module thoroughly with product water.

 
  • Take appropriate measures to prevent the mis-operation or accidents that could cause the chemicals to get into the product water.  Check the piping and correctly position of each valve before starting the chemical cleaning.

(7)    The standard conditions for chemical cleaning are shown in Table 1.
―The concentration and the circulation time shown in Table 1 should be observed.  Otherwise the membrane module may get damaged and/or the life of membrane may be shortened.
―The cleaning temperature should be 20 to 40 degree C.
―The circulation flow rate for each type of the module is as follows.
HFUG-2020AN:     62.5 L/min (16.5 gpm)
HFU-2020AN:     50 L/min (13 gpm)
HFU-1020AN:     20 L/min (5.3 gpm)
HFU-2020HN:     50 L/min (13 gpm)
HFU-B2315AN:     42 L/min (11 gpm)

Table   Standard conditions for chemical cleaning
Pollutants Chemicals Maximum Concentration Circulation Time (hr)
Inorganic substances Citric acid *1) 3.0 wt% 1 - 3
Organic substances Sodium hypochlorite 3,000 mg/L as chlorine (10<pH<12) 1 - 3
*1): Besides citric acid, hydrochloric acid (with the maximum concentration of 1.0 mol/L), oxalic acid (with the maximum concentration of 1.0 wt%), sulfuric acid (with the maximum concentration of 0.05 mol/L) and nitric acid (with the maximum concentration of 0.1 mol/L) are acceptable.

 
  • In the case of cleaning with acid and with sodium hypochlorite alternately, rinse the cleaning line and the module with clean water thoroughly after each cleaning.  Use product water for rinsing and make sure that pH of the water in the module is in the range between pH 6.5 and 7.5 after rinsing.
 
  • Do not use any other chemicals than those indicated above.
  • Do not mix sodium hypochlorite with acid.  Such mixture generates toxic chlorine gas.
 
The chemical cleaning should be done at least once a year.  
Otherwise the module filtration performance could be reduced.



[Notice]
This Instruction Manual 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.
The content of this Instruction Manual is subject to revision from time to time.  Unauthorized use or reproduction of this manual is forbidden.

[Remarks]
This content is extracted from “TORAY Pressurized PVDF Hollow Fiber Membrane Module  Instruction Manual”.
Please refer to other contents stated in manuals.
UF HFUG-Series Instruction Manual
UF HFU-Series (Type AN) Instruction Manual
UF HFU-Series (Type HN) Instruction Manual
UF HFU-Series (Type B2315AN) Instruction Manual