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Clean In Place (CIP) A
Use citric acid or HCl solution, and adjust pH value at 2-3.It is suitable for iron pollutes and carbonate crystallization fouling. 
CIP with acid solution is done with following procedures: 
1. Preparation
1.1. Close all valves; 
1.2. Prepare citric acid or HCl solution (pH value=2-3) in cleaning solution tank and mixed completely. 
2. Control the chemical solution’s temperature at 20-30ºC
1. Hollow Fiber UF membrane Modules need to be cleaned before initial use as following:
  • After installing the modules well in your plant, run the plant in normal operating process, and keep the feed water pressure at a low value of less than 0.1 MPa. 
  • After running 10 mins later, clean the modules for 30 seconds with backwash and air-scrubbing, then do backwash 1 for 30 seconds and then do backwash 2 for 30 seconds. 
  • Discharge the pollutants from the modules. 
  • Repeat the above procedures till the pH value of feed water is the same as brine water.
  • By now the UF plant is ready to start working. 

  • When  cleaning new modules here are attentions for different types of cleaning: When doing backwash and air-scrubbing, the air flow rate should be ≤ 2 NM3/h for each piece and backwashing water flow rate should be ≤0.4 M3 / h for each piece. 
  • When doing backwash 1 and backwash 2, the backwashing water flow rate should be ≤ 1 M3/h  for each piece. 
  • For smaller membranes for drinking water systems FI-204(ABS), FI-20 x 520(UPVC) and FI-90-100KH the flow should be lower ( not more than 40 % of designed flux.).

2. Hollow Fiber UF Membrane Module using instructions
  • The max. feed water pressure is 0.20 MPa. 
  • Backwashing water flow rate is 120 % of actual flux of the system.
  • Control the backwashing water inflow pressure at ≤ 0.15 MPa 
  • Air inflow is 1-2-4-8 NM3 /h for each piece (backwashing water inflow could be 90 % of actual flux, when doing backwash and air-scrubbing), and air inflow pressure should be controlled ≤ 0.1 MPa. 
  • The maximum Trans Membrane Pressure (TMP) is 0.15 MPa. 
  • When TMP is ≥ 0.12 MPa chemical cleaning (CIP) must be done immediately. 

3. Chemical cleaning notices 
  • All cleaning chemicals must inflow from feed water inlet. 
  • Backwash and air-scrubbing and backwash1 & 2 must be done completely before chemical cleaning (CIP). 
  • The complete chemical cleaning process needs about 2~4 hrs. 
  • If the modules are seriously polluted, then the modules need to be immersed in chemicals for more than 12 hrs. 
  • If the UF plant would stop working for more than 3 days after chemical cleaning, then the UF plant must be protected and serviced according to long term stop requirements. 
  • The chemical cleaning solution must be diluted with UF pure water or better quality water. 
  • Pollutants, which possibly exit in the chemical cleaning solution, must be removed before inputting chemical cleaning solution into the UF modules. 
  • When  Mixture  of  chemical  cleaning solution are necessary then the chemical cleaning solution and the bactericide should not do damage to membrane fibers and UF modules. 
  • Discharge chemical cleaning solution completely after each cleaning and flush the system with UF pure water or RO water. 
  • Then do chemical cleaning again.

  • Make sure to keep Hollow Fiber UF Membrane Modules wet at all times. 
  • Once the membrane fibers are dry, they will be irreversibly damaged.

4.How to protect UF system during long-term stop. 
  • If  the UF system stops working for short time (less than 3 days), do one backwash and air-scrubbing and backwash 1 & 2 everyday and then close all valves.  
  • If the UF plant stops working for 4-7 days, run the system for 30-60 mins every day (there into it must include one backwash and air-scrubbing and backwash 1 & 2), and then close all valves.
  • If the UF system stops working for more than 7 days, UF membrane modules must have complete chemical cleaning.
  • Then inject protect liquid (1 % hydrosulfite of sodium solution) into membrane modules and then close all valves.
  • Make sure to test pH value of the protect liquid every month, and change the protect liquid immediately when the pH value is ≤ 3.
  • If restart the plant after long-time stop, make sure to flush the UF system continuously until there is no foam in the pure water.
  • Make sure to keep UF membranes wet during the stop, once the membrane fibers are dry, they will be damaged irreversibly.

  • Make sure to keep Hollow Fiber UF Membrane Modules wet at all times. 
  • Once the membrane fibers are dry, they will be irreversibly damaged.
3. Clean 
  1. Backwash with air scrubbing (BAS) and Backwash must be completely done before CIP. 
  2. Drain down water from membranes before CIP too. (Attention: Insert chemicals to membranes immediately after draining down all water.) 
  3. Start  cleaning  pump, slowly open cleaning pump outlet valve and UF system cleaning solution inlet and outlet valves. 
  4. Control the cleaning solution flow rate at 0.4~1M3/h for each membrane module and re-flow to cleaning solution tank. 
  5. Recycle cleaning time is 30 min. 
  6. Test pH value, if it is more than 3, drain down cleaning solution, re-prepare cleaning solution and clean again. 
  7. Close cleaning pump, immerse 30-60 min without running.
  8. Recycle for 30 min at same flow rate after immersing. 
  9. Drain down cleaning solution tank and cleaning filter, and flush them with pure water. ​

​​4. Flush UF system. 

  1. Flush UF system to remove remaining chemicals. 
  2. Open UF system brine water discharge valve and pure water discharge valve, drain down all chemical cleaning solution. 
  3. Open UF system feed water valve. 
  4. Feed water flow into UF membrane modules, make it as Filtration status and goes into automatic Cleaning status, discharge brine water and pure water. 
  5. Make pure water flow into pure water tank until its pH value is more than 6. 
  6. Go back to production running status. ​
​​Backwash Design for this kind of raw water quality: 
  1. It is suggested backwash 1 time & flush 2 times in 30 minutes, the whole process will be in 2 minutes. 
  2. There will be backwash top & backwash bottom, backwash top for 30 seconds and backwash bottom for 30 seconds , flush for 15 seconds. 
  3. Please use UF filtrate water for backwash.
  4. Max. Backwash Pressure:≤ 0.15 MPa .
  5. Backwash Flowrate: 120 % of actual flux
  6. Backwash pump: 1 unit.

​​Chemical Cleaning Device:

  1. Chemical Cleaning Pump
  2. Chemical Cleaning Tank
  3. Chemical Cleaning Pressure:≤ 0.1 MPa
Chemical Cleaning Category
  1. Acid Cleaning:2%  Citric Acid diluted by UF permeated water, pH = 2
  2. Alkaline Cleaning: 0.5% Sodium Hydroxide and 30 ppm NaCLO diluted by UF permeated water, pH=12
Note: Do alkaline Cleaning after acid Cleaning, and finally washed by clean water until the pH = 7, otherwise it will affect the water flux.
Standard Operating Conditions: Filtration – Backwash and air-scrubbing – Backwash 1 –Backwash 2- Filtration
Clean in place (CIP) B 
NaClO 500~1000 mg / L + NaOH mixture solution pH=11~12, it is suitable to clean  organic fouling and bacteria pollution. 
CIP B is operated as following
1. Preparation: 
  1. Close all valves. 
  2. Prepare NaClO 500~1000 mg / L+ NaOH mixture solution in cleaning tank. 
  3. Make pH value at 11-12, and mix it completely. 
2. Control the standard chemical solution’s temperature at 20-30º C 
3. Cleaning
  1. If the cleaning solution’s pH value is less than 10, then drain down all solution, and re-prepare chemical cleaning solution. 
  2. All the other procedures are the same as CIP A.
Chemical Cleaning Process 
  1. Acid immersion for 60 minutes. 
  2. Acid cycle cleaning  for 60 minutes.
  3. Discharge acid chemicals.  
  4. Wash with clean water until PH=7. 
  5. Alkaline chemicals immersion for 60 minutes. 
  6. Alkaline cycle cleaning for 60 minutes. 
  7. Discharge Alkaline chemicals. 
  8. Wash with clean water until PH=7. 
  9. Make water running normally. 
Chemical Enhanced Backwash (CEB) 
  1. Make sure to remove most fouling before CEB.
  2. Make sure to immerse the module in chemicals completely. 
  3. Control the backwash water flow rate ( look at the schematic diagram above) at 1~2~ 4~6 M3/h for different models or 120 % of the flux, when adding chemicals. 
  4. Clean it for 30-60 mins.
  5. Make sure to back flush all chemicals from the complete system.
  6. Chemicals are chosen according to different fouling.
  7. If the membrane is mainly polluted by inorganic fouling, use HCl (pH=3-4). 
  8. While for organic fouling, use mixture of NaClO 200~500 mg / L + NaOH control the pH at 10-11.
  9. Sometimes, CEB NaOH / NaClO and CEB HCl can be used simultaneously or in turn. 

Holow Fiber (HF) Ultra Filtration (UF) Membrane Operation Manual