Common Problem and Solution of Reverse osmosis system

I. Pollution of mud particles and inorganic colloid

1.1 Phenomenon and symptoms:

(1) Mud and sand particles accumulate at the inlet water point of the first section membrane elements

(2) The system pressure increase while the desalination rate will be lower

(3) After dissect the membrane element, visible pollutants can be seen the surface of membrane and inlet flow channel.

1.2 Reason

(1) Pre-treatment part fails or design defects

(2) Insufficient backwash and quick wash of the multi-media /activated carbon filter

(3) The SDI value of inlet water is high

(4) Hard sand particles mechanically scratch the diaphragm.

1.3 Solution

(1) If it is difficult to recover by chemical cleaning, can try to use acid-base cleaning

(2) Strengthen the backwash of multi-media /activated carbon filter

(3) Strengthen the monitoring of SDI value

(4) Strengthen the monitoring and replacement of security filter elements

II. Pretreatment of activated carbon broken and leaked

2.1 Phenomenon and symptoms:

(1) Black material accumulate at the inlet water point of the first section membrane elements

(2) The system pressure increase while the desalination rate will be lower

(3) After dissect the membrane element, activated carbon particles can be seen the surface of membrane and inlet flow channel.

2.2 Reason

(1) Incorrect or insufficient backwashing and quick washing of activated carbon filter

(2) After a long period of operation, the activated carbon is broken due to the reduction of the mechanical strength due to the reaction and consumption of chlorine or ozone

(3) Activated carbon particles mechanically scratch the diaphragm.

2.3 Solution

(1) Replace with new activated carbon, sufficient backwash of the carbon bed; strengthen monitoring and replacement of security filter elements

III. Microbial contamination

3.1 Phenomenon and symptoms:

(1) The system pressure increase while the desalination rate will be lower

(2) After dissect the membrane element or open pressure vessels, there is a bad smell

3.2 Reason

(1) The inlet water is rich in nutrients, such as high TOC and COD

(2) The inlet water or scale inhibitor contains microorganisms

3.3 Solution

(1) Clean and disinfect the entire system, including the pretreatment and membrane body parts. At the same time, also should notice if cleaning and disinfection are not thorough, will occur re-contamination quickly

(2) The system can be cleaned and restored with strong Alkali, like using alkaline solution with PH=12~13

(3) Install or optimize pretreatment to deal with microbial contamination of raw water

(4) Eliminate the source of microorganisms

(5) Use anti-pollution membrane elements (FR series)

(6) Use non-oxidizing bactericide

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