Introduction of cleaning method after reverse osmosis membrane fouling

After the Ro Equipment has been in operation for a period of time, the Ro Membrane elements will be polluted by suspended solids or insoluble substances in the water, the most common of which are calcium carbonate scale, calcium sulfate scale, metal oxide scale and silicon deposits. The nature and pollution rate of pollutants are related to the water supply conditions. If measures are not taken early, the pollution will damage the performance of the Reverse Osmosis Membrane element and reduce the service time of the reverse osmosis membrane in a relatively short period of time. In this article, the editor will talk about the cleaning method after the reverse osmosis membrane is polluted.

• Removal of reverse osmosis membrane contaminants
  

  The removal of reverse osmosis membrane pollutants can be achieved by chemical cleaning and physical flushing, sometimes by changing the operating conditions. As a general rule, reverse osmosis membrane cleaning should be performed when one of the following conditions occurs.

  1. Produced water flow drops to 10 to 15% of normal at atmospheric pressure.
  2. To maintain product outlet flow, temperature-corrected feedwater pressure is increased by 10 to 15 percent.
  3. The water quality of reverse osmosis water is reduced by 10 to 15°C, and the salt permeability is increased by 10 to 15°C.
  4. Use 10 to 15% more pressure.
  5.The differential pressure of the RO Membrane increases significantly in different time periods.
  

• Common pollutants of reverse osmosis membrane and their removal methods:

  1. Calcium carbonate scale

  When the antiscalant addition system fails or an acid system occurs, the pH of the feed water increases and calcium carbonate can then be deposited. Precipitation of calcium carbonate scale should be detected as early as possible to prevent crystal growth on the reverse osmosis membrane surface.damage and early detection of calcium carbonate scale.It can be removed by running the pH of the feed water between 3.0 and 5.0 for 1 to 2 hours. For calcium carbonate scales that have been deposited for a long time, citric acid cleaning solution should be used for circular cleaning or soaking overnight.

  
  

  Make sure the pH of any cleaning solution is not lower than 2.0, or it may cause damage to the RO membrane elements, especially at higher temperatures.The maximum pH should not be higher than 11.0. Ammonia is used to increase the pH and sulfuric or hydrochloric acid is used to decrease the pH.

  2. Calcium sulfate scale
  Cleaning solutions are the best way to remove calcium sulfate scale from RO membrane surfaces.
  3. Metal oxide scale
  

  Deposited hydroxides can be removed using the Calcium Carbonate Scale Removal method described above.

  4. silicon scale

  Silica scales that do not co-exist with metallization or organic materials can only be removed by special cleaning methods.

  5.organic deposits
  

  Organic deposits (such as microbial slime or mold) can be removed with a cleaning solution. To prevent re-transmission, a professional sterile solution should be used to circulate and soak the system. Usually, it takes a long time to soak it, such as reverse osmosis equipment. After three days of use, it must be disinfected.