RO membrane fouling and cleaning methods researched in steel wastewater
The wastewater collected by the central water treatment station from iron-smelting,steelmaking,and steel rolling has high COD and salt content,which causes serious membrane fouling to the reverse osmosis membrane and directly affects the re-plenishment of new water for production.The membrane fouling caused by steel wastewater on reverse osmosis is a composite type of organic and inorganic pollutants.Relying on a single sodium hydroxide or hydrochloric acid cleaning method makes it difficult to remove membrane fouling and restore membrane flux.When cleaning the membrane,organic pollution should be removed first,and then inorganic pollution should be removed.When preparing organic pollution cleaning agents,complex organic pollution components should be considered,and active ingredients such as EDTA-4Na and sodium dodecyl benzene sulfonate should be added to the cleaning agent.Through elemental spectroscopy analysis,it was found that the inorganic pollutants are mainly com-posed of composite salts of CaSO4 and CaCO3 for scaling.When removing inorganic pollution,sodium carbonate solution should be used for cleaning first,and the slightly soluble CaSO4 should be converted into insoluble CaCO3 through displacement.Finally,rinse with a hydrochloric acid solution to restore membrane flux.
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