Calcium carbonate scale
Calcium carbonate scale is a mineral scale. When the scale inhibitor/dispersant addition system fails, or the acid addition pH adjustment system fails to cause the pH of the feedwater to increase, calcium carbonate scale may be deposited. Setting up a transparent tube on the concentrated water pipeline helps to find the fouling problem as soon as possible, and is extremely necessary to prevent the crystals deposited on the surface of the membrane from damaging the membrane elements. The calcium carbonate scale detected early can be removed by lowering the pH of the feed water to 3-5 and running for 1-2 hours. For calcium carbonate scale that has a long deposition time, it can be cleaned and removed with a low pH citric acid solution.
Calcium sulfate, barium sulfate, strontium sulfate scale
Sulfate scale is a mineral scale that is much harder than calcium carbonate scale and is not easy to remove. Failure of the scale inhibitor/dispersant addition system or the addition of sulfuric acid to adjust the pH may result in the deposition of sulfate scale. Sulfate scale should be discovered as soon as possible to prevent the crystals deposited on the surface of the membrane from damaging the membrane elements. Barium sulfate and strontium sulfate scale are more difficult to remove because they are difficult to dissolve in almost all cleaning solutions, so special attention should be paid.
Calcium phosphate scale
Calcium phosphate scale is more common in municipal wastewater treatment with high phosphorus content. Usually this kind of scale can be removed with acidic cleaning fluid. At present, the calculation of phosphate-free scale is not included in the RO design software of Hydra. If the phosphate content in the feed water reaches or exceeds 5PPm, please contact Hyde Energy.
Metal oxide/hydroxide pollution
Typical metal oxide and metal hydroxide pollution are iron, zinc, manganese, copper, aluminum and so on. The cause of the formation of this scale may be corrosion products of equipment pipelines, containers (tanks/tanks), or metal ions, chlorine, ozone, potassium, permanganate, or pretreatment filtration systems that are oxidized in the air. The use of iron or aluminum coagulant aids.
Polymeric silica scale
Silica gel scale is more difficult to remove and comes from soluble saturation or polymerization reaction in your country. Silica gel fouling is different from silica-based colloid pollution, the latter may be related to metal hydroxides and organics. It is almost impossible to deal with silica scale using traditional cleaning methods. If you encounter unfavorable cleaning conditions, please contact Hyde Energy. Existing chemical cleaning agents, such as ammonium bifluoride, have been successfully used in some projects, but they are very toxic and harmful to equipment.
A colloid is an inorganic substance suspended in water or a particle of a mixture of organic and inorganic substances. It does not settle by its own gravity. Colloids usually contain one or more of the following main components such as iron, aluminum, silicon, sulfur or organic matter.
Dissolved Natural Organic Matter (NOM)
Dissolved natural organic matter pollution (NOM, Natural Organic Matter) is usually caused by the decomposition of nutrients in surface water or deep well water. The chemical mechanism of organic pollution is very complicated. The main organic component is either humic acid or griseofulvic acid. The adsorption of insoluble NOM on the membrane surface can cause rapid pollution of RO membrane elements. Once adsorption occurs, the gel or block pollution process will begin.
Organic sediments are produced by bacterial slime, fungi, molds, etc. Such pollutants are difficult to remove, especially when the water supply channel is completely blocked. Blockage of the water supply channel will make it difficult for clean water to enter the membrane element sufficiently and evenly. In order to inhibit the further growth of such deposits, it is important not only to clean and maintain the RO system, but also to clean the pretreatment, pipes, and ends. When applying oxidative sterilization to membrane elements, please contact the technical support department of Hyde Energy and use a fungicide approved by Hyde Energy.