What are the water quality requirements for the reverse osmosis system?

As a new type of pure physical desalination process, reverse osmosis system has higher requirements for influent water due to the limitations of the structure, material and desalination mechanism of reverse osmosis membrane elements:

1. Temperature (℃): 1-45.
2. pH value: 2-11.
3. Silt density index (SDI value) <4.0.
4. Turbidity (NTU) <1.0.
5. Organic matter content (COD, mg/L) <1.5.
6. Residual chlorine content (mg/L) < 0.1 (actually controlled at 0).
7. Iron content (mg/L): when dissolved oxygen is >5mg/L, Fe<0.05.
8. SiO2 (mg/L): SiO2<100 in concentrated water.
9. LSI: pHb-pHs<0.
10. Ions that are easy to form insoluble salts such as Sr and Ba: Ipb<0.8Ksp.
    The last three items can be properly increased by adding scale inhibitors.

1. Fouling of RO reverse osmosis membrane.
2.  The RO reverse osmosis membrane is contaminated by metal oxides.
3. Suspended solids foul the RO reverse osmosis membrane.
4. Colloidal pollution.
5. The pollution of organic matter and microorganisms leads to the increase of COD in the effluent.

1. Reduce the water production of the reverse osmosis pure water system.
2. The quality of the product water of the reverse osmosis pure water system is low.
3. Increase the energy consumption of reverse osmosis equipment operation, including raw water and electricity consumption.
4. Increase the operating cost of water treatment, including reverse osmosis scale inhibitor, resin regeneration salt, and other water treatment chemicals.
   When the pretreatment is not done well, the quality of the reverse osmosis influent is seriously substandard, and the time is too long, it will cause irreversible physical and chemical damage to the reverse osmosis membrane element, and greatly shorten the service life of the reverse osmosis membrane element.

The pretreatment of the reverse osmosis unit plays a very important role in ensuring the safety, reliability and economy of the operation of the reverse osmosis unit. The purpose of reverse osmosis pretreatment is to solve the following problems to ensure the stable operation and service life of the reverse osmosis device.

1. Prevent scaling on the membrane surface (including CaCO3, CaSO4, SrSO4, CaF2, SiO2, iron and aluminum oxides, etc.).
2. Prevent the fouling of colloidal substances and suspended solid particles.
3. Prevent the fouling of organic substances.
4. Prevent microbial fouling.

Xian CHIWATEC Water Treatment Technology es una empresa de alta tecnología especializada en varios dispositivos de procesamiento de agua. Aparte de estos productos individuales, que cubren una serie de tipos y series, también podemos ayudar con proyectos de ingeniería integrales relacionados. Gracias a nuestro arduo trabajo y dedicación desde nuestra fundación, ahora somos uno de los fabricantes de equipos de tratamiento de agua de más rápido desarrollo en el oeste de China.

Otras lecturas:

• Pretratamiento y diseño del sistema de ósmosis inversa del equipo de agua pura de China(2)
• Pretratamiento y diseño del sistema de ósmosis inversa del equipo de agua pura de China(1)