RO system troubleshooting
In the daily operation of the reverse osmosis system, it is inevitable to encounter inorganic scaling, colloidal particle deposition, microbial growth, chemical pollution, and other issues, which affect the safe and stable operation of the system. The following mainly explains the problems and control methods that occur in the membrane system in daily life.
Inorganic scaling
The presence of Ca2+, Mg2+, Ba2+, Sr2+, CO32-, SO42-, PO43-, SiO2 plasma in water generally does not cause inorganic scaling. However, in reverse osmosis systems, due to the concentration of raw water by four times and a significant increase in pH, more difficult to dissolve substances will deposit, forming hard scale on the membrane surface, leading to an increase in system pressure (mainly the second stage pressure difference) and a decrease in water production, In severe cases, it can also cause damage to the membrane surface, reducing the desalination rate of the system.
Colloidal and particulate matter deposition
Colloidal and particulate matter pollution are relatively common reverse osmosis system pollution. abundant in waterParticulate matter such as slime, colloidal silica, metal oxides and organic matter are pre-treated in the reverse osmosis system these pollution sources in raw water can be controlled to a certain extent during management, so as not to cause short-term damage to the system operation will have a certain impact. However, due to long-term operation of the system, unsatisfactory pretreatment effects, incomplete pretreatment backwashing, and inadequate daily operations of operators, etc., contamination of system colloids and particulate matter will occur, resulting in an increase in pressure difference (mainly pressure difference), the water production volume decreases, and the salt rejection rate decreases.
microbial contamination
Tap water generally inhibits the growth of microorganisms by controlling residual chlorine. However, residual chlorine has strong oxidizing properties. It can oxidize the surface of the reverse osmosis membrane, affecting the life of the membrane and the quality of the water produced. Therefore, the operation of the reverse osmosis system has very high requirements for residual chlorine. Strict (<0.1), which provides a favorable environment for the survival and reproduction of microorganisms. The growth of microorganisms and the acidic slime excreted will block the pores of the membrane, causing the pressure difference to increase (the pressure difference in each section increases), the desalination rate to decrease, and the water production to decrease, posing serious safety risks to the safe operation of the system.
chemical pollution
Chemical pollution refers to the chemical reaction between certain substances in the incoming water and the membrane surface, causing deposition, precipitation and unconventional aging of the membrane surface, causing contamination of the membrane surface or deterioration of membrane performance.
Common situations include: improper selection of flocculants during pretreatment; improper selection of antiscalants during operation; improper selection of cleaning agents during cleaning; loose pretreatment control, resulting in substances harmful to the membrane being brought into the incoming water (such as: Excessive residual chlorine leads to oxidation of the active layer on the membrane surface). Chemical pollution treatment is mainly prevented by improving the system pretreatment and improving the technical level of operators. Once pollution occurs, it is difficult to clean or restore membrane performance.
In addition to the common problems mentioned above, we will also encounter scratches on the membrane caused by gravel and activity entering the membrane system. These are mainly caused by pretreatment defects or operating errors, and these should also attract sufficient attention.