During the entire operation of reverse osmosis system, in addition to all the normal attenuation coefficients, the attenuation coefficient of the performance of reverse osmosis system is more serious due to pollution. The key to general pollution is organic chemical dirt, organic compound and colloidal solution pollution, microbial strain pollution, etc. Different pollution is mainly manifested in different conditions.

1. Pollution cleaning effect of reverse osmosis element membrane

Reverse osmosis element membrane has different pollution time lengths and different performances. For example, reverse osmosis element membrane produces calcium bicarbonate pollution, and the pollution time is one week. The specific performance is that the salt removal rate drops rapidly, the pressure difference slowly expands, and the water production rate does not change significantly. Sodium citrate cleaning can completely restore the performance. The pollution time is one year, the salt diffusion coefficient increased from the original 2mg/L to 37mg/L, and the water production rate decreased from 230L/h to 50L/h. After cleaning with sodium citrate, the salt diffusion coefficient decreased to 7mg/L. The water production rate rose to 210L/h.

2. Pollution type of reverse osmosis element membrane

①. Colloid solution pollution: When colloidal solution pollution occurs, it generally has the following two characteristics: A. reverse osmosis membrane filter is blocked, especially the pressure difference rapidly expands. B. SDI value is generally above 2.5.
②. Microbial strain contamination: When microbial strain contamination occurs, the number of bacteria passing through reverse osmosis membrane filter and the concentrated water is very high, and it is usually impossible to perform maintenance, disinfection and sterilization as required.
③. Calcium scale: can be distinguished according to the main parameters of the raw water body and equipment. For sulfide type water, if the utilization rate is 75%, and the reverse osmosis scale inhibitor is added in the design plan, the LSI of the extract should be lower than 1; when the reverse osmosis inhibitor is not added, the LSI of the extract should be lower than zero, which is generally not easy Cause calcium scale.
④. You can insert the parts with 1/44 inch PVC plastic pipes to detect the performance changes of the parts at different positions.
⑤. According to the changes in the performance of reverse osmosis element membrane, distinguish the types of pollution.
⑥. Pickling passivation can distinguish calcium scale according to the cleaning effect and cleaning solution, and further confirm it according to the chemical composition analysis of the cleaning solution.

⑦. Analyze the chemical composition of the cleaning solution: take raw water, cleaning source solution, cleaning solution, and three samples for analysis. After determining the type of contamination, it is cleaned and then disinfected.