(2) Analyze the potential pollution and scaling components in the feed water.
(3) Analyze the pollutants collected by the membrane filter of SDI instrument.
(4) Analyze the pollutants in the filter element.
(5) Check the condition of the inner surface of the pipeline and both ends of the membrane element.
(6) When necessary, cut the membrane element for analysis to find out the pollution and scaling components.
2. Analysis method When the RO membrane was seriously polluted, the reasons were found and the fault location was determined by dyeing test, microscope analysis, Fourier transform infrared spectrum (FTIR) analysis, scanning electron microscope (SEM) analysis and energy frequency X-ray (EDX) analysis. The following are simple and easy analysis methods that are often used in practical applications.
(1) Visual inspection
When it is determined that the system has been polluted and needs chemical cleaning, it is best to open the end plate of the pressure vessel and directly observe the accumulation of pollutants in the gap between the end plate of the pressure vessel and the membrane element. Generally, the types of pollutants can be basically determined by direct observation, so as to determine the corresponding cleaning scheme.
(1) front pollution observation
When the pretreatment filter materials (quartz sand, activated carbon) leak, colloid pollution, organic pollution and biological pollution, the front end is the most serious, and particulate matter and viscous pollution can be observed from the entrance of the front end membrane element; When biological pollution occurs, you will find foul-smelling mucus substances, and the biological mucus (mucous membrane) scraped by burning will have the burnt smell of protein.
② terminal pollution observation
Inorganic salt scaling is the most serious at the end of the system, and rough powder can be felt at the end of the terminal membrane element. When dissolved with hydrochloric acid (pH3~4), gas comes out, indicating that the precipitate is probably CaCO3. Sulfate scale and silica scale are also difficult to dissolve at low pH. If the scale is dissolved in 0. 1mol/LHF solution, it may be silica scale.