Method for detecting membrane module flaw with the application of fluorescent particles

A method for detecting a membrane module flaw, comprising:

• preparing the first and the second fluorescent particles having a size of 0.5 to 1.5 μm using silica, the first and second fluorescent particles respectively emitting different colors from each other;
• injecting the first and second fluorescent particles in a concentration of greater than 0 mg/mL and less than 0.1 mg/mL or equal, to the inside or outside of a membrane module used in a sewage and wastewater treatment process;
• operating a pump to apply a pressure such that the first fluorescent particles injected to the outside of the membrane module leak to the inside of the membrane module, in case that the membrane module has a flaw;
• operating the pump to apply a pressure such that the second fluorescent particles injected to the inside of the membrane module leak to the outside of the membrane module, in case that the membrane module has a flaw;
• acquiring a digital image of the membrane module;
• and
• discriminating a portion colored with a superposed color of the first and second colors from a non-colored portion in the digital image.