Study on mechanism of reverse osmosis membrane pollution of water treatment in underground coal mine

As reverse osmosis technology is widely used in coal mine water treatment systems, the complexity of mine water quality is likely to cause reverse osmosis membrane pollution, which greatly affects the desalination efficiency and service life of membrane modules. In order to explore the reasons for the failure of the reverse osmosis membrane component of the water treatment device of the integrated liquid supply system in the fully-mechanized mining face of Shandong Xinjulongcoal mine, the turbidity, hardness, anion and cation concentration and total organic matter in the source water sample were detected and analyzed. Based on the Visual MINTEQ calculation tool for environmental water chemical balance, a pollutant prediction model was initially established. Visual inspection, LOI, scanning electron microscope (SEM) and Tengyuan test methods were adopted to reveal the mechanism of the failure of the reverse osmosis system. Based on the fact that a large number of solid particles were found inside the membrane element in the concentrated water channel and the membrane surface, the reverse osmosis membrane has varying degrees of mechanical damage caused by the particles, and it is inferred that the securLMity filter at the front end may fail. Considering that the pollutants on the membrane surface are mostly inorganic salts in a crystalline state, there is a small amount of organic pollution in the membrane, and non-oxidizing pollutants enter the reverse osmosis system, which eliminates the possibility of system failure caused by organic pollution.Based on the chemical equilibrium model of Visual MINTEQ, the composition of the fouling material was analyzed, and the results show that its main component was calcium ions. The quantitative analysis test on the composition of the membrane fouling sample verified the accuracy of the pollutant prediction model. The results show that the turbidity and hardness of the underground water supply in the mine are relatively high, and the fouling and particle deposition on the surface of the reverse osmosis membrane are the main reasons for the failure of the system. In view of the failure reasons, measures such as regular inspection and maintenance of the security filter, adding scale inhibitors in the RO pre-treatment stage, and the research direction of new water treatment processes are proposed.