1. Analysis of the causes of pollution of hollow fiber ultrafiltration membrane
Hollow fiber ultrafiltration membrane
pollution means that the particles, colloidal solution, organic matter, bacteria and other macromolecular substances in the liquid to be treated and hollow fiber ultrafiltration membrane produce physical and mechanical equipment effects, resulting in the adsorption of the membrane surface or ultrafiltration membrane pore size and the deposition of ultrafiltration membrane pore size Shrinking or clogging, resulting in a decrease in water permeability or separation capacity.
1) The surface of hollow fiber ultrafiltration membrane is relatively thick (about 1 cm), and the diameter of the porosity is between 0.005-0.01um. The fouling layer on the membrane surface is approximately a two-layer structure, the top layer is a loose layer of larger particles, and the fine layer near the membrane surface is a small particle. Due to the presence of the pollution layer, many membrane holes are covered. Moreover, the long-term interaction between the amount and concentration of organic matter, bacteria and other macromolecular substances and their residues can easily agglomerate on the surface of the membrane and prevent water from passing through.
2) The pores of the membrane are blocked by the amount and concentration of macromolecular substances such as colloidal solution, organic matter, bacteria, or the pores of the membrane are reduced or completely blocked due to the deposition of residues such as absorbed protein.
2. Whether hollow fiber ultrafiltration membrane needs to be cleaned
(1) According to the change of the pressure drop at the inlet and outlet of uf membrane module, in most cases, when the gas pressure exceeds the default value of 0.05 MPa, it indicates that the frictional resistance of the liquid has been significantly expanded. As a daily management method, a large flow cleaning method in the heat preservation process can be used for cleaning. If there is a failure, organic chemical cleaning methods can be used;
(2) According to the change of water permeability or water permeability quality, when the water permeability or water permeability of uf membrane module is reduced to an unacceptable level, it means that the passage is blocked or the peeling characteristics of the membrane are affected by the polarization of the concentration value. In this case, physical, organic and chemical cleaning methods are closely integrated, that is, physical methods are quickly cleaned to remove a large amount of polluting components, and then cleaned with organic chemical methods to save chemicals.