A method for recycling water treatment waste PVDF membrane

Abstract

The invention discloses a method for regenerating and extending the service life of scrapped PVDF membranes by adopting chemical cleaning-structural transformation-hydrophilic repair, which can realize regeneration and prolongation of scrapped PVDF membrane materials (that is, membranes that have reached their service life). The method comprises the following steps: after cleaning the discarded membrane with sodium hypochlorite and citric acid, treating the membrane with a structure transforming agent, while enlarging and hydrophilizing the PVDF membrane, washing out unrecoverable pollutants; subsequently, using dopamine The self-polymerization reaction on the surface of the membrane further improves the hydrophilicity of the membrane surface, improves the anti-pollution performance, and at the same time repairs the damaged points on the surface of the scrapped PVDF membrane during long-term operation. The water flux of the repaired regenerated membrane is not lower than that of the new membrane, the anti-pollution performance is improved, the service life of the membrane is extended, and the harm to the environment caused by the disposal of scrap PVDF membrane is significantly reduced. The operation method of the invention is simple and easy to realize industrial application.

Description

technical field [0001] The invention belongs to the technical field of water treatment separation membranes, and in particular relates to a method for reusing waste PVDF membranes for water treatment. Background technique [0002] Polyvinylidene fluoride (PVDF) microfiltration / ultrafiltration membranes are widely used in the field of water treatment, such as membrane bioreactors (MBR) commonly used in sewage treatment projects. During the actual use of PVDF membranes, due to the existence of colloids and microorganisms in the water body, membrane fouling will inevitably occur, so the membrane modules must be cleaned periodically. Although the PVDF membrane has good chemical stability, after long-term cleaning, the surface properties of the PVDF membrane will still change (such as becoming more hydrophobic), which greatly shortens the pollution-cleaning cycle and increases system maintenance costs. At the same time, due to the existence of irreversible fouling in membrane fo...

AI Technical Summary

Problems solved by technology

Although the chemical stability of the PVDF membrane is good, after long-term cleaning, the surface properties of the PVDF membrane will still change (such as becoming more hydrophobic), which greatly shortens the pollution-cleaning cycle and increases the maintenance cost of the system.

At the same time, due to the existence of irreversible fouling in membrane fouling, the overall membrane flux of the membrane shows a downward trend in the long-term fouling-cleaning cycle.

When the flux of the membrane drops to a low level, unable to meet the water production needs of the project, and it is difficult to recover after cleaning, the membrane will reach the end of its service life (usually 5 to 8 years). At this time, according to the traditional thinking, it needs to be scrapped and replaced with a new membrane. , which is a large investment for enterprises, but also a great burden on the environment

[0003] The essence of membrane scrapping can be decomposed into the following two points: (1) The membrane flux is too low and it is difficult to recover through conventional treatment; (2) The hydrophilicity of the membrane surface is poor, resulting in pollution-short cleaning cycle

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