Analysis Of Anti-fouling Performance Of Wide-channel Reverse Osmosis Membran

Reverse osmosis(RO)technology has been more and more applied to the preparation of pure water,reclaimed water reuse,seawater desalination and concentration process.However,membrane fouling is still an important factor limiting the development and application of reverse osmosis technology.In this paper,the concept of wide-channel reverse osmosis is introduced.Aiming at the typical problems often encountered in the operation of reverse osmosis system:concentration polarization,organic pollution and inorganic fouling pollution,the influence of the width of the side channel and the orientation angle of the dense water separator on the anti-fouling performance of the membrane module is systematically discussed.On this basis,the parameters of the optimum width of the channel and orientation angle of the separator are obtained.The anti-pollution performance of RO components is compared with that of traditional commercial components.The experimental results show that the increase of spacer xwidth can effectively increase the wrater flux of the membrane and slow down the concentration polarization in the membrane,but the anti-concentration polarization performance of the membrane module no longer improves significantly with the increase of spacer width when the spacer width increases to a certain extent.The anti-organic fouling performance of the membrane module shows that the optimization of spacer width can effectively reduce the fouling on the membrane surface.When the channel width increased to 30 mil,the flux attenuation rate decreased by 6.3%after 180 minutes,but the effect of further increasing the channel width was not obvious;the reverse osmosis membrane with high SDI intake and wide channel also showed lower flux attenuation;the analysis of the anti-inorganic fouling part showed that the increase of the channel width could effectively improve the accumulation of inorganic fouling in the membrane and alleviate the problem of inorganic fouling.The flux attenuation rate and low-pressure flushing efficiency were improved.The flux recovery rate of 30 mil after flushing was 9.5%higher than that of 20 mil membrane module.By analyzing the relationship between trade-off effect and recovery-desalination rate,the membrane module had better anti-fouling performance and separation performance when the width of the inlet channel reached 30 mil.The experimental results of directional angle show that the optimization of directional angle of spacer can effectively alleviate the concentration polarization phenomenon with a lower flux attenuation rate under the condition that the channel width is 30 mil unchanged,and the analysis of organic fouling shows that the flux attenuation rate of intima decreases by 25.5%in 180 minutes when the directional angle of spacer changes from 0 to 45 and the running time of membrane decreases by 25.5%in a low-pressure flushing.The flux recovery rate increased by 12.3%after low-pressure flushing,89.3%longer than that after low-pressure flushing.Compared with the width of the channel,the directional angle of the spacer had a greater effect on inorganic fouling in the membrane.The flux attenuation rate of the 30 mil-45 degree membrane module with the largest directional angle decreased by 14.6%after 180 minutes operation compared with that of the 0 degree directional angle,and showed a higher flux recovery rate after low-pressure flushing.After analysis,it can be seen that 45 degree membrane module has more advantages in anti-fouling and separation performance.On this basis,the optimum design parameters of wide channel reverse osmosis are selected as 30 mil channel width and 45 degree orientation angle,and the anti-fouling performance of 30 mil-45 module is compared with that of 20 mil-40 module which was sold in the market.It is found that the improved membrane module of 30 mil-45 has a higher improvement in the anti-concentration polarization,anti-organic fouling and the recovery of membrane cleaning performance.The performance of RO modules is obviously better than that of common RO modules which was sold in the market.