Investigation of high-intensity magnetic hydrogels in the application of membrane physical cleaning

• A new high-intensity magnetic hydrogels was synthesized for membrane physical cleaning.
• An optimal combination of factors and levels was got for the hydrogels cleaning.
• A new method containing enhanced cleaning in position was created for intensive cleaning.

A newly synthesized magnetic hydrogel was applied to physical cleaning of low pressure microfiltration (hollow fiber) membranes. MC(50%)-90-3 h was chosen from several kinds of high-intensity magnetic hydrogels for its superior performance. According to the properties of the hydrogels, membrane filtration and cleaning tests was conducted under a orthogonal experiment with different factors and levels. An optimal combination of factors and levels was got as particle size of 5 mm, aeration intensity of 1 L/min and volume percent of 10%. The comparison of traditional aeration cleaning, backwashing and the hydrogels cleaning showed the superiority of the hydrogels with the TMP recovery of 93.07%. The results of shear stress detection showed that the outlet of membrane module received the lowest shear stress in corresponding with the most serious fouling. Therefore, a new cleaning method containing enhanced cleaning in position was created to make the intensive cleaning to the position with severe fouling. The recovery of TMP reached up to 96.62% after cleaning of the new method which indicated that reversible fouling can almost be removed completely. This good cleaning effect was hoped to provide support for further membrane physical cleaning.

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