Comprehensive evaluation method for performance of contaminated flat membranes

Patent metadata

Field	Value
Publication number	US-10434475-B2
Application number	US-201715677022-A
Country	US
Kind code	B2
Filing date	Aug 15, 2017
Priority date	Oct 10, 2015
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

The present invention relates to a comprehensive evaluation method for the performance of contaminated flat membranes, which relates to the field of sewage and waste resource technology. The present invention firstly analyzed the composition of the surface elements of the contaminated membrane by EDX to determine the type of membrane contamination, and then designed different cleaning schemes for organic or inorganic pollution to obtain a sample membrane. When the tensile strength of the contaminated membrane decreased more than 50% than that of the control membrane, it is a waste membrane; when the tensile strength decreased less than 50% and the membrane flux reduced more than 30%, it is a waste membrane; when tensile strength decreased less than 50%, membrane flux reduced less than 30% and the carbon footprint was more than 188 g, it is a waste membrane; otherwise was a old membrane. The comprehensive evaluation method of the present invention can quantitatively, quickly and comprehensively define the difference between the old membrane and the waste membrane, and provides the basis for the selection of the contaminated membrane and the process of the regeneration and reuse.

First claim

What is claimed is:

1. A method for testing a subject membrane that has been exposed to waste water in a membrane bioreactor (MBR), comprising:
measuring a percentage of carbon element on the subject membrane;
upon determination that the percentage of carbon element on the subject membrane is higher than a percentage of carbon element on a control membrane that is identical to the subject membrane except that the control membrane has not been exposed to waste water, washing the subject membrane using sodium hypochlorite and then using citric acid or oxalic acid; upon determination that the percentage of carbon element on the subject membrane is not higher than the percentage of carbon element on the control membrane, washing the subject membrane using citric acid or oxalic acid and then using sodium hypochlorite;
measuring a tensile strength and a membrane flux of the subject membrane and measuring a carbon footprint of washing the subject membrane;
discarding the subject membrane upon determination that the tensile strength of the subject membrane is lower than 50% of a tensile strength of the control membrane or upon determination that the tensile strength of the subject membrane is not lower than 50% of the tensile strength of the control membrane, the membrane flux of the subject membrane is lower than 70% of a membrane flux of the control membrane, and the carbon footprint is greater than 188 g.

2. The method of claim 1 , wherein mass concentration of the sodium hypochlorite is between 0.1% and 5.0%, and mass concentration of the citric acid or oxalic acid is between 0.1% and 5.0%.

3. The method of claim 1 , wherein the subject membrane is a polyvinylidene fluoride membrane or a polyvinyl chloride membrane.

Assignees

• Univ Jiangnan

Inventors

• Li Xiufen
• Song Xiaoli
• Wang Xinhua
• Ren Yueping
• Qi Xiguang

Classifications

• B01D65/02 Primary

  Membrane cleaning or sterilisation {; Membrane regeneration} · CPC title

• B01D2321/162

  Use of acids · CPC title

• C02F3/2853

  using anaerobic membrane bioreactors · CPC title

• C02F2303/16

  Regeneration of sorbents, filters · CPC title

• B01D61/20

  Accessories; Auxiliary operations · CPC title