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CN-122006474-A - Nanofiltration membrane cleaning method

CN122006474ACN 122006474 ACN122006474 ACN 122006474ACN-122006474-A

Abstract

The invention relates to a method for cleaning a nanofiltration membrane, which comprises a first alkaline washing treatment, an enzyme washing treatment and a second alkaline washing treatment which are sequentially carried out. The invention adopts the cleaning sequence of alkali-enzyme-alkali, which can effectively remove organic matters, grease, protein and microorganism in the nanofiltration membrane, wherein the first alkali cleaning treatment opens a channel for the enzyme cleaning treatment, and the alkaline cleaning is carried out firstly and then the enzyme cleaning is carried out, so that the cleaning effect of the enzyme cleaning treatment can be obviously improved.

Inventors

  • WU WENXUE
  • TANG JUNSONG
  • ZHANG BIN
  • LUO JIAN
  • SHI GUOZHU
  • ZHU XIAOFEI
  • WU HUAN
  • JI WEI

Assignees

  • 苏州苏震生物工程有限公司

Dates

Publication Date
20260512
Application Date
20260402

Claims (10)

  1. 1. The nanofiltration membrane cleaning method is characterized by comprising a first alkaline washing treatment, an enzyme washing treatment and a second alkaline washing treatment which are sequentially carried out.
  2. 2. The cleaning method according to claim 1, wherein the temperature of the first alkaline cleaning treatment is 30-45 ℃; preferably, the time of the first alkaline washing treatment is 24-48 hours, preferably 36-48 hours.
  3. 3. The method according to claim 1 or 2, wherein an acidic protease solution is used in the enzymatic washing treatment.
  4. 4. The cleaning method according to any one of claims 1 to 3, wherein the temperature of the enzymatic cleaning treatment is 35 to 40 ℃; Preferably, the enzyme washing treatment time is 48-72 hours, preferably 60-72 hours.
  5. 5. The method according to claim 3, wherein the pH of the acidic protease solution is 3 to 5.
  6. 6. The method according to claim 3, wherein the concentration of the acidic protease solution used in the enzymatic washing treatment is 5000 to 7000ppm; preferably, the enzyme activity of the acid protease is 50000-200000U/mL.
  7. 7. The cleaning method according to any one of claims 1 to 6, wherein the temperature of the second alkaline cleaning treatment is 30 to 40 ℃; Preferably, the time of the second alkali washing treatment is 0.5-2 h.
  8. 8. The method according to any one of claims 1 to 7, wherein the alkaline solutions used in the first alkaline washing treatment and the second alkaline washing treatment each independently comprise a sodium hydroxide solution.
  9. 9. The method according to claim 8, wherein the alkaline solution has a pH of 10 to 12.
  10. 10. The cleaning method according to any one of claims 1 to 9, characterized in that the cleaning method comprises the steps of: (1) The first alkaline washing treatment, namely circularly washing the nanofiltration membrane by using an alkaline solution with the pH value of 10-12 at the temperature of 30-45 ℃ and soaking the nanofiltration membrane for 24-48 hours to obtain the nanofiltration membrane after the first alkaline washing; (2) Washing the first alkali washed nanofiltration membrane to a pH value of 6.5-7.5 by using water, and then circularly washing the first alkali washed nanofiltration membrane by using an acidic protease solution with a pH value of 3-5 at a temperature of 35-40 ℃ and soaking for 48-72 h to obtain the enzyme washed nanofiltration membrane; (3) And a second alkaline washing treatment, namely washing the nanofiltration membrane after enzyme washing by water until the pH value is 6.5-7.5, and then circularly washing the nanofiltration membrane after enzyme washing by using an alkaline solution with the pH value of 10-12 for 0.5-2 h at the temperature of 30-40 ℃.

Description

Nanofiltration membrane cleaning method Technical Field The invention relates to the technical field of filter membrane cleaning and filtering, in particular to a method for cleaning a nanofiltration membrane. Background In the production process of 1, 3-propylene glycol, the nanofiltration membrane can retain organic matters, grease, proteins and microorganisms in solution in long-term operation to form a compact and complex mixed pollution layer, so that the membrane flux is rapidly and irreversibly reduced. Conventional cleaning methods typically employ a single alkaline or acid wash, or a simple "alkali followed by acid" step, which has some effect on light contamination. However, for severe contamination with flux attenuation exceeding 50%, conventional methods often fail to effectively restore membrane performance. CN111217425A discloses a cleaning method of an immersed ultrafiltration membrane, which comprises the following steps of 1) carrying out primary alkali cleaning on the ultrafiltration membrane Chi Paikong, conveying an alkaline cleaning solution into an ultrafiltration membrane pool until the cleaning solution fully submerges ultrafiltration membrane wires, soaking the ultrafiltration membrane for 4-10 hours, aerating and stirring soaking solution and ultrafiltration membrane wires in the ultrafiltration membrane pool by using an air compressor or a Roots blower in the soaking process, aerating for 1-5 minutes every 1-2 hours, wherein the temperature of the alkaline cleaning solution is 20-38 ℃, the components are sodium hydroxide and sodium hypochlorite, the mass fraction of the sodium hydroxide is 1-3%, the sodium hypochlorite concentration is 2000-5000 ppm by an effective chlorine meter, and the rest is reverse osmosis produced water or tap water with low hardness; 2) backwashing the ultrafiltration membrane pool, namely discharging alkaline cleaning liquid in the ultrafiltration membrane pool, backwashing the ultrafiltration membrane by ultrafiltration water until the pH value and residual chlorine of the backwash water are close to the pH value and residual chlorine of the ultrafiltration water, and ending backwashing, respectively discharging alkaline cleaning liquid and backwash water, 3) first pickling, namely discharging the acidic cleaning liquid in the ultrafiltration membrane pool, namely delivering the acidic cleaning liquid to the ultrafiltration membrane pool to completely submerge ultrafiltration membrane wires, soaking the ultrafiltration membrane for 2-8 h, aerating and stirring the soaking liquid and the ultrafiltration membrane wires in the ultrafiltration membrane pool by using an air compressor or a Roots blower in the soaking process, aerating and stirring for 1-5 min every 0.5-1 h, wherein the temperature of the acidic cleaning liquid is 20-38 ℃, the main component is citric acid or oxalic acid, the mass fraction is 1-2%, and the balance is tap water with reverse osmosis water or low hardness, 4) backwashing the ultrafiltration membrane pool, namely discharging the acidic cleaning liquid in the ultrafiltration membrane pool, and ending backwashing, respectively discharging the acidic cleaning liquid and the backwash water when the pH value of the backwash water is close to the pH value of the ultrafiltration water, and ending backwashing water, respectively, and carrying out second alkaline cleaning and washing the ultrafiltration membrane to Chi Paikong, conveying alkaline cleaning liquid into an ultrafiltration membrane pool until ultrafiltration membrane filaments are completely immersed, soaking the ultrafiltration membrane for 4-8 hours, aerating and stirring the soaking liquid in the ultrafiltration membrane pool and the ultrafiltration membrane filaments by using air pressure air or a Roots blower in the soaking process, and aerating for 1-5 minutes every 1-2 hours, wherein the temperature of the alkaline cleaning liquid is 20-38 ℃, the main components are sodium hydroxide and tetra sodium ethylenediamine tetraacetate, the mass fraction of the sodium hydroxide is 0.6-1.5%, the mass fraction of the tetra sodium ethylenediamine tetraacetate is 0.4-1%, and the balance is reverse osmosis produced water or tap water with low hardness; the method comprises the steps of 6) carrying out back washing on an ultrafiltration membrane pool, namely discharging alkaline cleaning liquid in the ultrafiltration membrane pool, carrying out back washing on the ultrafiltration membrane pool by ultrafiltration water for a plurality of times, respectively emptying the ultrafiltration membrane pool, ending back washing when the pH value of the back washing water is close to the pH value of the ultrafiltration water, discharging alkaline cleaning liquid and back washing water, 7) carrying out second acid washing, namely conveying an acidic cleaning liquid into the ultrafiltration membrane pool until the ultrafiltration membrane filaments are completely immersed, soaking the ultrafiltr