Method of cleaning membrane assembly with detergent

• US 6,325,938 B1
• Filed: 07/07/2000
• Issued: 12/04/2001
• Est. Priority Date: 08/12/1998
• Status: Expired due to Term

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Rayon Engineering Co. Ltd. (Mitsubishi Chemical Group Corp.), Mitsubishi Rayon Company Limited (Mitsubishi Chemical Holdings Corporation)
• Inventors: Okazaki, Hiroyuki, Inoue, Noriko, Watari, Kenji, Kinoshita, Ikuo, Itakura, Masanori, Miyashita, Satoshi, Honjyo, Kenji, Kato, Osami, Takashima, Takamitsu
• Primary Examiner(s): Drodge, Joseph W.
• Application Number:
  US09/612,240
• Time in Patent Office: 515 Days
• Field of Search: 210/636, 210/651, 210/696, 210/698, 210/758, 210/759, 210/764, 134/22.1, 134/22.11, 510/162
• US Class Current: 210/636
• CPC Class Codes: B01D 2313/025 Specific membrane holders
• CPC Class Codes: B01D 2321/168 Use of other chemical agents
• CPC Class Codes: B01D 2321/185 Aeration
• CPC Class Codes: B01D 2321/2075 Ultrasonic treatment
• CPC Class Codes: B01D 61/18 Apparatus therefor
• CPC Class Codes: B01D 63/026 Wafer type modules or flat-surface type modules
• CPC Class Codes: B01D 63/043 with separate tube sheets
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: B01D 65/08 Prevention of membrane fouling or of concentration polarisation
• CPC Class Codes: B01F 2101/24 Mixing of ingredients for cleaning compositions
• CPC Class Codes: B01F 23/23123 consisting of rigid porous or perforated material
• CPC Class Codes: B01F 23/231265 being tubes, tubular elements, cylindrical elements or set of tubes

Abstract

A method for cleaning separating membranes uses a uniquely formulated detergent. The detergent includes a percarbonate-containing, material, existing in the condition in which hydrogen peroxide is adducted in carbonate and is desirably an alkali metal salt. The percarbonate decomposes the organisms deposited on the membrane surfaces while being environmentally desirable. The detergent preferably also includes at least one bivalent iron salt, which improves the cleaning capability of the percarbonate via the so-called Fenton'"'"'s reaction in which hydrogen peroxide adducted in the percarbonate reacts with the iron ions to form OH— radicals which have a very high oxidative reactivity. The detergent may also contain other oxidizers, a surfactant, a chelating agent, an acid and a pH regulator. The detergent is dissolved in water prior to use.

Claims

1. A method for cleaning separating membranes, comprising using a detergent containing percarbonate and a bivalent iron salt.

2. The mehtod of claim 1, wherein said percarbonate is at least one member selected from the group consisting of at least one alkali metal salt and at least one earth metal salt.

3. The mehtod of claim 1, wherein said percarbonate is sodium percarbonate.

4. The detergent of claim 1, wherein said detergent further comprises at least one member selected from the group consisting of an oxidizer other than hypochlorite and hydrogen peroxide, a surfactant, a chelating agent, and a pH regulator.

5. The method of claim 1, wherein said detergent further comprises a surfactant.

6. The method of claim 1, wherein said detergent further comprises a chelating agent.

7. The method of claim 1, wherein said detergent further comprises a pH regulator.

8. The method of claim 1, wherein said detergent further comprises an oxidizer other than hypochlorite and hydrogen peroxide.

9. The method of claim 1, wherein the percarbonate comprises an alkali metal percarbonate.

10. The method of claim 1, wherein the percarbonate comprises an alkali earth metal percarbonate.