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Method for cleaning calcium sulfate dirt of reverse osmosis membrane or nanofiltration membrane

A technology of reverse osmosis membrane and nanofiltration membrane, which is applied in the direction of semipermeable membrane separation, chemical instruments and methods, membrane technology, etc., can solve the problem that calcium sulfate fouling cannot be effectively removed, and achieve the effect of expanding the scope of application

Inactive Publication Date: 2010-09-01
TIANJIN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problem that conventional physical cleaning and chemical cleaning cannot effectively remove calcium sulfate fouling on reverse osmosis membranes or nanofiltration membranes, according to the characteristics of anaerobic bacteria, sulfate-reducing bacteria (SRB) were used in anaerobic Organic matter is decomposed under oxygen conditions, and the sulfate radical in the calcium sulfate dirt is used as the electron acceptor (oxidant) for metabolism. The sulfur ion in the sulfate radical obtains electrons under anaerobic conditions to form soluble hydrogen sulfide gas, making the calcium sulfate The solubility product is less than the saturation value, so that the calcium sulfate dirt is continuously dissolved and peeled off from the membrane surface, achieving the purpose of thorough cleaning

Method used

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  • Method for cleaning calcium sulfate dirt of reverse osmosis membrane or nanofiltration membrane
  • Method for cleaning calcium sulfate dirt of reverse osmosis membrane or nanofiltration membrane
  • Method for cleaning calcium sulfate dirt of reverse osmosis membrane or nanofiltration membrane

Examples

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Effect test

Embodiment 1

[0019] Inoculate 10 in distilled water 5 CFU / mL Desulfovibrio or Desulfobacterium, then add analytically pure glucose to prepare membrane washing solution, so that the COD of the washing solution Cr At about 400mg / L, add trace elements such as magnesium, iron, zinc, etc. to the washing solution, and adjust the pH value of the washing solution to about 7.0 with analytically pure sodium hydroxide; then inject the washing solution into the calcium sulfate stain Soak in the blocked reverse osmosis membrane module, keep the temperature at 20°C during soaking, the relationship between the soaking time and the amount of sulfate-reducing bacteria and membrane flux is as follows: figure 1 shown.

[0020] When measuring the membrane flux, first wash it with a hydrochloric acid solution with a pH of 2.5 for 2 hours, then wash it with a non-oxidizing 911 fungicide with a concentration of 200 mg / L for 40 minutes before measuring.

[0021] Embodiment shows: after finishing above-mentioned...

Embodiment 2

[0025] Inoculate 10 in distilled water 2 After CFU / mL of Desulfomonile or Desulfonema, add industrial grade sodium acetate to prepare membrane washing solution, so that the COD of the washing solution Cr At about 500mg / L, some trace elements are added to the membrane washing solution, and sodium hydroxide is added to adjust the pH value to 8.0; then the solution system is injected into the nanofiltration membrane module fouled by calcium sulfate for soaking, and keeps The temperature is 30°C, the soaking time is 48 hours, discharge after reaching the soaking time, and then discharge with a hydrochloric acid solution with a pH value of 2 for 1 hour, and then circulate with a non-oxidizing isothiazolinone fungicide with a concentration of 50mg / L After cleaning for 20 minutes, rinse with distilled water to complete the cleaning. After cleaning, the membrane flux has reached more than 98% of that before calcium sulfate fouling. After cleaning, the properties of the nanofiltration ...

Embodiment 3

[0027] Inoculate 10 in distilled water 4 CFU / mL Desulfobacterium (Desulfobacterium), then add starch, adjust the COD of the solution system Cr The content is 300mg / L, and sodium hydroxide is added to adjust the pH value to 8.5; then the solution system is injected into the nanofiltration membrane module fouled by calcium sulfate for soaking, and the temperature is kept at 25°C during soaking, and the soaking time is 75 hours, reaching Discharge after soaking time, rinse with hydrochloric acid solution with a pH value of 3 for 1.5 hours, then discharge with HY-220 non-oxidizing fungicide for 30 minutes, and finally rinse with distilled water to complete the cleaning. After cleaning, the membrane flux It has reached more than 98% before calcium sulfate fouling, the properties of the nanofiltration membrane have not changed, and the cleaning effect is good, but the chemical cleaning method can only recover to about 55% before calcium sulfate fouling. This example proves that sulf...

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Abstract

The invention relates to a method for cleaning calcium sulfate dirt of a reverse osmosis membrane or a nanofiltration membrane, which comprises the following steps of: 1) inoculating sulfate reducing bacteria in distilled water, wherein the inoculation amount of the sulfate reducing bacteria is 102 to 105CFU / mL; 2) adding easily degradable organic matters to ensure that the CODCr content of the solution is 300 to 500mg / L; 3) adjusting the pH value to between 6.5 and 8.5, keeping the temperature between 20 and 35 DEG C, injecting the solution to a membrane module, soaking for 48 to 96 hours, and discharging the solution; 4) circularly cleaning for 1 to 2 hours by adopting acid solution which is prepared from muriatic acid and distilled water and has the pH value between 2 and 3, and discharging the acid solution; and 5) cleaning for 20 to 40 minutes by adopting non oxidizing bactericide in concentration between 50 and 200mg / L, discharging the non oxidizing bactericide, and washing the membrane module with distilled water to complete cleaning the membrane. The method effectively solves the problem of cleaning calcium sulfate dirt of the reverse osmosis membrane or the nanofiltration membrane, has important significance for the promotion and application of reverse osmosis and nanofiltration in the aspects such as seawater desalting, soft water making, and advanced treatment and recycling of sewage, and expands the application range of membrane technology.

Description

technical field [0001] The invention relates to a method for cleaning reverse osmosis (RO) membranes or nanofiltration (NF) membrane calcium sulfate fouling, the method is mainly developed for the effective cleaning of reverse osmosis membranes or nanofiltration membrane calcium sulfate scale pollution, It belongs to the field of environmental protection. Background technique [0002] At present, with the development of industry and the improvement of sewage reuse requirements, reverse osmosis or nanofiltration technology has begun to be widely used in power plant boiler water supply, seawater desalination, softened water supply for medical and electronic industries, and advanced treatment of municipal sewage. It shows that inorganic salt fouling, especially calcium sulfate fouling is one of the important factors affecting the application and popularization of this technology. The combined cleaning of conventional alkali washing and pickling has almost no effect on the remo...

Claims

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Application Information

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IPC IPC(8): B01D65/08
CPCY02A20/131
Inventor 曹占平张景丽张宏伟
Owner TIANJIN POLYTECHNIC UNIV