Membrane Module Filtration for Microbial Culture Solutions

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Solution Overview

Problem

Filtration of microbial culture solutions using separation membranes is hindered by fouling due to high concentrations of sugars and proteins, leading to increased washing costs and reduced membrane effectiveness over time.

Innovation Solution

A method involving cross-flow filtration, water rinsing, and chemical solution washing, specifically using a combination of hypochlorite and a nonionic surfactant, is repeated to maintain stable filtration performance and extend membrane life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If cross-flow filtration is performed on microbial culture solution using a separation membrane, then high separation performance and excellent filtrate quality are achieved, but fouling occurs due to high concentrations of sugars and proteins adhering to the filtration surface, causing permeation flux to decrease at an early stage

Engineering Contradiction:
Improveseparation performanceVSAvoidpermeation flux
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent implements periodic washing cycles interspersed during the filtration process. The washing step is performed after a certain period of filtration when fouling begins to reduce permeation flux, restoring the membrane performance and allowing the filtration to continue efficiently. This periodic maintenance approach resolves the contradiction by temporarily interrupting filtration to clean the membrane surface of adhered sugars and proteins.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent changes the chemical parameters of the washing solution to effectively remove different types of fouling substances. By adjusting pH, temperature, and chemical composition (using enzymes, organic solvents, or chemical agents), the membrane can be cleaned of various adhered substances including proteins and sugars, thereby maintaining permeation flux while preserving high separation performance.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If chemical solution washing is performed frequently to remove fouling substances and maintain filtration ability, then membrane performance is restored, but washing costs increase

Engineering Contradiction:
Improvefiltration abilityVSAvoidwashing costs
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent employs self-cleaning mechanisms where the filtration system periodically cleans itself during operation. By integrating washing steps into the filtration process and using automatically circulated washing solutions, the system maintains its own performance without requiring external manual intervention or excessive chemical consumption, thereby reducing washing costs while preserving reliable filtration ability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent applies partial washing actions rather than complete frequent washing. Instead of washing the entire membrane surface frequently with large amounts of chemical solutions, the system performs targeted partial washing only when and where fouling occurs, using minimal necessary chemicals to restore filtration ability, thus reducing washing costs while maintaining reliability.

Inventive Principle:
Principle #16Partial or excessive action

3Duration of action of stationary object

If filtration and chemical solution washing are repeated multiple times, then membrane water permeability is restored, but fouling substances that cannot be washed accumulate gradually in the separation membrane, making it difficult to restore water permeability

Engineering Contradiction:
Improvemembrane reuseabilityVSAvoidaccumulated fouling substances
Core Design Contradiction:
Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent employs strong oxidizing agents such as ozone or hydrogen peroxide in the washing solution to decompose and remove stubborn fouling substances that accumulate in the membrane pores. These strong oxidants break down complex organic compounds like proteins and sugars that regular washing cannot remove, preventing accumulation and maintaining the membrane's water permeability and reuseability over extended periods.

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

Solution Approach 2:

The patent uses intermediary substances such as enzymes or chelating agents in the washing solution that specifically target and break down accumulated fouling substances. These intermediaries facilitate the removal of stubborn deposits by chemically transforming them into removable forms, preventing their accumulation in the membrane and preserving long-term permeability and reuseability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively removes fouling substances, maintains water permeability, and reduces operational costs by allowing for long-term stable filtration of microbial culture solutions.

Implementation Method 1

a method of separating a microorganism and a solution using a separation membrane

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Implementation Method 2

a filtration membrane used for membrane bioreactor of wastewater that contains an oil component such as a hydrocarbon compound or an aromatic compound or a hardly decomposable coloring component is washed with chloric acid or a salt thereof

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 3

washed with chloric acid or a salt thereof and a surfactant

Methodology Applied
Scientific EffectSurfactant action: Surfactant

Data Source

PatentEP3438243B1Method for filtering microbial culture solution using membrane module
Publication Date: 2021.11.17 TORAY INDUSTRIES INC
  • EP3438243B1 patent drawingFigure 1
  • EP3438243B1 patent drawingFigure 2
  • EP3438243B1 patent drawingFigure 3~4

AI summary

The present invention relates to a method for filtering a microbial culture solution using a membrane module, said method comprising four stages including (a) cross-flow filtration of the microbial culture solution, (b) rinsing with water, (c) washing with a chemical solution and (d) rinsing with water, wherein: the filtrate passing through the membrane module in the cross-flow filtration has a total sugar concentration of 1,000-100,000 mg/l inclusive and a protein concentration of 50-1,000 mg/l inclusive; the aforesaid stage (c) comprises step (c-1) for washing with a chemical solution containing a hypochlorite and a nonionic surfactant; and the aforesaid stages (a) to (d) are repeated in this order.