Recycled Fibre Suspension Treatment for Bacterial Endospore Reduction
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Solution Overview
Problem
Existing methods are ineffective in significantly reducing bacterial endospores in aqueous fibre suspensions from recycled cellulosic fibres, which limits the use of recycled fibres in paper and board products intended for hygiene or food packaging due to high bacterial contamination.
Innovation Solution
Adjusting the pH and oxidation-reduction potential (ORP) of the fibre suspension to specific values and treating it with performic acid to effectively reduce endospore levels, achieving a reduction of 2-4 logarithmic units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If recycled fibre material is used to increase sustainability, then environmental benefits are improved, but bacterial endospore contamination increases
Solution Approach 1:
The patent applies parameter changes by adjusting pH to ≤6.5 and oxidation-reduction potential to ≥200 mV to create optimal conditions for performic acid to destroy bacterial endospores in recycled fibre suspensions
Solution Approach 2:
The patent uses performic acid, a strong oxidizing agent, to chemically destroy bacterial endospores in the fibre suspension, achieving reduction of endospore amounts by 2-4 logarithmic units
2Object-affected harmful factors
If typical bacterial destruction methods are applied, then vegetative bacteria are reduced, but bacterial endospores remain viable
Solution Approach 1:
The patent employs performic acid, a strong oxidizing agent, which can penetrate and destroy the highly resistant endospore structure, unlike typical biocides that only affect vegetative bacteria
Solution Approach 2:
The patent modifies chemical parameters (pH ≤6.5 and ORP ≥200 mV) to enhance the effectiveness of performic acid in destroying endospores, creating conditions that overcome endospore resistance
3Reliability
If performic acid is added to fibre suspension, then endospore destruction is improved, but chemical consumption increases
Solution Approach 1:
The patent optimizes performic acid consumption by precisely controlling pH and oxidation-reduction potential parameters, ensuring the acid works at maximum efficiency and reducing the total amount needed
Solution Approach 2:
The patent implements monitoring of oxidation-reduction potential to control the addition of performic acid, using feedback from ORP measurements to optimize chemical consumption while maintaining effective endospore destruction
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
The method enables the use of treated fibre suspensions with recycled cellulosic fibres for producing paper and board grades suitable for hygienic purposes and food packaging by significantly decreasing bacterial endospore counts.
Implementation Method 1
treating it with performic acid to effectively reduce endospore levels
Implementation Method 2
Adjusting the pH and oxidation-reduction potential (ORP) of the fibre suspension to specific values
Implementation Method 3
Adjusting the pH and oxidation-reduction potential (ORP) of the fibre suspension to specific values
Data Source
AI summary
The invention relates to a method for reducing bacterial endospores in an aqueous fibre suspension comprising recycled cellulosic fibres, wherein the fibre suspension has an original endospore amount, preferably of ≥10 000 CFU/ml. The method comprises adjusting the pH of the fibre suspension to a pH value of ≤6.5, adjusting the oxidation-reduction potential (ORP) of the fibre suspension to an ORP value of ≥200 mV with a first oxidizing agent, and introducing an amount of performic acid as a second oxidizing agent to the fibre suspension for reducing the bacterial endospores to an endospore amount of ≤1000 CFU/ml.