Fibrous Web Manufacturing with Endospore-Sensitizing Surfactants
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Solution Overview
Problem
Existing methods struggle to effectively reduce and eliminate bacterial endospores in aqueous environments of pulp and paper mills, particularly after production stops, leading to quality issues in paper and board products intended for hygiene purposes.
Innovation Solution
A method using a germinant surfactant with a primary or secondary ammonium head group and a linear unsubstituted C12-alkyl tail, such as n-dodecylamine or dodecylguanidine salts, to sensitize endospores by disrupting their protective structure, making them susceptible to biocidal agents or heat, thereby reducing their content in fibrous webs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional biocides and heat treatment are used to destroy vegetative bacteria, then vegetative bacteria are eliminated, but bacterial endospores remain viable and dormant
Solution Approach 1:
The patent applies preliminary action by adding a germinant substance before the destruction step. The germinant triggers endospore germination into vegetative cells, which then become susceptible to conventional biocides and heat treatment. This two-step sequence (germination followed by destruction) resolves the contradiction by making endospores vulnerable to standard elimination methods.
Solution Approach 2:
The germinant substance acts as an intermediary that bridges the gap between endospores and biocidal agents. It mediates the transformation of endospores into a state where they can be effectively destroyed by conventional methods, enabling the combination of germination induction with subsequent elimination.
2Reliability
If nutrient-triggered germination is used to induce endospore germination, then endospores transform into vegetative cells, but excessive microbial activity increases and biocide dosages must be increased
Solution Approach 1:
The patent applies parameter changes by carefully controlling the type and dosage of germinant substance added to the pulp suspension. By selecting specific germinants and optimizing their concentration, the process triggers endospore germination while limiting excessive microbial proliferation, thus resolving the contradiction between germination effectiveness and microbial control.
3Productivity
If production stop occurs in storage towers, then pulp storage is maintained, but endospore formation increases due to changed conditions and inadequate mixing
Solution Approach 1:
The patent applies preliminary action by adding the germinant substance to the stored pulp during production stops, before resuming normal production. This preliminary treatment triggers endospore germination in the stored pulp, and subsequent biocidal treatment eliminates the germinated cells, preventing endospore contamination in the final product.
4Volume of stationary object
If large storage towers are used for pulp storage, then storage capacity is increased, but mixing effectiveness decreases and poorly mixed zones form
Solution Approach 1:
The germinant substance acts as an intermediary that can be effectively distributed throughout the large storage tower volume. By triggering germination through this intermediary, the process overcomes the mixing limitations of large towers, as the germinant can reach endospores even in poorly mixed zones, enabling uniform treatment throughout the storage volume.
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 effectively reduces bacterial endospores by at least 20% to 50% in the fibre suspension, enabling the production of hygienic paper or board with endospore content below 1000 CFU/g, ensuring compliance with hygiene standards.
Implementation Method 1
A method using a germinant surfactant with a primary or secondary ammonium head group and a linear unsubstituted C12-alkyl tail, such as n-dodecylamine or dodecylguanidine salts, to sensitize endospores by disrupting their protective structure
Implementation Method 2
making them susceptible to biocidal agents or heat, thereby reducing their content in fibrous webs
Data Source
AI summary
The invention relates to a method for manufacturing a fibrous web, such as web of paper, board, tissue or the like. The method comprises obtaining at least one fibre suspension of lignocellulosic and/or cellulosic fibres and feeding the fibre suspension into an intermediate residence entity, such as pulper, storage tower or broke tower. Fibre suspension, which comprises bacterial endospores, is discharged out of the intermediate residence entity via an outlet after a residence time of at least 2 hours in the intermediate residence entity and after a time delay the fibre suspension is formed into a fibrous web. Bacterial endospores are sensitised by adding a germinant surfactant, which comprises a primary or secondary ammonium head group and a linear unsubstituted C12-alkyl tail, to the fibre suspension at an addition point, which is located at the lower part of the intermediate residence entity or after the outlet of the intermediate residence entity, but before the formation of the fibrous web.