Papermaking Process Water Treatment for Starch Preservation and Scale Control
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Solution Overview
Problem
Recycled pulp in papermaking experiences starch degradation and calcium precipitation issues due to microbial activity, leading to reduced paper quality and increased maintenance costs in wastewater treatment systems.
Innovation Solution
A method involving the use of chloramine and sodium hypochlorite in a dual treatment process to control microorganisms and prevent starch-degrading enzyme activity, maintaining residual chloramine levels in process water to preserve starch content and reduce calcium ion concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If recycled pulp with high starch content is used to improve paper strength, then paper mechanical properties are enhanced, but microbial degradation of starch occurs leading to reduced paper quality
Solution Approach 1:
The patent applies preliminary action by treating process water with biocides and oxidants before starch degradation can occur. The treatment system proactively eliminates microorganisms and inactivates enzymes in advance, preventing starch breakdown before it affects paper quality. This is achieved through continuous dosing of biocides in the papermaking process to maintain a sterile environment that protects starch content throughout production.
Solution Approach 2:
The patent employs parameter changes by monitoring and controlling chemical parameters such as biocide concentration, oxidant dosage, and process water composition. By adjusting these parameters, the system optimizes starch preservation while maintaining paper quality. The treatment intensity and chemical dosages are dynamically modified based on measured starch content and microbial activity levels in the process water.
2Reliability
If biocides are used to control microbial activity and preserve starch, then starch degradation is reduced, but additional chemical treatment complexity is introduced
Solution Approach 1:
The patent applies universality by using chemical agents that perform multiple functions simultaneously. Biocides and oxidants serve both to eliminate microorganisms and inactivate starch-degrading enzymes, providing dual protection against starch degradation. This multi-functionality reduces the need for separate treatment systems and simplifies the overall chemical treatment approach while maintaining effective starch preservation.
Solution Approach 2:
The treatment system applies self-service through continuous automatic dosing and monitoring mechanisms that maintain biocide residuals without constant manual intervention. The system self-regulates by monitoring starch content and microbial activity, automatically adjusting chemical dosages to maintain optimal protection levels. This reduces operational complexity while ensuring consistent starch preservation throughout the papermaking process.
3Manufacturing precision
If calcium carbonate filler is used in recycled paper to improve paper properties, then paper quality is enhanced, but calcium precipitation and scaling occurs in wastewater treatment systems
Solution Approach 1:
The patent converts the harmful effect of calcium precipitation into a beneficial outcome by linking starch preservation to calcium control. Since starch degradation products trigger microbial growth that releases calcium from carbonate filler, preserving starch prevents this chain reaction. The same biocide treatment that protects starch also prevents microbial-mediated calcium release, thereby preventing scaling in wastewater systems while maintaining paper quality with calcium carbonate filler.
Solution Approach 2:
The system applies feedback by monitoring starch content, microbial activity, and calcium levels in process water to adjust treatment intensity. When starch degradation is detected or microbial activity increases, the system automatically increases biocide dosing to prevent calcium release. This closed-loop control ensures that calcium carbonate filler remains stable in the paper product while preventing scaling in wastewater treatment, dynamically balancing paper quality and environmental concerns.
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 enhances paper strength, reduces odor-causing materials, minimizes microbiological-related breaks, and decreases calcium precipitation, resulting in improved paper quality and reduced operational costs by maintaining starch content and filler retention.
Implementation Method 1
A method involving the use of chloramine and sodium hypochlorite in a dual treatment process to control microorganisms and prevent starch-degrading enzyme activity
Implementation Method 2
prevent starch-degrading enzyme activity, maintaining residual chloramine levels in process water to preserve starch content
Implementation Method 3
These extracellular enzymes degrade starch into glucose oligomers (e.g., maltose) and glucose
Implementation Method 4
The oligomers and monomers are taken up by bacteria and are fermented producing volatile fatty acid (VFAs)
Implementation Method 5
VFAs decrease the process pH (from 7 or higher to 6.5-6 or lower). The pH in localized areas around fermenting bacteria can be as low as 1 to 4. Low pH dissolves calcium carbonate filler (for instance as present in waste paper) into soluble calcium Ca2+
Implementation Method 6
Low pH dissolves calcium carbonate filler (for instance as present in waste paper) into soluble calcium Ca2+ (and CO2)
Implementation Method 7
dissolved calcium can cause deposit or scaling problems. With conversion of VFAs into CH4 and CO2 and a pH increase in the anaerobic digester, calcium scale forms
Data Source
AI summary
Methods to preserve starch present in pulp are provided and also methods to control calcium precipitation and/or scaling in digesters or BOD systems. The methods can be performed as part of a papermaking process. Process water containing pulp can be treated with a chloramine. Process water containing pulp with native starch can receive a double treatment with at least one biocide, such as chloramine, and at least one oxidant, such as sodium hypochlorite. The treatment can be performed in any suitable manner. The treatment can be performed at one or more stages or locations in a papermaking system. A target residual chloramine value or range can be achieved by the treatment. Packaging sheets/boards and other paper products manufactured using the methods provided exhibit superior strength and other desirable characteristics.