Unbleached Biomechanical Pulp from Straw via Enzymatic Hemicellulose Extraction
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Solution Overview
Problem
The paper industry in China faces a shortage of papermaking raw materials and significant pollution issues due to the reliance on imported waste paper, which will be prohibited, and traditional chemical pulping processes inefficiently use energy and degrade hemicellulose, leading to environmental concerns.
Innovation Solution
A method for preparing unbleached biomechanical pulp from straw involves treating straw with steam or hot water, adjusting pH with alkali, using alkaline biological enzymes for biological treatment, and refining the straw to produce high-quality pulp with low environmental impact, avoiding the need for alkali recovery and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional chemical pulping process is used to treat straw, then pulp production can be achieved, but hemicellulose is degraded and dissolved in black liquor causing energy waste and environmental pollution
Solution Approach 1:
The patent extracts and removes hemicellulose from the pulping system through enzymatic hydrolysis before the chemical pulping process. The enzymatic treatment selectively degrades hemicellulose into soluble sugars that can be separated, preventing hemicellulose from ending up in the black liquor and causing pollution. This extraction approach resolves the contradiction by removing the harmful substance before it causes environmental damage.
Solution Approach 2:
The patent recovers hemicellulose through enzymatic hydrolysis and separates it from the pulp stream. Instead of discarding hemicellulose with the black liquor (causing pollution), the process recovers it as a valuable byproduct that can be used for energy production or other applications, thus eliminating pollution while maintaining pulp production efficiency.
2Loss of energy
If black liquor is burned to recover heat energy and chemicals, then energy recovery is achieved, but hemicellulose with low heat of burning causes energy waste and resource loss
Solution Approach 1:
The patent extracts hemicellulose from the black liquor stream through enzymatic treatment before burning. By removing hemicellulose separately, the remaining black liquor contains higher concentration of valuable chemicals and has higher heating value, making energy recovery more efficient. Simultaneously, the extracted hemicellulose can be utilized as a separate biomass resource rather than being wasted in low-efficiency combustion.
Solution Approach 2:
The patent recovers hemicellulose from the black liquor through enzymatic hydrolysis and separation. This recovered hemicellulose can be used for producing biofuels, chemicals, or animal feed, thereby recovering valuable biomass resources that would otherwise be wasted. The process transforms a waste stream into valuable products, resolving the contradiction between energy recovery and resource conservation.
3Manufacturing precision
If alkali is used in the pulping process to adjust pH, then pulp quality can be improved, but alkali recovery becomes difficult and causes serious environmental pollution
Solution Approach 1:
The patent changes the pH parameter dynamically during the pulping process - using alkaline conditions during enzymatic hydrolysis to optimize enzyme activity and hemicellulose degradation, then adjusting to different pH levels in subsequent steps. This controlled parameter change allows achieving high pulp quality while minimizing alkali consumption and wastewater pollution, as alkali is used only where necessary and in controlled amounts.
4Ease of manufacture
If more alkali is added to adjust pH to 10-14 for hydrothermal saturation, then straw softening is improved, but alkali wastewater pollution increases
Solution Approach 1:
The patent performs enzymatic hydrolysis of hemicellulose as a preliminary action before the main pulping process. This preliminary treatment softens the straw structure and removes hemicellulose, reducing the subsequent need for high alkali concentrations during pulping. By preparing the material in advance, the process achieves effective straw softening with reduced alkali consumption and corresponding pollution.
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 method increases the utilization of agricultural residues, reduces environmental pollution, conserves energy, and achieves high pulp yield and quality, aligning with national industrial policies on resource conservation and emission reduction, while overcoming the challenges of alkali wastewater recovery and pollution in traditional processes.
Implementation Method 1
the straw is softened by hydrothermal saturation
Implementation Method 2
alkaline compound enzymes are added for biological treatment
Implementation Method 3
alkaline compound enzymes are added for biological treatment
Implementation Method 4
the water is treated with a multi-purpose evaporator, the solid residue is recovered for incineration
Implementation Method 5
the solid residue is recovered for incineration in a boiler, and the heat energy is recovered
Data Source
AI summary
A method for preparing unbleached biomechanical pulp from straw. Straw is used as a raw material, which is firstly pre-treated with hot water and hot steam, added with a small amount of alkali, and then softened by saturation with hot water, enzymatically treated by adding alkaline biological enzymes, refined, and washed. This method has the advantage that the whole production process does not need alkali recovery, thereby avoiding environmental pollution from the source. This technology conforms to the national industrial policy of resource conservation, economic recycling, energy saving and emission reduction. The present invention overcomes the problems of difficulty in recovering the alkali wastewater accompanying straw pulp and serious pollution in the prior art. This is of great significance for the industrial production of straw pulp and the development of the paper industry.