Integrated Lactic Acid Production and PLA Hydrolysis Purification
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Solution Overview
Problem
There is a need for cost-effective chemical recycling of polylactic acid (PLA) and improving the yield of lactic acid production, particularly from organic waste, while addressing the variability in carbohydrate content and the separation of enantiomers in existing lactic acid fermentation processes.
Innovation Solution
A method integrating lactic acid fermentation of organic waste with chemical hydrolysis of PLA to produce enantiomerically pure L-lactate salt by combining the lactate monomers from both processes in a single downstream purification, using alkaline compounds and metal oxides or hydroxides to adjust pH and produce a common counterion, which can be further purified to obtain L-lactate salt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lactic acid fermentation is performed using organic waste with variable carbohydrate content, then cost-effective substrate is utilized, but lactic acid yield varies significantly between batches
Solution Approach 1:
The patent combines lactic acid fermentation with PLA hydrolysis in a single integrated process. The hydrolysis step converts PLA polymers into lactate monomers that supplement the fermentation broth, ensuring consistent lactic acid yield regardless of variations in organic waste carbohydrate content. This merging of two processes resolves the contradiction between using low-cost variable substrate and maintaining stable productivity.
2Manufacturing precision
If multiple separate purification processes are used for fermentation broth and PLA hydrolysis products, then enantiomerically pure L-lactate salt is obtained, but capital and operational expenses increase
Solution Approach 1:
The patent integrates the purification processes for fermentation broth and PLA hydrolysis products into a single combined downstream processing train. The hydrolysis products are fed into the fermentation broth stream, allowing one unified purification sequence to handle both streams. This reduces the number of separate purification units required while maintaining enantiomerically pure L-lactate salt production, thereby reducing capital and operational expenses.
3Ease of repair
If PLA is recycled through chemical hydrolysis, then monomers are recovered for reuse, but additional processing steps and costs are incurred
Solution Approach 1:
The patent merges the PLA recycling hydrolysis process with the lactic acid fermentation process. The hydrolysis reactor and fermentation reactor are integrated, with hydrolysis products directly fed into the fermentation broth. This unified approach allows PLA recycling to occur within the existing fermentation infrastructure, reducing the need for separate dedicated recycling equipment and minimizing additional processing complexity while maintaining effective monomer recovery and reuse.
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 increases the yield of L-lactic acid production, improves reproducibility, and reduces capital and operational expenses by integrating the two processes, achieving high yields of L-lactate salt suitable for PLA production.
Implementation Method 1
fermenting organic waste with a lactic acid-producing microorganism in a fermenter to obtain a fermentation broth comprising L- lactate monomers
Implementation Method 2
using alkaline compounds and metal oxides or hydroxides to adjust pH and produce a common counterion
Implementation Method 3
purifying a mixture comprising the fermentation broth and the PLA hydrolysis slurry or the L- lactate monomers obtained in step (c) thereby obtaining L- lactate salt
Data Source
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AI summary
Industrial fermentation for the production of lactic acid from organic waste combined with chemical recycling of polylactic acid are provided, to obtain lactic acid at high yields.