PHA Accumulation via Intermittent Substrate Feeding
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Solution Overview
Problem
Existing methods for accumulating polyhydroxyalkanoates (PHAs) in biomass from wastewater do not effectively control the respiration rate or achieve high molecular weights, leading to suboptimal PHA production and wastewater treatment efficiency.
Innovation Solution
A method involving a bioreactor with two zones, where biomass is intermittently supplied with an organic carbon-containing substrate, controlling the frequency and amount to maintain a high respiration rate and achieve PHA molecular weights of at least 400,000 g/mole, while minimizing residual RBCOD in the wastewater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If substrate is continuously supplied to biomass for PHA accumulation, then PHA production quantity increases, but PHA molecular weight decreases and respiration rate drops
Solution Approach 1:
The patent applies periodic intermittent feeding of substrate to the biomass, creating cycles of substrate availability and depletion. This periodic action maintains respiration rates by preventing continuous substrate exposure, thereby preserving the conditions necessary for high molecular weight PHA accumulation while still achieving substantial PHA production over time through repeated feeding cycles.
Solution Approach 2:
The patent implements dynamic control of substrate feed rate based on real-time monitoring of respiration rate. The feed rate is adjusted dynamically to maintain respiration rate above threshold levels, preventing the drop that会导致低分子量PHA. This dynamic adaptation allows the system to optimize between production quantity and molecular weight based on current biomass state.
2Productivity
If substrate feed rate is increased to maintain high respiration rate, then PHA accumulation efficiency improves, but residual RBCOD in wastewater increases
Solution Approach 1:
The patent employs feedback control by monitoring respiration rate and using this information to adjust substrate feed rate. This closed-loop control ensures that substrate is supplied at optimal rates to maintain high PHA accumulation efficiency while preventing excessive substrate addition that would result in high residual RBCOD in the wastewater effluent.
Solution Approach 2:
The patent changes the feeding parameter from continuous to intermittent, and dynamically adjusts the timing and amount of substrate addition based on respiration rate measurements. This parameter optimization allows efficient PHA accumulation while minimizing residual organic matter in the treated wastewater.
3Manufacturing precision
If intermittent substrate feeding is used to maintain high molecular weight PHA, then PHA quality improves, but process time increases
Solution Approach 1:
The patent maintains continuous useful action by implementing frequent intermittent feeding cycles that keep the biomass in a state of sustained high respiration activity. This approach prevents long periods of substrate depletion that would slow PHA synthesis, thereby reducing total process time while still achieving high molecular weight PHA through the intermittent nature of each feeding event.
Data Source
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AI summary
A method or process for producing polyhydroxyalkanoates (PHAs) in biomass. The process entails feeding an organic carbon containing substrate to biomass enriched in PHA accumulating bacteria. Particularly the process entails intermittently supplying the substrate to the biomass at least three separate times over a selected period. The object of the process is to produce PHA having a relatively high molecular weight, at least 400,000 g/mole. By controlling the frequency at which the substrate is supplied to the biomass and by feeding a sufficient amount of the substrate to the biomass, the method or process produces the PHA having the relatively high molecular weight.