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Sludge retention time impacts on polyhydroxyalkanoate productivity in uncoupled storage/growth processes
Mariana Matos1, Rafaela A P Cruz1, Pedro Cardoso2
1UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal; Associate Laboratory i4HB - Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal.
Selecting the right mixed microbial culture (MMC) is key for producing polyhydroxyalkanoates (PHAs) from waste. Balancing culture growth and PHA storage capacity significantly boosts PHA production efficiency.
Area of Science:
- Biotechnology
- Environmental Science
- Microbiology
Background:
- Polyhydroxyalkanoates (PHAs) production using mixed microbial cultures (MMCs) and waste substrates offers a cost-effective alternative.
- Optimizing MMC selection for high PHA accumulation and growth rate is crucial for process feasibility.
Purpose of the Study:
- Investigate the interplay between growth and storage dynamics in MMCs fed with fermented fruit waste.
- Evaluate the impact of sludge retention times (SRTs) and organic loading rates (OLRs) on PHA production.
Main Methods:
- Utilized a pilot plant setup with uncoupled carbon and nitrogen feeding.
- Imposed varying SRTs (2 and 4 days) and OLRs (2.6–14.5 gCOD.L-1.d-1).
- Monitored PHA accumulation, growth rates, and storage capacities.
Main Results:
- Lower SRT cultures exhibited faster growth but lower PHA accumulation capacity and productivity.
- Polymer storage yield was independent of SRT and correlated with PHA-storing bacteria abundance.
- A 4-day SRT achieved 80% higher PHA productivity (4.6 ± 0.3 g.L-1.d-1) compared to lower SRTs.
Conclusions:
- A balance between culture growth and PHA accumulation capacity is vital for efficient PHA production from waste.
- Optimizing SRT is critical for maximizing PHA productivity in MMC-based bioprocesses.
- This study highlights a viable strategy for enhancing the economic feasibility of PHA production from fermented fruit waste.
