Influence of Aeration Rate on Uncoupled Fed Mixed Microbial Cultures for Polyhydroxybutyrate Production

Alessio Castagnoli, Serena Falcioni, Eleftherios Touloupakis, Francesco Pasciucco, Erika Pasciucco, Alessandro Michelotti, Renato Iannelli and Isabella Pecorini ()
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Alessio Castagnoli: Department of Energy, Systems, Territory and Construction Engineering (DESTEC), University of Pisa, 56122 Pisa, Italy
Serena Falcioni: Department of Civil and Environmental Engineering, University of Florence, Via di S. Marta 3, 50139 Florence, Italy
Eleftherios Touloupakis: Research Institute on Terrestrial Ecosystems, National Research Council, Via Madonna del Piano 10, Sesto Fiorentino, 50019 Florence, Italy
Francesco Pasciucco: Department of Energy, Systems, Territory and Construction Engineering (DESTEC), University of Pisa, 56122 Pisa, Italy
Erika Pasciucco: Department of Energy, Systems, Territory and Construction Engineering (DESTEC), University of Pisa, 56122 Pisa, Italy
Alessandro Michelotti: Department of Energy, Systems, Territory and Construction Engineering (DESTEC), University of Pisa, 56122 Pisa, Italy
Renato Iannelli: Department of Energy, Systems, Territory and Construction Engineering (DESTEC), University of Pisa, 56122 Pisa, Italy
Isabella Pecorini: Department of Energy, Systems, Territory and Construction Engineering (DESTEC), University of Pisa, 56122 Pisa, Italy

Sustainability, 2024, vol. 16, issue 7, 1-13

Abstract: The use of residual streams as feedstock for the production of polyhydroxyalkanoates (PHAs) is growing steadily, as it allows the valorization of waste and nutrients otherwise disposed of and the potential production of a biodegradable bioplastic. To date, the environmental and economic costs associated with this process limit its scale-up, which is why it is important to identify possible solutions and optimize the costliest steps. With this in mind, a laboratory-scale sequenced batch reactor (SBR, 5 L) was constructed to allow the selection of a mixed microbial culture able to convert volatile fatty acids (VFAs) into PHA. The reactor is fed with synthetic water containing VFAs, ammonium, phosphate, and micronutrients, typical compounds of fermented streams of certain wastes, such as cheese whey, food waste, or wastewater sludge. The biomass selected and produced by this first reactor is sent to an accumulation reactor, which is fed with a solution rich in VFAs, allowing the accumulation of PHAs. The role of aeration and its impacts on the main process parameters were analyzed. Three scenarios corresponding to different aeration rates were analyzed: 0.08, 0.16, and 0.32 vvm. The SBR was operated at an organic load rate of 600 mgCOD L −1 d −1 , under a dynamic feeding regime (feast–famine) and a short hydraulic retention time (HRT; 1 day). The results obtained showed that a value of 0.32 enabled better selection and better settling of the sludge. Furthermore, a potential correlation between aeration rate and VFA and NH 4 + consumption rates was identified. The resulting biomass was able to accumulate up to 0.15 ± 0.02 g PHA g VSS −1 .

Keywords: mixed microbial cultures; polyhydroxybutyrate; PHA; aeration rate; sequenced batch reactor; circular bioeconomy (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2024
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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