1. A comprehensive comparison between two strategies to produce polyhydroxyalkanoates from domestic sewage sludge.
- Author
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Mannina, Giorgio and Mineo, Antonio
- Subjects
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SEWAGE sludge , *SEWAGE , *ACOUSTIC emission testing , *ENVIRONMENTAL impact analysis , *POLYHYDROXYALKANOATES , *PLASTICS - Abstract
Biopolimer materials, such as polyhydroxyalkanoates (PHA), are essential to restrain the use of petroleum-based plastic material fostered by European Union regulation. Despite the recent development regarding the production of PHA, the scale-up of sewage sludge-based technology is still in its infancy since the literature lacks studies on the environmental impact of the process. This work aims to stand as a pioneer study reporting the direct greenhouse gas (GHG) emissions and carbon footprint (CF) of two sewage sludge-based PHA production strategies. The two strategies, aerobic dynamic feeding (ADF) and aerobic/anoxic enrichment (AE/AN), were monitored and compared based on the system's efficiency in removing carbon and nutrients, PHA's production and productivity, nitrous oxide direct emissions and the CF. The produced PHA accounted for 38.21 g PHA g−1 volatile suspended solids (VSS) % and 14.54 g PHA g−1 VSS %, for ADF and AE/AN, respectively. The N 2 O emissions were lower for ADF than the AE/AN enrichment, 0.39 N 2 O–N L−1 and 0.98 N 2 O–N L−1, respectively, as was the CF, which accounted for 3.56 kg CO 2 day−1 and 6.91 kg CO 2 day−1 for ADF and AE/AN respectively. This innovative study provides valuable insights into comparing the two above-mentioned strategies and a pilot for structuring and designing future studies comprehensively considering the environmental consequences of the process in future life cycle assessments. [Display omitted] • ADF and AE/AN were compared to assess the environmental impact of producing PHA. • ADF reached 38.21 % w/w of PHA produced, while AE/AN only achieved 14.54 % w/w. • AE/AN showed an increased amount of N 2 O emitted, up to 0.98 mg N 2 O–N L−1. • AE/AN almost doubled ADF's carbon footprint (CF), reaching 13.09 kg CO 2 day−1. • CF proves that a trade-off between efficiency and sustainability is yet to be found. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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