The products of an advanced sewage sludge fermentation process can be used to generate polyhydroxyalkanoates (PHAs), precursors of bioplastics considered excellent candidates for replacing petroleum-derived plastics. The aerobic feast-anoxic famine cycling strategy has proven to be an efficient method for enriching sewage sludge microbiota with PHA-producing microorganisms. This work evaluated the effect of different carbon to nitrogen ratios (C/N) of 3.5, 2, and 1 g COD/g N for modulating the structure of sewage sludge microbiota to improve PHA production. The study was executed on a pilot plant scale using wasted activated sludge as an organic carbon source derived from an oxic-settling anaerobic plant that collects wastewater from various facilities at the University of Palermo campus. PHA production performance was monitored over three experimental periods characterized by a different C/N ratio. The results showed that lower C/N ratios reduced PHA production with 20, 24, and 26 % w/w of PHAs for COD/N values of 1, 2, and 3.5 g COD/g N, respectively. In parallel, the metataxonomic analysis revealed a higher abundance of PHA-producing microorganisms at the ratio of 3.5 g COD/g N, such as Proteobacteria, specifically Betaproteobacteria. In addition, the analysis showed an increase in fungal abundance and diversity as decrease the ratio C/N decreased. Thus, these findings demonstrate the utility of metataxonomics in elucidating the relationships between operating conditions, bacterial and fungal microbiota structure and the achievement of specific outputs. The insights gained from this study demonstrated a positive correlation between C/N ratios, PHA-producing microorganisms, and PHA yields.

Di Leto, Y., Mineo, A., Capri, F.C., Puccio, G., Mercati, F., Alduina, R., et al. (2025). The role of carbon and nitrogen ratio on sewage sludge microbiota for producing polyhydroxyalkanoates. JOURNAL OF ENVIRONMENTAL MANAGEMENT, 375 [10.1016/j.jenvman.2025.124240].

The role of carbon and nitrogen ratio on sewage sludge microbiota for producing polyhydroxyalkanoates

Di Leto, Ylenia;Mineo, Antonio;Capri, Fanny Claire;Puccio, Guglielmo;Mercati, Francesco;Alduina, Rosa;Gallo, Giuseppe
;
Mannina, Giorgio
2025-01-28

Abstract

The products of an advanced sewage sludge fermentation process can be used to generate polyhydroxyalkanoates (PHAs), precursors of bioplastics considered excellent candidates for replacing petroleum-derived plastics. The aerobic feast-anoxic famine cycling strategy has proven to be an efficient method for enriching sewage sludge microbiota with PHA-producing microorganisms. This work evaluated the effect of different carbon to nitrogen ratios (C/N) of 3.5, 2, and 1 g COD/g N for modulating the structure of sewage sludge microbiota to improve PHA production. The study was executed on a pilot plant scale using wasted activated sludge as an organic carbon source derived from an oxic-settling anaerobic plant that collects wastewater from various facilities at the University of Palermo campus. PHA production performance was monitored over three experimental periods characterized by a different C/N ratio. The results showed that lower C/N ratios reduced PHA production with 20, 24, and 26 % w/w of PHAs for COD/N values of 1, 2, and 3.5 g COD/g N, respectively. In parallel, the metataxonomic analysis revealed a higher abundance of PHA-producing microorganisms at the ratio of 3.5 g COD/g N, such as Proteobacteria, specifically Betaproteobacteria. In addition, the analysis showed an increase in fungal abundance and diversity as decrease the ratio C/N decreased. Thus, these findings demonstrate the utility of metataxonomics in elucidating the relationships between operating conditions, bacterial and fungal microbiota structure and the achievement of specific outputs. The insights gained from this study demonstrated a positive correlation between C/N ratios, PHA-producing microorganisms, and PHA yields.
28-gen-2025
Settore BIOS-15/A - Microbiologia
Settore CEAR-02/A - Ingegneria sanitaria-ambientale
Di Leto, Y., Mineo, A., Capri, F.C., Puccio, G., Mercati, F., Alduina, R., et al. (2025). The role of carbon and nitrogen ratio on sewage sludge microbiota for producing polyhydroxyalkanoates. JOURNAL OF ENVIRONMENTAL MANAGEMENT, 375 [10.1016/j.jenvman.2025.124240].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/671925
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