Publicação
Enhancing anaerobic co-digestion of municipal mixed sludge with fruit and vegetable waste
| Resumo: | Anaerobic digestion is widely used to treat organic waste from the food industry and municipal wastewater treatment plants, converting organic matter into biogas. However, mono-digestion of municipal mixed sludge (a blend of primary and secondary sludge) faces challenges due to an imbalanced carbon-to‑nitrogen (C/N) ratio. Co-digestion has been proposed to address this issue, and fruit and vegetable waste provides a readily biodegradable carbon source that can enhance the anaerobic digestion of mixed sludge through synergistic effects. This study evaluated different mixtures of fruit and vegetable peel purées with municipal mixed sludge through batch trials, aiming to identify the optimal combination for full-scale application based on biogas yield and methane content. A blend of apple, banana, and carrot peel purées (40:30:30) was selected for further testing. Semi-continuous trials were conducted in a continuously stirred tank reactor (CSTR) with 10 and 15 % of the selected blend. The 10 % co-substrate addition improved biogas and methane production by 19.9 and 21.2 %, respectively, in batch tests. In CSTR trials, co-digestion reduced hydrogen sulfide (H₂S) levels by 50–71 % and increased specific methane production by 28–44 %, compared to mono-digestion. An energy gain of 0.877 kWh/kgTVS was achieved with the 10 % blend. |
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| Autores principais: | Azevedo, André |
| Outros Autores: | Moldão, Margarida; Duarte, Elizabeth; Lapa, Nuno |
| Assunto: | Biogas production Biomethane Circular economy Energy potential Peel waste SDG 11 - Sustainable Cities and Communities |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | Anaerobic digestion is widely used to treat organic waste from the food industry and municipal wastewater treatment plants, converting organic matter into biogas. However, mono-digestion of municipal mixed sludge (a blend of primary and secondary sludge) faces challenges due to an imbalanced carbon-to‑nitrogen (C/N) ratio. Co-digestion has been proposed to address this issue, and fruit and vegetable waste provides a readily biodegradable carbon source that can enhance the anaerobic digestion of mixed sludge through synergistic effects. This study evaluated different mixtures of fruit and vegetable peel purées with municipal mixed sludge through batch trials, aiming to identify the optimal combination for full-scale application based on biogas yield and methane content. A blend of apple, banana, and carrot peel purées (40:30:30) was selected for further testing. Semi-continuous trials were conducted in a continuously stirred tank reactor (CSTR) with 10 and 15 % of the selected blend. The 10 % co-substrate addition improved biogas and methane production by 19.9 and 21.2 %, respectively, in batch tests. In CSTR trials, co-digestion reduced hydrogen sulfide (H₂S) levels by 50–71 % and increased specific methane production by 28–44 %, compared to mono-digestion. An energy gain of 0.877 kWh/kgTVS was achieved with the 10 % blend. |
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