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Journal of Environmental Accounting and Management
António Mendes Lopes (editor), Jiazhong Zhang(editor)
António Mendes Lopes (editor)

University of Porto, Portugal


Jiazhong Zhang (editor)

School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China

Fax: +86 29 82668723 Email:

Biochar as Improver of Methane Production in Anaerobic Digestion of Food Waste

Journal of Environmental Accounting and Management 8(3) (2020) 267--279 | DOI:10.5890/JEAM.2020.09.005

Ciro Florio$^{1}$,$^{2}$, Paola Giudicianni$^{3}$, Domenico Pirozzi$^{2}$, Vincenzo Pasquale$^{1}$, Raffaele Ragucci$^{3}$, Stefano Dumontet$^{1}$

$^{1}$University of Naples “Parthenope”, Department of Science and Technology (DiST), Centro Direzionale di Napoli, ISOLA C4, 80143, Naples (Italy)

$^{2}$University of Naples “Federico II”, Department of Chemical Engineering, Materials and Industrial Production (DICMaPI), Piazzale Tecchio, 80, 80125, Naples (Italy)

$^{3}$Consiglio Nazionale delle Ricerche, Istituto di Ricerche sulla Combustione, Piazzale Tecchio, 80, 80125, Naples (Italy)

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Anaerobic digestion of food waste is aimed both at the reduction of the volume of waste and the production of methane. Carbonaceous additives such as activated carbons were widely studied as enhancer of methane production. In this paper a low-cost alternative additive, the biochar, was proposed to assess its use for improving both the operational stability and the energetic output of anaerobic digestion. The main objective of the present work is to assess and quantify the increase of CH4 yields induced by the biochar addition and to identify all the main mechanisms responsible of this improvement. The risk related to the Polycyclic Aromatic Hydrocarbons release from biochar in the anaerobic digestion media was discussed as well. To this aim, biochar obtained from steam assisted slow pyrolysis of Populus nigra L. up to 600 °C was used. Anaerobic digestion of food waste mixture was carried out in a batch reactor in mesophilic conditions (37 °C). Four tests were conducted by adding 0, 1, 4 and 10 wt% of biochar on wet food waste mixture basis. Results showed that more CH4 is produced even in the first hours of the anaerobic digestion test when 10 wt% of biochar was added to the food waste mixture (about 65 wt% more at 96 h), thus denoting a reduction of the lag phase. A total increase of CH4 yield of 14 and 42% when 4 and 10 wt% of biochar was added to the food waste mixture. In conclusion, analyses of both the liquid phase during the tests and biochar sampled at the end of anaerobic digestion process revealed that biochar favored the decomposition of acetic acid, adsorbed some inhibitors such as butyric acid, and provided a suitable habitat for microbial colonization.


The work was supported by the Accordo di Programma CNR-MSE 2013-2014 under the contract “Bioenergia Efficiente”. Authors thank Luca Micoli, Angelo Ausiello, Gaetano Zuccaro and Valentina Gargiulo for the technical support, and Claudio Ferone and Luciano Cortese for SEM analysis.


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