The interest for Renewable Energy Sources (RES) has strongly increased due to the need to reduce the greenhouse gas (GHG) emissions, as indicated, in particular, by the renewable energy directive 2018/2001/EU and to reuse organic waste and by-products that would otherwise have to be disposed of in an expensive way. The present article relates to a method and to a device to decompose a biomass matrix and to selectively extract methane, carbon dioxide, NPK (nitrogen, phosphorus and potassium) salts and clarified water. This method and device is the subject of an Italian and European patent registered by Stefano Farné and Vito Lavanga under the name of MBGC (Mini BioGas Continuous). The MBGC can be applied to the production of biomethane (for thermal and electrical purposes), of organic (protein and oleic) substances, of NPK salts, that can be used in the production of biofuels, fertilizing mixtures for various industrial sectors (livestock farms, chemical, etc.), of hydrogen, as present in solution in the liquid phase and of carbon dioxide for agronomic industries, metallurgical industries, fire services, agro-food etc. It has been analysed a meaningful literature on the subject of biogas production plants, with specific focus to those of small size and subsequently the MBGC plant is described in detail from the point of view of both plant engineering and its operation.

Keywords: Biogas, biomass, anaerobic digestion, biomethane, NPK salts.

Bacenetti, J., Fusi, A., Guidetti, R., & Fiala, M. (2013). Life Cycle Assessment of maize cultivation for biogas production. Journal of Agricultural Engineering, 44(2s). https://doi.org/10.4081/jae.2013.356.

Capodaglio A. G., Callegari A., Lopez M. V. (2016). European Framework for the Diffusion of Biogas.

Uses: Emerging Technologies, Acceptance, Incentive Strategies, and Institutional-Regulatory Support. Sustainability, 8(4), 298; https://doi.org/10.3390/su8040298.

Castellucci, S., Cocchi, S., Allegrini, E., & Vecchione, L. (2013). Anaerobic digestion and co-digestion of slaughterhouse wastes. Journal of Agricultural Engineering, 44(2s). https://doi.org/10.4081/jae.2013.346.

Cecchi, F., Battistoni, P., Pavan, P., Bolzonella, D., Innocenti, L. (2005). Digestione anaerobica della frazione organica dei rifiuti solidi. APAT, Manuali e linee guida, 13.

Comparetti, A., Febo, P., Greco, C., Orlando, S., Navickas, K., & Venslauskas, K. (2013). Sicilian potential biogas production. Journal of Agricultural Engineering, 44(2s). https://doi.org/10.4081/jae.2013.345.

Coppolecchia, D., Gardoni, D., Baldini, C., Borgonovo, F., & Guarino, M. (2015). The influence on biogas production of three slurry-handling systems in dairy farms. Journal of Agricultural Engineering, 46(1), 30-35. https://doi.org/10.4081/jae.2015.449.

dell’Antonia, D., Cividino, S., Carlino, A., Gubiani, R., & Pergher, G. (2013). Development perspectives for biogas production from agricultural waste in Friuli Venezia Giulia (Nord-East of Italy). Journal of Agricultural Engineering, 44(2s). https://doi.org/10.4081/jae.2013.354.

Dinuccio, E., Gioelli, F., Cuk, D., Rollè, L., & Balsari, P. (2014). The use of co-digested solid fraction as feedstock for biogas plants. Journal of Agricultural Engineering, 44(4), 153-159. https://doi.org/10.4081/jae.2013.208.

El-Mashad, H. M., van Loon, W. K. P., Zeeman, G., Bot, G. P. A., Lettinga G. (2004), Design of A Solar Thermophilic Anaerobic Reactor for Small Farms. Biosystems Engineering, Volume 87,  345-353.

Farné, S. (2015). Macchine. Macchine idrauliche, 1st ed.; Collana Synopsis, Casa editrice Medea: Pavia, Italy.

Farné, S., Lavanga, V. (2016). MBGC - Method for anaerobic digestion and device for implementing said method - Publication Number WO/2016/092582, Publication Date 16.06.2016, International Application No. PCT/IT2015/000306,  https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2016092582.

Farné, S., Lavanga, V. (2016). HWFC - DEVICE FOR PRODUCING HYDROGEN - Publication Number WO/2016/092578, Publication Date 16.06.2016, International Application No. PCT/IT2015/000298, https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2016092578.

Farné, S., Lavanga, V. (2016). SDNA - Publication Number WO/2016/092576, Publication Date 16.06.2016, International Application No. PCT/IT2015/000296, https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2016092576.

Farné, S., Lavanga, V. (2016). GSMF - METHOD TO SEPARATE THE COMPONENTS IN THESE GAS LIQUIDS, VAPOURS OR GAS, AND DEVICE FOR IMPLEMENTING SAID METHOD, Publication Number WO/2016/092577, Publication Date 16.06.2016, International Application No. PCT/IT2015/000297, https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2016092577.

Farné, S., Lavanga, V. (2016). MHLM - METHOD AND DEVICE FOR THE HOMOGENEOUS AND DELIMITED MIXING OF FLUIDS, Publication Number WO/2016/092579, Publication Date 16.06.2016, International Application No.PCT/IT2015/000299, https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2016092579.

Mostafaiyan M., Reza Saeb M., Emami Alorizi A., Farahani M. (2014). Application of evolutionary computational approach in design of horizontal three-phase gravity separator. Journal of petroleum science and engineering, 119, 28-35.

Oberti, R., Tenca, A., Perazzolo, F., Riva, E., Finzi, A., Naldi, E., Provolo, G., & Bodria, L. (2013). A farm-scale pilot plant for biohydrogen and biomethane production by two-stage fermentation. Journal of Agricultural Engineering, 44(2s). https://doi.org/10.4081/jae.2013.357.

Plöchl, M., Heiermann, M. (2006). Biogas Farming in Central and Northern Europe: A Strategy for Developing Countries? The CIGR journal, 8(1), 10-15.

Preto, R. (2016). Elementi di biomasse. University of Pavia, 12-16.

Valenti, F., Porto, S. M., Cascone, G., & Arcidiacono, C. (2017). Potential biogas production from agricultural by-products in Sicily. A case study of citrus pulp and olive pomace. Journal of Agricultural Engineering, 48(4), 196-202. https://doi.org/10.4081/jae.2017.727