Biomethanation of the by-products deriving from the agri-food chain in Campania region
The projects aimed at setting-up and operating a demo plant capable to produce biomethane from the biogas generated by the anaerobic digestion of organic substrates collected in Campania region agro-industrial activities.
Although several technologies have been proposed for the biogas clean-up, their limited application at large scale has required ad hoc experimemtal activities to identify a novel technological solution, evaluate its upscaling potential and investigate the best operating conditions to make it available among the operators of the agri-food chain.
The research activities performed within METAGRO project allowed:
- the design and realization of a modular system for the upgrading of biogas to biomethane through microalgal processes. The METAGRO plant builds on a novel upgrading system, relying on the alcalinity of the microalgae growth medium to absorb the carbon dioxide (CO2) contained in the biogas. The absorption process occurs in a column hydraulically connected to the photobioreactor for microalgae growth. An intensive experimental activity was needed to identify the optimal microalgae growth conditions as well as to assess the effect of the main operating parameters (i.e. biogas flow rate, CO2 concentration in the biogas, retention time, ...) on the CO2 removal yields, so that the prototype design could be improved.
- the set up of a process pursuing simultaneously the biogas upgrading and the ammonia nitrogen removal from the digestate originating from the anaerobic bioconversion of agro-industrial waste via microalgal processes. Differently from previous studies performed on pure microalgal cultures, the experimental activity was performed using mixed microalgal consortia, grown under non-sterile conditions: experimental outcomes, addressing a new concept of industrial symbiosis between anaerobic digestion and microalgal-based processes, were published (Policastro G., Cesaro A., Fabbricino M., Pirozzi F. (2022). Opportunities and challenges from symbiosis of agro-industrial residue anaerobic digestion with microalgae cultivation. Sustainability, 14, 15607, doi: 10.3390/su142315607).
- the dissemination among the main interested stakeholders, of the potential of biological processes (such as anaerobic digestion and microalgal-based processes) for the wider valorization of agro-industrial waste in Campania region.
The projects consisted of the design, building and application of the METAGRO plant to a target agro-industrial activity, with the aim of proposing an integrated system to treat the agricultural products of the Campania region and valorize them in the form of biomethane.
The project developed through the following activities:
- detailed design of the plant and system assemby;
- start up and experimental tests to optimize the novel biogas upgrading process;
- assessment of the applicability of the proposed solution at the C&F company;
- dissemination of the project results.
The production of energy from organic feedstocks is an important economic goal of our country, also having significant social impacts. Indeed, the biogas produced from the fermentation of biomasses can be used in the transportation sector, domestic heating and the production of semi finished products for the biochemical sector.
Italy is the third country worldwide as producer of biogas from organic feedstocks and boasts the highest number of methane-fueled vehicles after China and Germany. In Italy, approximately 1500 agricultural plants exist. In 2013, the agricultural plants contributed to the 10% of the electric power generated from renewable sources.
Currently, 90% of the agricultural plants is located in Northern Italy and is mainly fed with animal manure (50%) and agricultural residues (20%). The resources located in the regions of Southern Italy would correspond to 5.6 billions of euros and 8,000 job opportunities. The effect of these investments would lead to an increase of approximately 0.3 points of the gross domestic product (GDP) amounting 27,4 billions of euros.
Due to the long-term agricultural history of Campania region, high amounts of agricultural by-products and residues are available on the territory.
This project was framed within this context, with the aim of developing a strategy to valorize target organic agricultural wastes by converting them into biomethane. More specifcally, the main objective was to propose a “modular system” for biomethane production from a wide variety of agricultural residues of the Campania region.
The METAGRO plant is based on well-established treatment technologies (i.e. anaerobic digestion), which were coupled to other treatment steps such as the clean-up of the biogas produced (by e.g. microalgal processes). The latter have only been recently investigated in the scientific literature.
Therefore, the original aspect of this project lays in the original combination of such technologies, which mades the entire treatment innovative for the specific target to be pursued.