Use of Continuous Stirred Tank Reactors for Anaerobic Co-Digestion of Dairy and Meat Industry By-Products for Biogas Production

Alessandro Neri, Ferdinand Hummel, Souraya Benalia, Giuseppe Zimbalatti, Wolfgang Gabauer, Ivana Mihajlovic and Bruno Bernardi ()
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Alessandro Neri: Dipartimento di Agraria, Università Mediterranea di Reggio Calabria, Loc. Feo di Vito, 89122 Reggio Calabria, Italy
Ferdinand Hummel: Institute of Environmental Biotechnology, BOKU University, Konrad-Lorenz. Straße 20, 3430 Tulln an der Donau, Austria
Souraya Benalia: Dipartimento di Agraria, Università Mediterranea di Reggio Calabria, Loc. Feo di Vito, 89122 Reggio Calabria, Italy
Giuseppe Zimbalatti: Dipartimento di Agraria, Università Mediterranea di Reggio Calabria, Loc. Feo di Vito, 89122 Reggio Calabria, Italy
Wolfgang Gabauer: Institute of Environmental Biotechnology, BOKU University, Konrad-Lorenz. Straße 20, 3430 Tulln an der Donau, Austria
Ivana Mihajlovic: Institute of Environmental Biotechnology, BOKU University, Konrad-Lorenz. Straße 20, 3430 Tulln an der Donau, Austria
Bruno Bernardi: Dipartimento di Agraria, Università Mediterranea di Reggio Calabria, Loc. Feo di Vito, 89122 Reggio Calabria, Italy

Sustainability, 2024, vol. 16, issue 11, 1-14

Abstract: The dairy and meat industries generate thousands of tons of organic waste and by-products each year, making them two of the least environmentally sustainable sectors. Typical waste includes not only processing by-products such as curds but also commercial products that are defective or unsaleable due to expiration or damaged packaging. This study aimed to evaluate the methanogenic potential of a mixture of 80% inedible curds and 20% expired sausages, as a substrate, using two continuously stirred tank reactors (CSTR). The reactors were fed daily with increasing doses of the 80–20% mixture and an organic loading rate ranging from 0.31 gVS/litre/day at the beginning of the trials to 7.20 gVS/litre/day toward the end. The produced biogas was continuously analysed from both quantitative and qualitative point of view. Also, the process was continuously monitored by withdrawing samples from each reactor during the whole process, to analyse their physical–chemical parameters, including pH, total solids (TS), total volatile solids (TVS), chemical oxygen demand (COD), ammonium nitrogen (NH4 + -N), total Kjeldahl nitrogen (TKN) and total volatile fatty acids (VFA). The results of this study show a promising increase in biogas production with the increase in feed. In terms of biogas production, organic waste from the dairy and meat industry shows the potential to be exploited as a substrate to produce biomethane. Indeed, in this study, biomethane cumulative production reached 410.86 NL CH4 ∙gTVS −1 using an 8 L capacity reactor filled up to 6 L. This makes the tested by-products usable as a renewable energy source in the future, particularly within a circular economy approach, helping to mitigate the effects of global warming and addressing sustainable development goals.

Keywords: biogas; continuously stirred tank reactor (CSTR); organic loading rate (OLR); methane; mesophilic condition; sustainable energy (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2024
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