Suitability of Composting Process for the Disposal and Valorization of Brewer’s Spent Grain

Davide Assandri, Niccolò Pampuro, Giacomo Zara, Eugenio Cavallo and Marilena Budroni
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Davide Assandri: Department of Agricultural Science, University of Sassari, Viale Italia 39, 07100 Sassari, Italy
Niccolò Pampuro: Institute of Sciences and Technologies for Sustainable Energy and Mobility of the National Research Council of Italy, Strada delle Cacce 73, 10135 Torino, Italy
Giacomo Zara: Department of Agricultural Science, University of Sassari, Viale Italia 39, 07100 Sassari, Italy
Eugenio Cavallo: Institute of Sciences and Technologies for Sustainable Energy and Mobility of the National Research Council of Italy, Strada delle Cacce 73, 10135 Torino, Italy
Marilena Budroni: Department of Agricultural Science, University of Sassari, Viale Italia 39, 07100 Sassari, Italy

Agriculture, 2020, vol. 11, issue 1, 1-12

Abstract: The brewing industry is characterized by the large production of by-products. Following the fundamentals of a circular economy, several attempts to recycle brewers’ spent grain (BSG) have been investigated. However, little information is available on its use for composting. Considering the main parameters required for optimal development of composting, the objective of the present review was to analyze the literature to determine whether the microbial and physicochemical characteristics of BSG make it suitable for direct composting. As the main factors in the composting process, we considered the BSG moisture content, total carbon, total nitrogen, C/N ratio, and pH. As described in the literature, the BSG moisture content, C/N ratio, and pH range from 70.6% to 81.3%, 7.1 to 26.5, and 3.8 to 6.9, respectively. This C/N ratio range is lower than the composting target range (20–30). Instead, the mean moisture content in the literature is higher than the 60% to 65% recommended for composting. Optimum pH for aerobic stabilization of compost ranges from 5.5 to 7.5, while the BSG pH in the literature is typically more acidic. Therefore, BSG is not suitable for direct composting. Addition of lignocellulosic bulking agents improves the reduction of moisture content during composting, while also optimizing the substrate properties, such as C/N ratio, air spaces, and pH, to positively affect the composting process. Moreover, livestock manure should be included as a starting material to promote the composting process. In this context, two hypothetical initial mixtures of BSG plus a lignocellulosic bulking agent and livestock manure are presented.

Keywords: aerobic stabilization; agro-industry by-product; brewing industry; circular economy; organic fertilizer (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2020
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