Waste valorization through anaerobic co-digestion in coffee and swine farms: CH4 yield optimization and farm-scale viability

• Published in: Bioresource technology 2025-01, Vol.415, p.131667, Article 131667
• Main Authors: Alves Lourenço, Vitor, Pereira Camargo, Franciele, Kimiko Sakamoto, Isabel, Silva, Edson Luiz, Amâncio Varesche, Maria Bernadete
• Format: Article
• Language: English
• Subjects: COD/N ratio; Energetic potential; Manure; Methanolinea; Waste-to-energy
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131667

[Display omitted] •Higher CH4 production was observed with 8–15% coffee wastewater.•Above 15% ofcoffee wastewater negatively affected CH4 production.•Higher percentage of liquid swine manure was related to lag phase decrease.•Concentration above 8 gCOD L-1 resulted in low CH4 yield and high lag phase.•Optimization with 14% wastewater, 86% manure, and 7.3 gCOD L-1. Considering that the Brazilian southeast has several agricultural farms that produce coffee and raise swine, and that the waste generated in these farms has some complementary characteristics, the present study aimed to optimize the methane (CH4) yield in the batch anaerobic co-digestion of liquid swine manure (LSM), coffee wastewater (CFW), and coffee husk and pulp. The optimization occurred through a two-factor central composite rotational design with a variation of CFW percentage (8 to 22 %) in the mixing liquid substrates and the organic matter concentration (0.3 to 12 gCOD L-1). The optimized condition had an ideal nutritional condition (14 % of CFW, 86 % of LSM, 7.3 gCOD L-1 and COD/N ratio of 35) to obtain high CH4 production (971.7 mLCH4), yield (160.9 mLCH4 g-1VS), maximum specific production rate (1.6 mL h−1) and low lag phase (217.6 h).