Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Via Di Biasio 43, 03043 Cassino, Italy.
Department of Genetic and Bioengineering, Giresun University, 28000, Turkey.
Sci Total Environ. 2021 Mar 25;762:144178. doi: 10.1016/j.scitotenv.2020.144178. Epub 2020 Dec 17.
This study proposes new perspectives for the management and biorefinery of wastes deriving from the agri-food sector such as chestnut shell (CS), which was here used as an organic feedstock for biomethane production through anaerobic digestion (AD). 1-5% alkaline (i.e. NaOH and KOH), hydrothermal (i.e. at 100 °C) and combined hydrothermal-alkaline pretreatments were employed to enhance the CS biodegradability prior to biochemical methane potential (BMP) tests conducted under mesophilic conditions. The hydrothermally-pretreated CS with 3% NaOH achieved the highest biomethane yield of 253 (±9) mL CH·g VS coupled to a volatile solid reduction of 48%. The hydrothermal-alkaline pretreatment positively affected both delignification and hemicellulose polymerization, promoting an approximately 2.4-fold higher substrate biodegradability compared to the untreated CS, which only reached a CH production of 104 (±5) mL CH·g VS. AD proceeded via volatile fatty acid accumulation, subsequently followed by methane production that was effectively simulated via the modified Gompertz kinetic having a R of 0.974-0.999. Among the physical-chemical parameters characterizing the CS, the soluble chemical oxygen demand (sCOD) was highly correlated with the BMP showing a Pearson coefficient of 0.952. The cumulative biomethane yield, the sCOD and the cellulose, hemicellulose and lignin amount of CS were also processed through the least square method, obtaining a useful regression equation to predict the BMP. The economic assessment indicated that the hydrothermal-alkaline pretreatment is a cost-effective method to improve the BMP of CS, also for future full-scale applications.
本研究为农业食品废弃物（如板栗壳）的管理和生物炼制提供了新视角，将其作为有机原料通过厌氧消化（AD）生产生物甲烷。本研究采用 1-5%碱性（即 NaOH 和 KOH）、水热（即 100°C）和组合水热-碱性预处理方法，在中温条件下进行生物化学甲烷潜力（BMP）测试之前，提高板栗壳的生物降解性。3%NaOH 预处理的水热板栗壳的生物甲烷产率最高，为 253（±9）mL CH·g VS，挥发性固体减少 48%。水热-碱性预处理对木质素脱除和半纤维素聚合均有积极影响，与未经处理的板栗壳相比，底物生物降解性提高了约 2.4 倍，未经处理的板栗壳仅产生 104（±5）mL CH·g VS。AD 通过挥发性脂肪酸积累进行，随后进行甲烷生产，通过修正的 Gompertz 动力学有效模拟，R 为 0.974-0.999。在表征板栗壳的物理化学参数中，可溶解性化学需氧量（sCOD）与 BMP 高度相关，皮尔逊系数为 0.952。通过最小二乘法处理累积生物甲烷产率、sCOD 以及板栗壳的纤维素、半纤维素和木质素含量，获得了一个有用的回归方程来预测 BMP。经济评估表明，水热-碱性预处理是提高板栗壳 BMP 的一种具有成本效益的方法，也适用于未来的大规模应用。
