Faculty of Bioscience Engineering - Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Gent, Belgium.
Faculty of Bioscience Engineering - Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Gent, Belgium.
Waste Manag. 2023 Aug 1;168:334-343. doi: 10.1016/j.wasman.2023.06.008. Epub 2023 Jun 17.
During biogas production, a residual by-product rich in organic matter, nutrients, and trace elements - called digestate - is generated. Due to the nature of the anaerobic digestion process (i.e., conversion of organic matter into biogas) and the non-digestibility of trace elements, metal concentrations are higher in digestate than initially in the treated feedstock, resulting in a detrimental effect on the environment when directly applied as fertiliser on the soil. This study aims to predict the concentration of heavy metals in digestate through four different process parameters (Biogas yield - M, Biodegradable fraction - M, Dry matter - M and Power generation - M) in full-scale biogas plants. For the validation of the process parameters, the predictions were compared against laboratory analyses of feedstocks and digestates samples from mono- and co-digestion processes. The convergence between the conversion factors based on laboratory data and process parameters (C and C, respectively) ranged in the following order: M > M > M > M. Based on laboratory analyses, better predictions were obtained for Al, Cr, Cu, Fe, Mn, and Zn employing M. Moreover, a robust convergence was achieved between the C and C conversion factors for the mono-digestion process. Further assessment of a diverse range of feedstocks is needed to increase the convergence between the conversion factors based on process parameters and laboratory data, specifically for the co-digestion process M. The concentrations of Cd, Co, Ni, and Pb elements were below the detection limits, whereas Cr, Cu, and Zn did not exceed the legal threshold limits of the legislations.
在沼气生产过程中，会产生一种富含有机物、营养物质和微量元素的残余副产品，称为消化物。由于厌氧消化过程的性质（即将有机物转化为沼气）和微量元素的不可消化性，消化物中的金属浓度高于处理原料中的初始浓度，因此当直接作为肥料施用于土壤时，会对环境产生不利影响。本研究旨在通过全规模沼气厂中的四个不同工艺参数（沼气产量-M、可生物降解部分-M、干物质-M 和发电量-M）来预测消化物中重金属的浓度。为了验证工艺参数，将预测结果与单消化和共消化过程中的原料和消化物样品的实验室分析结果进行了比较。基于实验室数据的转化因子（C 和 C）与工艺参数（C、C 和 C）之间的收敛程度依次为：M > M > M > M。基于实验室分析，采用 M 对 Al、Cr、Cu、Fe、Mn 和 Zn 的预测效果更好。此外，单消化过程中 C 和 C 转化因子之间实现了稳健的收敛。需要进一步评估各种不同的原料，以增加基于工艺参数和实验室数据的转化因子之间的收敛性，特别是对于共消化过程 M。Cd、Co、Ni 和 Pb 元素的浓度低于检测限，而 Cr、Cu 和 Zn 未超过法规规定的法定阈值限制。
