Fuel properties characterization of hydrochars derived from agricultural - replication data

Poland's obligation to meet the EU's RES target has resulted in the growing interest in the biogas market. Simultaneously, the state's energy policy introduces solutions to support biogas plants. In addition, new developing technologies should also be applied to sufficiently increase the biogas production and to utilise the potential in generated biomass waste either from wastewater plant or agricultural production. That is why the detailed information of every aspect of the process including potential disposal of products and by-products from biogas plant and environmental impact has to be determined. Also, European energy policy is focussed on reduction of waste in the landfilling. Therefore, the thermal conversion of biogas plant waste is required thus hydrothermal carbonization (HTC) seems to be a promising method. This method is carried out in aqueous environment, that is why digestate is a suitable feedstock due to a high moisture content (c.a. 80%) and organic origin. The obtained products of HTC might be further process into biofuels, biofertilizers or absorbents. The researchers are interested in hydrothermal treatment of digestate from sewage sludge, mainly because it is proven to enhance its dewaterability, but the digestate derived from agriculture biogas plant is not so widely studied. Therefore, the scientific knowledge of the products properties and its formation is essential to fulfil this gap. The main aim of the project is to investigate the impact of the main parameters of the process (temperature and residence time) on the physical and chemical properties of HTC products from digestate. Additionally, the determination of its mechanism formation will be done by multifaceted description using highly advanced instrumental techniques. The tested material will be digestate from anaerobic treatment of municipal and agricultural wastes. The process will be conducted in a stainless steel Zipperclave Stirred Reactor equipped with a MagneDrive Agitator. Then, the wide description of physical and chemical properties of solid, liquid and gaseous products will be determined. Pathway formation and transformation of inorganic elements, in particular of heavy metals, in solid product-hydrochar will be analysed. The biofuel properties of hydrochar strongly depends on the process parameters and feedstock origin. Therefore, the in-depth discussion of those factors affecting the ultimate and proximate analysis, energy and mass yields, densification ratio, higher heating value for will be carried out. Also, the mechanism of combustion behaviour of hydrochar will be studied using thermal analysis. In addition, the gasification of hydrochar will be carried out to find out the potential of syngas production. The instrumental and chemical methods to study the fibre structure (van Soest method) and chemical bonds in hydrochar will be also used (FTIR) to investigate the mechanism of the pore structure formation in order to determine its sorptive and fertile properties (SSA and pores distribution). Furthermore, the impact of temperature and residence time of hydrothermal treatment will be studied on liquid phase when the complex reactions take place resulting in a high load of dissolved total organic carbon content and nutrients. That is why its chemical composition and main characteristic parameters will be analysed and discussed. In addition, the eco-toxicity properties and potential in a anaerobic digestion as a biomethane producer will be tested. Moreover, investigation of vacuum depth in vacuum distillation process of postprocessing liquid and its impact on rheological properties of distillation residue will be also studied. The elaboration of scientific dependences between digestates, process parameters and solid and liquid phases will be deeply discussed. The results will demonstrate the multicriterial analysis of tested materials giving a new fundamental knowledge about the hydrothermal process and its product properties. Moreover, the circular economic European goal to “reuse, replace and reduce” will be achieved by enhancing properties of digestate and its reduction in the landfilling.

波兰为履行欧盟可再生能源（Renewable Energy Sources, RES）目标，使得沼气市场的关注度持续提升。与此同时，该国能源政策出台多项举措扶持沼气厂建设。此外，还需应用新兴技术以充分提升沼气产能，并利用污水处理厂或农业生产产生的生物质废弃物潜在价值。因此，需明确该流程各环节的详细信息，包括沼气厂产品与副产物的潜在处置方式及环境影响。欧盟能源政策亦聚焦于减少填埋废弃物，因此需对沼气厂废弃物进行热转化，而水热碳化（Hydrothermal Carbonization, HTC）便是极具前景的技术路径。该技术在水环境中开展，沼渣因含水率高（约80%）且为有机来源，成为适宜的原料。HTC所得产物可进一步加工为生物燃料、生物肥料或吸附剂。现有研究多关注污水处理厂污泥厌氧消化后沼渣的水热改性，因其可有效提升沼渣脱水性能，但针对农业沼气厂沼渣的相关研究仍较为匮乏。因此，明确该过程产物特性与形成机制，对填补该研究空白至关重要。本项目的核心目标为：探究工艺主要参数（温度与停留时间）对农业沼渣水热碳化产物理化性质的影响。此外，将借助多种高端仪器表征技术，多维度解析产物的形成机制。试验所用原料为市政与农业废弃物厌氧消化所得沼渣。试验将采用配备磁驱动搅拌器（MagneDrive Agitator）的不锈钢Zipperclave搅拌反应器开展。随后，将全面表征固体、液体与气态产物的理化性质。将分析固体产物（水热炭）中无机元素（尤其是重金属）的赋存形态与转化路径。水热炭的生物燃料特性高度依赖工艺参数与原料来源，因此将深入探讨影响其元素分析、工业分析、能量产率、质量产率、致密化率与高位发热量的各类因素。此外，将通过热分析研究水热炭的燃烧行为机制。同时，将开展水热炭的气化试验，以评估其合成气生产潜力。将采用纤维结构分析（范·索斯特法）与化学键表征（傅里叶变换红外光谱, FTIR）等化学与仪器分析方法，探究孔结构的形成机制，以明确其吸附性能与肥沃性能（通过比表面积, SSA与孔径分布表征）。此外，将研究水热热处理参数对液相产物的影响：液相中会发生复杂反应，导致溶解性总有机碳与营养盐含量较高，因此将分析并讨论其化学组成与核心特征参数。同时，将测试液相产物的生态毒性，以及其作为厌氧消化产甲烷底物的潜力。另外，还将探究后处理液相产物的真空蒸馏真空度对蒸馏残渣流变性能的影响。将深入阐述沼渣特性、工艺参数与固液两相产物间的科学关联。研究结果将实现对试验材料的多准则分析，为水热碳化工艺及其产物特性提供全新的基础认知。此外，通过提升沼渣的利用价值并减少其填埋量，可助力欧盟达成“再利用、替代与减量”的循环经济目标。