有机化合物厌氧消化过程热力学特性研究

Bio-methane production by organic waste can effectively solve the problems of environmental pollution and energy shortage, has broad application prospects. But biogas project quality and efficiency is always restricted by low substrate conversion rate, slow fermentation rate and poor regulation method. The core problem is the lack of systematic thermodynamic analysis and optimization of anaerobic fermentation process. This study is to identify the entropy, enthalpy and exergy of anaerobic digestion system by physicochemical, biological and chemical methods. Analyzing the substance degradation process and coupling it with microbial metabolic process through the fluid thermodynamic properties, the biochemical reaction equilibrium constant and the microbial metabolic process. Construct and validate the thermodynamic state model based on the changes of pH value, VFA, ammonia and other characters, then revealing the entropy variation regularity by establishing an entropy calculation method of anaerobic digestion system with complex substrates. Interpret the variation regularity of enthalpy and exergy of anaerobic digestion system and quantitatively study the energy conversion pathway by developing an enthalpy energy balance and exergy analysis. Explore the effects of temperature, pressure, HRT, organic loading rates and agitation speed on thermodynamic state of fermentation; Determine the energy evaluation system and exergy controlling strategy of anaerobic digestion, achieve the optimization of energy efficiency by engineering verification.

有机废弃物制备生物甲烷能够有效缓解环境污染和能源短缺问题，具有广阔的应用前景。但底物转化率低、发酵速率慢、调控难等问题制约着工程提质增效，其核心问题是缺乏系统的厌氧发酵过程热力学分析与优化。本研究通过物化、生化热力学状态分析手段，确定复杂原料厌氧消化系统的熵、焓、㶲变特性。基于流体热力学性质、生化反应平衡常数和微生物代谢过程，解析厌氧消化阶段的物质变化过程，耦合物质变化和微生物代谢平衡模型，基于厌氧反应器内pH、VFA、氨氮等变化，构建热力学状态参数并验证模型；建立复杂原料厌氧消化体系的熵计算方法，揭示熵变规律；构建基于焓的能量衡算和㶲的能量分析方法，阐释厌氧消化体系的焓变及㶲变规律，定量考察能量转换途径；探索温度、压力、有机物负荷和搅拌等影响因素对发酵热力学状态的影响规律；确定能量评价指标体系和基于㶲的控制策略，通过工程验证实现能量效率最优化。

有机废弃物通过厌氧发酵技术进行资源化利用，并获得可再生能源生物燃气，是有效缓解环境污染和能源短缺问题的有效途径之一，具有广阔的应用前景。但有机废弃物在厌氧转化过程，其底物转化率低、发酵速率慢、调控难等问题制约着工程提质增效性能，其核心问题是缺乏系统的厌氧发酵过程热力学分析与优化。在本项目实施过程中，综合运用了方程和模型模拟、热力学特性分析、厌氧实验和结果验证等研究方法，将厌氧工艺参数与熵、焓、㶲变化特性进行结合分析，确定了复杂原料厌氧消化系统的熵、焓、㶲变特性；基于热力学性质、生化反应平衡常数和微生物代谢过程，定量和定性地研究和分析了厌氧消化各阶段的熵焓㶲变化规律，形成了物质变化和微生物代谢平衡模型；基于厌氧反应器内pH、挥发性脂肪酸(VFAs)、氨氮等变化，构建了热力学状态参数并验证了模型，阐释了厌氧消化体系的焓变和㶲变规律以及能量转换途径，确定了能量评价指标体系以及基于㶲的厌氧失稳预警和控制策略。基于本项目的理论研究成果，衍生开发了高负荷厌氧发酵预警和调控技术，可显著提高了工程的处理能力和运行效率，助力于我国有机废弃物的资源化利用、生态环境保护和“双碳”目标实现。