When evaluating the efficiency of biogas plants based on the residual energy content in the digestate, it is necessary to distinguish the anaerobically available and non-available portion of energy. Digestates from agricultural biogas plants typically contain lignin as anaerobically non-degradable matter. The aim of the present study was to examine, if the content of anaerobically non-degradable matter in digestates, as analysed by acid detergent lignin (ADL), can be predicted from gross calorific values (GCV). For that, 31 samples at different degradation states from 9 biogas plants were analysed. The results show that the VS-specific lignin fraction can be predicted from calorimetric measurements in the studied range from 0.03 to 0.36 with an accuracy of ±0.086 (±2*RMSECV). The accuracy of prediction of lignin in digestates was not significantly influenced by the passed hydraulic retention time of the material in the digester. The model equation allows distinguishing anaerobically degradable and non-degradable portions of organic matter and inherent energies in digestates, assuming lignin to be the only non-degradable component. Future efforts have to be made to extend the data set for a greater calibration range of ADL and generalise the model equation for a wider spectrum of biogas plants fed with a variety of substrates.

当根据消化液中的剩余能量含量评估沼气厂的效率时，有必要区分厌氧和可利用的部分能量。农业沼气厂的消化液通常含有木质素作为厌氧不可降解物质。本研究的目的是检查是否可以通过总热值（GCV）预测通过酸性洗涤剂木质素（ADL）分析的消化物中厌氧不可降解物质的含量。为此，分析了来自9个沼气厂的31种处于不同降解状态的样品。结果表明，可以通过量热测量在0.03至0.36的研究范围内预测VS特定木质素含量，准确度为±0.086（±2 * RMSECV）。消化物中木质素的预测准确性不受蒸煮器中物料通过的水力停留时间的影响很大。假设木质素是唯一的不可降解成分，该模型方程可区分消化物中有机物的厌氧降解和不可降解部分以及固有能量。必须做出进一步的努力来扩展数据集，以实现更大范围的ADL校准，并推广模型方程式，从而为使用各种底物的沼气厂提供更广泛的频谱。