Hrad Marlies, Piringer Martin, Kamarad Ludek, Baumann-Stanzer Kathrin, Huber-Humer Marion
Department of Water-Atmosphere-Environment, Institute of Waste Management, University of Natural Resources and Life Sciences, Muthgasse 107, 1190, Vienna, Austria,
Environ Monit Assess. 2014 Oct;186(10):6251-62. doi: 10.1007/s10661-014-3852-0. Epub 2014 May 29.
Open digestate storage tanks were identified as one of the main methane (CH4) emitters of a biogas plant. The main purpose of this paper is to determine these emission rates using an inverse dispersion technique in conjunction with open-path tunable diode laser spectroscopy (OP-TDLS) concentration measurements for multisource reconstruction. Since the condition number, a measure of "ill-conditioned" matrices, strongly influences the accuracy of source reconstruction, it is used as a diagnostic of error sensitivity. The investigations demonstrate that the condition number for a given source-sensor configuration in the highly disturbed flow field within the plant significantly depends on the meteorological conditions (e.g., wind speed, stratification, wind direction, etc.). The CH₄ emissions are retrieved by removing unrepresentative periods with high condition numbers, which indicate uncertainty in recovering the individual sources. In a final step, the CH₄ emissions are compared with the maximum biological methane potential (BMP) in the digestate analyzed under laboratory conditions. The retrieved methane emission rates represent an average of 50% of the maximum BMP of the stored digestate in the winter months, while they comprised an average of 85% during the measurement campaigns in the summer months. The results indicate that the open tanks have the potential to represent a substantial emission source even during colder periods.
敞开式沼液储存罐被确定为沼气厂的主要甲烷（CH₄）排放源之一。本文的主要目的是结合用于多源重建的开放路径可调谐二极管激光光谱（OP-TDLS）浓度测量，使用反扩散技术来确定这些排放速率。由于条件数（一种衡量“病态”矩阵的指标）对源重建的准确性有很大影响，因此将其用作误差敏感性的诊断指标。研究表明，在工厂内高度扰动的流场中，给定源 - 传感器配置的条件数显著取决于气象条件（例如风速、分层、风向等）。通过去除条件数高的无代表性时间段来获取CH₄排放，这些时间段表明在恢复各个源时存在不确定性。在最后一步中，将CH₄排放与在实验室条件下分析的沼液中的最大生物甲烷潜力（BMP）进行比较。在冬季月份，获取的甲烷排放速率平均占储存沼液最大BMP的50%，而在夏季测量活动期间，这一比例平均为85%。结果表明，即使在较冷的时期，敞开式储罐也有可能成为一个重要的排放源。
