This study is an attempt to assess CH₄ and N₂O emissions from all the treatment steps of a wastewater treatment plant (WWTP) in Sweden, serving 145 000 persons, and an adjacent biogas production facility. We have used novel mid-IR ground-based remote sensing with a hyperspectral camera to visualize and quantify the emissions on 21 days during a year, with resulting yearly fluxes of 90.4 ± 4.3 tonne CH₄/yr and 10.9 ± 1.3 tonne N₂O/yr for the entire plant. The most highly emitting CH₄ source was found to be sludge storage, which is seldom included in literature as in-situ methods are not suitable for measuring emissions extended over large surfaces, still contributing 90 % to the total CH₄ emission in our case. The dominating N₂O source was found to be a Stable High rate Ammonia Removal Over Nitrite reactor, contributing 89 % to the total N₂O emissions. We also discovered several unexpected CH₄ sources. Incomplete flaring of CH₄ gave fluxes of at least 30 kg CH₄/min, corresponding to plume concentrations of 2.5 %. Such highly episodic fluxes could double the plant-wide yearly emissions if they occur 2 days per year. From a distance of 250 m we found a leak in the biogas production facility, corresponding to 1.1 % of the CH₄ produced, and that loading of organic material onto trucks from a biofertilizer storage tank contributed with high emissions during loading events. These results indicate that WWTP emissions globally may have been grossly underestimated and that it is essential to have effective methods that can measure all types of fluxes, and discover new potential sources, in order to make adequate priorities and to take effective actions to mitigate greenhouse gas emissions from WWTPs.

本研究试图评估瑞典一家为 145 000 人提供服务的污水处理厂 (WWTP) 和邻近的沼气生产设施的所有处理步骤中的CH ₄和 N _{2 O 排放量。}我们使用带有高光谱相机的新型中红外地面遥感来可视化和量化一年中 21 天的排放量，产生的年通量为 90.4 ± 4.3 吨 CH ₄ /年和 10.9 ± 1.3 吨 N ₂ O /yr 为整个工厂。发现排放量最高的 CH ₄源是污泥储存，由于原位方法不适合测量大面积的排放量，因此很少包含在文献中，仍占总 CH _{4的 90%}在我们的例子中排放。主要的 N ₂ O 源被发现是在亚硝酸盐反应器上的稳定的高速率氨去除，占 N ₂ O 总排放量的 89%。我们还发现了几个意想不到的 CH ₄来源。_{CH 4}的不完全燃烧产生至少 30 kg CH ₄ /min 的通量，对应于 2.5% 的羽流浓度。如果每年发生 2 天，这种高度偶发性的通量可能会使全厂的年排放量增加一倍。从 250 m 的距离，我们发现沼气生产设施有泄漏，相当于 CH _{4的 1.1%}生产，并且从生物肥料储罐将有机材料装载到卡车上会导致装载事件期间的高排放。这些结果表明，全球污水处理厂的排放量可能被严重低估，必须有有效的方法来测量所有类型的通量，并发现新的潜在来源，以便确定适当的优先事项并采取有效行动来减少温室气体排放。污水处理厂的排放。