Mitigation of nitrous oxide emissions from wastewater treatment systems using nitrous oxide respiring bacteria

一氧化二氮(N2O；笑气)是一种强有力的温室气体和臭氧消耗物质。在过去的一个世纪里，由于人工固氮(Haber-Bosch过程)的发明和农业施肥实践的加强，大气中N2O的浓度一直在不断上升，这导致了全球生物地球化学氮循环的严重人为失衡。尽管N2O排放已被确认在气候变化中发挥重要作用，但相应的缓解战略仍未得到充分探讨。这一跨学科合作项目的目的是研究N2O呼吸细菌(NRB)及其对减少污水处理厂N2O排放的适用性。两个主要目标是(I)确定最适合这项任务的NRB和(Ii)将这些微生物暴露在可用于废水处理的连续条件下。工作计划包括在短期批量实验中对具有代表性的NRB进行彻底的微生物学表征，包括审查一氧化二氮呼吸对溶解氧的存在以及其他相关因素，如碳源和废水基质的影响。在连续的长期实验中，合适的NRB将暴露在类似废水的条件下。这些试验将在实验室规模的反应堆中进行，条件不同，例如溶解氧浓度的动态变化。该项目将提供关于在废水条件下使用NRB以及在废水处理系统中实施NRB的适宜性评估。它还将有助于开发几乎未被开发的N2O呼吸菌这一自然资源。

Nitrous oxide (N2O; laughing gas) is a potent greenhouse gas and ozone depleting substance. Over the last century the atmospheric concentration of N2O has been constantly on the rise as a consequence of the invention of man-made nitrogen fixation (the Haber-Bosch process) and intensification of agricultural fertilization practices that resulted in a severe anthropogenic imbalance of the global biogeochemical nitrogen cycle. Despite the fact that N2O emissions have been recognized to play an important role in climate change, corresponding mitigation strategies remained underexplored. The aim of this interdisciplinary and collaborative project is to investigate N2O respiring bacteria (NrB) and their applicability to mitigate N2O emissions from wastewater treatment plants. The two main objectives are (i) to identify the best-suited NrB for the task and (ii) to expose these organisms under continuous conditions that are realistic for wastewater treatment. The work program includes a thorough microbiological characterization of representative NrB in short-term batch experiments including scrutiny of nitrous oxide respiration towards the presence of dissolved oxygen and other relevant factors such as carbon source and impact of the wastewater matrix. Suitable NrB will be exposed to wastewater-like conditions in continuous long-term experiments. These trials will be performed in lab-scale reactors under varying conditions, e.g. dynamic changes in the dissolved oxygen concentration. The project will provide a suitability assessment regarding the use of NrB under wastewater conditions and the implementation of NrB in wastewater treatment systems. It will also contribute to exploit the almost untouched natural resource of N2O respiring bacteria.