Smart sewers: development of wireless in-situ sensors for dissolved gases in liquid waste

液体废物处理服务（LWS）的基础设施，例如在大温哥华地区（MV）的设施，包括一个庞大的污水管道网络、泵站和处理设施，以容纳大量的废物。然而，下水道环境为特定的细菌种类提供了理想的条件。作为它们代谢过程的副产品，会产生各种有害气体，包括硫化氢、氨、二氧化碳、甲烷和一氧化二氮。这些目标气体是造成腐蚀、恶臭和温室气体排放的原因。生物酸腐蚀尤其值得关注；生物过程可以从硫化氢中产生强酸，这大大减少了LWS基础设施的使用寿命，并增加了下水道管道倒塌的风险。采用各种缓解措施来控制和防止有害气体的产生及其相关后果。然而，用于这些治疗的化学物质是昂贵的，并且需要针对特定的生物气体“热点”来提高成本效益。由于气体生产发生在污水管道的液相内，因此人们明确表示需要一种能够长时间沿管道放置的探测器。这一行业问题将在以下研究目标中得到解决：(1)开发一种使用敏感金属氧化物半导体与选择性微流体扩散通道耦合的气体传感器。(2)将传感器与样品提取、过滤、样品输送、传感器回收和清洗的支持系统集成。(3)开发微控制器和数据采集组件，用于操作探测器的所有系统，并将数据传输到便携式设备上进行分析。(4)构建一个强大的平台，集成传感器和支持系统，并提供在浑浊下水道环境中的耐久性。(5)进行现场测试以优化设备并解决已发现的问题。该设备将为LWS人员提供实时数据，以更好地为他们的生物气体减排策略提供信息。最终，开发的技术将有助于延长LWS基础设施的使用寿命，减少LWS的碳足迹，并减轻周围社区的滋扰气味。******************

Liquid Waste Service (LWS) infrastructures, such as those at Metro Vancouver (MV), encompass a vast network of sewer pipes, pumping stations and treatment facilities to accommodate large volumes of waste. However, the sewer environment provides ideal conditions for particular bacteria species. As a byproduct of their metabolic processes various nuisance gases are produced, including hydrogen sulfide, ammonia, carbon dioxide, methane, and nitrous oxide. These target gases are responsible for corrosion, offensive fugitive odours, and greenhouse gas emissions. Biogenic acid corrosion is of particular concern; biological processes can create strong acids from hydrogen sulfide which drastically reduce the lifespan of the LWS infrastructure and increase the risk of sewer pipe collapse. A variety of mitigation treatments are used to control and prevent the production of nuisance gases and their related consequences. However, the chemicals used for these treatments are expensive and require targeting specific "hotspots" of biogenic gas to increase cost-effectiveness. Since gas production occurs within the liquid-phase of sewer pipes, there has been an expressed need for a detector capable of being situated along the pipeline over extended periods. This industry problem will be addressed in the following research objectives: (1) Develop a gas sensor using a sensitive metal oxide semiconductor coupled with a selective microfluidic diffusion channel. (2) Integrate the sensor with support systems for sample extraction, filtration, sample delivery, sensor recovery and cleansing. (3) Develop a microcontroller and data collection components to operate all the systems of the detector and to transmit data for analysis on portable devices. (4) Construct a robust platform to integrate the sensor and supporting systems and provide durability in the turbid sewer environment. (5) Conduct field tests to optimize the device and address identified issues. This device will provide real-time data to LWS personnel to better inform their biogenic gas mitigation strategies. Ultimately, the developed technology will help extend LWS infrastructure service life, reduce the carbon footprint of LWS, and mitigate nuisance odours to surrounding communities.******************