Evaluation of Microbial Population Dynamics in Anaerobic Digesters during Stable Operation, Reactor Failure and Performance Recovery

共同利用农业和工业废物流作为厌氧生物反应器系统的原料已成为一种有前途的增值产品合成技术。将来自食品加工和生物燃料生产行业的动物粪便和废物流转化为具有商业重要性的生物产品（如沼气）有助于实现环境改造、可再生燃料生产、温室气体减排和经济发展的多个目标。在加拿大，农业和工业废物的厌氧共消化是一个不断增长的行业，具有显著扩展的潜力。厌氧消化器面临的一个长期挑战是在不同的原料质量下保持系统稳定性，以确保可靠的能源供应和不间断的运行。过程不稳定性可能由有毒物质、有机物或液压过载引起。导致毒性过载的因素包括有毒化合物（抗菌消毒剂，抗生素）意外泄漏到流入液中，而可变的饲料浓度，过量的固体含量或停留时间不足可能导致有机过载。因此，蒸煮器通常不以其最大设计容量操作，以避免气体生产崩溃。需要更好地了解厌氧消化中涉及的复杂过程，以提高过程稳定性，监测和整体效率。 拟议的研究计划的主要目标是确定组内的微生物群落的厌氧消化器，可以作为一个预警指标，即将失败的各种过载条件下。最终，这些群体可以在消化池的常规分析中成为目标，并且可以制定管理策略以规避故障并保持稳定运行。为了确定是否有这样的可识别的指标组，一系列的故障预测测试将在连续进料厌氧消化器中进行，其中过程故障将被诱导，同时监测微生物群落的演变。有机超载将通过添加三种不同类型的共消化底物的牛粪消化器：废甘油，废脂肪酸（工业生物柴油设施的副产品），和废青贮饲料。毒性休克将通过引入奶牛场操作中常用的化学化合物引起：硫酸铜（用于足浴的抗菌溶液）和土霉素（一种常见的兽医抗生素）。将确定不断变化的微生物组，并采用最先进的宏基因组方法评估不断变化的种群的重要性。使用高通量Illumina测序将允许全面覆盖和表征微生物群落，同时提供对相对丰度低的生物体的访问。

The co-utilization of agricultural and industrial waste streams as feedstock for anaerobic bioreactor systems has emerged as a promising technology for value-added product synthesis. Conversion of animal manures and waste streams originating from food processing and biofuel production industries to commercially important bio-products (such as biogas) serves multiple goals of environmental reclamation, renewable fuel production, greenhouse gas mitigation, and economic development. Anaerobic co-digestion of agricultural and industrial wastes is a growing industry in Canada with potential for significant expansion. One of the enduring challenges of anaerobic digesters is system stability in the face of varying feedstock quality to ensure reliable energy supplies and uninterrupted operations. Process instability can be caused by toxic, organic, or hydraulic overload. Factors leading to toxic overload include accidental spillage of toxic compounds (antimicrobial disinfectants, antibiotics) into the influent, while variable feed consistency, excessive solids content or insufficient retention time can lead to organic overload. Consequently, digesters are usually not operated at their maximum design capacity in order to avoid collapse of gas production. A better understanding of the complex processes involved in anaerobic digestion is needed to improve process stability, monitoring and overall efficiency. The main goal of the proposed research program is to identify groups within the microbial community of an anaerobic digester that can serve as an early warning indicator of impending failure under a variety of overload conditions. Ultimately, these groups can then be targeted during routine analysis of digesters, and a management strategy can be developed to circumvent failure and maintain steady operation. In order to determine if there are such identifiable indicator groups, a series of failure prediction tests will be conducted in continuous-feed anaerobic digesters, where process failure will be induced while the evolution of the microbial community is monitored. Organic overload will be brought on by adding three different types of co-digestion substrates to dairy manure digesters: waste glycerol, waste fatty acids (both by-products of an industrial biodiesel facility), and waste silage. Toxic shocks will be induced by introducing chemical compounds commonly used on dairy-farm operations: copper sulfate (antibacterial solution used for foot-baths) and oxytetracycline (a common veterinary antibiotic). Changing microbial groups will be identified and the significance of the changing population evaluated with a cutting-edge metagenomic approach. The use of high-throughput Illumina sequencing will allow for comprehensive coverage and characterization of the microbial community while providing access to organisms with a low relative abundance.