Abstract

Volatile methyl siloxanes (VMS) are persistent contaminants extensively used in industrial applications. Their presence in biogas constitutes a major hindrance for its energetic valorization or its use as renewable natural gas. Current commercial siloxanes abatement technologies are based on physical-chemical methods, whose good performance is impaired by their high investment costs, and a hefty environmental impact. Research evidences that VMS are indeed biodegradable, which opens the possibility of implementing bio-based technologies as a cost-effective and sustainable alternative for the removal of these compounds. This review uncovers the most plausible organisms and microbial pathways involved in biological VMS degradation, a relatively unexplored area. Additionally, the most commonly applied configurations and the main operating challenges are thoroughly revised and discussed, evidencing that a feasible implementation relies on the optimization and scale-up of enhanced mass transfer bioreactors. Finally, the techno-economic and environmental analysis demonstrate that, although in a very early stage, emerging biological technologies for siloxanes removal will play an important key role on the future abatement of VMS from waste gas streams such as raw biogas.

摘要

挥发性甲基硅氧烷 (VMS) 是工业应用中广泛使用的持久性污染物。它们在沼气中的存在构成了其能量增值或用作可再生天然气的主要障碍。当前的商业硅氧烷减排技术基于物理化学方法，其良好的性能因其高投资成本和严重的环境影响而受损。研究表明 VMS 确实是可生物降解的，这为实施生物基技术作为去除这些化合物的成本效益和可持续替代方案提供了可能性。这篇综述揭示了参与生物 VMS 降解的最合理的生物体和微生物途径，这是一个相对未开发的领域。此外，对最常用的配置和主要操作挑战进行了彻底修改和讨论，证明可行的实施依赖于增强传质生物反应器的优化和放大。最后，技术经济和环境分析表明，尽管处于非常早期的阶段，新兴的硅氧烷去除生物技术将在未来从废气流（如原始沼气）中消除 VMS 中发挥重要的关键作用。