GENOCOV, Department of Chemical, Biological and Environmental Engineering, School of Engineering, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
GENOCOV, Department of Chemical, Biological and Environmental Engineering, School of Engineering, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain.
Water Res. 2024 Jun 1;256:121616. doi: 10.1016/j.watres.2024.121616. Epub 2024 Apr 16.
Microbial electrolysis cells (MECs) have garnered significant attention as a promising solution for industrial wastewater treatment, enabling the simultaneous degradation of organic compounds and biohydrogen production. Developing efficient and cost-effective cathodes to drive the hydrogen evolution reaction is central to the success of MECs as a sustainable technology. While numerous lab-scale experiments have been conducted to investigate different cathode materials, the transition to pilot-scale applications remains limited, leaving the actual performance of these scaled-up cathodes largely unknown. In this study, nickel-foam and stainless-steel wool cathodes were employed as catalysts to critically assess hydrogen production in a 150 L MEC pilot plant treating sugar-based industrial wastewater. Continuous hydrogen production was achieved in the reactor for more than 80 days, with a maximum COD removal efficiency of 40 %. Nickel-foam cathodes significantly enhanced hydrogen production and energy efficiency at non-limiting substrate concentration, yielding the maximum hydrogen production ever reported at pilot-scale (19.07 ± 0.46 L H m d and 0.21 ± 0.01 m m d). This is a 3.0-fold improve in hydrogen production compared to the previous stainless-steel wool cathode. On the other hand, the higher price of Ni-foam compared to stainless-steel should also be considered, which may constrain its use in real applications. By carefully analysing the energy balance of the system, this study demonstrates that MECs have the potential to be net energy producers, in addition to effectively oxidize organic matter in wastewater. While higher applied potentials led to increased energy requirements, they also resulted in enhanced hydrogen production. For our system, a conservative applied potential range from 0.9 to 1.0 V was found to be optimal. Finally, the microbial community established on the anode was found to be a syntrophic consortium of exoelectrogenic and fermentative bacteria, predominantly Geobacter and Bacteroides, which appeared to be well-suited to transform complex organic matter into hydrogen.
微生物电解池（MEC）作为一种有前途的工业废水处理解决方案，已经引起了广泛的关注，可以同时降解有机化合物和生产生物氢。开发高效且具有成本效益的阴极来驱动析氢反应是 MEC 作为可持续技术取得成功的关键。尽管已经进行了大量的实验室规模实验来研究不同的阴极材料，但向中试规模应用的转变仍然受到限制，这些扩大规模的阴极的实际性能在很大程度上仍然未知。在这项研究中，泡沫镍和不锈钢毛阴极作为催化剂，在处理基于糖的工业废水的 150 L MEC 中试工厂中评估了产氢情况。在反应器中连续产氢超过 80 天，最大 COD 去除效率为 40%。在非限制底物浓度下，泡沫镍阴极显著提高了产氢和能量效率，产生了中试规模下有史以来最大的产氢量（19.07±0.46 L H m d 和 0.21±0.01 m m d）。这比以前的不锈钢毛阴极提高了 3.0 倍。另一方面，与不锈钢相比，Ni-foam 的较高价格也应该考虑在内，这可能会限制其在实际应用中的使用。通过仔细分析系统的能量平衡，本研究表明，MEC 除了能够有效地氧化废水中的有机物外，还有潜力成为净能源生产者。虽然较高的施加电位导致能源需求增加，但也导致产氢增加。对于我们的系统，发现 0.9 至 1.0 V 的保守施加电位范围是最佳的。最后，发现阳极上建立的微生物群落是一种发酵和产电细菌的同型共生体，主要是 Geobacter 和 Bacteroides，它们似乎非常适合将复杂的有机物转化为氢气。
