Wetsus, European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9 8911 CE Leeuwarden, Netherlands; Environmental Technology, Wageningen University & Research, P.O. Box 17 6700 AA, Wageningen, Netherlands.
Environmental Technology, Wageningen University & Research, P.O. Box 17 6700 AA, Wageningen, Netherlands; Paqell B.V., Reactorweg 301 3542 CE Utrecht, Netherlands.
Water Res. 2024 Aug 1;259:121795. doi: 10.1016/j.watres.2024.121795. Epub 2024 May 17.
Biological desulfurization under haloalkaline conditions has been applied worldwide to remove hydrogen sulfide (HS) from sour gas steams. The process relies on sulfide-oxidizing bacteria (SOB) to oxidize HS to elemental sulfur (S), which can then be recovered and reused. Recently, a dual-reactor biological desulfurization system was implemented where an anaerobic (sulfidic) bioreactor was incorporated as an addition to a micro-oxic bioreactor, allowing for higher S selectivity by limiting by-product formation. The highly sulfidic bioreactor environment enabled the SOB to remove (poly)sulfides (S) in the absence of oxygen, with S speculated as a main substrate in the removal pathway, thus making it vital to understand its role in the process. The SOB are influenced by the oxidation-reduction potential (ORP) set-point of the micro-oxic bioreactor as it is used to control the product of oxidation (S vs. SO), while the uptake of S by SOB has been qualitatively linked to pH. Therefore, to quantify these effects, this work determined the concentration and speciation of S in the biological desulfurization process under various pH values and ORP set-points. The total S concentrations in the sulfidic zone increased at elevated pH (8.9) compared to low pH (< 8.0), with on average 3.3 ± 1.0 mM-S more S. Chain lengths varied, with S only doubling in concentration while S increased 9 fold, which is in contrast with observations from abiotic systems. Changes to the ORP set-point of the micro-oxic reactor did not produce substantial changes in S concentration in the sulfidic zone. This illustrates that the reduction degree of the SOB in the micro-oxic bioreactor does not enhance their ability to interact with S in the sulfidic bioreactor. This increased understanding of how both pH and ORP affect changes in S concentration and chain length can lead to improved efficiency and design of the dual-reactor biological desulfurization process.
在 haloalkaline 条件下进行生物脱硫已在全球范围内用于从酸性天然气中去除硫化氢 (HS)。该工艺依赖于硫化物氧化菌 (SOB) 将 HS 氧化为元素硫 (S)，然后可以回收和再利用。最近，实施了双反应器生物脱硫系统，其中将厌氧 (硫化物) 生物反应器作为微氧生物反应器的附加物，通过限制副产物的形成来提高 S 的选择性。高度硫化物的生物反应器环境使 SOB 能够在没有氧气的情况下去除 (多) 硫化物 (S)，S 被推测为去除途径中的主要底物，因此了解其在该过程中的作用至关重要。SOB 受到微氧生物反应器氧化还原电位 (ORP) 设置点的影响，因为它用于控制氧化产物 (S 与 SO)，而 SOB 对 S 的吸收与 pH 定性相关。因此，为了量化这些影响，本工作确定了在不同 pH 值和 ORP 设置点下生物脱硫过程中 S 的浓度和形态。与低 pH 值 (<8.0) 相比，升高 pH 值 (8.9) 时硫化物区中的总 S 浓度增加，平均增加了 3.3±1.0mM-S。链长不同，S 浓度仅增加一倍，而 S 增加 9 倍，这与非生物系统的观察结果相反。微氧反应器 ORP 设置点的变化并未在硫化物区产生 S 浓度的实质性变化。这表明微氧生物反应器中 SOB 的还原程度不会增强它们与硫化物生物反应器中 S 相互作用的能力。这种对 pH 和 ORP 如何影响 S 浓度和链长变化的理解的提高，可以提高双反应器生物脱硫工艺的效率和设计。
