Souring is the unwanted formation of hydrogen sulfide (H₂S) by sulfate-reducing microorganisms (SRM) in sewer systems and seawater flooded oil reservoirs. Nitrate treatment (NT) is one of the major methods to alleviate souring: The mechanism of souring remediation by NT is stimulation of nitrate reducing microorganisms (NRM) that depending on the nitrate reduction pathway can outcompete SRM for common electron donors, or oxidize sulfide to sulfate. However, some nitrate reduction pathways may challenge the efficacy of NT. Therefore, a precise understanding of souring rate, nitrate reduction rate and pathways is crucial for efficient souring management. Here, we investigate the necessity of incorporating two thermodynamic dependent kinetic parameters, namely, the growth yield (Y), and F_T, a parameter related to the minimum catabolic energy production required by cells to utilize a given catabolic reaction. We first show that depending on physiochemical conditions, Y and F_T for SRM change significantly in the range of [0-0.4] mole biomass per mole electron donor and [0.0006-0.5], respectively, suggesting that these parameters should not be considered constant and that it is important to couple souring models with thermodynamic models. Then, we highlight this further by showing an experimental dataset that can be modeled very well by considering variable F_T. Next, we show that nitrate based lithotrophic sulfide oxidation to sulfate (lNRM₃) is the dominant nitrate reduction pathway. Then, arguing that thermodynamics would suggest that S° consumption should proceed faster than S⁰ production, we infer that the reason for frequently observed S⁰ accumulation is its low solubility. Last, we suggest that nitrate based souring treatment will suffer less from S⁰ accumulation if we (i) act early, (ii) increase temperature and (iii) supplement stoichiometrically sufficient nitrate.

酸化是下水道系统和海水淹没油藏中硫酸盐还原微生物 (SRM)形成的不希望有的硫化氢 (H ₂ S)。硝酸盐处理 (NT) 是缓解酸味的主要方法之一：NT 酸味修复的机制是刺激硝酸盐还原微生物 (NRM)，根据硝酸盐还原途径可以在常见电子供体方面超越 SRM，或将硫化物氧化成硫酸盐。然而，一些硝酸盐还原途径可能会挑战 NT 的功效。因此，准确了解酸化率、硝酸盐还原率和途径对于有效的酸化管理至关重要。在这里，我们研究了结合两个热力学相关动力学参数的必要性，即生长产量 (Y) 和 F _T，与细胞利用给定分解代谢反应所需的最小分解代谢能量产生相关的参数。我们首先表明，根据理化条件，SRM 的Y 和 F _{T 分别}在每摩尔电子供体 [0-0.4] 摩尔生物量和 [0.0006-0.5] 的范围内显着变化，表明这些参数不应被视为恒定并且将酸化模型与热力学模型结合起来很重要。然后，我们通过展示一个可以通过考虑变量 F _T很好地建模的实验数据集来进一步强调这一点。接下来，我们展示了基于硝酸盐的岩石营养硫化物氧化为硫酸盐 (lNRM ₃) 是主要的硝酸盐还原途径。然后，认为热力学表明 S° 消耗应该比 S ⁰生产进行得更快，我们推断经常观察到 S ⁰积累的原因是其溶解度低。最后，我们建议，如果我们 (i) 及早采取行动，(ii) 提高温度和 (iii) 补充化学计量足够的硝酸盐，基于硝酸盐的酸化处理将减少 S ⁰积累。