High total dissolved solids in shale gas wastewater inhibit biodegradation of alkyl and nonylphenol ethoxylate surfactants
High total dissolved solids in shale gas wastewater inhibit biodegradation of alkyl and nonylphenol ethoxylate surfactants
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DOI：
10.1016/j.scitotenv.2019.03.041
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发表时间：
2019-06-10
影响因子：
9.8
通讯作者：
Mouser, Paula J.
中科院分区：
文献类型：
--
作者：
Hanson, Andrea J.;Luek, Jenna L.;Mouser, Paula J.
水力压裂液被注入到非常规石油和天然气系统中，以刺激碳氢化合物的生产，并在排液和含有外来添加剂和地源化合物的复杂混合物的产出水中返回地表。非离子聚氧乙烯酸酯是通常添加的表面活性剂，在水力压裂液配方中用作耐候剂、乳化剂、润湿剂和缓蚀剂。了解这些无处不在的添加剂的生物降解性对于采出水在再利用之前进行预处理以及改进外部有益的再利用处理系统至关重要。研究了非常规气井采出水总溶解固体(TDS)对烷基聚氧乙烯醚和壬基酚聚氧乙烯醚表面活性剂好氧生物降解性的影响。在75天的有氧潜伏期内，对表面活性物质浓度、形态和代谢物以及微生物群落组成和活性的变化进行了量化。与对照相比，TDS处理(10g L-1和40g L-1)对烷基聚氧乙烯醚(AEOS)的降解速度快于壬基酚聚氧乙烯醚(NPEO)，而化合物类和整体有机碳的降解速度都较慢。短链乙氧基化物的生物降解速度比长链乙氧基化物更快，丙酮、醇、烷基单元的羧酸盐和醛中间体等代谢物的相对丰度的变化表明，在较高产量的TDS存在下，代谢途径可能会发生变化。我们的关键发现是，聚乙氧基醇表面活性剂添加剂在高TDS下不太稳定，这对采出水管理具有重要意义，因为这些流体越来越多地被回收用于水力压裂液和其他目的的有益再利用。(C)2019爱思唯尔B.V.保留所有权利。
Hydraulic fracturing fluids are injected into unconventional oil and gas systems to stimulate hydrocarbon production, returning to the surface in flowback and produced waters containing a complex mixture of xenobiotic additives and geogenic compounds. Nonionic polyethoxylates are commonly added surfactants that act as weatherizers, emulsifiers, wetting agents, and corrosion inhibitors in hydraulic fracturing fluid formulations. Understanding the biodegradability of these ubiquitous additives is critical for produced water pre-treatment prior to reuse and for improving treatment trains for external beneficial reuse. The objective of this study was to determine the effect of produced water total dissolved solids (TDS) from an unconventional natural gas well on the aerobic biodegradation of alkyl ethoxylate and nonylphenol ethoxylate surfactants. Changes in surfactant concentrations, speciation and metabolites, as well as microbial community composition and activity were quantified over a 75-day aerobic incubation period. Alkyl ethoxylates (AEOs) were degraded faster than nonylphenol ethoxylates (NPEOs), and both compound classes and bulk organic carbon biodegraded slower in TDS treatments (10 g L-1, 40 g L-1) as compared to controls. Short-chain ethoxylates were more rapidly biodegraded than longer-chain ethoxylates, and changes in the relative abundance of metabolites including acetone, alcohols, and carboxylate and aldehyde intermediates of alkyl units indicated metabolic pathways may shift in the presence of higher produced water TDS. Our key finding that polyethoxylated alcohol surfactant additives are less labile at high TDS has important implications for produced water management, as these fluids are increasingly recycled for beneficial reuse in hydraulic fracturing fluids and other purposes. (C) 2019 Elsevier B.V. All rights reserved.