Deoxygenation Prevents Arsenic Mobilization during Deepwell Injection into Sulfide-Bearing Aquifers
| Autor: | Lauren Helm, Bhasker Rathi, Ryan Morris, Jing Sun, Henning Prommer, Adam J. Siade |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Sulfide
Water injection (oil production) 0208 environmental biotechnology chemistry.chemical_element 02 engineering and technology Sulfides 010501 environmental sciences engineering.material 01 natural sciences Arsenic Water Purification chemistry.chemical_compound Groundwater pollution Environmental Chemistry Water pollution Groundwater Deoxygenation 0105 earth and related environmental sciences chemistry.chemical_classification General Chemistry Phosphate 020801 environmental engineering chemistry Environmental chemistry engineering Pyrite Water Pollutants Chemical |
| Zdroj: | Environmental Science & Technology. 52:13801-13810 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/acs.est.8b05015 |
| Popis: | Coal seam gas (CSG) extraction generates large volumes of coproduced water. Injection of the excess water into deep aquifers is often the most sustainable management option. However, such injection risks undesired sediment-water interactions that mobilize metal(loid)s in the receiving aquifer. This risk can be mitigated through pretreatment of the injectant. Here, we conducted a sequence of three push-pull tests (PPTs) where the injectant was pretreated using acid amendment and/or deoxygenation to identify the processes controlling the fate of metal(loid)s and to understand the treatment requirements for large-scale CSG water injection. The injection and recovery cycles were closely monitored, followed by analysis of the observations through reactive transport modeling. While arsenic was mobilized in all three PPTs, significantly lower arsenic concentrations were observed in the recovered water when the injectant was deoxygenated, regardless of pH adjustment. The breakthrough of arsenic was commensurate with molybdenum, but distinct from phosphate. This allowed for the observed and modeled arsenic and molybdenum mobilization to be attributed to a stoichiometric codissolution process during pyrite oxidation, whereas phosphate mobility was governed by sorption. Understanding the nature of these hydrochemical processes explained the greater efficiency of pretreatment by deoxygenation on minimizing metal(loid) mobilization compared to the acid amendment. |
| Databáze: | OpenAIRE |
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