Crystallization Inhibitors and Their Remediation Potential on Brine‐Contaminated Soils

Abstract

Core Ideas Brine‐contaminated soils require remediation in many oil‐producing regions. A crystallization inhibitor induced harvestable salt efflorescence on contaminated soils. Crystallization inhibitors can be part of the remediation effort on brine‐contaminated soils. We hypothesize that a crystallization inhibitor will induce harvestable salt efflorescence on the surface of brine‐contaminated soils. If proven, the harvest of effloresced salts will provide a novel method for remediating brine spills. Our objectives were to evaluate salt efflorescence on brine‐contaminated soil columns as a function of (i) crystallization‐inhibitor concentration, (ii) application method, (iii) soil texture, (iv) subsequent harvesting, and (v) salt species. We conducted three laboratory incubations with 0.00001 to 0.01 M ferric hexacyanoferrate solutions applied to salt‐contaminated soil columns over 7 to 28 d. The 0.01 M solution successfully effloresced an average of 0.46, 0.57, and 0.29 g g−1 (i.e., grams of harvested salt at the soil surface per total grams of NaCl applied to the soil) on sandy loam, loam, and silty clay columns, respectively. However, negligible quantities of efflorescence occurred when applying the crystallization inhibitor (i) at concentrations <0.001 M, (ii) and subsequently mixing the soil, (iii) with NaCl solutions <0.6 M, (iv) and attempting to further induce salt efflorescence after a first harvesting, and (v) to soil with elevated levels of sulfate or calcium. This novel method for brine spill remediation shows great potential for remediating NaCl‐contaminated soils. Future research should include field evaluation on real brine spills to determine the efficacy of the new method in practice.

Produced water's impact on soil properties: Remediation challenges and opportunities

“…In laboratory experiments utilizing a surficial application of the crystallization inhibitor to NaCl‐contaminated sandy loam, loam, and silty clay soils, this method was found to reduce the mass of NaCl (34.75 g total) in the soil by 460, 570, and 290 g kg −1 (grams harvested salt at the soil surface per total grams of NaCl applied to the soil), respectively (Klaustermeier et al., 2017). In subsequent experiments, the authors found that the re‐application of the crystallization inhibitor following the initial harvest of salts produced little to no additional salt growth, indicating that this method may only be applicable for the partial remediation of brine‐impacted soils (Klaustermeier et al., 2017; Swallow & O'Sullivan, 2019). Furthermore, it was found that the effectiveness of the crystallization inhibitor was limited at low salt concentrations (<0.5 M NaCl) and produced little efflorescence when either soils were only dominated with SO 4 ‐based salts or when soil Ca levels where high enough to form Ca‐based crusts before NaCl hopper crystal growth could initiate (Klaustermeier et al., 2017).…”

“…In subsequent experiments, the authors found that the re‐application of the crystallization inhibitor following the initial harvest of salts produced little to no additional salt growth, indicating that this method may only be applicable for the partial remediation of brine‐impacted soils (Klaustermeier et al., 2017; Swallow & O'Sullivan, 2019). Furthermore, it was found that the effectiveness of the crystallization inhibitor was limited at low salt concentrations (<0.5 M NaCl) and produced little efflorescence when either soils were only dominated with SO 4 ‐based salts or when soil Ca levels where high enough to form Ca‐based crusts before NaCl hopper crystal growth could initiate (Klaustermeier et al., 2017). Irrespective of challenges, the potential use of these chemicals, especially on spills on well pads where soil removal may not be possible, deserves further exploration.…”

“…This characteristic process of dryland environments often limits the effectiveness of many conventional methods of in-situ remediation, such as leaching, and contributes to the high costs internalized by various stakeholders. To work with this process rather than against it, Daigh and Klaustermeier (2016) and Klaustermeier et al (2017) suggested the use of the crystallization inhibitor ferric hexacyanoferrate {Fe 4 [Fe(CN) 6 ] 3 } to induce hopper crystal growth of NaCl on the soil surface, which could then be harvested and permanently removed from the soil profile. Conceptually, this method would utilize the evaporative flux established at the soil surface following a brine spill and the capillary rise of soil water to accumulate salts in the upper portions of the soil profile, where the crystallization inhibitor would then induce the growth of NaCl hopper crystals.…”

Wicking Salts from Brine‐Contaminated Soils: A Potential Method for In Situ Remediation

“…In semiarid climates such as the Williston Basin, where annual evaporative demand is often four times that of annual precipitation, the potential for resalinization of the topsoil through upward capillary rise causes this method to be time‐intensive and costly while often achieving limited results (Harris et al, 2005). Given the limitations of traditional methods, novel forms of in situ remediation from the soil surface through the use of crystallization inhibitors and the capillary rise of water and dissolved salts have been presented in the literature with promising results (Klaustermeier et al, 2017; Swallow and O'Sullivan, 2019). The objective of this proof‐of‐concept study was to determine the efficacy of using highly absorbent “wicking” materials to draw water and dissolved salts from the soil profile as a means of permanent salt removal (Fig.…”

Geotextile covering: Potential technique for farmland salinization control

“…Previous research also reported applying certain chemical amendments. For example, several studies showed that soil amendment with ferrocyanide could be a potential option for removing salt from soil surface by efflorescing salt as soft, hollow hopper crystals (Daigh & Klaustermeier, 2016; Klaustermeier, Daigh, Limb, & Sedivec, 2017). However, applying this method would generate hypertoxic hydrocyanic acid.…”