Approaching Brine Spill Remediation from the Surface: A New In Situ Method

Abstract

Core Ideas In situ remediation of brine spills is possible via surface extraction of salts. A crystallization inhibitor allowed for 29 to 57% of salts to be harvested from the soil surface. Methods for surface extraction of salts can aid in expediting brine spill remediation timelines. Well drilling for energy resources innately produces brine waters. These brines often contain sodium in the 10,000 to >100,000 mg L−1 range. In situ soil remediation of brine spills traditionally consists of diluting salts with organic materials and then infiltrating divalent cations. This leaching technique can require years to centuries, as a function of soil clay content, to remove salts from the root zone. We present a new in situ remediation method that extracts salts from the soil surface and expedites remediation. Surface application of a crystallization inhibitor (ferric hexacyanoferrate) to brine‐contaminated soils followed by an evaporative flux resulted in dendritic crystal growth above the soil surface. This process allowed easy harvest of 29 to 57% of salts within 7 d without mechanical disturbance to the soil. Future studies should include loading‐rate optimization, in‐field testing, evaluation of reaction product fate and transport, and identification of other amendments to rapidly extract salts.

Crystallization Inhibitors and Their Remediation Potential on Brine‐Contaminated Soils

“…Additionally, other crystallization inhibitors with low toxicity reaction products may produce similar salt extraction rates. Therefore, hexacyanoferrate is used here only as an example of a crystallization inhibitor for remediating brine spills (Daigh and Klaustermeier, 2016).…”

“…To optimize crystallization inhibitor loading rate and application method for various soil textures, five concentrations of crystallization inhibitor (control, 0.00001, 0.0001, 0.001, and 0.01 M) in the mineral form were applied to NaCl‐contaminated soils (i.e., the sandy loam, loam, and silty clay) using the T1, T2, and T3 methods of application. The 0.01 M concentration applied with the T3 method was reported by Daigh and Klaustermeier (2016) as preliminary data; this data is presented here for comparison with the other experimental treatments. In the T1 and T2 application methods, the mixed NaCl, crystallization inhibitor, and NH 3 solution applied to the soil columns consisted of 34.75 g of NaCl, the crystallization inhibitor at a corresponding molar concentration in 110 mL of DI water, and 20 mL of a 0.01 g g −1 ammonium hydroxide solution.…”

“…The crystallization inhibitor used in this study was hexacyanoferrate in the mineral form of ferric hexacyanoferrate (Fe 4 [Fe (CN) 6 ] 3 ), commonly known as Prussian Blue. This mineral form requires a solvating agent to dissociate to the reaction product hexacyanoferrate (Daigh and Klaustermeier, 2016; Meeussen et al, 1992; Sharpe, 1976). The mineral form was applied as 0.00001, 0.0001, 0.001, or 0.01 M suspensions corresponding to experiment and treatment.…”

“…The mineral form was applied as 0.00001, 0.0001, 0.001, or 0.01 M suspensions corresponding to experiment and treatment. Ammonium hydroxide solutions (0.01 g g −1 ) were added to each suspension to solvate the crystallization inhibitor into 4Fe 3+ and 3[Fe(CN) 6 ] 4− complexes and stimulate the soft, hollow hopper salt crystal efflorescence (Daigh and Klaustermeier, 2016; Fernelius and Johnson, 1928). Application methods included the following: T1, surface application (i.e., flooding with subsequent infiltration) of a mixed NaCl, crystallization inhibitor, and NH 3 solution; T2, surface application (i.e., flooding) of a mixed NaCl, crystallization inhibitor, and NH 3 solution that was then mechanically incorporated and homogenized into the soil; and T3, surface application (i.e., flooding with subsequent infiltration) of a mixed crystallization inhibitor and NH 3 solution to soil previously contaminated with the NaCl solution where the salts had crystallized forming a cemented crust.…”

“…In a recent brief publication, we presented preliminary evidence of harvestable, noncrusted NaCl efflorescence from the surface of brine‐contaminated soil columns amended with the crystallization inhibitor ferric hexacyanoferrate {Fe 4 [Fe (CN) 6 ] 3 } (Daigh and Klaustermeier, 2016). Previous research evaluated crystallization inhibitors for reducing salt damage to bricks and stones associated with important landmarks across the world (Gupta et al, 2012; Rivas et al, 2010; Lubelli and van Hees, 2007; Rodriguez‐Navarro et al, 2002; Selwitz and Doehne, 2002).…”