Preferential flow channels with low hydraulic resistance in a single fracture can transmit large fluid volumes in fractured rock. Characterizing these channels and the associated flow channeling at the field scale, however, remains challenging. In this study, a hybrid iterative computational workflow was used to generate a field-scale (30 m diameter) synthetic fracture with self-affine surfaces and a high-resolution (2 mm spatial resolution) aperture field. We investigate the effects of anisotropic surface roughness, shearing displacement, and closure ratio on flow channeling in a radial flow system using advective Lagrangian particle tracking and advection-dispersion numerical simulations. Results show a transition from local microscale channeling effects to a homogenous flow pattern at the field-scale within rough-walled fractures. The transition is enhanced by the increasing microscale channels which occur via surface roughness anisotropy. Surface shearing displacement and anisotropic surface roughness control the fracture closure area and principal orientations, aligning with the tortuosity and direction of preferential flow pathways. The solute peak arrival times in synthetic fractures are similar to those in smooth fractures with an equivalent Cubic Law aperture. This demonstrates the applicability of the Cubic Law aperture in predicting bulk arrival times, even in the presence of flow channeling within sheared synthetic fractures. The strong flow channeling behavior observed in some field studies is therefore likely related to local geological conditions (stress included) and post-fracturing processes, underscoring the need to integrate initial fracturing and subsequent weathering history obtained using rock sample properties and outcrop analysis when investigating channeling effects.

The development of a conceptual site model for a site impacted by dense non-aqueous phase liquid (DNAPL) requires DNAPL source zone characterization. This characterization remains a challenge, and under- and overestimates of DNAPL footprint and mass are common. This study employed the results of a previous virtual site investigation to develop effective practice approaches (methods, strategies, or techniques that have been demonstrated through evidence or experience to yield positive results or outcomes that align with specific, pre-determined goals) for estimating DNAPL footprint and mass, referred to as the Bounding Box and Bulk Retention approaches, respectively. The accuracy and precision of those estimates were assessed using a stochastic approach applied to the virtual sites and evaluated against those by experienced practitioners. Results showed that the accuracy of the DNAPL footprint and mass estimates did not depend strongly on the borehole density, but that the precision of those estimates increased with increasing borehole density. This increase was more pronounced for DNAPL mass than for footprint (i.e., mass estimates were more precise than footprint estimates at the same borehole density), which suggests prioritizing DNAPL source zone delineation during site investigation. When estimates based on grid or random borehole locations were compared to estimates by an expert practitioner, expert judgment was beneficial at low borehole densities but resulted in similar estimates at higher densities, provided that effective practice was used. Estimates based on random borehole locations often outperformed those based on experienced judgment without effective practice, which highlights the importance of data analysis over borehole location for characterizing DNAPL source zones.

Low temperature thermal treatment (LTTT) is a technology that can enhance aqueous-phase degradation reactions for organic constituents in groundwater. Understanding heat transfer in groundwater is important for the design of LTTT applications. In this study, the effect of permeability heterogeneity on temperature distributions during and after the application of heat was investigated by numerical modeling. An enhanced reaction zone was determined for the hydrolysis of 1,1,1-trichloroethane (1,1,1-TCA) using an average half-life considering the temperature history during and after heating. For hydrolysis reactions, the average half-life could be reduced substantially by reaching a high temperature for a short period of time because their reaction rates increase exponentially with increased temperatures. Results showed that the enhanced reaction zone was shifted downstream of the heater well zone at high groundwater velocities. This suggests that heaters should be shifted upstream of the target treatment zone to fully utilize the applied heat. In addition, permeability heterogeneity leads to greater macroscopic dispersion at higher velocities. This resulted in higher spreading of heat and faster heat dissipation in the simulations with a heterogeneous permeability condition compared with a homogenous permeability condition. As a result, the enhanced reaction zone was smaller in simulations with higher levels of permeability heterogeneity at a mean velocity of 0.3 m/day.

Horizontal ball mills (HBMs) have been proven capable of remediating per- and polyfluoroalkyl substances (PFAS) in soil. Industrial-sized HBMs, which could easily be transported to impacted locations for on-site, ex-situ remediation, are readily available. This study examined PFAS degradation using an industrial-scale, 267 L cylinder HBM. This is the typical scale used in the industry before field application. Near-complete destruction of 6:2 fluorotelomer sulfonate (6:2 FTS), as well as the non-target PFAS in a modern fluorotelomer-based aqueous film forming foam (AFFF), was achieved when spiked onto nepheline syenite sand (NSS) and using potassium hydroxide (KOH) as a co-milling reagent. Perfluorooctanesulfonate (PFOS) showed much better and more consistent results with scale-up regardless of KOH. Perfluorooctanoate (PFOA) was examined for the first time using a HBM and behaved similarly to PFOS. Highly challenging field soils from a former firefighting training area (FFTA) were purposefully used to test the limits of the HBM. To quantify the effectiveness, free fluoride analysis was used; changes between unmilled and milled soil were measured up to 7.8 mg/kg, which is the equivalent of 12 mg/kg PFOS. Notably, this does not factor in insoluble fluoride complexes that may form in milled soils, so the actual amount of PFAS destroyed may be higher. Soil health, evaluated through the assessment of key microbial and associated plant health parameters, was not significantly affected as a result of milling, although it was characterized as poor to begin with. Leachability reached 100 % in milled soil with KOH, but already ranged from 81 to 96 % in unmilled soil. A limited assessment of the hazards associated with the inhalation of PFAS-impacted dust from ball-milling, as well as the cross-contamination potential to the environment, showed that the risk was low in both cases; however, precautions should always be taken.

<p>Per- and polyfluoroalkyl substances (PFAS) are a diverse group of manmade, fluorinated organic chemicals that gained notoriety for their diverse application, widespread distribution in the environment and toxicity. One of the main sources of PFAS to the environment is through aqueous film forming foam (AFFF), intended for use on fuel fires. AFFF may enter the environment through system testing, training activities, emergency use or accidental release. When AFFF enters the environment PFAS readily adsorb to porous media through hydrophobic and electrostatic interactions. As a result, PFAS impacted porous media may act as a long-term source of contamination to groundwater, potentially influencing water resources and human health. There is a demand for effective treatment of PFAS impacted porous media. Ball milling has emerged as a potential treatment option for PFAS, however, the viability of treating AFFF impacted porous media has been seldom explored. In this work four AFFF formulations were amended onto silica sand and milled without and with the use of potassium hydroxide (KOH) as a co-milling reagent. Six hour milling trials were conducted using a planetary ball mill with stainless steel grinding media. Significant destruction of perfluorosulfonic acids, perfluorocarboxylic acids (PFCAs), fluorotelomer sulfonates, fluorotelomer betaines and fluorotelomer sulfonamido betaines was observed. With the use of KOH as a co-milling reagent the total PFAS destruction percentage in all four AFFFs exceeded 90%. Greater destruction of PFAS was observed in fluorotelomer dominant AFFFs when compared to perfluoroalkyl acid dominant AFFFs. PFCAs and soluble fluoride were identified as destruction byproducts. KOH as a co-milling reagent had the effect of reducing PFCA byproduct formation and increasing fluoride recovery in three of four AFFFs. Fluoride recoveries indicate PFAS molecule defluorination occurs by ball milling. When PFAS in AFFF is compared to PFAS destruction in single analyte trials, less destruction is observed, displaying the necessity of evaluating realistic AFFF contamination events over single or multi analyte mixtures.</p>

The characterization and evaluation of heat dissipation effects in fractured rock is becoming a priority topic with respect to the potential application of low-temperature thermal remediation in these settings. A threedimensional numerical model was utilized to investigate heat dissipation-related thermo-hydrological processes in an upper fractured rock layer and a lower impermeable bedrock layer. To identify the factors controlling spatial temperature variances in the fractured rock layer accounting for a scaled heat source and variable groundwater flow, global sensitivity analyses were conducted on the variables using three categories: heat source, groundwater flow, and rock properties. A discrete Latin-hypercube-one-at-a-time method was used to conduct the analyses. A heat dissipation coefficient was proposed to evaluate the correlation between heat dissipation effects and transmissivity based on a case study using the hydrogeological setting of a wellcharacterized Canadian field site. The results show a significance ranking of three sets of variables controlling heat dissipation processes in both the central and the bottom areas of the heating zone: specifically, heat source > groundwater > rock. The groundwater influx and heat conduction in the rock matrix are key factors determining heat dissipation at the upstream and bottom areas of the heating zone, respectively. The heat dissipation coefficient is closely associated with the transmissivity of the fractured rock in a monotonic relationship. A significant growth rate of the heat dissipation coefficient appears when the transmissivity is between 1 x 10-6 and 2 x 10- 5 m2/s. The results suggest that the low-temperature thermal remediation can be a promising technique to adapt the significant heat dissipation in highly weathered fractured rock.

Thermal conductive heating (TCH) is an in-situ thermal treatment (ISTT) technology for treating non-aqueous phase liquid (NAPL) source zones. Numerical models can be useful tools for improving remedial performance, but traditional multiphase flow models are rarely used to simulate mass recovery during ISTT applications at the field scale due to their computational expense. This study developed a 3D model based on macroscopic invasion percolation to simulate the vaporization of NAPL, and the subsequent vapor migration and potential conden-sation at the field scale. The model was used to simulate the mass recovery of trichloroethene (TCE) from a NAPL source zone under seven scenarios of different heater placements, including three scenarios with an undersized target treatment zone (TTZ). Simulation results showed that TCH was effective in removing NAPL within the TTZ, but the treatment zone did not extend far from the perimeter heaters. In addition, during heating, NAPL condensation outside the TTZ due to the escaping vapor was observed in all scenarios. Overall, the resulting mass recovery was lower in the three scenarios with an undersized TTZ (91-95%) than in the other four scenarios (approximate to 99%). Moreover, the locations of unrecovered/condensed NAPL could be inferred by monitoring mass recovery tailing at individual extraction wells.

Ball milling has emerged as a promising destructive technique for treating per- and polyfluoroalkyl substances (PFAS)-impacted soils. Environmental media properties such as reactive species generated upon ball milling and particle size are postulated to influence the effectiveness of the technology. In this study, four media types amended with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were planetary ball milled to investigate destruction, fluoride recovery without additional co-milling reagents and the relationship between PFOA and PFOS destruction, particle size during milling, and electron generation. Silica sand, nepheline syenite sand, calcite and marble were sieved to achieve similar initial particle sizes (6/35 distribution), amended with PFOA and PFOS, and milled for 4 h. Particle size analysis was conducted throughout milling and 2,2-diphenyl-1-picrylhydrazyl (DPPH•) was used as a radical scavenger to assess electron generation from the four media types. Particle size reduction was observed to be positively correlated to PFOA and PFOS destruction and DPPH• neutralization (demonstrating electron generation by milling) in silica sand and nepheline syenite sand. Milling of a fine fraction (< 500 μm) of silica sand revealed less destruction compared to the 6/35 distribution suggesting the ability to fracture grains in silicate media is integral to PFOA and PFOS destruction. DPPH• neutralization was demonstrated in all four amended media types, confirming silicate sands and calcium carbonates generate electrons as a reactive species during ball milling. Fluoride loss as a function of milling time was observed in all amended media types. A sodium fluoride (NaF) spiked was used to quantify fluoride loss in the media independent of PFAS. A method was developed using the NaF-amended media fluoride concentrations to estimate the total fluorine liberated from PFOA and PFOS by ball milling. Estimates produced suggest complete recovery of theoretical fluorine yield is obtained. Data from this study was used to propose a reductive destruction mechanism for PFOA and PFOS.

The development of a conceptual site model (CSM) is essential to support decision making for the investigation and remediation of contaminated sites, including sites impacted by dense nonaqueous phase liquids (DNAPLs). Dynamic investigation strategies using high-resolution site investigation tools can be used to increase the accuracy, and increase the precision (reduce the uncertainty) of a CSM, while balancing life-cycle costs. However, the evaluation of CSM accuracy is limited by the hydrogeological and biogeochemical complexities inherent in subsurface systems. This study simulated DNAPL migration, dissolution, and reactive transport to create three high-resolution "virtual sites" composed of 0.4-1 billion parameter values each, which were investigated by teams of leading practitioners. Use of these virtual sites allowed key hydrogeological and biogeochemical parameters to be known by the model developers but not the investigation teams. Comparison of the CSMs developed by these practitioners to the simulated values across multiple metrics (e.g., dissolved concentrations, DNAPL mass, and mass discharge) showed that 92% of those metrics were estimated within a factor of 10 and 63% were within a factor of 3 of the true (simulated) values. Furthermore, estimates of dissolved phase plume footprint were often more accurate than estimates of DNAPL source footprint, and the approaches used for investigation and data analysis were both important for CSM development. Overall, none of the site investigation approaches used to develop the CSMs resulted in the highest accuracy for all metrics, which demonstrates the need to establish best-practices that draw from multiple approaches and vary depending on investigation objectives.

In many situations, fluids other than groundwater such as non‑aqueous phase liquids (NAPLs) are present in the subsurface, many of which are hazardous industrial chemicals. NAPLs include liquids lighter than water (LNAPLs)—for example, gasoline and diesel fuel—and liquids denser than water (DNAPLs)—including chlorinated solvents and coal tar. This book is an introduction to the fundamentals of NAPL flow in porous media, and presents properties and concepts that dictate how NAPLs are distributed in porous media, including the importance of interfacial tension, wettability, and capillary pressure. Further, the authors describe the relationships among capillary pressure, relative permeability, and fluid saturation, and include more detailed discussions of LNAPL and DNAPL distribution. This book provides the reader with a foundation for understanding conceptual and numerical models of groundwater contamination as well as strategies for the investigation and remediation of NAPL‑affected sites.

In this study, we have compared heat and solute transport in a discrete fracture using numerical modeling. Fracture aperture heterogeneity was described using geostatistical properties with fracture aperture means of up to 1000 mu m, variances of 10,000 mu m(2) and isotropic correlation lengths up to 10 m. Groundwater flow in the matrix was assumed to be negligible and flow in the fracture was set to values typical for natural groundwater conditions with velocities less than 100 m/day and associated hydraulic gradients of less than 0.05. A uniform isotropic thermal conductivity of 2 W/m ? was set for the matrix. Based on 50 realizations, three-dimensional and two-dimensional conduction in the matrix and in the fracture, respectively, play an important role in controlling the development and the shape of the thermal plume under natural flow conditions. In contrast, solute transport exhibits limited penetration depth in the matrix. The results of this research indicate that, contrary to solute transport in discrete fracture settings where channeling is sometimes a major contributor to solute migration rates, no significant thermal channeling is observed under natural groundwater flow conditions. The use of tracer experiments or the monitoring of solute transport in fractured rock will not therefore provide a reliable prediction of the migration of heat in the same setting.

There is a need for destructive technologies for per- and polyfluoroalkyl substances (PFAS) in soil. While planetary ball mill have been shown successful degradation of PFAS, there are issues surrounding scale up (maximum size is typically 0.5 L cylinders). While having lower energy outputs, horizontal ball mills, for which scale up is not a limiting factor, already exist at commercial/industrial sizes from the mining, metallurgic and agricultural industries, which could be re-purposed. This study evaluated the effectiveness of horizontal ball mills in degrading perfluorooctanesulfonate (PFOS), 6:2 fluorotelomer sulfonate (6:2 FTSA), and aqueous film forming foam (AFFF) spiked on nepheline syenite sand. Horizontal ball milling was also applied to two different soil types (sand dominant and clay dominant) collected from a firefighting training area (FFTA). Liquid chromatography tandem mass spectrometry was used to track 21 target PFAS throughout the milling process. High-resolution accurate mass spectrometry was also used to identify the presence and degradation of 19 non-target fluorotelomer substances, including 6:2 fluorotelomer sulfonamido betaine (FtSaB), 7:3 fluorotelomer betaine (FtB), and 6:2 fluorotelomer thioether amido sulfonate (FtTAoS). In the presence of potassium hydroxide (KOH), used as a co-milling reagent, PFOS, 6:2 FTSA, and the non-target fluorotelomer substances in the AFFF were found to undergo upwards of 81%, 97%, and 100% degradation, respectively. Despite the inherent added complexity associated with field soils, better PFAS degradation was observed on the FFTA soils over the spiked NSS, and more specifically, on the FFTA clay over the FFTA sand. These results held through scale-up, going from the 1 L to the 25 L cylinders. The results of this study support further scale-up in preparation for on-site pilot tests.

Thermal conductive heating is an in-situ groundwater remediation technique that can be implemented in weathered or fractured rock. However, the characterization and identification of heat transfer in fractured rock is challenging because of complex hydrogeological and thermodynamic processes, particularly for irregular heat source configurations. As an effective practice, sensitivity analysis has been widely used to screen, rank, and quantify the influential factors in complex systems. In this study, a three-dimensional numerical model was applied to investigate, using global and local sensitivity analyses, the significance of six input factors that influence the heating of fractured rock. The factors include the radius and energy delivery strength of the heat source (which were used to study the scale effect and heating processes), the fracture aperture, fracture spacing, groundwater velocity, and the thermal conductivity of the rock matrix. A discrete Latin Hypercube-One at A Time (LH-OAT) approach is proposed and utilized as an experimental design and data analysis method for the discrete input factors that apply to this study. We also used Machine Learning techniques to enhance the robustness of simulation results with a significant reduction of computational cost. The results show that at all locations within the heating area, the radius of the source and energy delivery strength are the most influential input factors. The scale effect associated with the radius of the heat source is significant for the rock matrix temperature. The groundwater flow related factors jointly determine the temperature variation in the upstream areas. The contribution of the thermal conductivity of the rock matrix to heat dissipation is nearly isotropic in the heating area. A nonlinear trending of sensitivity indices is observed for all factors in the input space. Based on these results, the discrete LH-OAT approach has been demonstrated to efficiently identify influential factors within a discrete input value space. The use of a two-way OAT perturbation approach is suggested to avoid potential errors caused by the one-way perturbation method for parameter ranking.

In recent decades, numerous analytical solutions have been developed to quantify temperature perturbations in fractured rock having mobile and immobile fluid phases. The assumption of one-dimensional heat conduction in the matrix, or neglecting heat dispersion and storage in fractures, however, are typical simplifications adopted to overcome the difficulties in mathematically representing the problem. In this study, we propose a two-dimensional semi-analytical solution framework based on Green's function approach for a flexible heat source definition, including source dimensions, energy delivery strength and duration, and the presence of a heat source in the matrix and/or fracture. The solution fully accounts for heat conduction, advection, dispersion, and transient heat exchange between the fracture fluid and rock matrix in a system of parallel fractures. The solution having a strip heat source extending from a fracture into the matrix indicates that one-dimensional heat conduction in the matrix underestimates and overestimates temperature responses at early and later times, respectively. Additionally, the temperature peak arrival time is also substantially delayed by simplification. The fracture temperature grows slower near the heat source area as the fracture aperture increases. The fracture temperature growth is enhanced via the overlapped heating areas between the parallel fractures. The transient temperature analyses imply that the spatial temperature variation is strongly associated with heat delivery strength. The early time temperature variances are closely related to the heat source configurations, and the later time temperatures in the domain are mainly determined by the total energy being delivered into the domain.

The removal of dissolved volatile organic compounds (VOCs) from low-permeability lenses is important to limit back diffusion at sites impacted by dense non-aqueous phase liquids (DNAPLs). In situ thermal treatment (ISTT) technologies have the potential to treat DNAPL-impacted sites by enhancing diffusion from low-permeability lenses during heating. A series of two-dimensional laboratory tank experiments was conducted to investigate heating, gas formation, and trichloroethene (TCE) removal from a clay lens surrounded by sand. Results showed preferential heating of the clay and substantial TCE removal, with post-heating relative concentrations less than 0.06. The extent of TCE removal was not explained by only an increase in the aqueous TCE diffusion coefficient with increased temperature. Modelling estimates based on 1D diffusion from the lens showed that diffusion through both gas and water phases was required to match observations. Gas formation in the interior of the lens was also indicated by measured changes in bulk electrical conductivity of the clay during cool down, with gas saturations estimated to be greater than 0.21 at the end of heating. These estimates were larger than those needed to match the observed removal by diffusion, and suggest that connected gas pathways were created in the lens during heating, but that not all of the gas produced was part of those pathways. These results suggest that ISTT technologies may be effective in removing dissolved VOCs from thin clay lenses, and that gas formation within the clay should be considered when predicting the extent and rate of removal.

In situ thermal treatment (ISTT) technologies can be used to remove mass from non-aqueous phase liquid (NAPL) source zones. Ensuring the vaporization of NAPL and the capture of vapors are crucial, and numerical models are useful for understanding the processes that affect performance to help improve design and operation. In this paper, a two-dimensional model that combines a continuum approach based on finite difference for heat transfer with a macroscopic invasion percolation (macro-IP) approach for gas migration was developed to simulate thermal conductive heating (TCH) applications at the field-scale. This approach simulates heat transport and gas migration, but is different than a traditional continuum multiphase approach. Mass recovery for 60 randomly generated realizations under three degrees of heterogeneity of the permeability field were simulated. The mass recovery curves had an overall similar shape for the various permeability fields. However, a wider range of completion times was observed for domains with a higher permeability variance. Results also showed that NAPL pools that were highly saturated, deep, and away from the heaters needed more heating time to be depleted, and that total NAPL mass was not a good indicator of completion time. The completion time was positively correlated with the maximum value of the mixed spatial moment of NAPL saturation about the heaters in the lateral and vertical direction, and the NAPL pool with the highest moment could increase the heating time by as much as 35%. This effect was most notable in simulations with a high permeability variance and suggests the potential to reduce heating time by locating the largest NAPL pools and placing TCH heaters accordingly.

Per- and polyfluoroalkyl substances (PFAS) are manmade, fluorinated organic chemicals which have been identified as persistent organic pollutants. PFAS have surface active properties that have made them suitable for applications in oil- and water-resistant products, as well as many firefighting foams. No on-site remediation strategies exist to treat PFAS impacted soils. Mechanochemical remediation of PFOS- and PFOA-amended sand via a planetary ball mill was studied. The effect of sand mass, KOH as a co-milling reagent, and water saturation on the degradation of PFOA and PFOS was evaluated. By 4 h of milling concentrations were reduced by up to 98% for PFOS-amended dry sand and 99% for PFOA-amended dry sand without the addition of a co-milling reagent. Water saturation was determined to be a significant hindrance on the mechanochemical destruction of PFOS and PFOA. A maximum of 89% of fluoride was recovered from PFOS-amended sand when KOH was used as a co-milling reagent. It is hypothesized that reactive particles generated from the fracture of sand grains react with PFAS molecules to initiate destruction, which can result in full defluorination. Milling experiments were also conducted on soils from a Canadian firefighting training area (FFTA), demonstrating that PFOS concentrations can be reduced by up to 96% in site soils. For the first time, ball milling for the remediation of PFAS in environmental media has been demonstrated using amended sand and legacy soils from a FFTA.

Treatability tests can be carried out to assess the potential effectiveness of thermal treatment technologies under different site conditions and are important for specific technology selection and design. In order to reduce the costs for laboratory tests and expand the insights from previous treatability studies, a one-dimensional (1D) radial finite difference model was developed to simulate the removal of volatile organic compounds (VOCs) in laboratory thermal treatability tests. The processes considered in the model include heat conduction, co-boiling of single-component or multi-component NAPLs with water, and water boiling. An explicit approach is used to simulate the evolution of NAPL composition for multi-component NAPLs during heating. The developed model adopts only two fitting parameters and was calibrated and validated using previous laboratory experiments. In this paper, the developed model was first calibrated to three laboratory experiments using temperature measurements, which resulted in matches to the NAPL and gas saturations. After calibration, the model was able to predict the temperature, NAPL and gas saturations for the remaining seven experiments, including those with single and multi-component NAPLs, using the average value of each fitting parameter.

In situ thermal treatment (ISTT) technologies have been applied at sites impacted by non-aqueous phase liquids (NAPLs). There is a need to establish expectations for the treatment of semi-volatile NAPLs, including those consisting primarily of polycyclic aromatic hydrocarbons (PAHs), and the potential benefits and limitations of partial NAPL removal. A series of laboratory experiments was conducted to investigate NAPL removal and soil concentrations during the heating of creosote-impacted sand, as well as aqueous concentrations during post heating dissolution. The results showed co-boiling near the water boiling temperature due to the low volatility of most creosote components, with limited decreases in NAPL saturation (from 30% to 21% of the pore space). Decreases in soil concentration were more substantial than decreases in NAPL saturation (by a factor of 2-180), with greater removal for higher-volatility components at higher treatment temperatures. Results of the dissolution experiments showed mixed results, with decreases in the aqueous concentrations for 12 of 15 components, but increases in aqueous concentrations for phenanthrene, fluoranthene and pyrene after heating to 205 degrees C or 320 degrees C. Overall, the results illustrate the utility of bench-scale treatability tests in helping to establish ISTT goals and expectations.