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Introduction: Bacillus anthracis, the etiological agent of anthrax, produces long-lived spores, which are resistant to heat, cold, pH, desiccation, and chemical agents. The spores maintain their ability to produce viable bacteria even after decades, and when inhaled can cause fatal disease in over half of the clinical cases. Owing to these characteristics, anthrax has been repeatedly selected for both bioweapon and bioterrorism use. In the event of a bioterrorism attack, surfaces in the vicinity of the attack will be contaminated, and recovering from such an event requires rapid and effective decontamination. Previous decontamination method development has focused mainly on temperatures >0°C, and have shown poor efficacy at subzero temperatures. Methods: In this study, we demonstrate the use of calcium chloride (CaCl(2)) as a freezing point depression agent for pH-adjusted sodium hypochlorite (NaOCl) for the effective and rapid decontamination of B. anthracis Sterne strain spores at subzero temperatures. Results: We show the complete decontamination of 10(6) B. anthracis Sterne strain spores at temperatures as low as −20°C within 2.5 min by submersion in solution containing 25% (w/v) CaCl(2), 0.50% NaOCl, and 0.40% (v/v) acetic acid. We also demonstrate significant reduction in number of spores at −28°C. Conclusions: The results show promise for rapidly decontaminating equipment and materials used in the response to bioterrorism events using readily available consumer chemicals. Future study should examine the efficacy of these results on complex surfaces.

Water chemistry and its impact on mineral processing operations are not well understood and often not adequately monitored. CanmetMINING, as part of its water management research program, has been involved in a project initiated to identify opportunities for improving water recovery, water treatment, and recycling in the mining and mineral processing operations. One of the main objectives of this work is to evaluate and assess water chemistry and identify factors that impact mineral recovery, concentrate grade, and metal extraction efficiencies in order to understand and mitigate negative impacts of water recycling and improve process efficiency. In collaboration with a North American concentrator, CanmetMINING has been involved in assessing the water chemistry in the mill and evaluating water recycling options for select process streams to reduce fresh water intake and maximize recycling. The overall goal of the project is to investigate options for water recycling (increase the thickener overflow recirculation from thickener overflow tank) without affecting nickel and copper metallurgy. The results of the sampling campaigns showed that the water chemistry of the streams was fairly consistent throughout the year with no significant seasonal variations. The laboratory tests illustrated that when higher quantities of thickener overflow from thickener overflow were used, the nickel + copper grade versus nickel recovery curves shifted towards lower values. These observations were observed for the plant water samples obtained in April, June and August 2019.

Effective decontamination of large-scale areas such as roads and parking lots after an accidental or intentional radiological incident is important in order to contain the spread of contamination and avoid the need for long-term evacuation of urban areas. As a simulation, large coupons (surface area 3600 cm2) made of concrete patio stone and aged asphalt (from a parking lot) were contaminated with either 60Co or 137Cs solutions and then decontaminated. The decontamination process consisted of a six-component water-based chemical formulation applied using a common house-hold carpet cleaner. Tests were carried out to compare the effectiveness of decontamination using deionized water (simulating rain fall) and chemical formulation. Test results showed that rain fall prior to decontamination lowered the effectiveness of a subsequent decontamination regardless of the surface type or radionuclide. Tests were also carried out to determine if the decontamination effectiveness increased with multiple applications. Using multiple applications of the chemical formulation, the removal of 60Co from concrete patio stone and aged asphalt were 65 ± 2% and 70 ± 3%, respectively, while the removal of 137Cs was 53 ± 3% from asphalt surfaces and 21 ± 8% from concrete patio stone. This paper summarizes the work carried out to prepare for the tests, presents the test results and compares the process to several other processes in terms of effectiveness and suitability for application on a large scale.

Steam assisted gravity drainage (SAGD) is an energy and water intensive oil recovery technology for in-situ extraction of oil sands bitumen. It is essential to recycle the SAGD produced water (PW) to reduce water consumption and improve the energy efficiency of the process. This work investigated the removal of residual organic matter (ROM) in the SAGD-PW by the ceramic nanofiltration (NF) membrane process. The overall removal efficiency of ROM in the SAGD-PW was influenced by their polarities, membrane pore size, and membrane material. Non-polar oil components including saturated and aromatic hydrocarbons were completely removed; meanwhile, approximately 80% of polar components were removed by the membrane nanofiltration. Membrane nanofiltration significantly altered the chemical composition of the SAGD-PW by removing 95.0–98.3% of total solvent extracted material (TSEM). The chemical fingerprints of the solvent extracted materials in the feed and permeate samples were characterized. The profile of polar components such as naphthenic acids (NAs) in the permeate samples is significantly different from that in the feed samples.

Due to environmental reasons and water shortage, concentrators have to increase water recirculation in the plant. The water originates from different sources, and depending on their origins, the water chemistry varies from stream to stream. Water chemistry has many significant impacts on flotation, beneficial or non-beneficial. Flotation tests have been conducted using process water (originates from tailings treatment facilities and is clean water that can be released to the environment) and thickener tank overflow water obtained from a North American concentrator. The concentrator would like to increase the recirculation of the thickener tank overflow water and reduce process water consumption. In this work, the flotation results between process water (PW) and thickener tank overflow water recirculated at various degrees were compared. Reverse osmosis (RO) at different degrees of recirculation (0%, 20%, 40%, 60% and 80% RO) was used to simulate water thickener tank overflow water recirculation. The results showed that higher pyrrhotite recoveries were obtained when thickener tank overflow water recirculated (0%, 20%, 40%, 60%, and 80% RO) was used compared to that obtained with process water. However, the pyrrhotite recovery did not increase between 0% and 20%, 40%, 60% and 80% RO. Relative to the process water, the higher pyrrhotite recovery using thickener tank overflow water at various degrees of recirculation did not appear to have been caused by a higher relative proportion of activating species on grain surfaces. Most likely, the higher pyrrhotite recovery in the thickener tank overflow water (0%, 20%, 40%, 60%, and 80% RO) relative to that of process water was due to higher bubble surface area flux (smaller air bubbles) caused by the higher total dissolved solids (TDS) relative to that of process water. Non-sulphide gangue (Ga) recovery was similar for all tests and was mainly due to water entrainment. The nickel and copper recoveries increased at 60% and 80% RO relative to that of process water, probably due to the higher bubble surface area flux generated by the higher total dissolved solids (TDS) in the recycled thickener tank overflow water. Pentlandite (nickel-bearing mineral) grains from the 80% RO and process water samples showed similar proportions of gangue species (e.g. calcium and magnesium) on their surfaces. However, nickel and iron oxide species were slightly higher on pentlandite from the 80% RO sample relative to the process water. The marginally higher amount of hydrophilic oxidative species on pentlandite from the 80% RO could perhaps account in part for the difference in flotation kinetics observed between the samples.

The total oxidizable precursor (TOP) assay can be useful for integrating precursors to perfluoroalkyl acids (pre-PFAAs) into the assessment of sites contaminated by per- and polyfluoroalkyl substances (PFAS). Current research gaps include risks of instrumental matrix effects due to the complexity of post-oxidation extracts, potential reproducibility issues during TOP itself, and limited information for zwitterionic and cationic pre-PFAAs. We first investigated a suitable method for the analysis of groundwater samples, using liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS). Initial sample pre-treatment through filtration could affect the dissolved PFAS concentrations and was therefore avoided. Amending the postoxidation samples with methanol allowed for improved precision and low instrumental matrix effects. We also documented the oxidation yields of 23 anionic, neutral, zwitterionic, and cationic precursor compounds of PFAAs. These precursor compounds were amenable to TOP conversion. The total oxidative yield of 6:2 fluorotelomer sulfonamidoalkyl betaine (6:2 FTAB), for instance, was 80 mol%, with C3-C5 PFCAs as major oxidation products (minor: C6-C7 PFCAs). The method was applied to determine a wide range of PFAS (n = 41) without oxidation as well as ΔPFCA via persulfate oxidation in AFFF-impacted groundwater samples from fire-equipment testing sites in Ontario and Newfoundland, Canada. Summed PFAS concentrations as high as 5 mg L−1 were reported before oxidation, and post-oxidation increases of PFCAs up to + 2300% were observed. A significant contribution of increases in individual PFCAs was attributed to precursors such as 6:2 FTAB, fluorotelomer sulfonates (6:2 FtS, 8:2 FtS), perfluorooctane sulfonamidoalkyl amine (PFOSAm), and perfluorohexane sulfonamide (FHxSA) at the active firefighting training site.

The world of per- and polyfluoroalkyl substances (PFAS) is full of many useful and unique industrial and consumer products. Groundwater treatment for contaminated soil leachate is generally a reactionary measure that has been proven effective for preventing PFAS release to sources of drinking water. P. J. Lasier studied the transfer of PFAS from soil to an aquatic worm, Lumbriculus variegatus, and calculated bioaccumulation factors. The two main paths of PFAS entry into soil are industrial waste sites and the application of aqueous film-forming foams at military bases, airports, and municipal firefighting training areas. All remediation of PFAS methods can be divided into two categories: destructive and nondestructive. Destructive methods involve chemical transformations of PFAS leading to a change in their toxicological characteristics. The plan also included excavation of all soils on site that exceeded the Minnesota industrial soil reference values for perfluorooctanesulfonate and perfluorooctanoic acid, followed by backfilling of the site with uncontaminated soil.

This paper summarizes the results of the decontamination of the infrastructure materials concrete, limestone, brick and asphalt contaminated with 60Co, 85Sr, 137Cs and 241Am. The paper focuses on the effect of differences in substrate properties and of the pH of the radionuclide solution used for surface contamination on adsorption or ion exchange of the radionuclides and how these factors affect the decontamination effectiveness. A six-component chemical formulation was used and a process effectiveness of up to 76% was obtained depending on the substrate and radionuclide. Asphalt was the easiest material to decontaminate because of its more hydrophobic nature. Concrete and limestone (and to some extent brick) were less effectively decontaminated as their porous surfaces allowed penetration of radionuclides into water-filled pores in the substrate facilitating adsorption or ion exchange and making them difficult to remove. Brick was the most difficult material to decontaminate because the major component of brick is clay which retains most mono- and divalent ions. The removal of 60Co, 85Sr and 137Cs from the surfaces of concrete, limestone and brick increased when the pH of the radionuclide solutions was moderately acidic to neutral compared to when they were highly acidic. The variability in the test results was similar to that observed in other studies using other decontamination methods, attributed to the inhomogeneity of the substrates used and considered representative of real infrastructure materials.

Perfluorinated compounds (PFCs) are emerging environmental pollutants. Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are the two primary PFC contaminants that are widely found in water, particularly in groundwater. This study compared the adsorption behaviors of PFOS and PFOA on several commercially available adsorbents in water. The tested adsorbents include granular activated carbon (GAC: Filtrasorb 400), powdered activated carbon, multi-walled carbon nanotube (MCN), double-walled carbon nanotube, anion-exchange resin (AER: IRA67), non-ion-exchange polymer, alumina, and silica. The study demonstrated that adsorption is an effective technique for the removal of PFOS/PFOA from aqueous solutions. The kinetic tests showed that the adsorption onto AER reaches equilibrium rapidly (2 h), while it takes approximately 4 and 24 h to reach equilibrium for MCN and GAC, respectively. In terms of adsorption capacity, AER and GAC were identified as the most effective adsorbents to remove PFOS/PFOA from water. Furthermore, MCN, AER, and GAC proved to have high PFOS/PFOA removal efficiencies (≥98%). AER (IRA67) and GAC (Filtrasorb 400) were thus identified as the most promising adsorbents for treating PFOS/PFOA-contaminated groundwater at mg L−1 level based on their equilibrium times, adsorption capacities, removal efficiencies, and associated costs.

Sensitive equipment materials were decontaminated from organophosphorus compounds paraoxon or parathion by immersion into a catalytic reactive solution and by spraying with the same solution. Immersion of contaminated material samples into methanol-based catalytic solutions resulted in an effective decontamination. Greater than 99% decontamination was observed for paraoxon on high-impact polystyrene (HI-PS) over 15 min of reaction time. Under the same process conditions, the decontamination from parathion did not exceed 95%. The catalytic decompositions of paraoxon and parathion followed first-order reaction kinetics with rate constants of 5.4 × 10–3 and 1.3 × 10–3 s–1, respectively. These values were by an order of a magnitude lower than the respective rate constants reported for homogeneous reactions in a methanol solution. Decontamination by spraying the catalyst on the contaminated surface revealed that multiple applications would be required to overcome a rapid evaporation of methanol from the surfac...

Decontamination of sensitive equipment materials contaminated by organophosphorus (OP) compounds by a two-stage process was evaluated. The process involved extraction of OP from contaminated materials with methanol (first stage), followed by decomposition of OP by heterogeneous catalytic methanolysis (second stage). In a series of tests diazinon, malathion, paraoxon, parathion, and other organophosphorus pesticides were spiked onto sensitive equipment materials and extracted with methanol after a presented contact time. After extraction, the lowest quantity of residue was found for diazinon, while parathion was the most persistent. High-impact polystyrene (HI-PS) retained 10-fold or more mass of OP than other tested materials. The surface of the HI-PS was deteriorated after contacting with OP due to a plasticizing effect. A longer contact time with HI-PS and lower polarity factor of OP resulted in higher residual amounts of OP after extraction. In the second stage of the process, diazinon and paraoxon wer...

The paper focuses on the evaluation of membrane filtration for the treatment of liquid radioactive streams generated in area decontamination operations. In this work, semi-permeable membranes were demonstrated to be effective reducing the volume of wastewater containing cesium and cobalt by two orders of a magnitude. The efficiency of membrane separation was enhanced by employing additives that enlarged the size of target radionuclide species and improved their rejection by the membranes. This was achieved by chelation with synthetic water-soluble polymers and by adsorption on micro particles of adsorbent coupled with micelle formation. The effect of wastewater composition and that of the radionuclide-binding additives on the volume reduction was investigated. Membrane treatment is expected to help simplify further processing and decrease disposal costs.

The applications of separation techniques using ultrafiltration in connection with functional soluble polymers for the removal of environmentally relevant and toxic substances from waters are reviewed. The types of interactions of the soluble polymers with low molecular mass compounds, the criteria for selecting the appropriate polymeric agents, and the binding conditions are discussed. Several factors influencing the separation of the target substances such as membrane type, solution composition, synergism, polymer adsorption, deformation of macromolecules, and hydrodynamics are evaluated and highlighted. Chemical, electrochemical, and thermal regeneration aspects are also covered. Finally, an overview on varius preparative and analytical application examples is presented.

A hybrid membrane separation technique was investigated for the selective removal of metals from ground waters. This two-step process included the addition of a water-soluble polymer to bind the metals which was followed by microfiltration. This method was used for the extraction of hazardous components of ground water and for reduction of hardness. The influence of several process parameters on the efficiency of the membrane separation was studied. This paper describes results of the experiments carried out on a bench-scale level.

A series of experiments were performed to quantify the adsorption of cesium on ceiling tiles as a representative of urban construction materials. Adsorption was carried out from solutions to mimic wet environmental conditions. Non-radioactive cesium chloride was used as a surrogate of the radioactive 137Cs. The experiments were performed in the range of initial cesium concentrations of 0.114–23.9 mg L−1 at room temperature (21 °C) around three weeks. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The quantity of adsorbed Cs was calculated by mass balance as a function of time. Two kinetic and three equilibrium models were employed to interpret the test results. Determination of kinetic parameters for adsorption was carried out using the first-order reaction model and the intra-particle diffusion model. Adsorption equilibrium was studied using Langmuir, Freundlich and three-parameter Langmuir–Freundlich adsorption isotherm models. A satisfactory correlation between the experimental and the predicted values was observed.

A hybrid method incorporating selective polymeric binding and membrane separation was used for the removal of arsenic from contaminated groundwater. Two types of polymers, polyethylenimine (PEI) and poly-diallyl dimethyl ammonium chloride (DADMAC) and an ultrafiltration membrane were used at various concentrations and pH. Bench-scale tests demonstrated a high degree of arsenic removal. The retention of arsenic was also determined in the presence of various background salts such as NaCl, NaNO3, Na2SO4, Na2CO3. Retention was found to depend on the concentration and type of anion present in solution.

Commercial sodium lignosulphonate, a by–product of sulphite pulp leaching, was evaluated for the remediation of soil and water contaminated with hexavalent chromium. Two series of bench–scale tests were performed: (a) removal of chromium from water using reagent binding and membrane separation; and (b) stabilisation of chromium in the soil using chemical soil flushing. Water treatment tests were performed in a batch mode in stirred ultrafiltration cells. The test results revealed that lignosulphonates can bind hexavalent chromium and facilitate its removal from water when used in conjunction with ex–situ water treatment (membrane filtration). Soil treatment tests carried out in a column revealed that lignosulphonates reduced chromium mobility and helped stabilise it within the soil matrix. These tests showed that lignosulphonate fixation can be used to stabilise chromium in soil with in–situ treatment (soil flushing).

The release of the organochlorine pesticide lindane (γ-hexachlorocyclohexane) from several types of contaminated building materials was studied to assess inhalation hazard and decontamination requirements in response to accidental and/or intentional spills. The materials included glass, polypropylene carpet, latex-painted drywall, ceramic tiles, vinyl floor tiles, and gypsum ceiling tiles. For each surface concentration, an equilibrium concentration was determined in the vapour phase of the surrounding air. Vapor concentrations depended upon initial surface concentration, temperature, and type of building material. A time-weighted average (TWA) concentration in the air was used to quantify the health risk associated with the inhalation of lindane vapors. Transformation products of lindane, namely α-hexachlorocyclohexane and pentachlorocyclohexene, were detected in the vapour phase at both temperatures and for all of the test materials. Their formation was greater on glass and ceramic tiles, compared to other building materials. An empiric Sips isotherm model was employed to approximate experimental results and to estimate the release of lindane and its transformation products. This helped determine the extent of decontamination required to reduce the surface concentrations of lindane to the levels corresponding to vapor concentrations below TWA.