Minding the Archipelago: What Svalbard Means to NATO

Although the opportunity, form and level of NATO’s High North engagement have long been a matter of debate, the renewed invasion of Ukraine by Russia and its strategic implications at the global level have dragged a reunified NATO into the Arctic as a fait accompli. Yet, the Arctic is not one uniform bloc. When pondering its involvement, the Alliance should consider the particulars of each Arctic territory in its area of responsibility. The Svalbard archipelago, under the sovereignty of Norway -the most vocal advocate of NATO’s High North increased presence- is one of the Arctic areas falling under NATO’s responsibility. Global geopolitical trends, combined with Svalbard’s specific points of contention, may exacerbate the risk of conflict affecting the archipelago. This paper argues that NATO should consider the security concerns specific to Svalbard when pondering its High North involvement and highlights two elements that should be factored in the Alliance’s strategic and operational thinking over the archipelago. The first relates to the diverging interpretations of Article 9 of the Svalbard Treaty while the second lies in Svalbard’s vulnerability to gray-zone tactics due to its particular legal and geographical features. Bearing these particulars in mind, the paper provides key recommendations for NATO to adopt a tailored approach to the archipelago

Influence de la matière organique et inorganiquede l'eau sur l'élimination des pesticides par nanofiltration

Ce travail explore les performances de deux types de membranes de nanofiltration (Desal DK et NF200) dans l'élimination dans les eaux de certains pesticides (l'atrazine et son métabolite la déséthylatrazine (DEA), la simazine, la cyanazine, l'isoproturon et le diuron) et évalue l'influence de la présence de matière organique ou inorganique dans la matrice d'eau sur l'efficacité de ce traitement.Des eaux synthétiques, composées à partir d'eau distillée à laquelle a été ajoutée de la matière organique (acides humiques) ou inorganique (CaCl2 ou CaSO4), ont été traitées sur un pilote de nanofiltration durant 96 heures. Les taux rétention en pesticides et ceux de leur adsorption sur les membranes ont été calculés et comparés aux résultats obtenus sur une matrice d'eau distillée pure. Une influence du type de membrane et de la présence de la matière humique sur le taux d'abattement de certains pesticides a été constatée. L'influence de la matière inorganique est pratiquement insignifiante.The intensive use of pesticides in agriculture has resulted in the contamination of groundwater and surface waters. The removal of these organic pollutants by the usual methods such as adsorption by activated carbon (in powdered or granular form) or oxidation by ozone have some disadvantages. Recently, the removal of organic pollutants by membrane retention (reverse osmosis, ultrafiltration and nanofiltration) has become increasingly popular and due to its low cost, nanofiltration has become an interesting option.This study examined the efficiency of two different nanofiltration membranes (Desal DK and NF200) in the removal of some pesticides (atrazine and its metabolite desethylatrazine (DEA), simazine, cyanazine, isoproturon and diuron) from water and, in addition, investigated the influence that organic and inorganic matter may have on the efficiency of this removal. Synthetic waters were made from distilled water and organic matter (humic acids) or inorganic matter (CaCl2 or CaSO4) was added, as well as 1 µg/l of each pesticide. The samples were then filtered by a nanofiltration pilot for 96 hours. Samples of the feed, permeate and the retentate were taken after 4, 24, 48, 72 and 96 h. The samples were replaced with equivalent volumes of the original solution in the feed tank. The different samples were analysed by an on-line SPE / HPLC system. The different concentrations obtained allowed the determination of the proportion of the pesticides that adsorbed to the membrane.The removal efficiency of pesticides from pure distilled water differed according to the membrane. For example, the Desal DK membrane eliminated more than 90% of all the pesticides (with the exception of diuron). In contrast, the NF200 membrane, eliminated more than 75% of all the pesticides (with the exception of diuron). The removal efficiency of Diuron was the lowest by both the membranes: 70 % by Desal DK and 45 % by NF200. The adsorption efficiency of the pesticides was similar for both membranes (between 30 and 40%). In pure water, pesticide removal is a function of both the specific properties of each pesticide (solubility, molecular mass, Stokes diameter, equivalent molar diameter, calculated equivalent diameter and polarity) and the physical characteristics of the membrane (molecular weight cut-off and current load).The influence of inorganic matter on pesticide removal efficiency changed according to the type of membrane. For example, we noted an improvement in removal efficiency with the NF200 membrane from low removal with CaCl2 to high removal with CaSO4 for all pesticides examined including diuron. In contrast, for the Desal DK membrane, very little change was noted (a slight decrease in the removal efficiency of DEA and simazine with CaCl2). Adsorption by the membranes remained stable for all the pesticides tested on the two types of membrane. The improvement in the removal of pesticides by the NF200 membrane was probably linked to pores being blocked by ions at high concentrations. It could be concluded from these results that elimination of pesticides is quantitatively linked to the physical characteristics of the membranes and that inorganic matter only has an effect with wide-pore membranes (NF200 membrane) and, furthermore, it has no influence on the adsorption of the pesticides on the membranes.For water containing organic matter, we have noted an improvement in the removal of certain pesticides with the NF200 membrane when compared to distilled water (except diuron). With the Desal DK membrane, we observed a slight decrease in the removal of DEA, simazine and isoproturon, and a substantial drop for diuron (20 %) with no change for cyanazine and atrazine. Adsorption of the pesticides on the membranes remained unchanged with the NF200 membrane but increased by about 10% on the Desal DK membrane for all molecules. Pesticides, notably triazines, adsorb easily on organic matter by physiosorption (weak links) and by chemisorption (ionic links) to form macromolecules. The steric congestion and the density of these pseudo-complexes is high, which facilitated the elimination of certain pesticides with the (wide-pore) NF200 membrane by accentuating the effects of steric exclusion and electrostsatic repulsion and decreasing adsorption. For the Desal DK membrane, the increased adsorption of the pesticides on the membrane generated a more significant transition of these molecules in the direction of the permeate. This had a negative influence on the removal of some pesticides, depending on their size; the largest molecules underwent the least change. Diuron behaved differently from the other pesticides examined. This molecule did not bind to humic acids and its removal rate did not change with a wide-pore (NF200) membrane. However a greater adsorption of organic matter by the narrower-pore (Desal DK) membrane favored diuron adsorption and, consequently, its diffusion into the permeate. The effect of organic matter and, more specifically, of humic acids on the elimination of pesticides depends not only on the structure of the molecules, but also on the cut-off threshold of the membrane.The two main mechanisms that govern the process of pesticide elimination by NF are repulsion (steric and electrostatic) by the membrane and adsorption on the membrane. This latter phenomenon must be minimized, to reduce the elimination of pesticides by fostering their transition in the direction of the permeate. In addition, removal of the pesticides by NF was favoured by the high-molecular weight organic matter fraction (i.e., humic acids). The influence of the inorganic matter (CaCl2 and CaSO4), for its part, is greater with the wide-pore membrane

Competitive adsorption of phenolic compounds from aqueous solution using sludge‐based activated carbon.

Preparation of activated carbon from sewage sludge is a promising approach to produce cheap and efficient adsorbent for pollutants removal as well as to dispose of sewage sludge. The first objective of this study was to investigate the physical and chemical properties (BET surface area, ash and elemental content, surface functional groups by Boehm titration and weight loss by thermogravimetric analysis) of the sludge‐based activated carbon (SBAC) so as to give a basic understanding of its structure and to compare to those of two commercial activated carbons, PICA S23 and F22. The second and main objective was to evaluate the performance of SBAC for single and competitive adsorption of four substituted phenols (p‐nitrophenol, p‐chlorophenol, p‐hydroxy benzoic acid and phenol) from their aqueous solutions. The results indicated that, despite moderate micropore and mesopore surface areas, SBAC had remarkable adsorption capacity for phenols, though less than PICA carbons. Uptake of the phenolic compound was found to be dependent on both the porosity and surface chemistry of the carbons. Furthermore, the electronegativity and the hydrophobicity of the adsorbate have significant influence on the adsorption capacity. The Langmuir and Freundlich models were used for the mathematical description of the adsorption equilibrium for single‐solute isotherms. Moreover, the Langmuir–Freundlich model gave satisfactory results for describing multicomponent system isotherms. The capacity of the studied activated carbons to adsorb phenols from a multi‐solute system was in the following order: p‐nitrophenol > p‐chlorophenol > PHBA > phenol

Stratégies d'élimination de l'azote d'un effluent urbain dans un réacteur discontinu séquentiel (SBR)

Le traitement des effluents urbains par réacteurs discontinus séquentiels (SBR : Sequencing Batch Reactor) constitue une solution alternative aux traitements par systèmes à boue activée en effectuant le traitement du carbone, la séparation liquide solide et l'élimination des nutriments au sein d'un bassin unique grâce à une gestion adéquate des cycles temporels de réaction. L'alternance de phases aérées et anoxiques suivie d'une période de décantation conduit en théorie à l'élimination quasi totale des ions nitrate formés lors de la phase de nitrification aérobie. Cependant, selon la charge appliquée, le carbone totalement dégradé lors de la phase préliminaire d'aération ne peut servir de source de carbone pour la dénitrification exogène.Afin d'accélérer la dénitrification, plusieurs solutions sont possibles : l'une consiste à allonger la deuxième phase d'anoxie suffisamment longtemps pour traiter les ions nitrate résiduels au cours d'un processus de dénitrification endogène, l'autre à diminuer le temps de réaction aérobie tout en augmentant la fréquence des séquences aérobie/anoxie afin de conserver du carbone résiduel lors de la dénitrification. Une troisième solution réside dans l'ajout d'une source de carbone exogène suite à l'étape de nitrification de manière à permettre une assimilation plus rapide et plus efficace des ions nitrate formés (dénitrification exogène).L'article compare les résultats d'abattement sur le carbone et l'azote d'une eau usée urbaine en utilisant les trois types de fonctionnement. Il en résulte la définition d'une stratégie globale de contrôle du procédé, chacun des scénarii pouvant être privilégié en fonction de la qualité de l'effluent de départ et des contraintes de traitement.Wastewater treatment by a Sequencing Batch Reactor (SBR) provides an alternative solution to activated sludge treatment, by carrying out carbon treatment, liquid-solid separation and nutrient removal in a single tank, thanks to the appropriate management of the temporal reaction cycles. Alternating the aeration and anoxic phases, followed by a decantation period, leads, in theory, to the almost total removal of nitrate ions formed during the aerobic nitrification phase. However, depending on the applied load, the carbon that is totally degraded during the preliminary aeration phase, cannot be used as a source of carbon for exogenic denitrification.Several solutions are possible in order to accelerate denitrification: one consists of lengthening sufficiently the second anoxic phase to treat the residual nitrate ions during the endogenous denitrification process; another strategy involves reducing the aerobic reaction time, while increasing the frequency of aerobic/anoxic sequences in order to preserve residual carbon during denitrification. A third solution lies in the addition of a source of exogenic carbon after the nitrification stage, to allow a quicker and more efficient assimilation of the nitrate ions that are formed (exogenic denitrification). This article compares the results of reducing carbon and nitrogen in wastewater, using three types of operation.The cycle of reference has been established starting from previous bibliographical results (WUN JERN and DROSTE, 1989) and simulations using the model ASM1 (HENZE et al., 1986). It consists of an anoxic feeding, followed by an anoxic phase, then an aerobic phase and another anoxic phase. The cycle ends by the settling and decanting phases. The lengths of these different phases are: 1 h, 0.5 h, 4.5 h, 3.25 h, 1 h, 1 h. This reference cycle, carried out at the laboratory, leads to the elimination of 90% of the Chemical Oxygen Demand (COD), 95% of the Biological Oxygen Demand (BOD5) and more than 80% of total nitrogen, i.e. with residual concentrations of 60 mg×L-1 for the Dissolved Organic Carbon (DOC), 5 mg×L-1 for the Biological Oxygen Demand, and 10 mg×L-1 for total nitrogen. These results are comparable with those in the literature (IRVINE et al., 1987, MELCER et al., 1987, YANG et al., 1999).The results obtained during the reference cycle enabled us to reach a rate of total nitrogen removal of 85% and a global nitrogen concentration in the effluent of 11 mg×L-1. Nitrification and denitrification rates yielded values of 0.8 mg N-NH4+×gMVS-1 ×h-1 and 0.8 mg N-NO3 -×gMVS-1×h-1 respectively. Total nitrogen removal was not completely achieved because of the lack of available carbon. This lack of carbon favours endogenic denitrification, characterized by a slow denitrification rate 0.8 mg N-NO3 -×mgMVS-1×h-1, compared to exogenic denitrification characterized by a higher nitrogen reduction rate (about 2 mg N-NO3 -×mgMVS-1 ×h-1). This fact was experimentally confirmed with carbon addition in the form of acetate at the beginning of the second anoxic phase. In this case, carbon addition significantly improves the denitrification rate compared to the same experiment without exogenic carbon addition: 2 mg N-NO3 -×mgMVS-1 ×h-1 versus 0.8 mg N-NO3 -×mgMVS-1 ×h-1. However, this method raises operating costs for the process.In order to reach complete nitrogen removal without the addition of synthetic carbon, it is possible to increase the anoxic phase time scale from 3 hours to 15 hours. Although the results in term of carbon and nitrogen removal are satisfactory when the anoxia phase is lengthened, the concentration in the discharged effluent is 0.33 mg total N×L-1, and thus this technique decreases the productivity of the SBR. The feeding cycles of a biological reactor being variable, a regulation based on the use of the evolution of the pH, or the redox potential, can be considered (PAVELJ et al., 2001; ANDREOTTOLA et al., 2001). This regulation would make it possible to adapt the duration of the phases of anoxia to the necessary treatment.To overcome this drawback, a possible approach consists in replacing the aerobic / anoxic phase in the reference cycle by five aerobic / anoxic phases during the same time. Unfortunately, this method leads to a decrease in nitrogen removal and in the nitrification rate, compared to classical cycle (65% versus 85%, and 0.4 mg N-NO3 - ×mgMVS-1 ×h-1 versus 0.8 mg N-NO3 -×mgMVS-1 ×h-1, respectively). The nitrification rate is, in this case, half that obtained in the reference cycle, probably due to delays related to the induction of nitrification and denitrification. This strategy, consisting of increasing the aeration / no aeration frequency, has to be optimized in term of nitrification and denitrification ratios.A better solution from the economic and productivity points of view is the addition of wastewater at the beginning of anoxic phase. This strategy implies the modification of the cycle. First, after the anoxic feeding, an aerobic phase allows carbon and nitrogen oxidation. In order to supply an available carbon source for exogenic denitrifcation, a second feeding is introduced at the beginning of the second anoxic phase. This addition also contains ammonium ions and implies new nitrification and denitrification steps. This last denitrification phase is then endogenic.Carbon addition in the form of wastewater leads to an improvement in nitrogen removal. The exogenic denitrification rate is twice the value for endogenous denitrification for the same cycle of operation (1.6 mg N-NO3 -×gMVS-1 ×h-1 versus 0.9 mg N-NO3 -×gMVS-1 ×h-1 respectively). This strategy yields a final concentration of 3 mg N×L-1 and the nitrification and denitrification rates are similar to those of the traditional processes.In conclusion, the addition of synthetic carbon in the form of acetate must be preserved as a means of acting quickly in the event of dysfunction (that can be detected by monitoring the redox potential or the pH), although this technique significantly increases the cost of operation. Although the best economic solution to improve denitrification is carbon addition in the form of wastewater, other strategies can be undertaken according to the goals of the treatment process. When the wastewater load is sufficiently weak (night period), the endogenous phase of denitrification can be lengthened. In the event of an important load, carbon addition (in synthetic form or as waste water) makes it possible to eliminate the nitrate ions exogenically

Static Sorption of Phenol and 4-Nitrophenol onto Composite Geomaterials based on Montmorillonite, Activated Carbon and Cement

International audienceThis paper studies the sorption of phenol and 4-nitrophenol (4NP) onto solid sorbents derived from mixtures of montmorillonite, activated carbon (AC) and cement, denoted herein MACC. These materials are mesoporous and some of their physicochemical properties have been measured and discussed. The weight fraction X1 (%) of montmorillonite in the mixtures strongly influences the sorbate removal rate. The sorption isotherms were experimentally established by batch testing on geomaterials with various X1 values at 20 °C and at different pH values (from 3 to 8). The Langmuir model correctly fits the sorption isotherm data (R2 > 0.95). The results show increased sorption behavior for both phenol and 4NP on the composite geomaterials compared to the pure components, yielding the order: MACC > AC > montmorillonite