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Sulfate reduction for remediation of gypsiferous soils and solid wastes / Application de la réduction biologique des sulfates pour le traitement des sols et déchets gypseuxKijjanapanich, Pimluck 18 November 2013 (has links)
Ce travail de thèse visait à développer des procédés d'élimination des sulfates permettant la réduction des teneurs en sulfates des DC et des sols gypsifères afin d'améliorer la qualité des déchets et des sols à des fins agricoles ou des applications de recyclage. Le concept de traitement des DC par lixiviation à l'eau a été étudié (colonne de lixiviation). Les sulfates contenus dans les lixiviats sont ensuite éliminés à l'aide d'un traitement chimique ou biologique. L'approche biologique mise en oeuvre dans ce travail a consisté à mettre en oeuvre la réduction biologique des sulfates au sein de bioréacteurs de conception différente (i.e. réacteur UASB, réacteur à lit fluidisé inverse (IFB) ou d'un réacteur anaérobie gas lift). L'efficacité d'élimination des sulfates la plus élevée atteinte par ces trois systèmes varie de 75 à 95%. L'eau traitée provenant du bioréacteur peut alors ensuite être réutilisé dans la colonne de lixiviation. Le traitement chimique des sulfates est une option alternative pour traiter les lixiviats. Plusieurs produits chimiques ont été testés, (chlorure de baryum, nitrate de plomb (II), le chlorure de calcium, le carbonate de calcium, l'oxyde de calcium, et du sable recouvert d'un mélange d'oxydes d'aluminium et de fer). Un rendement de 99,9% d'élimination des sulfates (par précipitation) a été atteint avec le chlorure de baryum et le nitrate de plomb (II).Pour le traitement des DMA et des sols gypseux, cinq types de substrat organique tel que les copeaux de bambou, les boues d'épuration des eaux usées municipales, de l'écorce de riz, de coques de noix de coco broyée et des boues d'épuration des eaux usées d'une ferme porcine ont été testés comme donneurs d'électrons pour la réduction biologique des sulfates. L'efficacité de la réduction des sulfates la plus élevé (84%) a été obtenue en utilisant un mélange d'écorce de riz, de coques de noix de coco broyée et des boues d'épuration des eaux usées d'une ferme porcine comme donneurs d'électrons. Ensuite, ce mélange organique a été utilisé pour le traitement des sols gypsifères. Le sol de la mine de gypse a été mélangé avec le mélange organique en différentes proportions (10, 20, 30 et 40% de sol). Le rendement le plus élevé de 59 % de réduction des sulfates a été atteint dans le mélange de sol qui contient 40 % de matière organique. L'élimination des sulfures présents dans l'effluent des procédés de réduction biologique des sulfates est nécessaire. En effet, les sulfures peuvent causer plusieurs impacts environnementaux ou être ré-oxydé en sulfate si ils sont directement rejetés dans l'environnement. Le traitement électrochimique des effluents est l'une des solutions alternatives pour la récupération du soufre élémentaire à partir des sulfures. Une électrode de graphite a été testée comme électrode permettant l'oxydation électrochimique des sulfures en soufre élémentaire. Une électrode en graphite de grande surface est nécessaire afin d'avoir une résistance électrique la plus faible possible. La vitesse d'oxydation des sulfures la plus élevée est atteinte lors de l'application d'une résistance de 30 Ω à une concentration en sulfure de 250 mg.L-1 / Solid wastes containing sulfate, such as construction and demolition debris (CDD), are an important source of pollution, which can create a lot of environmental problems. It is suggested that these wastes have to be separated from other wastes, especially organic waste, and place it in a specific area of the landfill. This results in the rapid rise of the disposal costs of these gypsum wastes. Although these wastes can be reused as soil amendment or to make building materials, a concern has been raised by regulators regarding the chemical characteristics of the material and the potential risks to human health and the environment due to CDD containing heavy metals and a high sulfate content. Soils containing gypsum, namely gypsiferous soils, also have several problems during agricultural development such as low water retention capacity, shallow depth to a hardpan and vertical crusting. In some mining areas, gypsiferous soil problems occur, coupled with acid mine drainage (AMD) problems which cause a significant environmental threat. Reduction of the sulfate content of these wastes and soils is an option to overcome the above mentioned problems. This study aimed to develop sulfate removal systems to reduce the sulfate content of CDD and gypsiferous soils in order to decrease the amount of solid wastes as well as to improve the quality of wastes and soils for recycling purposes or agricultural applications. The treatment concept leaches the gypsum contained in the CDD by water in a leaching step. The sulfate containing leachate is further treated in biotic or abiotic systems. Biological sulfate reduction systems used in this research were the Upflow Anaerobic Sludge Blanket (UASB) reactor, Inverse Fluidized Bed (IFB) Reactor and Gas Lift Anaerobic Membrane Bioreactor (GL-AnMBR). The highest sulfate removal efficiency achieved from these three systems ranges from 75 to 95%. The treated water from the bioreactor can then be reused in the leaching column. Chemical sulfate removal (abiotic system) is an alternative option to treat the CDD leachate. Several chemicals were tested including barium chloride, lead(II) nitrate, calcium chloride, calcium carbonate, calcium oxide, aluminium oxide and iron oxide coated sand. A sulfate removal efficiency of 99.9% was achieved with barium chloride and lead(II) nitrate.For AMD and gypsiferous soils treatment, five types of organic substrate including bamboo chips (BC), municipal wastewater treatment sludge (MWTS), rice husk (RH), coconut husk chip (CHC) and pig farm wastewater treatment sludge (PWTS) were tested as electron donors for biological sulfate reduction treating AMD. The highest sulfate reduction efficiency (84%) was achieved when using the combination of PWTS, RH and CHC as electron donors. Then, this organic mixture was further used for treatment of the gypsiferous soils. The gypsum mine soil (overburden) was mixed with an organic mixture in different amounts including 10, 20, 30 and 40% of soil. The highest sulfate removal efficiency of 59% was achieved in the soil mixture which contained 40% organic material.The removal of sulfide from the effluent of the biological sulfate reduction process is required as sulfide can cause several environmental impacts or be re-oxidized to sulfate if directly discharged to the environment. Electrochemical treatment is one of the alternatives for sulfur recovery from aqueous sulfide. A non-catalyzed graphite electrode was tested as electrode for the electrochemical sulfide oxidation. A high surface area of the graphite electrode is required in order to have less internal resistance as much as possible. The highest sulfide oxidation rate was achieved when using the external resistance at 30 Ω at a sulfide concentration of 250 mg L-1
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Sulfate reduction for remediation of gypsiferous soils and solid wastesKijjanapanich, Pimluck 18 November 2013 (has links) (PDF)
Solid wastes containing sulfate, such as construction and demolition debris (CDD), are an important source of pollution, which can create a lot of environmental problems. It is suggested that these wastes have to be separated from other wastes, especially organic waste, and place it in a specific area of the landfill. This results in the rapid rise of the disposal costs of these gypsum wastes. Although these wastes can be reused as soil amendment or to make building materials, a concern has been raised by regulators regarding the chemical characteristics of the material and the potential risks to human health and the environment due to CDD containing heavy metals and a high sulfate content. Soils containing gypsum, namely gypsiferous soils, also have several problems during agricultural development such as low water retention capacity, shallow depth to a hardpan and vertical crusting. In some mining areas, gypsiferous soil problems occur, coupled with acid mine drainage (AMD) problems which cause a significant environmental threat. Reduction of the sulfate content of these wastes and soils is an option to overcome the above mentioned problems. This study aimed to develop sulfate removal systems to reduce the sulfate content of CDD and gypsiferous soils in order to decrease the amount of solid wastes as well as to improve the quality of wastes and soils for recycling purposes or agricultural applications. The treatment concept leaches the gypsum contained in the CDD by water in a leaching step. The sulfate containing leachate is further treated in biotic or abiotic systems. Biological sulfate reduction systems used in this research were the Upflow Anaerobic Sludge Blanket (UASB) reactor, Inverse Fluidized Bed (IFB) Reactor and Gas Lift Anaerobic Membrane Bioreactor (GL-AnMBR). The highest sulfate removal efficiency achieved from these three systems ranges from 75 to 95%. The treated water from the bioreactor can then be reused in the leaching column. Chemical sulfate removal (abiotic system) is an alternative option to treat the CDD leachate. Several chemicals were tested including barium chloride, lead(II) nitrate, calcium chloride, calcium carbonate, calcium oxide, aluminium oxide and iron oxide coated sand. A sulfate removal efficiency of 99.9% was achieved with barium chloride and lead(II) nitrate.For AMD and gypsiferous soils treatment, five types of organic substrate including bamboo chips (BC), municipal wastewater treatment sludge (MWTS), rice husk (RH), coconut husk chip (CHC) and pig farm wastewater treatment sludge (PWTS) were tested as electron donors for biological sulfate reduction treating AMD. The highest sulfate reduction efficiency (84%) was achieved when using the combination of PWTS, RH and CHC as electron donors. Then, this organic mixture was further used for treatment of the gypsiferous soils. The gypsum mine soil (overburden) was mixed with an organic mixture in different amounts including 10, 20, 30 and 40% of soil. The highest sulfate removal efficiency of 59% was achieved in the soil mixture which contained 40% organic material.The removal of sulfide from the effluent of the biological sulfate reduction process is required as sulfide can cause several environmental impacts or be re-oxidized to sulfate if directly discharged to the environment. Electrochemical treatment is one of the alternatives for sulfur recovery from aqueous sulfide. A non-catalyzed graphite electrode was tested as electrode for the electrochemical sulfide oxidation. A high surface area of the graphite electrode is required in order to have less internal resistance as much as possible. The highest sulfide oxidation rate was achieved when using the external resistance at 30 Ω at a sulfide concentration of 250 mg L-1
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