No description available.

Polychlorinated Biphenyls (PCBs) are hazardous and toxic chemicals to both humans and animals. In the late 1960’s PCBs were discovered to be a harmful pollutant which could cause environmental contamination due to its slow degradation and even trace amounts of PCBs were regarded as toxic to both human and animals. Oil spills are a frequent occurrence at Eskom substations which could contain PCBs. The contaminated sediments which are easily carried away by rain and wind can further contaminate the environment and aquatic bodies. Eskom currently disposes of soil and ballast stones contaminated with PCBs by thermal destruction. This is a costly process as PCBs are regarded as hazardous materials and needs to be safely transported and disposed of at a licensed disposal facility. Based on literature, ozone has been used on a laboratory scale to treat soil contaminated with PCBs with the addition of chemicals such as hexane and acetone which assist in breaking down PCBs. The objective of this study was to evaluate whether ozone without the addition of chemicals could reduce the levels of PCBs present in contaminated soil. In this study, two soil samples and one ballast stone sample were contaminated with 50 ppm, 200 ppm and 600 ppm of PCBs and then exposed to 0.4, 0.5 and 0.6 l/min of ozone for a period of 60 minutes to examine the effects of increasing ozone flow rates on PCB destruction in soil. The results of the experimental tests showed that ozone gas reduced the concentration of PCBs in the soil and ballast stone samples for the different total gas flow rates. The literature study identified that the final products of the ozonation of PCBs are carbon dioxide and water and that any products formed after this process could possibly be degraded by the soil natural microorganisms. Calculations based on the Shin et al. (2004) model proved that ozone was in excess after the ozonation process. The results of the experiments also confirmed this, as the PCB residuals were similar for all three total gas flows, which showed that there was no dependence on the gas flow rates hence, ozone was in excess. The experimental data was then trended with zero, first and second order reaction equations, which showed that the best fit was obtained with the firstorder reaction equation. It is recommended that ozone be used for the treatment of PCB contaminated soil at Eskom substations. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.

The relocation of Chongqing Iron and Steel Company (CIS) in 2011 resulted in its old site’s demolition in 2012. As one of the largest post-industrial sites in Chongqing, it faces many future challenges. Framed by an existing redevelopment plan, this practicum proposes a design that responds to the current site conditions and lays groundwork for its future. The design capitalizes on the existing attributes of the site to create a variety of experiences. It employs phytotehcnologies to remediate contaminated soil and also offers opportunities for research, education and recreation. Personal experiences and reflections on China’s post-industrial regeneration are also discussed. / October 2016

As atividades industriais e de mineração, juntamente com o uso inadequado de fertilizantes e pesticidas, tem contribuído para o aumento da contaminação do solo, cursos d\'água e lençol freático por elementos tóxicos. A procura pelo desenvolvimento de soluções tecnológicas tem aumentado para atender à legislação ambiental. Segundo a ABETRE, no Brasil, apenas 22% dos 2,9 milhões de toneladas de resíduos industriais perigosos produzidos nas últimas décadas recebem tratamento adequado, sendo os 78% restantes colocados indevidamente em lixões sem tratamento prévio. Vários métodos de remediação de solos contaminados são conhecidos, entre eles estão o isolamento, imobilização, redução da toxicidade, separação física e extração. Neste contexto, destaca-se a vermicompostagem que utiliza as minhocas para degradar a matéria orgânica recente, tonando-a um material quimicamente mais estabilizado, além de remover os elementos tóxicos do solo acumulando-os em seu organismo. Dentre outros benefícios dessa técnica, destacam-se a manutenção da fertilidade do solo e a grande aceitação pública por ser uma tecnologia verde. Este trabalho tem como objetivo determinar a relação entre as concentrações de elementos tóxicos (Cr, Cu e Pb) com o vermicomposto. É avaliada a adição do material adsorvente aos solos com o intuito de conhecer a capacidade de retenção deste material para posterior descontaminação de solos contaminados. Propriedades químicas, como: pH, teor de matéria orgânica, capacidade de troca catiônica, carbono orgânico total, e físicas: umidade e granulometria são estudadas. Conclui-se com este trabalho que o vermicomposto mostrou-se um excelente material adsorvente para as espécies metálicas estudadas, sendo a ordem de adsorção Pb2+ < Cu2+ < Cr3+. / Industrial and mining activities, as well as the inappropriate use of fertilizers and pesticides, have been contributing to the increase of the contamination of soils, watercourses and water tables by toxic elements. The search for the development of technological solutions has grown to comply with the environment legislation. According to ABETRE, only 22% of 2.9 million of tones of dangerous industrial residues, produced in Brazil, received an appropriate treatment in recent decades. The remaining 78% are thrown in dumps without previous treatment. Many methods of contaminated soil remediation are known, among them isolation, immobilization, toxicity reduction, physical separation and extraction. In this context, it stands out vermicomposting that uses worms to degrade the recent organic matter, which becomes a more chemically stabilized material, and this practice also removes accumulated toxic elements from soil. Among others benefits of this practice there are soil fertility maintenance and the acceptance of people as it is a green technology. This work aims at determining the relation between the concentration of toxic elements (Cr, Cu e Pb) and the vermicompost. The addition of the adsorptive material to soil is assessed by determining the retention capacity of this material for a later decontamination of soils. Both chemical (pH, organic matter content, cationic change capacity and total organic carbon) and physical properties (humidity and granulometry) have been studied. In this study, it was concluded that vermicompost proved to be an excellent adsorbent material to the studied metallic species, and the adsorption order was Pb2+ < Cu2+ < Cr3+.

No description available.

As atividades industriais e de mineração, juntamente com o uso inadequado de fertilizantes e pesticidas, tem contribuído para o aumento da contaminação do solo, cursos d\'água e lençol freático por elementos tóxicos. A procura pelo desenvolvimento de soluções tecnológicas tem aumentado para atender à legislação ambiental. Segundo a ABETRE, no Brasil, apenas 22% dos 2,9 milhões de toneladas de resíduos industriais perigosos produzidos nas últimas décadas recebem tratamento adequado, sendo os 78% restantes colocados indevidamente em lixões sem tratamento prévio. Vários métodos de remediação de solos contaminados são conhecidos, entre eles estão o isolamento, imobilização, redução da toxicidade, separação física e extração. Neste contexto, destaca-se a vermicompostagem que utiliza as minhocas para degradar a matéria orgânica recente, tonando-a um material quimicamente mais estabilizado, além de remover os elementos tóxicos do solo acumulando-os em seu organismo. Dentre outros benefícios dessa técnica, destacam-se a manutenção da fertilidade do solo e a grande aceitação pública por ser uma tecnologia verde. Este trabalho tem como objetivo determinar a relação entre as concentrações de elementos tóxicos (Cr, Cu e Pb) com o vermicomposto. É avaliada a adição do material adsorvente aos solos com o intuito de conhecer a capacidade de retenção deste material para posterior descontaminação de solos contaminados. Propriedades químicas, como: pH, teor de matéria orgânica, capacidade de troca catiônica, carbono orgânico total, e físicas: umidade e granulometria são estudadas. Conclui-se com este trabalho que o vermicomposto mostrou-se um excelente material adsorvente para as espécies metálicas estudadas, sendo a ordem de adsorção Pb2+ < Cu2+ < Cr3+. / Industrial and mining activities, as well as the inappropriate use of fertilizers and pesticides, have been contributing to the increase of the contamination of soils, watercourses and water tables by toxic elements. The search for the development of technological solutions has grown to comply with the environment legislation. According to ABETRE, only 22% of 2.9 million of tones of dangerous industrial residues, produced in Brazil, received an appropriate treatment in recent decades. The remaining 78% are thrown in dumps without previous treatment. Many methods of contaminated soil remediation are known, among them isolation, immobilization, toxicity reduction, physical separation and extraction. In this context, it stands out vermicomposting that uses worms to degrade the recent organic matter, which becomes a more chemically stabilized material, and this practice also removes accumulated toxic elements from soil. Among others benefits of this practice there are soil fertility maintenance and the acceptance of people as it is a green technology. This work aims at determining the relation between the concentration of toxic elements (Cr, Cu e Pb) and the vermicompost. The addition of the adsorptive material to soil is assessed by determining the retention capacity of this material for a later decontamination of soils. Both chemical (pH, organic matter content, cationic change capacity and total organic carbon) and physical properties (humidity and granulometry) have been studied. In this study, it was concluded that vermicompost proved to be an excellent adsorbent material to the studied metallic species, and the adsorption order was Pb2+ < Cu2+ < Cr3+.

No description available.

Succinic acid, a low molecular weight dicarboxylic acid was used to leach out heavy metals from Willamette Valley soil (contaminated separately with lead, copper, and zinc) in form of water-soluble organo-metal complexes. The research tasks included developing synthetic contaminated soils representative of those found at Superfund sites and making heavy metal adsorption and desorption studies. Fixed amounts of single-metal contaminated soil were treated with succinic acid under varying conditions of pH and organic ligand concentration. Based on the total metal mobilized into the aqueous phase, the optimum values of pH and organic acid were established for each metal. Since the direct determination of all species solubilized by the organic acid solution was not possible, a computer speciation program called MICROQL was used to determine the concentration of metal species in solution containing several metals and potential ligands. The results indicate that succinic acid is capable of significantly altering the partitioning of metals between the soil and the aqueous phase. Higher concentrations of the organic acid resulted in higher removal of metal from the soil. In case of lead and copper, low pH (3.5) succinic acid flushing solution was found to be the most effective, while a pH range of 4.5-5.5 was deemed optimum for zinc. The results also established that the extent of removal of any metal depended not only upon the the stability constant of the organo-metal complex, but also on its mode of retention within the soil. / Graduation date: 1993

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 292-310). Available also in a digital version from Dissertation Abstracts.

Weak organic acids and/or their salts were tested as soil washing or flushing agents for the ex- or in-situ remediation of soils polluted by heavy metals. Three soils naturally with heavy metals were used for the tea. / The three soils were characterized as a clay loam, loam and sandy clay loam. Their organic matter, pH, saturated hydraulic conductivity, cation exchange capacity, particle density and heavy metal contents were also characterized. The different retention forms of heavy metals in all 3 soils were studied by sequential extraction. The clay loam was contaminated with Cr, Hg, Mn and Pb while the loam and sandy clay loam were contaminated with Cd, Pb, Cu and Zn. Weak organic adds and/or their salts and chelating agents (EDTA and DTPA) were used at different pH, levels of concentration and leaching time in batch experiments to establish optimum conditions for maximum removal of heavy metals from the three soils. Citrate and tartarate were found to be quite effective, in leaching heavy metals from these soils. The rate of leaching of heavy metals from soils with citrate, tartarate and EDTA was modeled using two-reaction model at a constant pH and temperature. / Three contaminated soils of different textures were flushed in a column at optimum pH with a salt of weak organic acids, namely, citrate, tartarate, citrate+oxalate or a chelating agent such as EDTA and DTPA. The citrate and tartarate (ammonium salts) were found to be quite effective in removing heavy metals from the three contaminated soils while leaching little macronutrients and improving the soil's structure. An in-situ soil remediation simulation was also successfully tested using the sandy clay loam at large scale level in a tub (plastic container) using citrate as a flushing liquid. EDTA and DTPA were effective in removing the heavy metals except for Hg, but these strong chelating agents extracted important quantities of macronutrients from the soil. These chelating agents are also known to pollute the soil by being adsorbed on the soil particles. / A bioremediation process was developed using the fungus Aspergillus niger to produce weak organic acids (mainly citrate and partly oxalate depending on pH) for the leaching of heavy metals from contaminated soils. The fungus was cultivated on the surface of the three contaminated soils for 15 days at 30°C and a pH ≤ 4 to enhance the production of citric acid rather than oxalic acid which hinders Pb leaching. By extrapolating the result, the three contaminated soils were expected to be sufficiently remediated to meet the A category (Quebec clean up criteria for cleaning soils contaminated by heavy metals) after 20 to 25 days of leaching using this technique. / Finally, the leachate, collected following the soil remediation using weak organic acids and/or their salts, EDTA and DTPA was treated effectively using granular activated carbon.