Arsenic (As), a known carcinogen, is a groundwater contaminant in many parts of the world. Arsenic contamination is enhanced through carbon addition, such as biostimulation, a remediation process, which has been used to remove trichloroethylene (TCE) from sediment and groundwater. Two studies were designed to evaluate the effect of different carbon sources on the removal of TCE through dechlorination and on As solubilization and mobilization in response to carbon addition. The first set of columns (15.2 cm diameter, 183 cm long) used whey, Newman Zone® standard surfactant emulsified oil, Newman Zone® nonionic surfactant emulsified oil, and no carbon controls as carbon and energy sources and were fed for 7.5 years. The second set (7.62 cm diameter and length) used whey, lactate, and no carbon control as carbon sources with columns being dismantled and analyzed over a 5-month time period. These studies showed that reducing conditions, caused by the carbon sources, was the driving force for As mobilization as As(V) was reduced to the more mobile As(III). Total As mass in the sediment was lost with all carbon treatments within the first study with whey having a greater loss; however, within the second study, both whey and lactate treatments had the same extent of As mass loss over time. The results also indicated that some As could be attenuating with carbonates or other highly soluble minerals.

Made available in DSpace on 2017-07-10T17:40:53Z (GMT). No. of bitstreams: 1 Edneia_Santos_de_Oliveira_Lourenco.pdf: 2286442 bytes, checksum: e0afd0c13867ce75e65439763df6c6b0 (MD5) Previous issue date: 2014-08-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Agriculture in general has become dependent on pesticides. Among the classes of pesticides, herbicides followed by insecticides and fungicides are the most marketed. The Atrazine (ATZ) is a selective herbicide recommended for weed control due to its high potential for leaching has been detected frequently in natural waters.The aim of this study was to evaluate the efficiency of processes: Fenton,solar and artificial photo-Fenton, solar and artificial photolysis and H2O2/UV in the treatment of water contaminated with atrazine and its toxicity using Lactuca sativa L. species. The experiments were conducted in laboratory scale. The reactor consisted of a beaker with borosilicate in batch system. The survey was conducted in three stages. In the first step an experimental design was proposed: central rotational compost design (CRCD) by artificial photo-Fenton process having five levels as a variable concentration of ATZ (5,86; 10; 20; 30 and 34,14 mgL-1) and five levels of Fe2+(15,14; 40; 100; 160; 184,85mgL-1). The operating parameters of the reactors were based on statistically significant response reduction of dissolved organic carbon (DOC). Subsequently the best conditions were reproduced assessing the mineralization of atrazine in Fenton, artificial photo-Fenton, artificial photolysis and H2O2 /UV processes. In the second stage was performed the same planning through the Fenton process using five levels of iron (1,76; 3; 6; 9 e10,24 mgL-1) and five levels of hydrogen peroxide (15,86; 20; 30; 50 and 58,28 mg L-1). The best conditions obtained in the planning were reproduced in the kinetic tests in Fenton process, artificial photo-Fenton, solar photo-Fenton and solar photolysis taking in response to ATZ degradation and mineralization processes. In the third step it was performed the toxicity test of treated ATZ using Lactuca sativa L. seeds in response to the germination and hypocotyl elongation. The results showed that the efficiency of Fenton is improved by the presence of artificial and solar lights and increasing process efficiency. After 120 min of reaction ATZ reduced by 98%, while the FFA and FFS in only 40 min of reaction reduced to 90% under the same conditions. Solar photolysis was the less efficient: in 120 min reaction only reduced the concentration of ATZ by 40%. The process was more efficient in reducing and mineralization of ATZ was the photo-Fenton artificial, but during the degradation process is likely to have formed intermediates, which showed high toxicity in relation to germination, radicle growth and elongation hypocotyls. The greatest inhibition occurred at concentrations of 30% and ATZ treated without dilution (100%). Despite the significant reduction of ATZ, it did not reach the maximum permissible values (VMP) of 2μg L-1 established by OMS (2004) and CONAMA (2011). Advanced oxidation processes seed in this research showed that they are efficient reducing the concentration of ATZ to considerable values and it could be an alternative for the pesticide packaging recycling companies, since it uses clean and renewable energy, and reagents of easy access. However to improve the toxic conditions to the living organisms and the environment, it is suggested a complementary treatment / A agricultura de um modo geral se tornou dependente dos agrotóxicos. Dentre as classes dos agrotóxicos, os herbicidas seguidos de inseticidas e fungicidas são os mais comercializados. A Atrazina (ATZ) é um herbicida seletivo recomendado para o controle de plantas daninhas, devido ao seu alto potencial de lixiviação tem sido detectada com frequência em águas naturais. O objetivo deste estudo foi avaliar a eficiência dos processos: Fenton, foto-Fenton artificial e solar, fotólise artificial e solar e H2O2/UV no tratamento da água contaminada com o herbicida ATZ e sua toxicidade utilizando a espécie Lactuca sativa L. Os experimentos foram conduzidos em escala laboratorial. O reator foi constituído por um béquer de borossilicato em sistema de batelada. A pesquisa foi realizada em três etapas. Na primeira etapa foi proposto um planejamento experimental delineamento central composto rotacional (DCCR) 22, pelo processo foto-Fenton artificial, tendo como variáveis cinco níveis da concentração de ATZ (5,86; 10; 20; 30 e 34,14 mgL-1) e cinco níveis de Fe2+ (15,14; 40; 100; 160; 184,85 mgL-1).Os parâmetros operacionais dos reatores foram baseadas nas respostas estatisticamente significativas da redução do carbono orgânico dissolvido (COD). Posteriormente as melhores condições foram reproduzidas avaliando a mineralização da ATZ nos processos Fenton, foto-Fenton artificial fotólise artificial e H2O2/UV. Na segunda etapa foi realizado o mesmo planejamento pelo processo Fenton utilizando cinco níveis de Fe2+ (1,76; 3; 6; 9 e 10,24 mgL-1) e cinco níveis do peróxido de hidrogênio (15,86; 20; 30; 50 e 58,28 mgL-1). As melhores condições obtidas no planejamento foram reproduzidas nos testes cinéticos nos processos Fenton, foto-fenton artificial, foto-Fenton solar e fotólise solar tendo como resposta a degradação e mineralização da ATZ. Na terceira etapa realizou-se o teste de toxicidade da ATZ tratada utilizando sementes da Lactuca sativa L. em resposta a germinação e alongamento do hipocótilo. Os resultados mostraram que a eficiência do Fenton é melhorada pela presença da irradiação artificial e solar aumentando a eficiência do processo. Em 120 min de reação reduziu a ATZ em 98%, enquanto no FFA e FFS em apenas 40 min de reação reduziu a 90%, nas mesmas condições. A fotólise solar foi o menos eficiente: dentro dos120 min de reação reduziu somente em 40% a concentração da ATZ. O processo que se mostrou mais eficiente quanto à redução e mineralização da ATZ foi o foto-Fenton artificial, porém durante o processo de degradação é possível que tenha formado compostos intermediários, os quais apresentaram alta toxicidade em relação à germinação, crescimento da radícula e alongamento do hipocótilo. As maiores inibições ocorreram nas concentrações de 30% da ATZ tratada e sem diluição (100%). Apesar da significativa redução da ATZ, esta não atingiu os valores máximos permissíveis (VMP) de 2g L-1 estabelecido pela OMS (2004) e CONAMA (2011). Os processos oxidativos avançados utilizados nesta pesquisa mostraram que são eficientes reduzindo a concentração da ATZ a valores consideráveis, podendo ser uma alternativa para as empresas recicladoras de embalagens de agrotóxicos, uma vez que se utiliza energia limpa e renovável e reagentes de fácil acesso. No entanto para melhorar as condições tóxicas aos organismos vivos e ao meio ambiente sugere-se um tratamento complementar

The Department of Defense (DoD) has numerous sites that contain groundwater contaminated with 2,4,6-trinitrotoluene (TNT). The currently applied technologies for treating TNT contaminated waters are carbon adsorption and chemical oxidation. Carbon adsorption is a non-destructive technology, which could create future liability issues and is inefficient at relatively low TNT concentrations. On the other hand, application of chemical oxidation for the treatment of TNT contaminated water generates trinitrobenzene (TNB), a by-product of the incomplete oxidation of TNT. TNB is regulated as strictly as TNT. Additionally, over 70% of the reactor required treatment time for meeting target levels is due solely for TNB removal. This study evaluated the potential integration of zero-valent metallic species and advanced oxidation for the treatment of waters contaminated with TNT. The idea was to reduce treatment time, and thus, operational costs, when advanced oxidation is used as a stand-alone treatment technology by reducing TNT prior to oxidation. The use of zero-valent metals as the first treatment step transformed TNT into reduced organic compounds which were easily oxidized. The effectiveness of zinc, iron, nickel, copper, and tin as TNT reducing agents was evaluated. Zinc and iron were selected for further study based on their performance degrading TNT. Then, the reduction mechanism (pathway) and associated by-products of TNT reduction using zinc were examined using a zinc specimen manufactured by Sigma Corporation. Three amines were identified during reduction : 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, and 2,4-diamino-toluene. Other intermediates were observed but not identified. Many of these reduction by-products adsorbed strongly onto the metal surface, significantly reducing the rate of TNT degradation during aging experiments. The aging of the metallic species was modeled using a power decay law parameter with the rate expression for TNT degradation. Corrosion promoters such as KCl addition, ozonation, and peroxone were evaluated as alternatives to reactivate zinc and iron to achieve steady TNT degradation. The addition of KCl performed significantly better than ozonation and peroxone. Furthermore, addition of KCl during the reduction step using iron or zinc generated organics that were successfully mineralized by ozonation or peroxone.