ABSTRACT
Fenton's reagent has shown its applicability to oxidizing these biorefractory organic contaminants. The purpose of this contribution was to investigate the influence of operating parameters on the process efficiency for soil highly contaminated by PAHs. Five variables were selected: pH, reaction time, UV irradiation, hydrogen peroxide concentration and Fe (II) amendment. Their effects on the oxidation of (i) phenanthrene and on (ii) phenanthrene and pyrene present in freshly contaminated soil samples were studied through batch reactor experiments following factorial designs. For phenanthrene oxidation run with a soil contaminated at 700 mg kg(-1), one set of variables enabled us to reach a residual concentration lower than 40 mg kg(-1) (Dutch legislation threshold). The most important factor was the reaction time, followed at a certain distance by UV irradiation, Fe (II), H(2)O(2) concentration and pH, this last variable being the least significant. The possibility of operating without pH adjustment is of importance in the treatment at the field scale. This shows the feasibility of photo-Fenton-like oxidation for the treatment of soil highly contaminated with PAH and the relative importance of the process variables.
Subject(s)
Hydrogen Peroxide/chemistry , Iron/chemistry , Oxygen/chemistry , Phenanthrenes/chemistry , Pyrenes/chemistry , Soil Pollutants/analysis , Chemistry Techniques, Analytical/methods , Hydrogen-Ion Concentration , Industrial Waste , Models, Statistical , Polycyclic Aromatic Hydrocarbons/chemistry , Soil , Time Factors , Ultraviolet RaysABSTRACT
A água, essencial à vida de todo ser humano, atua também como importante veículo de contaminaçäo de inúmeras doenças, seja em decorrência de excretos humanos ou de outros animais, seja pela presença de substâncias químicas nocivas à saúde humana. As águas do Riacho Cavouco, no munícipio de Recife - PE, säo classificadas como águas doces, classe 04, destinadas à navegaçäo, à harmonia paisagística e aos usos menos exigentes. O nível de contaminaçäo microbiológica de cada ponto de contribuiçäo do Riacho Cavouco, no "campus" da Universidade Federal de Pernambuco, foi avaliado durante um período de 6 (seis) meses. Em alguns pontos de contribuiçäo, essas águas residuárias näo säo constituídas essencialmente de esgoto bruto. Foi detectada uma variaçäo de 100 mil a 10 bilhöes no NMP de coliformes totais e 10 mil a 1 milhäo no NMP de coliformes fecais. Os testes realizados confirmaram a presença de Eschirichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa, Serratia sp., Staphylococcus aureus e Streptococcus faecalis. As águas desse Riacho precisam ser tratadas para que possam ser utilizadas para criaçäo de peixes, dentre outros objetivos incluídos na revitalizaçäo e urbanizaçäo desse riacho, como também para evitar poluiçäo de lençóis de água subterrâneos.
