RESUMEN
Calcium and magnesium peroxides were applied for the treatment of soil contaminated by polychlorinated biphenyls-containing electrical insulating oil (Aroclor 1016). The removal of PCB-containing electrical insulating oil was achieved with the addition of either calcium peroxide or magnesium peroxide alone and dependent on dosages of the chemical. A 21-d treatment of 60% watered soil with the moderate addition (chemical/oil weight ratio of 0.005/1) of either calcium peroxide or magnesium peroxide resulted in nearly complete (96 ± 2%) oil removal, unsubstantial increase in soil pH and almost no changes in oxygen consumption and dehydrogenase activity, making it suitable for the soil decontamination.
Asunto(s)
Arocloros/química , Restauración y Remediación Ambiental/métodos , Compuestos de Magnesio/química , Peróxidos/química , Bifenilos Policlorados/química , Contaminantes del Suelo/química , Arocloros/metabolismo , Análisis de la Demanda Biológica de Oxígeno , Residuos Electrónicos , Compuestos de Magnesio/metabolismo , Oxidorreductasas/análisis , Peróxidos/metabolismo , Bifenilos Policlorados/metabolismo , Suelo/química , Microbiología del Suelo , Contaminantes del Suelo/metabolismoRESUMEN
Three wastewater samples from a pharmaceutical plant formulating medical ointments were subjected to lab-scale treatment by a Fenton-like system in combination with lime coagulation. All samples were plant pre-treated by adsorption/flocculation/filtration processes with utilization of bentonite, but the quality of effluents did not comply with the regulations for wastewater discharged to local sewerage. The optimization of Fenton-like oxidation demonstrated the highest process efficacy at H(2)O(2)/COD weight ratio of 2:1, H(2)O(2)/Fe(2+) molar ratio of 10:1 and 2h of treatment time. The fast pH decrease to acidic values approximately 3 during first min of oxidation for all effluents suggested that pH adjustment was unnecessary. Combination of Fe(III) precipitation and lime coagulation proved feasible to improve considerably COD and residual iron concentration reduction in pharmaceutical effluents. Additionally, considerable BOD(7) reduction and BOD(7)/COD ratio improvement of pharmaceutical wastewater samples was achieved by combined treatment. The application of Fenton-like oxidation with subsequent iron (III)/lime coagulation did not only enhance the quality of pharmaceutical effluents with different chemical characteristics and help to meet the requirements for wastewater discharged to sewage, but also improve the biodegradability of pharmaceutical effluents.
Asunto(s)
Residuos Industriales , Preparaciones Farmacéuticas/química , Eliminación de Residuos Líquidos/métodos , Adsorción , Bentonita/química , Compuestos de Calcio/química , Filtración , Floculación , Peróxido de Hidrógeno/química , Hierro/química , Pomadas , Oxidación-Reducción , Óxidos/química , Aguas del Alcantarillado/químicaRESUMEN
Combined chemical (Fenton-like and ozonation) and biological treatment for the remediation of shale oil and transformer oil contaminated soil has been under study. Chemical treatment of shale oil and transformer oil adsorbed in peat resulted in lower contaminants' removal and required higher addition of chemicals than chemical treatment of contaminants in sand matrix. The acidic pH (3.0) conditions favoured Fenton-like oxidation of oil in soil. Nevertheless, it was concluded that remediation of contaminated soil using in situ Fenton-like treatment will be more feasible at natural soil pH. Both investigated chemical processes (Fenton-like and ozonation) allowed improving the subsequent biodegradability of oil. Moderate doses of chemical oxidants (hydrogen peroxide, ozone) should be applied in combination of chemical treatment (both, Fenton-like or ozonation) and biotreatment. For remediation of transformer oil and shale oil contaminated soil Fenton-like pre-treatment followed by biodegradation was found to be the most efficient.