Biological treatment of concentrated hazardous, toxic, andradionuclide mixed wastes without dilution

Abstract

Approximately 10% of all radioactive wastes produced in the U. S. are mixed with hazardous or toxic chemicals and therefore can not be placed in secure land disposal facilities.Mixed wastes containing hazardous organic chemicals are often incinerated, but volatile radioactive elements are released directly into the biosphere. Some mixed wastes do not currently have any identified disposal option and are stored locally awaiting new developments.Biological treatment has been proposed as a potentially safer alternative to incineration for the treatment of hazardous organic mixed wastes, since biological treatment would not release volatile radioisotopes and the residual low-level radioactive waste would no longer be restricted from land disposal. Prior studies have shown that toxicity associated with acetonitrile is a significant limiting factor for the application of biotreatment to mixed wastes and excessive dilution was required to avoid inhibition of biological treatment. In this study, we demonstrate that a novel reactor configuration, where the concentrated toxic waste is drip-fed into a complete-mix bioreactor containing a pre-concentrated active microbial population, can be used to treat a surrogate acetonitrile mixed waste stream without excessive dilution. Using a drip-feed bioreactor, we were able to treat a 90,000 mg/L acetonitrile solution to less than 0.1 mg/L final concentration using a dilution factor of only 3.4. It was determined that the acetonitrile degradation reaction was inhibited at a pH above 7.2 and that the reactor could be modeled using conventional kinetic and mass balance approaches. Using a drip-feed reactor configuration addresses a major limiting factor (toxic inhibition) for the biological treatment of toxic, hazardous, or radioactive mixed wastes and suggests that drip-feed bioreactors could be used to treat other concentrated toxic waste streams, such as chemical warfare materiel.

BIOTRANSFORMASI ADIPONITRIL OLEH Bacillus licheniformis BA2

“…Pengamatan terhadap pertumbuhan sel, pH, dan konsentrasi amonium dilakukan setiap 4 jam. Pertumbuhan sel diamati secara kolorimetris, sedangkan penentuan konsentrasi amonium dilakukan dengan metode Nessler (Stringfellow et al, 2003).…”

Biodegradação de rejeitos radioativos líquidos orgânicos provenientes do reprocessamento do combustível nuclear

“…Os rejeitos radioativos podem ser classificados por diversos critérios: de acordo com a origem , o estado físico, os níveis de radioatividade, as quantidades de radionuclídeos de meia -vida longa e curta, a intensidade da radiação, os (AMPHLETT, 1961;IAEA, 1984;IAEA, 1983 ) (ISHIKAWA, 1985;MACASKIE, 1991;IRWIN, 1995;OLIVERA et al, 1997;THOMAS et al, 1997a;THOMAS et al, 1997b;THOMAS & MACASKIE, 1998;VANDERBERG et al,1999;DOBLE & KUMAR, 2005, STRINGFELLOW et al, 2004BITTON, 2005 , 1989;IRWIN et al, 1997).…”

Estudo da aplicação de biossorventes no tratamento de rejeitos radioativos líquidos contendo Amerício-241.

“…As técnicas convencionais de remoção de íons metálicos de soluções, tais como a precipitação, troca iônica e processos eletroquímicos nem sempre são adequadas para o tratamento de rejeitos radioativos devido aos grandes volumes de rejeitos, baixas concentrações de íons metálicos em soluções aquosas e por razões econômicas. Em muitos países esses rejeitos são tratados por incineração, que destrói os compostos orgânicos perigosos e os radionuclídeos presentes são capturados pelas cinzas volantes ou liberados com os gases (STRINGFELLOW et al, 2000).…”