Preliminary identification of the bioremediation limiting factors of a clay bearing soil contaminated with crude oil

Abstract

A biorremediação é uma alternativa atraente para o tratamento de solos contaminados com hidrocarbonetos de petróleo. No entanto, a efetividade do processo pode ser limitada não só pelas características do contaminante, mas também pela sua biodisponibilidade. Este trabalho tem como meta o estabelecimento de procedimento preliminar para identificar o fator principal (recalcitrância ou biodisponibilidade) que interfere negativamente na biodegradação, resultando em baixas eficiên-cias. Foram realizados testes em microcosmos contendo solo aplicando as técnicas de bioestímulo e bioaumento. Experimentos semelhantes foram conduzidos em meio líquido contendo óleo cru e microorganismos extraídos do solo contaminado, nutrientes e inóculo microbiano (Rhodoturula glutinis e Nocardia nova). Após 30 dias, o maior nível de biodegradação (98.8%) foi obtido na condição com bioaumento em meio líquido, indicando que o problema principal de biodegradação de hidrocarbonetos de petróleo pode estar associado à baixa biodisponibilidade destes no solo e não apenas a recalcitrância intrínseca do poluente residual.Bioremediation is an attractive alternative to treat soils contaminated with petroleum hydrocarbons. However, the effectiveness of biodegradation process can be limited by both contaminant characteristics and its bioavailability in soil. This work aims at establishing a preliminary procedure to identify the main factor (hydrocarbon recalcitrance or its bioavailability) that impairs the biodegradation, possibly resulting in low remediation efficiencies. Tests in soil microcosms were carried out applying biostimulation and bioaugmentation techniques. Similar experiments were conducted using liquid medium containing crude oil and microorganisms, both of them extracted from a weathered contaminated soil sample, nutrients and microbial inoculum constituted of Rhodoturula glutinis and Nocardia nova. After 30 days, highest microcosms biodegradation levels (98.8%) were obtained with bioaugmentation in liquid medium, pointing out that the main problem of petroleum hydrocarbon utilization by microorganisms was associated to its availability and not only to the intrinsic recalcitrancy of remaining pollutants.

Enhanced Biodegradation of Naphthalene and Anthracene by Modified Vermiculite Mixed with Soil

“…This behavior has been observed by other authors (Fava and Ciccotosto 2002;Peyton et al 2007). Whereas the degradation of naphthalene and anthracene is an oxidation-reduction reaction, oxygen becomes the limiting factor of the reaction (Rizzo et al 2008) because the experiments were conducted in an aerobic environment, and thus oxygen receives the electrons, so the products of the reaction are carbon dioxide and water.…”

“…2.3 Determination of CO 2 CO 2 generated during the experiments was concentrated following the procedures described by Rizzo et al (2008). A Hewlett-Packard 6890A II gas chromatograph was used to analyze the headspaces from a hermetically stoppered Pyrex filter flask containing the vermiculite mix with soil.…”

“…PAHs are considered the main pollutants of oil according to EPA and the European Community, while 16 of them were identified as the main carcinogenic and/or mutagenic substance. One of these is naphthalene, which when ingested or inhaled by humans can cause several health problems, including: hemolytic anemia, cataracts, enlarged spleen and kidneys, and damage to the brain (Rizzo et al 2008). Due to this constant increase in contamination incidents, it is necessary to develop techniques for the rapid decontamination of water and soil.…”

Phylogenetic analysis and characterization of an alkane-degrading yeast strain isolated from oil-polluted soil

“…The Rhodotorula species have hydrocarbon-degrading abilities and produce sophorolipids, polyol lipids, and carbohydrate-protein complex types of biosurfactants (Mulligan, 2004;Nunez et al, 2004;Nerurkar et al, 2009;Chandran and Das, 2011). R. glutinis is one of the most representative species of the genus due mainly to the wide incidence of its strains in soil, seawater, atmosphere, fruits, and the human body (Barnett et al, 1984;Kurtzmann et al, 2011) and to its practical applications in obtaining lipids and biodiesel, in biocontrol, and in bioremediation (Van Hamme et al, 2003;Dai et al, 2007;Rizzo et al, 2008;Easterling et al, 2009;Sharma et al, 2009). …”

Laboratory study on the bioremediation of diesel oil contaminated soil from a petrol station

“…In addition to provide these , optimum conditions, it is also important to know that the pollutant degradation in soil is influenced by mass transfer phenomena. Providing a way to reduce the sorption of the hydrophobic organic contaminants to the soil matrix can increase the rate and extent of biodegradation (26). For this purpose, the addition of surfactants into the soil aims to enhance the emulsification of hydrocarbons and therefore they have the potential to solubilize hydrocarbons and increase their bioavailability and subsequent biodegradation (20,24,25,30).…”