Biodegradation of oil refinery residues using mixed-culture of microorganisms isolated from a landfarming

In this study, the potential for using an inoculum composed of a mixed-culture of bacteria and fungi, isolated from a landfarming at the Paulínia Oil Refinery, Brazil, to degrade oil residues generated in the process of petroleum refinement was investigated. The isolation of these microorganisms was carried out beforehand, assuming that they would be better adapted to petroleum hydrocarbons, as the landfarming consisted of an area impacted by the deposit of such compounds. The Bartha and Pramer respirometric test was used to measure the rate of biodegradation of the hydrocarbons by the mixed-culture of microorganisms via the evolution of CO2. The results obtained with respect to the efficiency of biodegradation showed no significant differences (P>0.05), indicating no increase in the biodegradation process using the inoculum. The addition of nutrients (N, P, K) also did not contribute to an increase in biodegradation of the oil residue studied.<br>Neste estudo foi investigado o potencial de um inóculo composto de cultura mista de bactérias e fungos, isolados do landfarming da Refinaria de Paulínia, Brasil, em degradar resíduos oleosos gerados no processo de refinamento de petróleo. O isolamento desses microrganismos foi realizado previamente, supondo-se que estejam melhor adaptados aos hidrocarbonetos de petróleo uma vez que o landfarming consiste em área impactada por deposição de tais compostos. Utilizou-se o teste respirométrico de Bartha e Pramer no intuito de verificar a taxa de biodegradação dos hidrocarbonetos pela cultura mista de microrganismos através da evolução de CO2. Os resultados obtidos para a eficiência da biodegradação não apresentaram diferença estatisticamente significativa (P>0.05) indicando que não houve aumento do processo de biodegradação com o uso do inóculo. A adição de nutrientes (N, P, K) tampouco contribuiu para aumentar a biodegradação do resíduo oleoso estudado

Bioremediation of Oil Sludge in Shengli Oilfield

Abstract Large quantity of dehydrated oil sludge, gen-erated in the disposal process of oil-containing sewage in Shengli oilfield, needs to be rendered harmless to human and to the environment. Bioremediation has been accepted as an important method for the treatment of oil sludge by employing indigenous or extraneous microbial flora. The bioremediation of a dehydrated oil sludge of 960 m3 in volume was carried out in a pre-pared bed in Binyi oil-containing sewage disposal station, Shengli oil fields, China. Four different treat-ments were made to study the impact of certain process parameters on the bioremediation efficiency. Of the oil contaminants, 52.75 % was degraded within 160 days when treated in a greenhouse, while the oil contamina-tions decreased by only 15.46 % in the untreated sludge. The variations of the physical and chemical properties of oil sludge, the amount and the functional diversity of microorganisms in sludge were characterized. The results indicated that the water-holding capacity of oil sludge, the amount and the metabolism functional diversity of microorganisms in sludge in the three treatments increased markedly compared with the control

Effect of soil contaminated by diesel oil on the germination of seeds and the growth of Schinus terebinthifolius Raddi (Anacardiaceae) Seedlings

The effect of soil polluted by diesel oil on the germination of seeds and the growth of Schinus terebinthifolius Raddi seedlings was analyzed at different times after contamination of the soil. The experiments were conducted under greenhouse conditions, with four treatments and five repetitions. The four treatments included: soil contaminated 30 (T30), 90 (T90) or 180 (T180) days before planting as well as a non-polluted soil (T0) (control). Soil saturated to 50% of its maximum retention capacity (MRC) was contaminated with diesel oil at a rate of 92.4 mL per kg. The germination rate and germination speed index (GSI) were significantly affected only in T30. The development of the plants was affected significantly in all the treatments, with reductions of biomass and eophyll area. It could be concluded that diesel oil significantly affected the germination, GSI and seedling growth of S. terebinthifolius, but the toxic effect decreased over the time

Bioremediation of diesel contamination at an underground storage tank site: a spatial analysis of the microbial community

The present study reports on a real case of contamination due to the chronic leakage of diesel fuel from an underground tank at a dismissed service station. Speciation of the microbial community according to both lateral and vertical gradients from the origin of the contaminant release was analyzed by means of the PCR-DGGE technique. Moreover, the effects of a landfarming treatment on both the microbial community structure and the abatement of contamination were analyzed. The concentration of total petrol hydrocarbons (TPHs) decreased along the horizontal gradient (from 7042.2 ± 521.9 to 112.2 ± 24.3 mg kg(-1)), while increased downwards from the position of the tank (from 502.6 ± 43.7 to 4972.5 ± 275.3 mg kg(-1)). PCR-DGGE analyses and further statistical treatment of the data indicated a correlation between structure of the bacterial communities and amount of diesel fuel contamination. On the other hand, level of contamination, soil texture and depth were shown to affect the fungal community. Chloroflexi and Ascomycota were the most abundant microbes ascertained through culture-independent procedures. Landfarming promoted 91.6 % reduction of TPHs in 75 days. Furthermore, PCR-DGGE analyses evidenced that both bacterial and fungal communities of the treated soil were restored to the pristine conditions of uncontaminated topsoil. The present study demonstrated that bacterial and fungal communities were affected differently by soil factors such as level of hydrocarbon contamination as well as soil depth and texture. This report shows that a well-planned landfarming treatment can drive the restoration of the soil in terms of both abatement of the contaminants and resilience of the microbial community structure