Article

Bioremediation by composting of heavy oil refinery sludge in semiarid conditions.

Department of Soil and Water Conservation and Waste Management, CEBAS-CSIC, Espinardo, Murcia, Spain.
Biodegradation (Impact Factor: 2.49). 07/2006; 17(3):251-61. DOI: 10.1007/s10532-005-5020-2
Source: PubMed

ABSTRACT The present work attempts to ascertain the efficacy of low cost technology (in our case, composting) as a bioremediation technique for reducing the hydrocarbon content of oil refinery sludge with a large total hydrocarbon content (250-300 g kg(-1)), in semiarid conditions. The oil sludge was produced in a refinery sited in SE Spain The composting system designed, which involved open air piles turned periodically over a period of 3 months, proved to be inexpensive and reliable. The influence on hydrocarbon biodegradation of adding a bulking agent (wood shavings) and inoculation of the composting piles with pig slurry (a liquid organic fertiliser which adds nutrients and microbial biomass to the pile) was also studied. The most difficult part during the composting process was maintaining a suitable level of humidity in the piles. The most effective treatment was the one in which the bulking agent was added, where the initial hydrocarbon content was reduced by 60% in 3 months, compared with the 32% reduction achieved without the bulking agent. The introduction of the organic fertiliser did not significantly improve the degree of hydrocarbon degradation (56% hydrocarbon degraded). The composting process undoubtedly led to the biodegradation of toxic compounds, as was demonstrated by ecotoxicity tests using luminescent bacteria and tests on plants in Petri dishes.

Full-text

Available from: José L Moreno, Feb 20, 2015
1 Follower
 · 
101 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sludge is a complex emulsion of various petroleum hydrocarbons (PHCs), water, heavy metals, and solid particles. Polycyclic aromatic hydrocarbons (PAHs), which are components of crude oil sludge, constitute serious environmental concerns, as many of them are cytotoxic, mutagenic and potentially carcinogenic. It also affects the soil fertility. Treatment of oil sludge includes physical, chemical and biological process but still cost effective method is needed. Composting can serve as remedy to treat the sludge provided factors such as nutrients, pH, moisture, aeration and temperature within the compost pile. For maintaining the humidity different bulking agent can be used. High microbial diversity and activity during composting, due to the abundance of substrates in feedstocks, promotes degradation of xenobiotic organic compounds, such as pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). Microorganisms can also bio transform pollutants into less toxic substances. The exhaustive investigation of oily sludge treatment methods will provide researchers to have a thorough understanding of recent developments and future research directions.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Oily sludge obtained from a refinery in India contained 10–11% oil associated with fine particulates. Along with Fe, Ca and Mg various toxic elements were associated with the sludge solids (Pb, Mn, Cu, Zn, As, Bi, Cd, Cr, Co, Ni and V). The oil contained 41–56% asphaltenes and the maltenes comprised of 49 ± 4%, 42 ± 2% and 4 ± 2%, aliphatic, aromatic and polar fractions, respectively. Biodegradation studies with the maltene fraction of oil provided as sole substrate revealed higher degradation by various 3-5 membered reconstituted consortia compared to pure bacterial strains and up to 42 ± 8% degradation could be achieved over 30 days. In contrast, over the same period up to 71.5 ± 2% oil degradation could be achieved using dried oily sludge (15% w/v) as sole substrate. Significant biodegradation observed in the un-inoculated controls indicated the presence of indigenous microorganisms in oily sludge. However, large variability in oil degradation was observed in the un-inoculated controls. Greater biodegradation of the maltene fraction led to significant enrichment of asphaltenes in residual oil associated with the sludge.
    Journal of Environmental Management 02/2015; 149:118-125. DOI:10.1016/j.jenvman.2014.10.007 · 3.19 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Heavy crude oils from Venezuelan Orinoco belt needs special and costly handling processes due to its high viscosity, sulfur and metals content. Different biotechnological applications have been aimed to improve these properties. However, emulsified systems have not been assessed to increase the bioavailability of crude oil for microorganisms. In the present study were evaluated changes induced in two extra heavy crude oils by bacterial consortium using oil in water emulsified systems. For 5 day incubation period, larger detectable changes were observed for Boscán than Carabobo crude oil. The changes were an increase of the initial boiling point, decrease of the light fractions content, as well as a decrease of total sulfur. These changes were mainly observed after treatment with consortia grown in naphthalene. A 45 day incubation period of Carabobo crude oil treated with consortia grown in naphthalene exhibited an increase of the initial boiling point, CH2 and CH3 groups and partial loss of the lighter crude oil components. A relevant change was found after subsequent thermal treatment, it was a slight decrease of the 550 °C+ residues; also an important biodesulfurization was found under the same conditions. Finally, the study shows that bacterial degradation of extra heavy crude oils using emulsions is a sensitive procedure. The changes could depend on the heavy crude oil, bacterial consortium, culture medium, incubation time and temperature; as well as the implementation of thermal treatments.
    Journal of Petroleum Science and Engineering 02/2015; 127. DOI:10.1016/j.petrol.2015.01.039 · 1.10 Impact Factor