Polycyclic aromatic hydrocarbon degradation by developed consortium in microcosms study.

摘要

A feasibility study was conducted prior to onsite full-scale bioremediation study. This feasibility study has investigated the possibility of bioaugmentation of polycyclic aromatic hydrocarbon (PAH)-polluted soil with PAH-degrading strains or consortia. Five treatment options- Oil alone, Oil + Indigenous microflora, Oil + nutrients, Oil + nutrient + tilling, Oil + nutrient + tilling + developed consortium were evaluated. Out of five treatments the application of bacterial consortium, nutrients and environmental factors resulted in 79.16% removal of TPH in 60days, compared to 30.24% removal of TPH carried out by indigenous microflora. The results of High-pressure liquid chromatographic analysis showed that the ratio of di / tri aromatics decreased from initial 0.63 to 0.25 with progressive treatment of nutrient addition, nutrient+tilling, nutrient+tilling+microbial seeding. Similar effect was observed in di / di+tri aromatics ratios which also decreased 0.31 to 0.20 by bioaugmentation only. Introduction Polycyclic aromatic hydrocarbons (PAHs) constitute a group of priority environmental pollutants, which are ubiquitous contaminants in soils and sediments and are of environmental concern because of their toxic, mutagenic and/or carcinogenic effects (Mastrangelo et al., 1996 Marston et al., 2001; Xue & Warshawsky, 2005, Mallick et al ., 2007). Bioremediation is a technique that enhances the natural rate of biodegradation of pollutants through reactions carried out by selected microorganisms (Providenti et al., 1993). Bioremediation of agricultural land polluted with polycyclic aromatic hydrocarbons (PAHs), can be achieved in two ways: by enhancing the growth and activity of microorganisms already present at the site of pollution through nutrient addition (a process, called by some “biostimulation”), and by adding more selected microorganisms (Bioaugmentation) to the pollution site (Ted and Udall, 1991; Andrew and Jackson, 1996). The use of bacteria to achieve these functions has been widely studied (Atlas, 1981; Rocha et al., 1992; Kampfer et al., 1991; Mercade et al., 1996). Various studies have investigated the possibility of bioaugmentation of polycyclic aromatic hydrocarbon (PAH)-polluted soil with PAH-degrading strains or consortia.There are many definitions of 'microcosm' a typical one is that of an intact, minimally disturbed piece of an ecosystem brought into the laboratory for study in its natural state (Prichard and Bourquin, 1984). Microcosms can vary in complexity from simple static soil jars of contaminated soil to highly sophisticated systems designed to enable variations in various environmental parameters encountered on site to be more accurately simulated in the laboratory.A feasibility study was conducted to assess the short term bioremediation potential of a sandy loam soil of Haridwar region, freshly contaminated with un-weathered Sobhasan crude oil well # Y. Five treatment options- Oil alone, Oil + Indigenous Microflora, Oil + Nutrients, Oil + Nutrient (Fertilizer) + Tilling (Aeration), Oil + Nutrient (Fertilizer) + Tilling (Aeration) + Developed consortium were evaluated. An indigenous microbial consortium was developed by assembling selected microbial strains, Pseudomonas strains PS-I, PS-II and PS-III, this developed consortium was used for the cleanup of oil contaminated soil. This work reports degradation of aromatic fractions of crude oil by High pressure liquid chromatographic (HPLC) analysis to test the decontamination and conservation of a garden soil polluted with crude oil after bioremediation using “adapted” strains of Pseudomonas PS-I, PS-II and PS-III. Material And Methods Isolation and characterization of bacterial strain: The test organisms used in this study (Pseudomonas (PSI, PSII, and PSIII) were isolated from Oil production site of ONGC, oil wells from Sobhasan oil field project, Gujarat. in western India, as described elsewhere (Mittal et al., 2005). by the enrichment culture technique wi