Bioremediation of gasoline contaminated soil by a bacterial consortium amended with poultry litter, coir pith, and rhamnolipid biosurfactant

The aim of the present study was to find methods for enhancing rates of hyd rocarbon biodegradation in gasoline contaminated soil by ex situ bioremedia tion. Red soil (RS) was treated with gasoline-spilled soil (GS) from a gaso line station and different combinations of amendments were prepared using ( i) mixed bacterial consortium (MC), (ii) poultry litter (PL), (iii) coir pi th (CP) and (iv) rhamnolipid biosurfactant (BS) produced by Pseudomonas sp. DS10-129. The study was conducted for a period of 90 days during which bac terial growth, hydrocarbon degradation and growth parameters of Phaseolus a ureus RoxB including seed germination, chlorophyll content, shoot and root length were measured. Approximately 67% and 78% of the hydrocarbons were ef fectively degraded within 60 days in soil samples amended with RS+GS+MC+PLCP+BS at 0.1% and 1%. Maximum percentage of seed germination, shoot length, root length and chlorophyll content in P. aureus were recorded after 60 da ys in the above amendments. Further incubation to 90 days did not exhibit s ignificant improvements. Statistical analysis using analysis of variance (A NOVA) and Duncan's multiple range test (DMRT) revealed that the level of am endments, incubation time and combination of amendments significantly influ enced bacterial growth, hydrocarbon degradation, seed germination and chlor ophyll content at a 1% probability level. All tested additives MC, PL, CP a nd rhamnolipid BS had significant positive effects on the bioremediation of GS. (C) 2001 Elsevier Science Ltd. All rights reserved.