Evaluación de la bioestimulación en la biodegradación de TPHs en suelos contaminados con petróleo

The present study evaluated the effect of the nutrients addition (N and P) by using the amendment of inorganic simple fertilizer (SIS) and inorganic compound fertilizers (FIC) in the biodegradation of total hydrocarbon petroleum (TPH). Mesocosmos were used with contaminated soil (20,000 mgTPH/kgdw), abiotic control and a control without nutrient (n=3) were used to evaluate the effect of nutrient amendment. The study was conducted during 125 days with 5 sampling events (EM). During the study two analytical methods for the determination of total petroleum hydrocarbons (TPHs): Method D-5831 (ASTM) and the modified extraction by mechanical agitation and gravimetric determination method (EAMG) (EPA, 1994; Schawab et al., 1999) were evaluated and compared. To monitor the bioremediation physic-chemical (pH, % moisture, and nutrients) and microbiological (heterotrophic and hydrocarbon degrader microorganisms) parameters were evaluated. The highest TPH degradation rates were observed during the first 28 days in the SIS and FIC treatments (278 and 235 mgTPHs/kgdw/d, respectively) compared to the controls (110 mgTPHs/kgdw/d). The abiotic control indicated that the intrinsic bioremediation was the main process during the TPH degradation. Although, there was not significant differences between treatments and the control without nutrients, SIS showed the highest TPH degradation (39% and 41% by D-5831 and EAMG methods, respectively). The low pH (4,1) at the end of the study and the low degraders numbers (1x103 NMP/gdw) in the treatments could be the limiting factors to achieve higher degradations rates. Stenotrophomonas maltophilia was the predominant microorganism during the study (34%).