Biodegradation of PAHs from crude oil spilled on a beach in Pernambuco, Brazil

Crude oil accidents pose a threat to health and the environment due to the degree of recalcitrance of the hydrocarbons present. This work aimed to verify the reduction of Polycyclic Aromatic Hydrocarbons (PAHs) in samples of beach sand contaminated by crude oil on the coast of Pernambuco, with allochthonous bioaugmentation, on a laboratory scale, using Pseudomonas aeruginosa TGC-04. Microcosms were prepared containing pasteurized fine sand, mixed with contaminated sand (ratio 1:4), added to the inoculum (inoculum:sand ratio; 1:10; 1:100; 1:1000). After mixing, dolomite coupons (100 mm2) were embedded in the subsurface for biofilm quantification. The test lasted 21 days at 29±º1C. Abiotic losses were calculated using microcosms kept sterilized with 10% (w/v) AgNO3. Biofilm quantification was performed using the crystal violet technique. Between ≈ 40 and 60% of the 16 USEPA PAHs were consumed, preferably those with 4-6 rings. The best microcosm ratio was 1:100 and the preference for 4-6 ring PAHs was similar among all microcosms. For PAHs with up to 3 rings, degradation rate varied between ≈ 15 and 34% and naphthalene was partly degraded. The cell population in the biofilm increased by 4 log units. The results indicated that allochthonous bioaugmentation was an important strategy for detoxifying oil-contaminated sand.