Use of Agro-Industrial Waste in the Removal of Phenanthrene and Pyrene by Microbial Consortia in Soil

Abstract

The addition of co-substrates as adjuvants to the bioremediation process enables almost complete removal of the polycyclic aromatic hydrocarbons (PAH) in the soil. The aim of this work was to associate biostimulation and bioaugmentation, represented respectively by the addition of residues from the processing of three oilseeds, and by the addition of consortia formed by Pseudomonas aeruginosa and Burkholderia cepacia strains, in the removal of phenanthrene and pyrene from a soil contaminated by a lubricating oil mixture containing approximately 50\xa0mg/kg PAH. Three consortia were prepared from antimicrobial activity tests and each was stimulated with cotton, peanut or sesame cakes (20 and 40\xa0mg/kg). The biodegradation tests were carried out on polyethylene reactors filled with 200\xa0g of sandy soil. After 60 days incubation at room temperature, between 65 and 80% of the phenanthrene and pyrene was removed with preferential degradation of the three consortia by pyrene. In all cases, the most successful condition was obtained when the cake contents were added, independent of amount of contaminant content (40 or 80 mL/kg), emphasizing the importance of the use of co-substrate and reuse of agro-industrial wastes in bioremediation. Phytotoxicity assays demonstrated that Zea mays was the best indicator of soil fertility after treatment.