Petroleum pollution is still one or crucial environmental problems. Bioaugmcntation is a popular technique used in soil remediation. The aim of soil inoculation is acceleration or decomposition processes or improving the degradation efficiency. Effectiveness of bioaugmentation processes depends on the number and activity of microorganisms adapted to pollutant degradation. Enhancement of microorganisms' activity can be reached by the use or plants. Roots or plants excrete organic substances that stimulate microorganisms' growth. Among different species or plants interesting arc papilionaceous plants because of their nitrogen fixation ability in symbiosis with bacteria. The effects or using papilionaceous plants (Trifolium pratense), multiplied autochthonous microorganisms and commercial biopreparation in aged-petroleumpolluted soil were studied. The samples of soil were taken from the refinery in Czechowice-Dziedzice (Poland) and classified as heavily degraded with a C/N-ratio or 100:0.7. Investigations were conducted for 14 weeks. Microbiological analysis included: total bacteria, fungi, Actinomycetes and Pscudonionas counts. Concentration or heavy fractions, TPH (total petroleum hydrocarbons) and PAHs (polycyclic aromatic hydrocarbons) were measured at the start and at the end of the experiment. Presence of pap il ionaceous plant (Trifolium pratensei enhanced the growth or microorganisms, nitrogen concentration and biodegradation processes (removal of 63% or TPH, 44% or heavy fractions, 9% or 4-6 aromatic PAHand 80% of 2-3 aromatic PAH) in polluted soil. An increasing number of Pseudomonas species was observed in samples in which pollution removal was more effective.

The effects of using three different biopreparations (one natural N2 and two commercial Kl and K2) in petroleum hydrocarbons age-polluted clay soil were studied. The samples of soil were taken from refinery in Czechowice-Dziedzice and classified as heavily degraded in proportion C:N = 100:0,7. Changes after introducing biopreparations into soil (bioaugmentation), their influence on microflora development and effects of removing polluting substances were studied. Bioaugmentation did not result in intensive growth of bacterial number, which was on the control sample's level during experiment. Soil's biodegradation activity also increased in level smaller than expected.