EVALUATION OF BIOAUGMENTATION AND BIOSTIMULATION IN DIESELCONTAMINATED SOIL MICROCOSMS

Soil pollution due to agrochemicals, chlorinated compounds, dyes, heavy metals, hydrocarbons, plastics, and sewage threatens the healthiness of environment, animals and humans. According to estimates, in Europe there are 2.5 millions of potentially contaminated sites, of which only 340,000 have been identified, up to now. It is reported that in about 60% of the cases the contamination is due to hydrocarbon species (van Liedekerke et al., 2014). The extensive extraction, processing and utilisation of fossil fuels is the source of soil and water contamination with hydrocarbons, mainly due to accidental spills, leakages and improper treatment of wastes. In last decades, several physical and chemical techniques to recover polluted sites were developed. Usually these technologies are expensive and can generate a large quantity of wastes to be treated or disposed. For this reason, the biological approach (bioremediation) is getting more and more attention, as it is considered a cost-effective and environmental-friendly alternative. Bioremediation involves the exploitation of both aerobic and anaerobic microorganisms for the reduction of pollutant concentration and includes biodegradation, detoxification and transformation of hazardous species. The bioremediation approach usually follows two strategies: biostimulation and bioaugmentation. Both of the options can be used and combined in different ways according to the nature of hydrocarbon contaminants and the geophysical and environmental conditions. Biostimulation consists of the addition of nutrients such as nitrogen, phosphorous, carbon and oxygen to stimulate the activity of indigenous microbial population, while bioaugmentation involves the addition of microorganisms, with the capability to degrade hydrocarbons. Our project aims to apply a synergic approach, comprising biological and geophysical methods, to the optimization and control of diesel oil bioremediation in soil. To this end, biostimulation and bioaugmentation tests were performed in aerobic microcosms, at laboratory scale.