Biorémédiation augmentée de sols contaminés aux hydrocarbures lourds par ajout de substrats organiques

Abstract

Soil pollution by organic pollutants such as petroleum hydrocarbons (HP) has long been a problem for the environment because several of these compounds are persistent and difficult to biodegradable. It has been demonstrated that their physicochemical properties and sometimes the complexity of the soil do not favor their bioavailability in the face of attacks of microorganisms. That is why it is proposed in this experimental project to study a method of treatment alternative of these contaminated soils by inputs of organic substrates (residues urban organic manure or of poultry). It will enable the use of these organic substrates in composting as adsorbante matrix to organic pollutants not (or little) available to microorganisms, then a support for these pollutants by the consortium of microorganisms present in the composting process (which induces itself an elevation of temperature favorable to the biochemical reactions). This method will thus put in evidence the biodegradation of petroleum hydrocarbons in the soil by a process of co-composting of organic substrates, and the influence of certain parameters of study such as the temperature, carbon/nitrogen ratio, the nature and rate of organic substrate amended, etc. on the improvement of the rate of abatement of HP. The tests performed at the laboratory scale, in bioreactors of 18.9 liters have presented promising results on the role played by the organic substrates on the biostimulation (intake of nutrients) and bioaugmentation (microbial contribution) of indigenous microorganisms of the soil, but also on the bioavailability of organic pollutants through the intimate reconciliation of the two matrices (soil/compost). It has also been shown on this scale, the temperature and the organic substrate level consistently improve the rate of biodegradation of petroleum hydrocarbons. Similarly it has been proved that the heat generated by the microorganisms is commensurate with the nature and the organic substrate rate used. With 60 % (w/w) of chicken manure, to a C:N ratio of 20:1 and a moisture content of between 52-58 %, microbial activity was able to generate heat in excess of 58°C and improved the rate of reduction of petroleum hydrocarbons by 68 % for the C10-C50 and 48 % for PAH and this in only 42 days of treatment. The results of such an experimental project could contribute to the widening of the various techniques for the rehabilitation of polluted soils, possibly at lower cost.

Date	11 Jan 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Frédéric Monette (Supervisor)