Functional potential of sewage sludge digestate microbes to degrade aliphatic hydrocarbons during bioremediation of a petroleum hydrocarbons contaminated soil

Anna Gielnik (1) , Yoan Pechaud (1) , David Huguenot (1) , Aurélie Cebron (2) , Giovanni Esposito (3) , Eric van Hullebusch (4)

1 LGE - Laboratoire Géomatériaux et Environnement
2 LIEC - Laboratoire Interdisciplinaire des Environnements Continentaux
3 Department of Civil and Mechanical Engineering
4 IPGP (UMR_7154) - Institut de Physique du Globe de Paris

Sewage sludge digestate is a valuable organic waste which can be used as fertilizer in soil bioremediation. Sewage sludge digestate is not only a good source of nutrients but is also rich in bacteria carrying alkB genes, which are involved in aliphatic hydrocarbons metabolism. Increase of alkB genes ratio in polluted soils has been observed to improve bioremediation efficiency. In this study, for the first time, the genetic potential of indigenous microorganisms of digestate to degrade petroleum products was assessed. The objectives were to study petroleum hydrocarbons (PHCs) removal together with shifts in soil taxa and changes in the concentration of alkB genes after digestate application. Initial alkB genes concentration in contaminated soils and digestate was 1.5% and 4.5%, respectively. During soil incubation with digestate, alkB genes percentage increased up to 11.5% and after the addition of bacteria immobilized onto biochar this value increased up to 60%. Application of digestate positively affected soil respiration and bacterial density, which was concomitant with enhanced PHCs degradation. Incubation of soil amended with digestate resulted in 74% PHCs decrease in 2 months, while extra addition of bacteria immobilized onto biochar increased this value up to 95%. The use of digestate affected the microbial community profiles by increasing initial bacterial density and diversity, including taxa containing recognized PHCs degraders. This study reveals the great potential of digestate as a soil amendment which additionally improves the abundance of alkB genes in petroleum contaminated soils.

Mots clés: alkB genes; Bioreactors; Organic wastes; Soil clean-up; PHCs

Domaines: Ingénierie de l'environnement; Ingénierie de l'environnement

Anna Gielnik, Yoan Pechaud, David Huguenot, Aurélie Cebron, Giovanni Esposito, et al.. Functional potential of sewage sludge digestate microbes to degrade aliphatic hydrocarbons during bioremediation of a petroleum hydrocarbons contaminated soil. Journal of Environmental Management, 2020, ⟨10.1016/j.jenvman.2020.111648⟩. ⟨hal-03018606⟩