Heavy fuel oil-contaminated soil remediation by individual and bioaugmentation-assisted phytoremediation with Medicago sativa and with cold plasma-treated M. sativa.

Abstract

Developing an optimal environmentally friendly bioremediation strategy for petroleum products is of high interest. This study investigated heavy fuel oil (HFO)-contaminated soil (4 and 6gkg-1) remediation by individual and combined bioaugmentation-assisted phytoremediation with alfalfa (Medicago sativa L.) and with cold plasma (CP)-treated M. sativa. After 14weeks of remediation, HFO removal efficiency was in the range between 61 and 80% depending on HFO concentration and remediation technique. Natural attenuation had the lowest HFO removal rate. As demonstrated by growth rate and biomass acquisition, M. sativa showed good tolerance to HFO contamination. Cultivation of M. sativa enhanced HFO degradation and soil quality improvement. Bioaugmentation-assisted phytoremediation was up to 18% more efficient in HFO removal through alleviated HFO stress to plants, stimulated plant growth, and biomass acquisition. Cold plasma seed treatment enhanced HFO removal by M. sativa at low HFO contamination and in combination with bioaugmentation it resulted in up to 14% better HFO removal compared to remediation with CP non-treated and non-bioaugmented M. sativa. Our results show that the combination of different remediation techniques is an effective soil rehabilitation strategy to remove HFO and improve soil quality. CP plant seed treatment could be a promising option in soil clean-up and valorization.