Bioremediation of clay with high oil content and biological response after restoration

Xiaokang Li,Tao Yu,Mingming Du,Chengtun Qu,Jinling Li

doi:10.1038/s41598-021-88033-w

Xiaokang Li, Tao Yu + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-88033-w

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Abstract

The clay with high oil content form soil lumps, which is hard for microbes to repair. In this paper, the bioaugmentation and biostimulation technology were applied to improve the bioremediation effect of the soil with high oil content, that modified by local cow dung and sandy soil, the ecological toxicity of the soil after restoration was further analyzed. After 53 days of bioremediation, the degradation efficiency with respect to the total petroleum hydrocarbons (TPH) content reached 76.9% ± 2.2%. The soil bacterial count of M5 group reached log10 CFU/g soil = 7.69 ± 0.03 and the results were better than other experimental groups. The relative abundances of petroleum-degrading bacteria added to M5 remained high (Achromobacter 9.44%, Pseudomonas 31.06%, and Acinetobacter 14.11%), and the proportions of some other indigenous bacteria (Alcanivorax and Paenibacillus) also increased. The toxicity of the bioremediated soil was reduced by seed germination and earthworm survival experiments.

Highlights

Natural attenuation (NA): 100 g distilled water + 385 g modified clay c (45 wt% clay with high oil content, 55 wt% sandy soil)
In view of the characteristics of oil-contaminated clay, this paper proposes a simple and effective bioaugmentation and biostimulation technology, which was applied to modified petroleum-contaminated clay to reduce oil content and viscosity, and repair the oil on the clay particles
The toxic effect on bacteria will increase if the content of petroleum in soil is higher than 6%15

Summary

Introduction

Natural attenuation (NA): 100 g distilled water + 385 g modified clay c (45 wt% clay with high oil content, 55 wt% sandy soil). Biostimulation-1 (BS-1): 100 g nutrient solution + 385 g modified clay c (45 wt% clay with high oil content, 55 wt% sandy soil). Bioaugmentation (BA): 75 g distilled water 385 g modified clay d (45 wt% clay with high oil content, 45 wt% sandy soil, 10 wt% cow dung) + 25 g bacterial solution. Biostimulation (BS) + bioaugmentation (BA): 75 g nutrient solution + 385 g modified clay d (45 wt% clay with high oil content, 45 wt% sandy soil, 10 wt% cow dung) + 25 g bacterial solution. The ecological restoration ability of the modified soils was evaluated to ensure the vegetation cover in the later stage

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Results

Conclusion