A Combinational Strategy Mitigated Old-Aged Petroleum Contaminants: Ineffectiveness of Biostimulation as a Bioremediation Technique.

Hamidreza Garousin,Hossein Ali Alikhani,Najmeh Yazdanfar,Ahmad Ali Pourbabaee

doi:10.3389/fmicb.2021.642215

Hamidreza Garousin, Hossein Ali Alikhani + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2021.642215

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Abstract

Hydrocarbon contamination emerging from the crude oil industrial-related activities has led to severe environmental issues. Prolonged contamination with the constant infiltration of crude oil into the soil is a severe problem in remediating contaminated soils. Hence, the current study focuses on comparing various bioremediation strategies, thereby isolating native bacteria competent to reduce TPH in both liquid and microcosm environments in an old-aged petroleum hydrocarbon contaminated soil. Assays in the modified 6SW-Vit medium after 7 days of incubation revealed that Bacillus altitudinis strain HRG-1 was highly hydrophobic and had a suitable ability to decrease surface tension (40.98%) and TPH (73.3%). The results of biodegradation in the microcosm proved that among the designated treatments, including bio-stimulated microcosm (SM), bacterialized microcosm (BM), a combined bio-stimulated microcosm and bacterialized microcosm (SB), and natural attenuation (NA), the SB treatment was the most effective in mitigating TPH (38.2%). However, the SM treatment indicated the lowest TPH biodegradation (18%). Pearson correlation coefficient among microcosm biological indicators under investigation revealed that soil basal respiration had the highest correlation with the amount of residual TPH (r = −0.73915, P < 0.0001), followed by the microbial population (r = −0.65218, P < 0.0001), catalase activity (r = 0.48323, P = 0.0028), polyphenol oxidase activity (r = −0.43842, P = 0.0075), and dehydrogenase activity (r = −0.34990, P = 0.0364), respectively. Nevertheless, considering the capability of strain HRG-1 and the higher efficiency of the combined technique, their use is recommended to diminish the concentration of petroleum hydrocarbons in hot and dry contaminated areas.

Highlights

Total petroleum hydrocarbons are one of the most momentous contaminants in the environment
Bioremediation denotes the use of Mitigation of Old-Aged Petroleum Contaminants living indigenous or exogenous microorganisms with the property of degradation of contaminants or improvement of various physical-chemical soil conditions to stimulate the growth of efficient microorganisms (Wilson and Jones, 1993; MarGesin et al, 2000)
Due to the long aging of soil contaminants, SB was the most effective and robust strategy to reduce TPH (38.2%) over a 60-day period

Summary

Introduction

Total petroleum hydrocarbons are one of the most momentous contaminants in the environment. Considering the harmful effects of crude oil leakage on the region’s ecosystem, it is necessary to remove them from the environment. One of the most effective, low-cost, and applicable techniques to remove contaminants is called bioremediation. Solving the contamination problem has attracted many researchers’ attention in recent years; the aging of organic contaminants and the successive entry of petroleum hydrocarbons into the soil have been less discussed and investigated. Numerous studies have reported using different bioremediation strategies in petroleum-contaminated soils, each of which presenting different results. Liu et al (2011) said bioaugmentation as a superior strategy, while in another study, Wu et al (2019) considered biostimulation a preferable approach. In other researchers’ works, the combined bioaugmentation and biostimulation has been proposed as the most efficient strategy (Varjani and Upasani, 2019)

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