Evaluation of Biodegradation of BTEX in the Subsurface of a Petrochemical Site near the Yangtze River, China

Abstract

The contamination of soil and groundwater with BTEX (benzene, toluene, ethyl benzene, and xylenes) is a common issue at petrochemical sites, posing a threat to the ecosystems and human health. The goal of this study was to evaluate the biodegradation of BTEX in the subsurface of a petrochemical site near the Yangtze River, thus providing scientific basis for bioremediation of the contaminated site. Both molecular analysis of field samples and microcosm study in the laboratory were performed for the evaluation. Soil and groundwater samples were collected from the site. Microcosms were constructed with inoculum from the soil and incubated anaerobically in the presence of nitrate, ferric oxide, manganese oxide, sulfate, and sodium bicarbonate, respectively. The initial concentration of each component of BTEX (benzene, toluene, ethyl benzene, o-xylene) was 4–5 mg/L. Actinobacteria was dominant in the highly contaminated soil, while Proteobacteria was dominant in the slightly contaminated soil and the groundwater. The relative abundances of Firmicutes, Spirochaetes, and Caldiserica were higher in the highly contaminated soil and groundwater samples compared to those in the corresponding slightly contaminated samples. The relative abundances of predicted functions, such as carbohydrate transport and metabolism, nucleotide transport and metabolism, coenzyme transport and metabolism, amino acid transport and metabolism, etc., in the highly contaminated soil and groundwater samples were higher than those in the corresponding slightly contaminated samples. In microcosms, biodegradations of BTEX occurred, and the first-order rate constants in the presence of various electron acceptors had the following order: sulfate (0.08–0.10/d) > sodium bicarbonate (0.07–0.09/d) > ferric oxide (0.04–0.06/d) > nitrate (0.03–0.05/d) > manganese oxide (0.01–0.04/d).

Bioremediation of contaminated soil and groundwater by in situ biostimulation

“…Aerobic degradation is often more efficient than anaerobic (Tarasov et al, 2004;Kauppi et al, 2011), encouraging the addition of oxygen as a gas straight into the soil or the aquatic phase (Penttinen, 2001), or as a breakdown product of chemicals such as peroxide, persulfate, ozone or permanganate (Tarasov et al, 2004;Goi et al, 2006;Yen et al, 2011;Nykänen et al, 2012;Simpanen et al, 2016a;Bajagain et al, 2018Bajagain et al, , 2020b. The dissolvability of oxygen is comparatively low; alternatives like nitrate and sulfate sidestep this problem but come with a heightened risk of groundwater pollution (Chen et al, 2022).…”

“…The benefits of using nitrate as the nitrogen source are that it can also function as an electron acceptor (Kim et al, 2013;Chen et al, 2022) and is readily soluble in water as opposed to gaseous oxygen.…”

Influence of Environmental Exposure to Steel Waste on Endocrine Dysregulation and PER3 Gene Polymorphisms

“…Such industrial waste pollutes the soil, air, surface and groundwater, and food, posing a health risk to those who are exposed. This is because these contaminants can harm many organs and systems, including the endocrine system, and thus affect their biological functions [ 4 , 13 , 14 , 15 , 16 ].…”

Field investigations and reactive transport modelling of biodegrading coal tar compounds at a complex former manufactured gas plant

“…Contamination with hydrocarbons has been associated with an increase of members belonging to Proteobacteria [10]. Chen et al ( 2022) reported some indigenous microorganisms coming from polluted groundwater or soil, such as Actinobacteria, Proteobacteria and some members of Actinomycetota such as Rhodococcus and Arthrobacter strains to have high BTEX degradation activity in their study [54]. Outcomes of this study showed that the highest relative abundance of Proteobacteria was observed in the BTEX mixture and the lowest in BTEXIeIaN.…”

“…Following the argument above, we report on the iron and sulphate reducing rates found for all species, even when in this Chapter only the rates given for benzene, naphthalene, ethylbenzene (used for the lumped MAH) and 1-methyl-naphthalene (used for the lumped PAH) are used. Hydrocarbon degradation rates under iron and sulphate reducing conditions in literature vary greatly [54,184,274]. Values for the BTEX compounds were taken from a review study by Suarez and Rifai (1999) [274].…”