Search

Abstract: An ultrasound-enhanced elution system employing water at a temperature of 70°C was used to remedy weathered soils contaminated with severely biodegraded heavy oil (SBHO). The effect of varying the ultrasonic irradiation time from 0 to 1800s on the elution of SBHO and three characteristic biomarkers (C26–34 17α 25-norhopanes, C26–28 TAS, and C27–29 MTAS) was analyzed using GC/MS, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Elution of the three biomarkers was closely related to the carbon number of the marker. C26–34 17α 25-norhopanes and C26–28 TAS species with higher carbon numbers and C27–29 MTAS species with lower carbon numbers were more readily eluted using sonication times of 1080–1800s, while smaller TAS homologs were more readily eluted after sonication times of 0–360s. SEM images of samples treated for longer periods revealed larger “bare patches” on the soil surface. The results of XRD and energy spectroscopy experiments indicated that ultrasound irradiation for 1080s negatively affected the deposition of CaCO3, but overall improved the mineral and chemical compositions of treated soils and removal of SBHO. [Copyright &y& Elsevier]

The widely applied aromatic nitration in modern industry leads to toxic p -nitrophenol (PNP) in environment. Exploring its efficient degradation routes is of great interests. In this study, a novel four-step sequential modification procedure was developed to increase the specific surface area, functional group, hydrophilicity, and conductivity of carbon felt (CF). The implementation of the modified CF promoted reductive PNP biodegradation, attaining 95.2 ± 0.8% of removal efficiency with less accumulation of highly toxic organic intermediates (e.g., p -aminophenol), compared to carrier-free and CF-packed biosystems. The constructed anaerobic-aerobic process with modified CF in 219-d continuous operation achieved further removal of carbon and nitrogen containing intermediates and partial mineralization of PNP. The modified CF promoted the secretion of extracellular polymeric substances (EPS) and cytochrome c (Cyt c), which were essential components to facilitate direct interspecies electron transfer (DIET). Synergistic relationship was deduced that glucose was converted into volatile fatty acids by fermenters (e.g., Longilinea and Syntrophobacter), which donated electrons to the PNP degraders (e.g., Bacteroidetes_vadinHA17) through DIET channels (CF, Cyt c, EPS) to complete PNP removal. This study proposes a novel strategy using engineered conductive material to enhance the DIET process for efficient and sustainable PNP bioremediation. [Display omitted] • Four-step sequential modification for carbon felt (CF) was conducted. • Modified CF promoted PNP biodegradation, with less accumulation of PAP. • DIET was enhanced between fermenters and PNP degraders. • Contents of EPS and Cyt c facilitating DIET increased. [ABSTRACT FROM AUTHOR]