Field Test of In Situ Groundwater Treatment Applying Oxygen Diffusion and Bioaugmentation Methods in an Area with Sustained Total Petroleum Hydrocarbon (TPH) Contaminant Flow

Contamination of groundwater by petroleum hydrocarbons is a widespread environmental problem in many regions. Contamination of unsaturated and saturated zones could also pose a significant risk to human health. The main purpose of the study was to assess the efficiency of biodegradation of total petroleum hydrocarbon (TPH) in situ, in an area with loam and sandy loam soils, and to identify features and characteristics related to groundwater treatment in an area with a persistent flow of pollutants. We used methods of biostimulation (oxygen as stimulatory supplement) and bioaugmentation to improve water quality. Oxygen was added to the groundwater by diffusion through silicone tubing. The efficiency of groundwater treatment was determined by detailed monitoring. Implementation of the applied measure resulted in an average reduction in TPH concentration of 73.1% compared with the initial average concentration (4.33 mg/L), and in the local area, TPH content was reduced by 95.5%. The authors hope that this paper will contribute to a better understanding of the topic of groundwater treatment by in situ biodegradation of TPH. Further studies on this topic are particularly needed to provide more data and details on the efficiency of groundwater treatment under adverse geological conditions.

Genetic and Comparative Genome Analysis of Exiguobacterium aurantiacum SW-20, a Petroleum-Degrading Bacteria with Salt Tolerance and Heavy Metal-Tolerance Isolated from Produced Water of Changqing Oilfield, China

The genome of Exiguobacterium aurantiacum SW-20 (E. aurantiacum SW-20), a salt-tolerant microorganism with petroleum hydrocarbon-degrading ability isolated from the Changqing Oilfield, was sequenced and analyzed. Genomic data mining even comparative transcriptomics revealed that some genes existed in SW-20 might be related to the salt tolerance. Besides, genes related to petroleum hydrocarbon degradation discovered in genomic clusters were also found in the genome, indicating that these genes have a certain potential in the bioremediation of petroleum pollutants. Multiple natural product biosynthesis gene clusters were detected, which was critical for survival in the extreme conditions. Transcriptomic studies revealed that some genes were significantly up-regulated as salinity increased, implying that these genes might be related to the salt tolerance of SW-20 when living in a high salt environment. In our study, gene clusters including salt tolerance, heavy metal tolerance and alkane degradation were all compared. When the same functional gene clusters from different strains, it was discovered that the gene composition differed. Comparative genomics and in-depth analysis provided insights into the physiological features and adaptation strategies of E. aurantiacum SW-20 in the oilfield environment. Our research increased the understanding of niches adaption of SW-20 at genomic level.

Biostimulatory Influence of Biochar on Degradation of Petroleum Hydrocarbon Impacted Soil

Soil pollution caused by petroleum hydrocarbon and its derivatives has become a grave global issue. Physico-chemical techniques are often expensive. However, bioremediation of petroleum hydrocarbon polluted soil is cost-effective. Therefore, the study was carried out to assess the biostimulatory influence of biochar on the degradation of petroleum hydrocarbon impacted soil in NNPC Depot, kano state. Soil samples were randomly collected from the polluted site to obtain a composite sample. About 400 g of the polluted soil was filled into pots and arranged in a 2x2 factorial experiment in a completely randomized design with three replications. Bone and wood char was at 2 levels (0 and 50 g/pot) each. Data were collected on the physicochemical properties (pH, TN, and Av. P) of the soil, Total Petroleum Hydrocarbon (TPH), and bacterial population. Data were analyzed using ANOVA at α0. 05. Results obtained from the study show that biochar application significantly (p<0.05) enhanced TPH degradation and bacterial population in the polluted soil. However, Bone char significantly(p<0.05) enhanced TPH degradation and bacterial population the most compared to wood char. Combined bone and wood char application resulted in significantly (p<0.05) lower residual TPH content in the polluted soil compared to using bone or wood char alone. Thus, bone and wood char should be used in the bioremediation of petroleum hydrocarbon impacted soils.