Biodegradation Of Total Petroleum Hydrocarbons Research Articles

Reduction of the soil environmental impact caused by the presence of total petroleum hydrocarbons (TPH) by using Pseudomonas sp.

This research focuses on the bioaugmentation with Pseudomonas sp. (native) and Pseudomonas aeruginosa (commercial) for the biodegradation of total petroleum hydrocarbons (TPH) of the environmental soil samples of the AqLab laboratory in Orellana, Ecuador. Two treatments of sterilized soil (one inoculated with the native strain and the other inoculated with the commercial strain), where used for physical- -chemical analyzes as well as the degradation of TPH. They were evaluated every 20 days for a total period of 80–100 days. The native bacterium was isolated from the laboratory agglomerates in a selective culture medium specific for Pseudomonas sp. The biodegradation of the TPH exhibited a positive result after 80 and 100 days of treatment, with a reduction of 84 and 96% of initial TPH after the bacterial inoculation. The comparison between the two strains evaluated, commercial and native, showed a greater efficiency of biodegradation by the native strain isolated directly from the agglomerates, suggesting working with native strains of the place that have a greater adaptability to the contaminated environment that would ensure bioremediation processes faster and more efficient, low cost and environmentally friendly.

Evaluation of the Effectiveness of the Biopreparation in Combination with the Polymer γ-PGA for the Biodegradation of Petroleum Contaminants in Soil.

Biodegradation is a method of effectively removing petroleum hydrocarbons from the natural environment. This research focuses on the biodegradation of aliphatic hydrocarbons, monoaromatic hydrocarbons such as benzene, toluene, ethylbenzene, and all three xylene isomers (BTEX) and polycyclic aromatic hydrocarbons (PAHs) as a result of soil inoculation with a biopreparation A1 based on autochthonous microorganisms and a biopreparation A1 with the addition of γ-PGA. The research used biopreparation A1 made of the following strains: Dietzia sp. IN133, Gordonia sp. IN138 Mycolicibacterium frederiksbergense IN53, Rhodococcus erythropolis IN119, Rhodococcus sp. IN136 and Pseudomonas sp. IN132. The experiments were carried out in laboratory conditions (microbiological tests, respirometric tests, and in semi-technical conditions (ex-situ prism method). The biodegradation efficiency was assessed on the basis of respirometric tests, chromatographic analyses and toxicological tests. As a result of inoculation of AB soil with the biopreparation A1 within 6 months, a reduction of total petroleum hydrocarbons (TPH) (66.03%), BTEX (80.08%) and PAHs (38.86%) was achieved and its toxicity was reduced. Inoculation of AB soil with the biopreparation A1 with the addition of γ-PGA reduced the concentration of TPH, BTEX and PAHs by 79.21%, 90.19%, and 51.18%, respectively, and reduced its toxicity. The conducted research has shown that the addition of γ-PGA affects the efficiency of the biodegradation process of petroleum pollutants, increasing the degree of TPH biodegradation by 13.18%, BTEX by 10.11% and PAHs by 12.32% compared to pure biopreparation A1.

A highly efficient method with low energy and water consumption in biodegradation of total petroleum hydrocarbons of oily sludge

The hydrocarbons in petroleum sludge are environmental pollutants. It is crucial to eliminate this type of pollution. In this study, a comprehensive and operational study has been conducted on the total petroleum hydrocarbons (TPH) biodegradation in oily sludge. The experiments were performed in a semi-solid phase by two degrader bacterium, Arthrobacter citreus and Rhodococcus jostii, and they were compared with the slurry phase. Solid samples were prepared in three mixing modes of oily sludge with clay. Experiments were conducted by semi-solid bioreactors and other methods on samples contaminated with petroleum hydrocarbons. The performance of the semi-solid bioreactor for the removal of clay-free oily sludge samples showed the best results, in which biodegradation of TPH was 90.33%. GC analyses were conducted on samples before and after biodegradation. It was observed that the contaminants were decomposed uniformly by the microorganisms, except for a combination with a large peak in 12 min. For the best case, the GC-MS test was performed before and after biodegradation. Compounds with a high concentration in the sludge were significantly reduced. Only one heavy aromatic compound was detected in 51.628 min, which decomposed quite slowly and produced a large peak. It was found that 78.2% of the compounds were removed completely.

Enhanced biodegradation of total petroleum hydrocarbons by implementing a novel two-step bioaugmentation strategy using indigenous bacterial consortium

In the present study, a two-step bioaugmentation strategy (TSBS) was implemented by using indigenous bacterial consortium to enhance the degradation of total petroleum hydrocarbons (TPH) from petroleum refinery sludge (PRS). A bacterial consortium was developed using four indigenous isolated strains, Dietzia sp. IRB191, Dietzia sp. IRB192, Staphylococcus sp. BSM19 and Stenotrophomonas sp. IRB19 from PRS. The optimum conditions of pH, temperature, and sludge concentration were 7, 34 °C, and 2% (w/v), respectively, for maximum TPH degradation, obtained using one variable at a time approach. Under the optimal culture conditions, the developed consortium was inoculated twice to the culturing medium, at the beginning (0th day) and again on the 10th day for implementing a novel TSBS. The maximum TPH degradation of 91.5 ± 2.28% was found with TSBS, which was 1.18 times higher than that of SSBS (77.3 ± 2.6%) in 15 days of incubation. GC-FID study also confirmed that the TPH present in the PRS was effectively degraded by the bacterial consortium with TSBS. The TPH degradation by using TSBS proceeded according to the first-order kinetics with a rate constant of 0.155 d−1. Hence, biodegradation using a TSBS can be considered an effective and eco-friendly process for safe disposal of petroleum refinery sludge.

Bio-remediation of crude oil contaminated soil using recombinant native microbial strain

The manufacture, carriage, refining, and storage of crude oil are several surface and subsurface soil pollution sources. In crude oil handling operations, there is a significant number of polluted sites worldwide. This research was performed on trays with particular prominence in the biodegradation of n-alkanes to biodegrade artificially produced oil-polluted soil by microorganic strains. Two native isolates from five isolates were selected for preliminary oil degradation potential study. Previously microbial strains are isolated from crude oil contaminated soil collected from nearby oil well areas in Thiruvarur district, Tamil Nadu state, India. One promising isolate among the two microbial strains is selected for recombinant progression after completing the recombinant process. The wild and recombinant microbial strain was inoculated in the soil at ambient conditions for 42 days with different oil concentrations of 0.5%, 1%., 3%, and 5%. The total petroleum hydrocarbon (TPH) analysis has been quantitatively tracked. The biodegradation process is monitored by a gas chromatographic–mass spectrometer (GC–MS) analysis. Following 42 days of incubation, the findings showed a higher TPH biodegradation performance of the recombinant microbial strain than that of the wild microbial strain. The recombinant microbial strain showed total normal alkanes degradation significantly. This work will untie a new corridor of bioremediation of crude oil contaminated soil using recombinant microbial strain. • A detailed study on oil contamination caused by the spillage in oil drilling stations in Cauvery delta region. • Bio-remediation and microbial and molecular techniques have been discussed thoroughly. • Pseudomonas guguanensis bacteria were isolated in Indian hydrocarbon contaminated soil. • Biodegradation and evaluation of hydrocarbon in contaminated soil are experimentally studied. • Recombinant strain biodegradation potential is high compared to native microorganisms.

Reactivation of aerobic granular sludge for the treatment of industrial shipboard slop wastewater: Effects of long-term storage on granules structure, biofilm activity and microbial community

This work reports on reactivation of aerobic granular sludge (AGS) for the treatment of industrial recalcitrant wastewater (slop wastewater) characterized by high salinity and hydrocarbons. AGS were reactivated in two reactors, R1 and R2, to treat industrial slop wastewater after a long-term storage for 12-months at 4 °C. In R1, salt-adapted mature aerobic granules were previously subjected to a step-wise increase of hydrocarbons, whereas in R2 aerobic granules were previously cultivated in presence of salinity and hydrocarbons. After a short-term reactivation period, the slop dosage caused a simultaneous decrease of granules dimensions and proteins/polysaccharides (PN/PS) ratio down to 1.76 (R1) and 2.35 (R2). Then, the increase of granules dimensions and of the PN/PS ratio up to 5.63 (R1) and 4.22 (R2), suggested a new granulation process. The difference in total petroleum hydrocarbons (TPHs) removal efficiencies (≈87 % R1, and ≈97 % R2) was mainly due to a biodegradation effect in R2 where granules were previously cultivated with slop. This was confirmed by a simultaneous decrease of TPHs concentration in the bulk and adsorbed into granules. Based on Next Generation Sequencing of metagenomic 16S encoding genes, in R2 typical oil-polluted seawater-associated bacteria were detected, which probably played key roles in TPHs biodegradation.

Remediation of weathered diesel-oil contaminated soils using biopile systems: An amendment selection and pilot-scale study

Weathered diesel oil (WDO) has less biodegradable and volatile characteristics, and its bioremediation could be a challenge. In this study, the effectiveness of enhanced bioremediation via biopile processes for the cleanup of WDO-contaminated soils was evaluated. Six biopiles were constructed and operated with the following six different amendments addition: red bran (12 kg), water-soluble fertilizer (20 L/week), highly oxygenated water (20 L/d, dissolved oxygen = 25 mg/L), petroleum hydrocarbon-degrading bacterial culture (20 L/week), mixture of the above amendments, and natural attenuation (no amendment). Each biopile contained 5 m3 [2.5 m (L) × 2 m (W) × 1 m (H)] of WDO-contaminated soils [initial total petroleum hydrocarbon (TPH) concentrations = 3015 to 3785 mg/kg]. Soils were mixed with amendments and tilled for air supplement twice a week with soil moisture around 25%. Metagenomics analyses were applied to determine the microbial biodiversity and strains responsible for hydrocarbon biodegradation. Results show that the biopile system with mixed supplements (mixture group) had the highest TPH removal efficiency (79% of TPH removal) followed by red bran addition group with a removal efficiency of approximately 73% during the 42-day operation. The first-order TPH decay rates in mixture and red bran biopiles were around 3.2 × 10−2 1/d, which was 4.8 times higher than that obtained from natural attenuation biopile. Biopiles with red bran and mixture supplements contained carbon substrates and nutrients, which could effectively activate microbial activities and accelerate the TPH biodegradation. High carbon number compounds (C > 20) in WDO could be biodegraded within 24 days in the biopile with mixed amendments. Results from metagenomics study indicate that Sphingomonas and Pseudomonas might cause removal of heavy components (C24–30) and light components of petroleum hydrocarbons (C10–16), respectively.

Bioaugmentation of Native Fungi, an Efficient Strategy for the Bioremediation of an Aged Industrially Polluted Soil With Heavy Hydrocarbons.

The concurrence of structurally complex petroleum-associated contaminants at relatively high concentrations, with diverse climatic conditions and textural soil characteristics, hinders conventional bioremediation processes. Recalcitrant compounds such as high molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) and heavy alkanes commonly remain after standard soil bioremediation at concentrations above regulatory limits. The present study assessed the potential of native fungal bioaugmentation as a strategy to promote the bioremediation of an aged industrially polluted soil enriched with heavy hydrocarbon fractions. Microcosms assays were performed by means of biostimulation and bioaugmentation, by inoculating a defined consortium of six potentially hydrocarbonoclastic fungi belonging to the genera Penicillium, Ulocladium, Aspergillus, and Fusarium, which were isolated previously from the polluted soil. The biodegradation performance of fungal bioaugmentation was compared with soil biostimulation (water and nutrient addition) and with untreated soil as a control. Fungal bioaugmentation resulted in a higher biodegradation of total petroleum hydrocarbons (TPH) and of HMW-PAHs than with biostimulation. TPH (C14-C35) decreased by a 39.90 ± 1.99% in bioaugmented microcosms vs. a 24.17 ± 1.31% in biostimulated microcosms. As for the effect of fungal bioaugmentation on HMW-PAHs, the 5-ringed benzo(a)fluoranthene and benzo(a)pyrene were reduced by a 36% and 46%, respectively, while the 6-ringed benzoperylene decreased by a 28%, after 120 days of treatment. Biostimulated microcosm exhibited a significantly lower reduction of 5- and 6-ringed PAHs (8% and 5% respectively). Higher TPH and HMW-PAHs biodegradation levels in bioaugmented microcosms were also associated to a significant decrease in acute ecotoxicity (EC50) by Vibrio fischeri bioluminiscence inhibition assays. Molecular profiling and counting of viable hydrocarbon-degrading bacteria from soil microcosms revealed that fungal bioaugmentation promoted the growth of autochthonous active hydrocarbon-degrading bacteria. The implementation of such an approach to enhance hydrocarbon biodegradation should be considered as a novel bioremediation strategy for the treatment of the most recalcitrant and highly genotoxic hydrocarbons in aged industrially polluted soils.

Improved Delivery of Remedial Agents Using Surface Foam Spraying with Vertical Holes into Unsaturated Diesel-Contaminated Soil for Total Petroleum Hydrocarbon Removal

Surface foam spraying technologies, employing natural infiltration processes, have recently been suggested to not disturb or mix contaminated soils. However, effective delivery of reactive remedial agents to the bottom area of a contaminated region using only natural infiltration processes can be a challenge. This study aimed to improve the delivery of remedial agents such as oxidants, microorganisms, and nutrients to all depths of 30 cm thick unsaturated diesel-contaminated soil using small vertical soil holes. Three vertical holes, occupying 0.8% of the total soil volume and 3% of the soil surface area, were made inside the 17.3 kg soil column. Persulfate oxidation foam and subsequent bioaugmentation foam spraying were applied for remediation of contaminated soil. Foam spraying with vertical soil holes improved the uniformity of distribution of remedial agents throughout the soil, as evidenced by the uniform pH, higher volumetric soil water content, and a microbial population of >107 CFU/g. Therefore, the total petroleum hydrocarbon (TPH) removal efficiency (88–90%) from bottom soils was enhanced compared to soil columns without holes (72–73%) and the control test (5–9%). The kinetic study revealed that relatively similar TPH biodegradation rates (0.054–0.057 d−1) can be obtained for all soil depths by using this new and simple approach.

Insights into Bacterial Community Involved in Bioremediation of Aged Oil-Contaminated Soil in Arid Environment.

Soil contamination by hydrocarbons due to oil spills has become a global concern and it has more implications in oil producing regions. Biostimulation is considered as one of the promising remediation techniques that can be adopted to enhance the rate of degradation of crude oil. The soil microbial consortia play a critical role in governing the biodegradation of total petroleum hydrocarbons (TPHs), in particular polycyclic aromatic hydrocarbons (PAHs). In this study, the degradation pattern of TPHs and PAHs of Kuwait soil biopiles was measured at three-month intervals. Then, the microbial consortium associated with oil degradation at each interval was revealed through 16S rRNA based next generation sequencing. Rapid degradation of TPHs and most of the PAHs was noticed at the first 3 months of biostimulation with a degradation rate of pyrene significantly higher compared to other PAHs counterparts. The taxonomic profiling of individual stages of remediation revealed that, biostimulation of the investigated soil favored the growth of Proteobacteria, Alphaprotobacteria, Chloroflexi, Chlorobi, and Acidobacteria groups. These findings provide a key step towards the restoration of oil-contaminated lands in the arid environment.

Biodegradation of total petroleum hydrocarbons in oily sludge: a comparative study of biostimulation, bioaugmentation, and combination of methods

AbstractBACKGROUNDOne of the major parts of global environmental pollution is petroleum‐derived products. The purpose of this study was the biodegradation of total petroleum hydrocarbons (TPH) in oily sludge using biostimulation and bioaugmentation methods. The oily sludge was dredged from the bottoms of kerosene and oil gas storage tanks, and it was characterized according to American Society for Testing and Materials D1796 and the CHNS (equipment for determination Carbon, Hydrogen, Nitrogen and Sulfour) elements analysis. The TPH biodegradation potential of the indigenous bacteria in the oily sludge was investigated via biostimulation applying mineral salt medium(N). Besides it was compared with bioaugmentation with two oil degrader bacterium, namely Arthrobacter citreus (strain E) and Rhodococcus jostii (strain D), being separated from the oil‐contaminated soil. The gravimetric and GC (Gas Chromatography) methods were used for TPH removal assays.RESULTSThe results indicated that the biodegradation efficiency was dependent on treatment time and microbial species. Increasing pH and TPH biodegradation % for samples were observed over time. The highest removal degradations of hydrocarbons (75.1%) was reported using the inoculum mixture of strains D & E (pH = 7.02) at the 5th week.CONCLUSIONThis method could be used for bioremediation purposes at petroleum hydrocarbon‐contaminated sites as a biological technique. © 2020 Society of Chemical Industry

Treatment of petroleum refinery sludge by petroleum degrading bacterium Stenotrophomonas pavanii IRB19 as an efficient novel technology

Petroleum hydrocarbons (PHCs) in petroleum refinery sludge (PRS) are the most adverse components because of their toxic nature, which are harmful to human health and the aquatic ecosystem. This study aimed to identify and characterize an indigenous bacterium isolated from PRS of Indian oil corporation ltd. (IOCL), Haldia, India, and evaluate its performance for biodegradation of total petroleum hydrocarbon (TPH) of PRS. The bacterium molecularly characterized as Stenotrophomonas sp. IRB19 by 16S rRNA sequencing and phylogenetic analysis. The strain IRB19 showed a significant ability to utilize four different oils (kerosene, diesel, petrol and hexadecane) in-vitro. IRB19 could able to degrade up to 65 ± 2.4% of TPH in 28 d of incubation. Solvent extraction study showed that PRS contain 180.57 ± 3.44 g kg−1 of TPH and maltene fraction composed of aliphatic, aromatics and polar components of 52 ± 4, 39 ± 2 and 9 ± 1%, respectively. The TPH degradation best fitted for the Gompertz model and followed the first-order kinetics having the rate constant (k) and half-life period (t 1/2) of 0.036 d−1 and 19 d, respectively. Results of this study verified the suitability of the novel strain IRB19 for the biodegradation of PHCs.

Bioremediation Strategy Based on Risk Assessment of Exposure to Residual Polycyclic Aromatic Hydrocarbons

In this study, application of risk assessment was the basis for the selection of an optimum treatment option for the potential bioremediation of a hydrocarbon polluted environment. This approach was applied in a hydrocarbon polluted swampy terrain in the Niger Delta of Nigeria and could actually be applied to any other hydrocarbon polluted environment. Three nutrient sources namely compost, liquid organic fertilizer and NPK were employed in the laboratory biostimulation of the biodegradation of the hydrocarbons experiments using three levels of concentration for each nutrient as 5, 10 and 20% (w/w). Total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbons (PAH) were the analytes used in assessing the biodegradation potential of the various treatments. The residual concentration of these analytes post biodegradation was measured by means of gas chromatography-flame ionization detector and gas chromatography-mass spectrometry. Results indicate that compost and liquid organic fertilizer at 5% (w/w) were very poor in biostimulating the biodegradation of the hydrocarbons (less than 20% biodegradation of TPH and 3–30% biodegradation of the PAHs). NPK performed better than the other two sources of nutrients as it effected 74–84% TPH biodegradation and 39–90% PAHs biodegradation.On screening the three NPK treatment options using risk assessment, the 5% w/w NPK treatment option was rejected as its associated residual PAHs posed risks that exceeded the risk threshold of 10^-6 whereas the other two (10 and 20% w/w NPK) were successful with risk values less than the threshold. However, the 10% w/w NPK treatment offers a cheaper option between the two hence it is selected as the optimum bioremediation option based on risk management.

Formulation of Bio-Based Washing Agent and Its Application for Removal of Petroleum Hydrocarbons From Drill Cuttings Before Bioremediation.

Drill cuttings from petroleum exploration and production sites can cause diverse environmental problems. Total petroleum hydrocarbons (TPHs) are a major pollutant from the use of polyolefin-based mud. As an alternative to incineration, this study investigated the application of surfactant-enhanced washing technology prior to bioremediation. The washing step was necessary because the initial TPH concentrations were quite high at approximately 15% (w/w). Washing agents were formulated by varying the concentration of lipopeptide biosurfactant (in foamate or cell-free broth), Dehydol LS7TH (fatty alcohol ethoxylate 7EO, oleochemical surfactant) and butanol (as a lipophilic linker) at different salinities. The most efficient formula produced a Winsor Type I microemulsion (oil-in-water microemulsion) with polyolefin and contained only 20% (v/v) foamate and 2% (v/v) Dehydol LS7TH in water. Due to the synergistic behavior between the anionic lipopeptides and non-ionic Dehydol LS7TH, the formula efficiently removed 92% of the TPHs from the drill cuttings when applied in a jar test. To reduce the cost, the concentrations of each surfactant should be reduced; thus, the formula was optimized by the simplex lattice mixture design. In addition, cell-free broth, at a pH of 10, containing 3.0 g/L lipopeptides was applied instead of foamate because it was easy to prepare. The optimized formula removed 81.2% of the TPHs and contained 72.0% cell-free broth and 1.4% Dehydol LS7TH in water. A 20-kg soil washing system was later tested where the petroleum removal efficiency decreased to 70.7% due to polyolefin redeposition during separation of the washing solution. The remaining TPHs (4.5%) in the washed drilled cuttings were further degraded by a mixture of Marinobacter salsuginis RK5, Microbacterium saccharophilum RK15 and Gordonia amicalis JC11. To promote TPH biodegradation, biochar and fertilizer were applied along with bacterial consortia in a microcosm experiment. After 49-day incubation, the TPHs were reduced to 0.9% by both physical and biological mechanisms, while the TPHs in the unamended samples remained unaffected. With the use of the formulated bio-based washing agent and bioremediation approach, the on-site treatment of drill cuttings could be conducted with an acceptable cost and low environmental impacts.

Kinetic Monitoring of Bioremediators for Biodegradation of Gasoil-Polluted Soil

In the present study, total petroleum hydrocarbon biodegradation by wheat straw biochar and active carbon (TPH) was investigated in gasoil-polluted soil around oil refinery of Shiraz, Iran. The experiment was conducted as split-split-plot in time based on completely randomized design with three replications. Various weights of biochar and active carbon (0, 20, 40, 60, 80, and 100 g kg−1) were assigned to main plots, whereas particle sizes (1–2 mm for biochar and 0.05–2.05 mm for active carbon) were assigned to subplots, and the effects were monitored weekly. Biodegradation constant (K) for active carbon ranged from 0.0139 to 0.0328 day−1, whereas it varied from 0.0145 to 0.0369 day−1 for biochar. Also, this value was 0.0088 for control soil. Half-life for control soil was 78.7 days, which decreased as result of applying various size and weights of active carbon (21.13–49.8 days) and biochar (18.7–47.8 days). Thus, the technology used in this study provides a cheap, efficient, and environment friendly method which may be successfully applied in gasoil-polluted soils to enhance the environment for plants and soil microorganisms.

Biodegradation of total petroleum hydrocarbons in contaminated soils using indigenous bacterial consortium

Background: Biodegradation of hydrocarbon compounds is a great environmental concern due to their toxic nature and ubiquitous occurrence. In this study, biodegradation potential of oily soils was investigated in an oil field using indigenous bacterial consortium. Methods: The bacterial strains present in the contaminated and non-contaminated soils were identified via DNA extraction using 16S rDNA gene sequencing during six months. Furthermore, total petroleum hydrocarbons (TPH) were removed from oil-contaminated soils. The TPH values were determined using a gas chromatograph equipped with a flame ionization detector (GC-FID). Results: The bacterial consortium identified in oil-contaminated soils (case) belonged to the families Halomonadaceae (91.5%) and Bacillaceae (8.5%), which was significantly different from those identified in non-contaminated soils (control) belonging to the families Enterobacteriaceae (84.6%), Paenibacillaceae (6%), and Bacillaceae (9.4%). It was revealed that the diversity of bacterial strains was less in oil-contaminated soils and varied significantly between case and control samples. Indigenous bacterial consortium was used in oil-contaminated soils without need for amplification of heterogeneous bacteria and the results showed that the identified bacterial strains could be introduced as a sufficient consortium for biodegradation of oil-contaminated soils with similar texture, which is one of the innovative aspects of this research. Conclusion: An oil-contaminated soil sample with TPH concentration of 1640 mg/kg was subjected to bioremediation during 6 months using indigenous bacterial consortium and a TPH removal efficiency of 28.1% was obtained.

Biodegradation of Total Petroleum Hydrocarbons in Soil: Isolation and Characterization of Bacterial Strains from Oil Contaminated Soil

In this study, we isolated seven strains (termed BY1–7) from polluted soil at an oil station and evaluated their abilities to degrade total petroleum hydrocarbons (TPHs). Following 16 rRNA sequence analysis, the strains were identified as belonging to the genera Bacillus, Acinetobacter, Sphingobium, Rhodococcus, and Pseudomonas, respectively. Growth characterization studies indicated that the optimal growth conditions for the majority of the strains was at 30 °C, with a pH value of approximately 7. Under these conditions, the strains showed a high TPH removal efficiency (50%) after incubation in beef extract peptone medium for seven days. Additionally, we investigated the effect of different growth media on growth impact factors that could potentially affect the strains’ biodegradation rates. Our results suggest a potential application for these strains to facilitate the biodegradation of TPH-contaminated soil.

Biochar amendment as a remediation strategy for surface soils impacted by crude oil

The impact of organic bulking agents on the biodegradation of petroleum hydrocarbons in crude oil impacted soils was evaluated in batch laboratory experiments. Crude oil impacted soils from three separate locations were amended with fertilizer and bulking agents consisting of biochars derived from walnut shells or ponderosa pine wood chips produced at 900 °C. The batch reactors were incubated at 25 °C and sampled at pre-determined intervals to measure changes in total petroleum hydrocarbons (TPH) over time. For the duration of the incubation, the soil moisture content was adjusted to 75% of the maximum water holding capacity (MWHC) and prior to each sampling event, the sample was manually stirred. Results show that the addition of fertilizer and bulking agents increased biodegradation rates of TPH. Soil samples amended with ponderosa pine wood biochar achieved the highest biodegradation rate, whereas the walnut shell biochar was inhibitory to TPH biodegradation. The beneficial impact of biochars on TPH biodegredation was more pronounced for a soil impacted with lighter hydrocarbons compared to a soil impacted with heavier hydrocarbons. This study demonstrates that some biochars, in combination with fertilizer, have the potential to be a low-technology and eco-friendly remediation strategy for crude oil impacted soils.

Evaluation of accelerated biodegradation of oil-SPM aggregates (OSAs)

The studies of the formation of oil-Suspended Particulate Matter (SPM) aggregates (OSAs) have advanced significantly in the scientific community, however there is a need to accelerate oil biodegradation that was dispersed by the formation of OSAs. The present research presents a pioneering character regarding the addition of nutrients as biostimulus for autochthonous hydrocarboclastic bacteria in the biodegradation of Total Petroleum Hydrocarbons (TPH) dispersed by the formation of OSAs. Water aliquots were taken over 60 days from eight bioreactors to perform ionic species analysis, pH, salinity and temperature monitoring, liquid/liquid extraction, serial dilution methodology and filter membrane. TPH quantification was performed on the gas chromatograph with a flame ionisation detector (GC-FID). The addition of nutrients contributed positively to the rate and extent of biodegradation of TPH in association with field-collected SPM. The best result found was with the lowest nutrient concentration (Bio 1) with an average of 98.65% of TPH reduction.

Assessment of Biodegradation Efficiency of Polychlorinated Biphenyls (PCBs) and Petroleum Hydrocarbons (TPH) in Soil Using Three Individual Bacterial Strains and Their Mixed Culture.

Biodegradation is one of the most effective and profitable methods for the elimination of toxic polychlorinated biphenyls (PCBs) and total petroleum hydrocarbons (TPH) from the environment. In this study, aerobic degradation of the mentioned pollutants by bacterial strains Mycolicibacterium frederiksbergense IN53, Rhodococcus erythropolis IN129, and Rhodococcus sp. IN306 and mixed culture M1 developed based on those strains at 1:1:1 ratio was analyzed. The effectiveness of individual strains and of the mixed culture was assessed based on carried out respirometric tests and chromatographic analyses. The Rhodococcus sp. IN306 turned out most effective in terms of 18 PCB congeners biodegradation (54.4%). The biodegradation index was decreasing with an increasing number of chlorine atoms in a molecule. Instead, the Mycolicobacterium frederiksbergense IN53 was the best TPH degrader (37.2%). In a sterile soil, contaminated with PCBs and TPH, the highest biodegradation effectiveness was obtained using inoculation with mixed culture M1, which allowed to reduce both the PCBs (51.8%) and TPH (34.6%) content. The PCBs and TPH biodegradation capacity of the defined mixed culture M1 was verified ex-situ with prism method in a non-sterile soil polluted with aged petroleum hydrocarbons (TPH) and spent transformer oil (PCBs). After inoculation with mixed culture M1, the PCBs were reduced during 6 months by 84.5% and TPH by 70.8% as well as soil toxicity was decreased.