Total Hydrocarbon Degradation Research Articles

Evaluating Different Soil Amendments as Bioremediation Strategy for Wetland Soil Contaminated by Crude Oil

This study evaluated the efficacy of using Tween 80 surfactant (TW80) and food-waste anaerobic digestate fibre (FWAD) as soil amendments for the remediation of wetlands contaminated by crude oil. A 112-day mesocosms experiment was carried out to simulate hydrocarbon degradation under typical acidified wetland conditions. Soil was spiked with 50,000 mg kg−1 crude oil and TW80 and FWAD were added to mesocosms at 10%, 20% and 30% w/w. The soil basal respiration, microbial community dynamics, environmental stress, alkanes, and PAHs degradation were monitored throughout the mesocosm experiment. Amending the mesocosms with FWAD and TW80 enabled the recovery of the soil microbial activities. This was evidenced by soil basal respiration which was the highest in the 30% FWAD and 30% TW80 mesocosms and translated into increased degradation rate of 32% and 23% for alkanes, and 33% and 26% for PAHs compared to natural attenuation, respectively. Efficient total hydrocarbon degradation was achieved in soil mesocosms with 30% FWAD and 30% TW80 at 90% and 86.8%, respectively after 49 days. Maize seed germination results showed significant improvement from 29% to over 90% following the FWAD and TW80 treatment.

Photocatalytic degradation of hydrocarbons present in water, using Fe (III) modified TiO2

ABSTRACT
 This research work focused on the degradation of total hydrocarbons in synthetic water mixtures and in samples obtained from the inflow of a skimmer (production water) by means of heterogeneous photocatalysis. Titanium dioxide (TiO2) was used, modified with iron oxide (III) as photocatalyst, supported on polymethyl methacrylate plates, arranged in two reactors with volumetric capacities of 15.0 mL and 1.0 L. The degradation process was studied using two analysis methods: Photometric detection and gravimetric partition. Degradation percentages of 91.2% and 98% were obtained in field samples and synthetic mixtures respectively, with 4 h times; this allows for assessment of this technique's impact on the treatment of produced water in the oil industry, seeking for an alternative to the methods for treating water contaminated with hydrocarbons.

Responses of microbial community from northern Gulf of Mexico sandy sediments following exposure to deepwater horizon crude oil

In the present study, microbial community responses to exposure to unweathered Macondo Well crude oil and conventional diesel in a sandy beach environment were determined. Biodegradation was assessed in mesocosm experiments with differing fuel amounts (2,000 and 4,000 mg/kg) and with or without inorganic nutrient amendment. Carbon dioxide production was measured daily for 42 d. Aerobic alkane, total hydrocarbon, and polycyclic aromatic hydrocarbon (PAH) degraders were enumerated in treated and control mesocosms and changes in their abundances were measured weekly. Hydrocarbon mineralization occurred in all treatments. In the inorganic nutrient-amended treatments, the degradation rates were 2.31 and 2.00 times greater in the 2,000 mg/kg diesel and crude oil treatments, respectively, and 3.52 (diesel) and 4.14 (crude) times higher for the fuel types at the 4,000 mg/kg fuel concentrations compared to unamended treatments. Microbial lag phases were short (<3 d) and alkane and total hydrocarbon degrader numbers increased by five orders of magnitude compared to the uncontaminated treatments within 7 d in most treatments. Hydrocarbon degrader numbers in diesel and in crude oil treatments were similar; however, the PAH degraders were more abundant in the crude oil relative to diesel treatment. These findings indicate that hydrocarbon degradation by extant microbial populations in the northern Gulf of Mexico sandy beach environments can be stimulated and enhanced by inorganic nutrient addition.

Seasonal Monitoring of Hydrocarbon Degraders in Alabama Marine Ecosystems Following the Deepwater Horizon Oil Spill

Following the Deepwater Horizon explosion and crude oil contamination of a marsh ecosystem in AL in June 2010, hydrocarbon-degrader microbial abundances of aerobic alkane, total hydrocarbon, and polycyclic aromatic hydrocarbon (PAH) degraders were enumerated seasonally. Surface sediment samples were collected in October and December of 2010 and in April and July of 2011 along 40–70-m transects from the high tide to the intertidal zone including Spartina alterniflora-vegetated marsh, seagrass (Ruppia maritima)-dominated sediments, and nonvegetated sediments. Alkane and total hydrocarbon degraders in the sediment were detected, while PAH degraders were below detection limit at all locations examined during the sampling periods. The highest counts for microbial alkane degraders were observed at the high tide line in April and averaged to 8.65 × 105 of cells/g dry weight (dw) sediment. The abundance of alkane degraders during other months ranged from 9.49 × 103 to 3.87 × 104, while for total hydrocarbon degraders, it ranged between 5.62 × 103 and 1.14 × 105 of cells/g dw sediment. Pore water nutrient concentrations (NH 4 + , NO 3 − , NO 2 − , and PO 4 3− ) showed seasonal changes with minimum values observed in December and April and maximum values in October and July. Concentrations of total petroleum hydrocarbons in sediments averaged 100.4 ± 52.4 and 141.9 ± 57.5 mg/kg in January and July, 2011, respectively. The presence of aerobic microbial communities during all seasons in these nearshore ecosystems suggests that an active and resident microbial community is capable of mineralizing a fraction of petroleum hydrocarbons.

Enhancement of Biodegradation of Crude Petroleum-Oil in Contaminated Water by the Addition of Nitrogen Sources

Addition of nitrogen sources as supplementary nutrient into MSM medium to enhance biodegradation by stimulating the growth four isolates, Acinetobacter faecalis, Staphylococcus sp., Pseudomonas putida and Neisseria elongata isolated from petroleum contaminated groundwater, wastewater aeration pond and biopond at the oil refinery Terengganu Malaysia was investigated. The organic nitrogen sources tested not only supported growth but also enhances biodegradation of 1% Tapis crude oil. All four isolates showed good growth especially when peptone was employed as the organic nitrogen compared to growth in the basal medium. Gas chromatography showed that more then 91, 93, 94 and 95% degradation of total hydrocarbon was observed after 5 days of incubation by isolates Pseudomonas putida, Neisseria elongate, Acinetobacter faecalis and Staphylococcus sp., respectively.

Development of Three Bacteria Consortium for the Bioremediation of Crude Petroleum-oil in Contaminated Water

We have to developed active microbial consortium that could be of higher degradation of crude oil contaminated groundwater, wastewater aeration pond and biopond at the oil refinery Terengganu Malaysia. Among four isolates that showed good growth only three different isolates (Acinetobacter faecalis WD2, Staphylococcus. sp DD3 and Neisseria elongate TDA4.) were selected based on the growth ability and degradation. Significant growth and effectiveness of hydrocarbon biodegradation of the bacterial consortium examined bacterial strains and their mixtures in both were observed after 5, 10 and 15 days of degradation. Gas chromatography showed that more than 96 and 98% degradation of total hydrocarbon by consortia sp respectively.

Biodegradation of Maya crude oil fractions by bacterial strains and a defined mixed culture isolated from Cyperus laxus rhizosphere soil in a contaminated site.

Ten bacterial strains were isolated by enrichment culture, using as carbon sources either aliphatics or an aromatic-polar mixture. Oxygen uptake rate was used as a criterion to determine culture transfer timing at each enrichment stage. Biodegradation of aliphatics (10,000 mg L(-1)) and an aromatic-polar mixture (5000 mg L(-1), 2:1) was evaluated for each of the bacterial strains and for a defined culture made up with a standardized mixture of the isolated strains. Degradation of total hydrocarbons (10,000 mg L(-1)) was also determined for the defined mixed culture. Five bacterial strains were able to degrade more than 50% of the aliphatic fraction. The most extensive biodegradation (74%) was obtained with strain Bs 9A, while strains Ps 2AP and UAM 10AP were able to degrade up to 15% of the aromatic-polar mixture. The defined mixed culture degraded 47% of the aliphatics and 6% of the aromatic-polar mixture. The defined mixed culture was able to degrade about 40% of the aliphatic fraction and 26% of the aromatic fraction when grown in the presence of total hydrocarbons, while these microorganisms did not consume the polar hydrocarbons fraction. The proposed strategy that combines enrichment culture together with oxygen uptake rate allowed the isolation of bacterial strains that are able to degrade specific hydrocarbons fractions at high consumption rates.

Effects of nitrogen limitation on biofilm formation in a hydrocarbon-degrading trickle-bed filter.

The effect of nitrogen limitation on young and mature steady-state biofilm in a trickle-bed filter was studied. Toluene and n-heptane were the sole carbon source. Biomass concentration, respiration, substrate-induced respiration, metabolic quotient, and total hydrocarbon degradation efficiency were measured. The aim of the experiment was to control excess biomass production in the trickle-bed filter by limiting the mineral nutrients and to achieve increased mineralization of the carbon source. Biofilm growth responded strongly to the amount of available nitrogen, whereas hydrocarbon degradation efficiency reached a maximum of 60% and could not be increased even by further addition of nitrogen. The experiments showed that 95% of the adsorbed carbon was mineralized completely and only 5% was used for biofilm formation. This complete mineralization can also be concluded from the metabolic quotient. The value of the latter was about 6-10 mg CO2-C g-1 Cmic h-1, indicating an expanded energy demand due to stress effects in the presence of nutrient deficiency. It was postulated that determination of the metabolic quotient could be an simple instrument to measure the rate of mineralization of carbon sources and also the rate of biomass formation in trickle-bed filters or biofilters.

Effect of chromium and lead on degradation of South Louisiana crude oil in sediment

The effect of chromium (Cr) and lead (Pb) on degradation of South Louisiana Crude oil in sediment collected from a produced water discharge site was measured in laboratory microcosms under oxidized and reduced conditions. Chromium was added to the sediment at rates of 0 to 5,000 μ,g, g‐1 sediment. Lead was added at rates from 0 to 2,500 μ,g, g‐1 sediment. The effect on degradation of alkane petroleum hydrocarbon fractions was determined over time. Metal content had no impact on total hydrocarbon degradation content based on changes in concentration. Even on a percentage basis, which normalizes for differences in hydrocarbon concentrations no statistical influence of Cr (5,000 μ,g, g‐1) and Pb (2,500 μ,g, g‐1) on degradation could be measured under reducing conditions. A more sensitive analysis of metal impact on degradation depicted by an analysis of reduction of selected alkane fractions also showed little effect on degradation. Only degradation of octadecane was shown to be statistically inhibited at 5,000 μ,g g‐1 of added Cr and only under reducing conditions. The sediment, due to the clay content, sequested much of the added metals. Under reducing conditions, 25 percent of water soluble and exchangeable Cr and Pb remained in solution at the highest Pb (2,500 μg, g‐1) and Cr (5,000 μg, g‐1) levels compared to oxidized sediments. The amount in solution was not great enough to impact hydrocarbon degradation. The study demonstrates that Cr and Pb entering sediment at this produced water site would have minimal impact on degradation rates unless extremely high levels were added.

THE SAN RAFAEL DE LAYA OIL SPILL: A CASE OF CLEANUP AND REMEDIATION IN VENEZUELA

ABSTRACT In November 1994, a 16-inch pipeline rupture resulted in a spill of about 10,000 barrels of crude oil extending on 4 hectares of agricultural land, including part of a freshwater lagoon. The spill was contained 2 kilometers away from the accident by a dike constructed across the lagoon during the first response operation. Oil cleanup activities included a bioremediation process (land farming) where harrowing, water irrigation, and fertilization of contaminated soil were applied Physical removal qfthe oil with sorbents, booms, and pads, aswell as a drum skimmer, were used to dean up and restore the lagoon. Laboratory tests reported mat total crude oübiodegrodation rates were stabilized within 2 months, with a mean total hydrocarbons degradation of 80%.

Oil Sludge Landfarming Biodegradation Experiment Conducted At A Tropical Site In Eastern Venezuela

Although climatic conditions are optimal for biodegradation processes to occur, little attention has been given to the application of oil sludge landfarming methods in tropical regions. Here, partial results of our landfarming operations are described for a tropical site in eastern Venezuela, an area characterized by intense oil exploitation and low agricultural productivity. Experiments were carried out in an area of 1 ha and incorporated eight separate treatment plots, including harrowing, water irrigation, fertilization, microbial inoculation or combinations of these. Results showed that total crude oil biodegredation rates of the sludges were stabilized within 6-9 months, with a mean total hydrocarbon degradation of 80%. Saturated hydrocarbon fraction degradation rates were significantly lower (overall slope t -tests P<0.001) in treatments where aeration (harrowing), watering and fertilization were applied, contributing the most to microbial activation of site-specific soil and sludge. The effectiveness of each method was also evaluated by comparison with "control" crop yields. These results are part of the efforts by INTEVEP, S.A., to search for new management disposal alternatives best suited to tropical conditions.

Oil Sludge Landfarming Biodegradation Experiment Conducted At a Tropical Site in Eastern Venezuela

Although climatic conditions are optimal for biodegradation processes to occur, little attention has been given to the application of oil sludge landfarming methods in tropical regions. Here, partial results of our landfarming operations are described for a tropical site in eastern Venezuela, an area characterized by intense oil exploitation and low agricultural productivity. Experiments were carried out in an area of 1 ha and incorporated eight separate treatment plots, including harrowing, water irrigation, fertilization, microbial inoculation or combinations of these. Results showed that total crude oil biodegredation rates of the sludges were stabilized within 6-9 months, with a mean total hydrocarbon degradation of 80%. Saturated hydrocarbon fraction degradation rates were significantly lower (overall slope t-tests P&lt;0.001) in treatments where aeration (harrowing), watering and fertilization were applied, contributing the most to microbial activation of site-specific soil and sludge. The effectiveness of each method was also evaluated by comparison with "control" crop yields. These results are part of the efforts by INTEVEP, S.A., to search for new management disposal alternatives best suited to tropical conditions.

Effect of bioremediation on polycyclic aromatic hydrocarbon residues in soil

Soil contamination (60 mg/g of soil) by a diesel oil (DO) spill was simulated in outdoor lysimeter units and the effect of bioremediation treatment consisting of liming, fertilization, and tilling on the persistence of polycyclic aromatic hydrocarbon (PAH) components of DO was measured. After solvent extraction from soil and class separation on silica gel, PAH components were identified and partially quantified by GC-ITD analysis. Residual mutagenicity and acute toxicity of the contaminated soil was also assessed by Ames and Microtox tests. Bioremediation treatment, while increasing the rate of total hydrocarbon degradation, had an even greater effect on PAH persistence, almost completely eliminating these compounds in 12 weeks. Without bioremediation, 12.5-32.5% of the higher molecular weight PAH were still present at 12 weeks. Mutagenicity and toxicity tests corroborated the above results. After substantial initial mutagenicity and toxicity, the contaminated soil approached the background level of uncontaminated soil after 12 weeks of bioremediation. Detoxification was complete in 20 weeks.