Highest Total Petroleum Hydrocarbon Removal Research Articles

Remediation of petroleum‐contaminated soil by Fenton oxidation–pyrolysis

AbstractPetroleum‐contaminated soil (PCS) is urgently to be remediated due to its risk to ecological environment and human health. In this study, a Fenton oxidation–pyrolysis strategy was employed to accomplish effective petroleum removal and PCS remediation. The highest total petroleum hydrocarbon removal efficiency could achieve 99.6% after 2 h Fenton oxidation, with H2O2/Fe2+, 6:1, and pH 3, followed by pyrolysis at 370°C. The organic compositions of the soil after Fenton oxidation, the kinetics and process of the pyrolysis, morphologies and structures of the treated soil, as well as energy consumption and cost savings were comprehensively researched and analyzed. Through the Fenton oxidation–pyrolysis treatment, the macromolecules were effectively degraded and the contents of asphaltenes and resins were significantly reduced in the soil. Graphitized carbon was dominatingly existed after the pyrolysis. A 1.5 order reaction model was proposed to reasonably describe the pyrolysis remediation process of PCS. The Fenton oxidation–pyrolysis treatment can reduce energy consumption and cost compared with pyrolysis alone. This work not only offered an alternative approach of PCS remediation, but also provided theoretical guidance for practical soil remediation.

Bioremediation of soil contaminated by hydrocarbons with the combination of three technologies: bioaugmentation, phytoremediation, and vermiremediation

The aim of this study was to evaluate the removal of total petroleum hydrocarbons (TPH), alkanes and polycyclic aromatic hydrocarbons (PAH). Using phytoremediation (Panicum maximum) (G), vermiremediation (Pontoscolex corethrurus) (E), and bioaugmentation (encapsulated bacterial consortium) (B), individually and in combination, in contaminated soil by oil (PS) with sterilized (St) and non-sterilized treatments. Grass and earthworm biomass and the number of cocoons were determined after 112 days. The biomass of the P. maximum increased significantly from 1.7 to 2.6-folds overtime when it was cultivated in contaminated soil, either alone, in combination with earthworms, or with the bacterial consortium. After 112 days, the earthworm biomass significantly increased 2.0–2.6-folds with the highest increase in combination with the bacterial (PS+E+B), and its population increased from 4.9 to 8.5 times. P. corethrurus was not affected by the contamination so that deposition and hatch of cocoons (12–20) were observed. In sterilized treatments, no earthworms were detected after 112 days, which indicated that soil microorganisms are necessary for the earthworm’s survival and colonization. Most alkane and PAH removal occurred within 28 days; at 112 days, the alkane was 78.5–94.5% and the PAH 54.5–77.2% in non-sterilized soil. Panicum maximum treatment (SP+G) removed 74–99% of alkanes from C10 to C38 and also removed PAHs in 43–50% (2–3 rings), 46–90% (4 rings), 73% (5 rings), and 59% (6 rings) after 112 days. The combination of the grass with P. corethrurus and the bacterial increased the PAHs removal of 2 and 3 rings (54–62%), 4 rings (56–92%), 5 rings (80%), and 6 rings (70%) after 112 days. In non-sterilized treatments, the highest TPH removal was with earthworms plus bacterial (E+B) (86.4%), followed by E+G+B (82.7%) and B (82.6%). The use of endogeic earthworms and plants species from the same contaminated field can be an efficient alternative for increasing hydrocarbon removal.

Fast Biodegradation of Diesel Hydrocarbons at High Concentration by the Sophorolipid-Producing Yeast Candida catenulata KP324968

In the last decades, biodegradation as an environmentally friendly approach has raised interest in connection with the removal of hydrocarbon pollutants. Its capacity for removing pollutants strongly depends on the type of living cell and environmental conditions. The degradative activity of a new sophorolipid-producing yeast, Candida catenulata KP324968, in the removal of high concentrations of diesel from effluents was statistically evaluated considering the initial pH, the agitation speed, and the initial diesel concentration. The optimal setting of the operational variables at an initial pH of 4.7, an agitation speed of 204 rpm, and an initial diesel concentration of 93.4 g L^–1 resulted in the highest total petroleum hydrocarbon removal efficiency: about 82.1% after 6 days (biodegradation rate: 0.378 g g_cell^–1 h^–1). During the cell growth phase, the emulsification index in the medium increased and reached its highest level at 64.6% after 48 h. Further tests indicated that the emulsification capacity was obtained by in situ production of two sophorolipid molecules with an m/z of 533 and 583. In summary, its effective diesel removal and high emulsification capacity makes C. catenulata KP324968 an attractive candidate yeast for the degradation of hydrocarbons from aqueous environments.

Biodegradation of used engine oil in a wastewater sludge-amended agricultural soil

Soil contamination by used engine oil is a common occurrence in most developing countries. This has been shown to have harmful effects on the environment and human beings at large. Used oils are considered to be hazardous waste materials. These are composed of toxic chemicals, such as heavy metals (which come from additives and wear and tear of engine parts), combustion products, light hydrocarbons, polar compounds, uninuclear and polynuclear aromatic compounds, resinous materials, and organometallic compounds. Some of these pollutants are carcinogenic in nature. The objective of this study was to evaluate the effects of used engine oil (doses of 0.5% and 5%) with hydrocarbon pollution on total petroleum hydrocarbon (TPH) removal from soil and determine the fate of TPHs at different temperatures (18 °C and 28 °C) during an incubation period of 240 days. The possible use of wastewater sludge as a biostimulating agent in used engine oil-contaminated soils was also evaluated. The results of 240 days of incubation indicated that TPH removal percentages in used engine oil-contaminated+sludge amended soils at 18 °C were 68% and 66% for doses of 0.5% and 5%, respectively. Incubation at 28 °C resulted in higher TPH removal with values of 56% (dose of 0.5%) and 74% (dose of 5%). Based on the first-order kinetics model, the high dose (5%) of used engine oil-contaminated soil amended with wastewater sludge showed the highest biodegradation rate of 0.00562/day and half-life of 123.13 days at the end of the incubation period at 28 °C. These rates were significantly higher than those of the control soil (0.00366/day and 189.01 days).

Evaluation of constraints in bioremediation of weathered hydrocarbon-contaminated arid soils through microcosm biopile study

This research investigated the factors influencing bioremediation (biopile) of arid soils contaminated by weathered hydrocarbons. Five soils were thoroughly characterised to determine total petroleum hydrocarbons (TPH), their physicochemical properties and microbial diversity. Identified biopile-limiting factors are to be elevated petroleum hydrocarbon concentrations, high electrical conductivity and the magnitude of the recalcitrant hydrocarbon fraction. To optimise the biopile parameters, microcosm study was conducted which showed significant TPH reduction in three of five soils (BP-1, BP-2 and BP-4) but not in other two (BP-3 and BP-5), where BP-3 had a very high hydrocarbon concentration (123,757 mg kg−1) and BP-5 had a high proportion of recalcitrant hydrocarbons (>70 % of C29). Highest TPH removal (68 %) occurred in soil BP-2 and the lowest (5 %) in soil BP-3 over 56 days. Surfactant (Triton) addition, nutrient amendment or the soil dilution did not improve TPH degradation in soils BP-3 and BP-5. Phylogenetic analysis conducted during the remediation process found that hydrocarbon concentration and hydrocarbon fraction exerted the main effect on bacterial abundance, diversity and assemblage composition. At lower concentrations (~1000–4000 mg kg−1), bacterial diversity and abundance increased significantly, whilst decreased in higher concentrations. Although high TPH content and detection of TPH degraders, TPH biodegradation is limited in soil (BP-5) due to the presence of less soluble hydrocarbon fraction which indicated low TPH bioavailability (~7 %). Biopile could be applied as a technology to remediate three soils (BP-1, BP-2 and BP-4) but further modification of the biopile treatments required for other two soils BP-3 and BP-5.

Effect of Flooding Frequency and Nutrient Addition on Plant Growth and Total Petroleum Hydrocarbons Removal in Mangrove Microcosms

The addition of nutrients to accelerate biodegradation of oil is an adequate strategy to clean up polluted mangrove soils which pollutes mangrove soils. However, the hydrology of these ecosystems might interfere with such strategy. The effect of flooding frequency and nutrient addition on hydrocarbon removal in mangrove sediments was investigated in this study. Microcosms consisted of pots with 5 kg of fresh mangrove sediments and one seedling of Avicennia germinans. Treatments included: planted microcosms with fertilizer and crude oil (PNC), planted microcosms with oil (PC), non-planted microcosms with oil and fertilizer (NC), planted microcosms with fertilizer (PN) and planted microcosms without oil or fertilizer (P). Mexican Maya crude oil and inorganic nutrients were added in a single dose of approximately 5.0 g DW·kg-1, 0.33 g of N DW·kg-1 and 0.06 g P DW·kg-1. Microcosms were either permanently flooded (PF) or intermittently flooded (IF: 14 hours drained and 10 hours flooded), and kept in a glasshouse in Xalapa, Veracruz, Mexico. In both flooding conditions, oil decreased the relative growth rate of A. germinans by 56% in (PC) treatments and 40% in (PNC) treatments. Redox potential in the oiled treatments (-44.73 to +75.34 mV) was lower than non-oiled treatments (-1.31 to +163.43 mV). Total Petroleum Hydrocarbons (TPHs) removal in PC treatments was low in both permanent (2.99% ± 3.51%) and intermittently flooding conditions (11.75% ± 1.46%). The highest TPHs removal was observed in (PNC) and (NC) under IF conditions (47% ± 3.86% and 50.32% ± 7.15% after 4 months, respectively). It was concluded that nutrient addition increased TPHs removal but only under IF conditions and helped mangrove plants to deal with TPHs toxicity.

Application of <i>In Situ</i> Chemical Oxidation for the Remediation of TPH-Contaminated Soils

Soils at many existing and former industrial areas and disposal sites are contaminated by petroleum hydrocarbons. In this study, laboratory bench-scale experiments were performed to evaluate the effectiveness of applying in situ chemical oxidation (ISCO) on the treatment of petroleum-hydrocarbon contaminated soils. Three different oxidation processes including Fenton’s oxidation, persulfate oxidation, and permanganate oxidation were evaluated with initial total petroleum hydrocarbon (TPH) concentration of approximately 3,920 mg/kg. The major control factors were oxidant species (hydrogen peroxide, persulfate, permanganate) and soil to liquid volume ratios (1 to 3). The oxidant concentration was 5 wt.%. Ferrous iron was used as the catalyst during the Fenton’s oxidation and persulfate oxidation processes, and the oxidant to ferrous iron molar ratio was 1 to 0.1. Among these three oxidation processes, contaminated soils treated by permanganate oxidation had the highest TPH removal efficiency (94% of TPH removal) during 360 min of operation. Approximately 75 and 61% of TPH removal was observed in batch experiments applying Fenton’s oxidation and persulfate oxidation, respectively. Due to the consumption of ferrous iron (used as the catalytic chemical) in the early stage during the operational period, both persulfate and Fenton’s oxidation processes had less TPH removal efficiencies. Frequent supplement of catalyst is required when persulfate and Fenton’s oxidation is applied for field application. Results from this study indicate that the ISCO scheme is a feasible technology for the treatment of petroleum-hydrocarbon contaminated soils within a short treatment period. The experimental results can be used for a scale-up system for practical application.

Succession of bacterial community along with the removal of heavy crude oil pollutants by multiple biostimulation treatments in the Yellow River Delta, China

Multiple biostimulation treatments were applied to enhance the removal of heavy crude oil pollutants in the saline soil of Yellow River Delta. Changes of the soil bacterial community were monitored using the terminal restriction fragment length polymorphism (T-RFLP) and clone library analyses. The 140-day microcosm experiments showed that low C:N:P ratio, high availability of surfactant and addition of bulking agent significantly enhanced the performance, leading to the highest total petroleum hydrocarbon removal. Meanwhile, the bacterial community was remarkably changed by the multiple biostimulation treatments, with the Deltaproteobacteria, Firmicutes, Actinobacteria, Acidobacteria and Planctomycetes being inhibited and the Alpha- and Beta-proteobacteria and some unknown Gammaproteobacteria bacteria being enriched. In addition, different hydrocarbon-degraders came to power in the following turn. At the first stage, the Alcanivorax-veldXed Gammaproteobacteria bacteria dominated in the biostimulated soil and contributed mainly to the biodegradation of easily degradable portion of the heavy crude oil. Then the bacteria belonging to Alphaproteobacteria, followed by bacteria belonging to Candidate division OD1, became the dominant oil-degraders to degrade the remaining recalcitrant constituents of the heavy crude oil.

Design of a new rotating drum bioreactor operated at atmospheric pressure on the bioremediation of a polluted soil

This paper reports the effect of the operation and design characteristics of rotating drum bioreactors (RDBs) aerated by natural convection and applied to the treatment of a soil highly polluted with weathered total petroleum hydrocarbons (TPH) (55,000 +/- 2,600 mg/kg). The parameters studied were length to diameter ratio (L/D), rotating speed (N) and lifter type. The highest TPH removal (59.6 +/- 0.7%) was obtained with the RDB of the lowest L/D ratio (1.5). Removals diminished by 27, 36 and 56%, with a ratio increment of 2.1, 3.1 and 5.1, respectively. Increment of the N, at an optimal value and lifter change from straight to helicoidal showed an improvement on the TPH removal of 20 and 30%, respectively. According to these results, slurry surface renewal through the variation of the N and the change of slurry flow was able to improve TPH removal in RDBs operated by natural convection.

Solid culture amended with small amounts of raw coffee beans for the removal of petroleum hydrocarbon from weathered contaminated soil

Solid culture with small amounts of low-quality raw coffee beans was used for total petroleum hydrocarbon (TPH) removal from a weathered and polluted soil. Soil contaminated with 58 000 mg kg −1 of TPH was treated with soil:coffee bean ratios of 98:2, 96:4, 94:6, and 92:8, at a C:N:P ratio of 100:10:1, 20% humidity, and 28 °C, for periods of 15, 60, and 90 days. The highest TPH removal (63%) was obtained with a soil/bean ratio of 98:2 over 15 days, corresponding with the highest rates of microbial respiration and the greatest increases in bacterial and fungal counts to 9 lnCFU and 6 lnCFU, respectively. Scanning electron microscopy showed high fungal colonization of coffee beans, with Mucor sp., Aspergillus sp., Aspergillus niger. , and Penicillium sp. growing on TPH as sole carbon source.

A field trial for an ex-situ bioremediation of a drilling mud-polluted site

The remediation of drilling mud-polluted sites in the Southeast of Mexico is a top priority for Mexican oil industry. The objective of this work was to find a technology to remediate these sites. A field trial was performed by composting in biopiles, where four 1 ton soil-biopiles were established, one treatment in triplicate and one unamended biopile. Amended biopiles were added with nutrients to get a C/N/P ratio of 100/3/0.5 plus a bulking agent (straw) at a soil/straw ratio of 97/3. Moisture content was maintained around 30–35%. Results showed that, after 180 d, total petroleum hydrocarbon (TPH) concentrations decreased from 99 300 ± 23 000 mg TPH kg −1 soil to 5500 ± 770 mg TPH kg −1 for amended biopiles and to 22 900 ± 7800 mg TPH kg −1 for unamended biopile. An undisturbed soil control showed no change in TPH concentrations. Gas chromatographic analysis showed residual alkyl dibenzothiophene type compounds. Highest bacterial counts were observed during the first 30 d which correlated with highest TPH removal, whereas fungal count increased at the end of the experimentation period. Results suggested an important role of the straw, nutrient addition and water content in stimulating aerobic microbial activity and thus hydrocarbon removal. This finding opens an opportunity to remediate old polluted sites with recalcitrant and high TPH concentration.

Biodegradation of total petroleum hydrocarbon (TPH) in Jordanian petroleum sludge

Bioremediation, or the use of micro-organisms to decontaminate soil or groundwater, is being increasingly seen as an effective, environment-friendly treatment for oil-contaminated sites. In this study, the results are presented concerning a laboratory screening of several natural bacterial consortia and laboratory tests to establish the performance in degradation of hydrocarbons contained in oily sludge from the Jordan Oil Refinery Plant. As a result of the laboratory screening, 18 isolates were selected and grouped into two main clusters; cluster 1 containing 12 isolates grown at 43°C, and cluster 2 containing six isolates grown at 37°C. Three natural bacterial consortia with ability to degrade total petroleum hydrocarbons (TPH) were prepared from these isolates. Experiments were conducted in Erlenmeyer flasks under aerobic conditions, with TPH removal percentage varying from 5.9% to 25.1%, depending upon consortia type and concentration. Consortia 7B and 13B exhibited the highest TPH removal percentages of 25% and 23%, respectively before nutrient addition. TPH removal rate was enhanced after addition of nutrients to incubated flasks. The highest TPH reduction (37%) was estimated after addition of a combination of nitrogen, phosphorus and sulphur to consortia 7B. This is the first report concerning biological treatment of total petroleum hydrocarbon by bacteria isolated from the oil refinery plant, where it lay the ground for full integrated studies recommended for hydrocarbon degradation that assist in solving sludge problems.