Soil Total Petroleum Hydrocarbon Concentrations Research Articles

Organic stimulants for enhancing phytoremediation of crude oil polluted soil: A study on cowpea

Petroleum hydrocarbon (PH) contamination of soils remains a major threat to environmental health and food security. A two-years phytoremediation study was conducted on a crude oil polluted soil to assess changes in soil total petroleum hydrocarbon concentration (TPHsoil) following use of pawpaw seed powder (PSP), moringa seed powder (MSP) and their combination (PSP + MSP) as organic stimulants in cowpea cultivation. The stimulants were tested at different application rates (100, 150, 200 and 250 g m−2), with the control (No stimulant) for their effectiveness in reducing TPHsoil and accelerating the removal rate (R) of PH from soil. The TPHsoil did not differ significantly (p < 0.05) among the treatments in year 1, but was highest in the control (11,600 mg kg−1) and least in 200 g m−2 PSP (7400.0 mg kg−1). In year 2, mean TPHsoil varied significantly (p < 0.05) and remained highest in control (7100 mg kg−1) but lowest in 150 g m−2 PSP (2700 mg kg−1). Application of 150 g m-2 PSP gave the highest R (78.2%), followed by 150 g m-2 PSP+MSP (77.4%), and least by the control (42.7%) over two years of study. The average fresh pod yield of cowpea over two years was highest in 250 g m−2 PSP (2416.67 kg ha−1), followed by 150 g m−2 PSP (2173.34 kg ha−1) and least in control (1302.22 kg ha−1). There was significant negative association between TPHsoil and fresh pod yield (r = −0.403; p < 0.01). However, application of 150 g m−2 PSP appeared most effective for enhanced phytoremediation of crude oil polluted soil and improvement of cowpea yield.

Spatial ecological risk assessment for contaminated soil in oiled fields

Soil total petroleum hydrocarbon (TPH) pollution in oil fields is a worldwide environmental problem. In particular, the dense distribution of oil wells in low-permeability oil reservoirs has caused regional pollution superposition. We proposed a feasible method for the spatial ecological assessment for soil pollution in oil fields. Typical TPH-contaminated soil in the Shengli oil field was examined according to the classification of oil well properties, including the spatial structure, distribution density, and exploitation history. Soil TPH concentrations of each oil filed site was calculated by Monte Carlo simulation. The risks were assessed according to multiple receptors and risk sources. The results indicated that the average TPH concentration was greater than 2100 mg·kg−1. The differences of TPH concentrations were mainly correlated to the exploitation period. The soil TPH content demonstrated a spatial cluster pattern according to the Anselin Local Moran’s Index (p < 0.01). The risk for wheat and earthworms showed that more than 98% of the study area was under a low risk level. However, high risk accounted for only 0.9% when bacteria was used as a bioindicator, and the composition of different risk levels was similar to that of the ecological risk assessed based on the soil quality index.

Effects of 5-Aminolevulinic Acid (ALA) on Zinnia hybrida Growth and Phytoremediation Effects in Oil-Contaminated Soil

In this study, we compared plant height, weight, soil TPH concentration, and soil DHA level after 18 weeks of Zennia hybrida cultivation with four different concentrations of 5-Aminolevulinic acid (ALA)-based liquid fertilizer: 1500-fold, 5000-fold, and 8000-fold dilutions, along with a non-treatment control of diluted ALA. The plants of ALA-treated were significantly taller than the non-treatment control. The plants of ALA-treated plants were higher in shoot fresh weight, shoot dry weight, and root dry weight than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold dilution was significantly highest in shoot fresh weight, shoot dry weight, and root dry weight. ALA-treated plants were lower in the soil Total Petroleum Hydrocarbon (TPH) concentration than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold was significantly lowest in the TPH concentration. In addition, ALA-treated plants were higher in the soil dehydrogenase activity (DHA) than the non-treatment control. The plot of ALA-based liquid fertilizer with the 5000-fold was significantly highest in the TPH concentration. This study indicated that ALA-applied zinnia-grown oil-contaminated soil is more effective than not. The remediation in oil-contaminated soil with ALA-based liquid fertilizer is more effective than the non-treatment control; furthermore, ALA application with 5000-fold dilution was most suitable in oil-contaminated soil among other plots.

Concentration of Total petroleum Hydrocarbons and Selected Heavy Metals In Soil And plant nearby Al-Nassiriya oil Refinery South of Iraq

The present study deal with measure concentration of Total petroleum hydrocarbons (TPHs) and selected heavy metals (HMs) (Cd , Pb , Co , V, and Ni) in soil and plant phragmits austriles (cav.) nearby AL-Nassiriya oil refinery during the period extended from winter up to summer 2018 . Some environmental factors such as , pH, salinity‰ , Electrical conductivity (Ec.) and soil temperature were measured , also total organic carbon (Toc) % content in soil was determined, and soil texture was analyzed and both of them expressed as percentage . The result observed that the range of the following factors were : soil temp. ranged from (26-36) ◦c , pH (7.3-7.9) , Ec. (14.3-25.3) µs/cm and salinity (5.1-7.3)‰ , while the value of Toc ranged from (0.7-8.55)% , soil texture was silty soil in control station , but they were sandy soil at polluted stations . The mean concentration of TPHs in soil , St.1 , St.2 , St.3 and St.4 were (16.47 ,14.78 ,12.65 and 1.36) µg /gm dry weight respectively , while the mean concentration of HMs in the soil for both season were Cd (0.78 ), Pb (26.85), Co (26.83), Ni (227.17) and V (95.67) µg /gm dry weight . In plant (shoot and root) part , mean concentration of TPHs were (4.86 and 8 .44) µg /gm dry weight respectively ,whereas the mean concentration of heavy metals in both parts for both seasons were Cd (0.49 and 0.65) , Pb (30.36 and 49.25).

Relationships between root growth of Zinnia hybrid “profusion orange” flowers and phytoremediation of oil-contaminated soil

Relationships exist between plant root growth and the phytoremediation of oil-contaminated soils. In a previous study, we demonstrated that zinnia flowers are well suited for the remediation of oil-contaminated soil. In this study, our goal was to quantify the relationship between zinnia root growth and purification of oil-contaminated soils. Three treatments were used: (1) cultivation of zinnia in oil-contaminated soil (contaminated pots), (2) cultivation in non-contaminated soil (non-contaminated pots), and (3) contaminated soil with no cultivation and only irrigation (irrigated pots). Growth of the Zinnia plants, including their roots, was significantly reduced in the contaminated pots compared with the noncontaminated pots. The soil dehydrogenase activity increased between 45 and 90 days after planting in all parts of the contaminated pots, especially the upper parts. The soil total petroleum hydrocarbon (TPH) concentrations in the contaminated pots decreased throughout the study period. Interestingly, the soil dehydrogenase activity increased, and the soil TPH concentration decreased even in lower parts of the pots where there was very little root growth. Therefore, the cultivation of plants can have a remediative effect on oil-contaminated soil even below the depth reached by the plant roots.

Feasibility of oxidation-biodegradation serial foam spraying for total petroleum hydrocarbon removal without soil disturbance

This study evaluated surface foam spraying technology, which avoids disturbing the soil, to deliver chemical oxidant and oil-degrading microbes to unsaturated soil for 30 days. Hydrogen peroxide foam was sprayed once onto diesel contaminated soil for oxidation of soil total petroleum hydrocarbon (TPH). Periodic bioaugmentation foam was sprayed every three days for biodegradation of soil TPH. Foam spraying employing oxidation-bioaugmentation serial application significantly reduced soil TPH concentrations to 550 mg·kg−1 from an initial 7470 mg·kg−1. This study selected an optimal hydrogen peroxide concentration of 5%, which is capable of treating diesel oil contaminated soil following biodegradation without supplementary iron. Application of hydrogen peroxide by foam spraying increased the infiltration of hydrogen peroxide into the unsaturated soil. Surface foam spraying provided the aqueous phase of remediation agents evenly to the unsaturated soil and resulted in relatively similar soil water content throughout the soil. The easy and even infiltration of remediation reagents increased their contact with contaminants, resulting in enhanced oxidation and biodegradation. Fractional analysis of TPH showed C18-C22 present in diesel as biodegradation recalcitrant hydrocarbons. Recalcitrant hydrocarbons were reduced by 92% using oxidation-biodegradation serial foam, while biodegradation alone only reduced the recalcitrant fraction by 25%.

Effect of Replanting Zinnia Plants for Remediation of Oil-Contaminated Soil

Previously, we demonstrated that the zinnia plant was effective for the phytoremediation of oil-contaminated soils and that it had a higher remediation effect during the initial growth period. Therefore, repeated planting of zinnia for the initial growth period might enhance the remediation of contaminated soils, so we performed the following study. Seeds were sown in soils containing 4% (w/w) diesel oil and grown for 100 days. We carried out two treatments: replanted plots where above-ground parts of plants were cut after 50 days, and new seeds were sown; or non-replanted plots where plants were allowed to grow for 100 days. The soil dehydrogenase activity and soil total petroleum hydrocarbon concentrations were analyzed. At the end of the study, no significant differences were found between replanted and non-replanted plots for either measurement. Therefore, replanting did not affect remediation. Degradable oil components in the soils may have been degraded in the initial growth period of the first planting, but by the time of replanting there may have been few degradable oil components left in the soil, so there was no beneficial effect of replanting. We concluded that replanting is unsuitable for phytoremediation of oil-contaminated soils.

Application of an in-situ soil sampler for assessing subsurface biogeochemical dynamics in a diesel-contaminated coastal site during soil flushing operations

Subsurface biogeochemistry and contaminant dynamics during the remediation of diesel-contamination by in-situ soil flushing were investigated at a site located in a coastal region. An in-situ sampler containing diesel-contaminated soils separated into two size fractions (<0.063- and <2-mm) was utilized in two monitoring wells: DH1 (located close to the injection and extraction wells for in-situ soil flushing) and DH2 (located beyond sheet piles placed to block the transport of leaked diesel). Total petroleum hydrocarbon (TPH) concentrations and biogeochemical properties were monitored both in soil and groundwater for six months. A shift occurred in the groundwater type from Ca-HCO3 to Na-Cl due to seawater intrusion during intense pumping, while the concentrations of Ni, Cu, Co, V, Cr, and Se increased substantially following surfactant (TWEEN 80) injection. The in-situ sampler with fine particles was more sensitive to variations in conditions during the remedial soil flushing process. In both wells, soil TPH concentrations in the <0.063-mm fraction were much higher than those in the <2-mm fraction. Increases in soil TPH in DH1 were consistent with the expected outcomes following well pumping and surfactant injection used to enhance TPH extraction. However, the number of diesel-degrading microorganisms decreased after surfactant injection. 16S-rRNA gene-based analysis also showed that the community composition and diversity depended on both particle size and diesel contamination. The multidisciplinary approach to the contaminated site assessments showed that soil flushing with surfactant enhanced diesel extraction, but negatively impacted in-situ diesel biodegradation as well as groundwater quality. The results also suggest that the in-situ sampler can be an effective monitoring tool for subsurface biogeochemistry as well as contaminant dynamics.

Response of salt marshes to oiling from the Deepwater Horizon spill: Implications for plant growth, soil surface-erosion, and shoreline stability

We investigated the initial impacts and post spill recovery of salt marshes over a 3.5-year period along northern Barataria Bay, LA, USA exposed to varying degrees of Deepwater Horizon oiling to determine the effects on shoreline-stabilizing vegetation and soil processes. In moderately oiled marshes, surface soil total petroleum hydrocarbon concentrations were ~70mgg−1 nine months after the spill. Though initial impacts of moderate oiling were evident, Spartina alterniflora and Juncus roemerianus aboveground biomass and total live belowground biomass were equivalent to reference marshes within 24–30months post spill. In contrast, heavily oiled marsh plants did not fully recover from oiling with surface soil total petroleum hydrocarbon concentrations that exceeded 500mgg−1 nine months after oiling. Initially, heavy oiling resulted in near complete plant mortality, and subsequent recovery of live aboveground biomass was only 50% of reference marshes 42months after the spill. Heavy oiling also changed the vegetation structure of shoreline marshes from a mixed Spartina–Juncus community to predominantly Spartina; live Spartina aboveground biomass recovered within 2–3years, however, Juncus showed no recovery. In addition, live belowground biomass (0–12cm) in heavily oiled marshes was reduced by 76% three and a half years after the spill. Detrimental effects of heavy oiling on marsh plants also corresponded with significantly lower soil shear strength, lower sedimentation rates, and higher vertical soil-surface erosion rates, thus potentially affecting shoreline salt marsh stability.

Assessment of soil organic contamination in a typical petrochemical industry park in China.

The concentrations of total petroleum hydrocarbons (TPH), n-alkanes (n-C8 through n-C40), and 16 polycyclic aromatic hydrocarbons (PAHs) in soils were determined to assess the level of organic contamination in soils from the Da-gang Petrochemical Industry Park with several big state-run enterprises, a recent rapid flourishing park in China. The results showed that the concentration of TPH in soil was high, up to 20 ng/g-12.8478%; in particular, the content in most sites ranged from 1 to 2%. Thus, it is clear that soil environment in the Da-gang Petrochemical Industry Park has been seriously polluted by TPH according to the Nemerow pollution index method. Furthermore, the average concentration of Σ(n-C>16 through n-C34) in 30 sampling sites was above the maximum limit set for F3 under all the conditions in the Canada-wide standards for petroleum hydrocarbons (PHC CWS) with 43.33-93.33% soil samples exceeding F3 standards, and n-alkanes possessing higher concentrations were proved much abundant alkanes in this study. Besides, the predominance of even n-alkanes and lower carbon preference index (CPI) demonstrated that n-alkanes in surface soils were mainly caused by anthropogenic inputs, while the concentration of Σ16-PAHs was in the range of 1652.5-8217.3 ng/g and the BaA/(BaA + Chr) and Flu/(Flu + Pyr) ratios indicated that pyrogenic PAHs may be the dominant PAHs in most soils with the contribution of petrogenic hydrocarbons in some sites.

경유 주입량과 토양 조성에 따른 유류 오염토양 내 TPH 측정 농도 변화 연구

This study investigated the effects of oil dose and soil texture on the analysis results for total petroleum hydrocarbon (TPH) in artificially oil-contaminated soils. The same amount of diesel was mixed with soils having different soil texture, and soil TPH concentrations were then analyzed for comparison. Presence of clay in the soil showed lower soil TPH analysis results than that of sand only. As the clay content was increased in the soil, the lower soil TPH concentration was obtained by incompleteness of solvent extraction. As the organic matter content in soil was increased from 5.2% to 10% (weight basis), a higher concentration of TPH was obtained by TPH analysis. However, at a higher organic content in the soil, 18%, resulted in a lower TPH concentration than those of 5.2% and 10%. Gasoline dose to the soil resulted in a significantly low TPH concentration due to the volatilization of gasoline while soil mixing and analysis. This study results would provide fundamental information either to the expectation of TPH concentration in artificially oil-contaminated soil or to estimation of oil release in the real oil-contaminated site.

Simple surface foam application enhances bioremediation of oil-contaminated soil in cold conditions

Landfarming of oil-contaminated soil is ineffective at low temperatures, because the number and activity of micro-organisms declines. This study presents a simple and versatile technique for bioremediation of diesel-contaminated soil, which involves spraying foam on the soil surface without additional works such as tilling, or supply of water and air. Surfactant foam containing psychrophilic oil-degrading microbes and nutrients was sprayed twice daily over diesel-contaminated soil at 6°C. Removal efficiencies in total petroleum hydrocarbon (TPH) at 30 days were 46.3% for landfarming and 73.7% for foam-spraying. The first-order kinetic biodegradation rates for landfarming and foam-spraying were calculated as 0.019d−1 and 0.044d−1, respectively. Foam acted as an insulating medium, keeping the soil 2°C warmer than ambient air. Sprayed foam was slowly converted to aqueous solution within 10–12h and infiltrated the soil, providing microbes, nutrients, water, and air for bioaugmentation. Furthermore, surfactant present in the aqueous solution accelerated the dissolution of oil from the soil, resulting in readily biodegradable aqueous form. Significant reductions in hydrocarbon concentration were simultaneously observed in both semi-volatile and non-volatile fractions. As the initial soil TPH concentration increased, the TPH removal rate of the foam-spraying method also increased.

Field Note: Phytoremediation of Petroleum Sludge Contaminated Field Using Sedge Species, Cyperus Rotundus (Linn.) and Cyperus Brevifolius (Rottb.) Hassk

The aim of this study was to degrade total petroleum hydrocarbon (TPH) in a petroleum sludge contaminated site (initial TPH concentration of 65,000–75,000 mg.kg–1) with two native sedge species namely Cyperus rotundus (Linn.) and Cyperus brevifolius (Rottb.) Hassk. Fertilized and unfertilized treatments were maintained separately to record the influence of fertilizer in TPH degradation. The average biomass production (twenty plants from each treatment) of C. rotundus was 345.5 g and that of C. brevifolius was 250.6 g in fertilized soil during 360 days. Decrease in soil TPH concentration was higher in fertilized soil (75% for C. rotundus and 64% for C. brevifolius) than in unfertilized soil (36% for C. rotundus and 32% for C. brevifolius). In unvegetated treatments, decrease in soil TPH concentration in fertilized (12%) and unfertilized soil (8%) can be attributed to natural attenuation and microbial degradation. TPH accumulation in roots and shoots was significantly higher in fertilized soil in comparison to unfertilized soils (p < 0.05). Most probable number (MPN) in planted treatments was significantly higher than in unplanted treatments (p < 0.05).

Distribution and Fractional Composition of Petroleum Hydrocarbons in Roadside Soils

Total petroleum hydrocarbon (TPH) concentrations and their fractional composition (medium fraction: n-alkane chain-length C15 to C27, heavy fraction: &gt;C27) were determined at distances from 1 to 60 m from roads and at soil depths from 0.5 to 15 cm. The traffic intensities were up to 25000 vehicles per day. Soil TPH concentrations were highest within 15 m distance (665 and 3198 mg kg−1at the windward and leeward sides, resp.), followed by a rapid drop to background values beyond (196 and 115 mg kg−1in 60 m distance at the windward and leeward sides, resp.). The data variability was lowest at distances of 1 m and highest within tree plantations at distances of 15 m from the road. The TPH concentrations decreased with depth but were significantly higher than the background at all depths investigated. A principal component analysis revealed a positive relation between the medium-to-heavy fraction ratio and soil depth. A fractional differentiation of hydrocarbons with distance from road was not observed. It was concluded that the assessment of the potential of hydrocarbons to translocate, accumulate, or degrade in soil necessitates their subdivision into fractions based on their physicochemical and metabolic properties.

Development of a Four-Phase Remedial Scheme to Clean Up Petroleum-Hydrocarbon Contaminated Soils

In this study, a four-phase remedial scheme was developed for in situ cleanup of petroleum-hydrocarbon contaminated soils. The developed remedial scheme contained the following four phases: surfactant flushing, groundwater flushing, chemical oxidation using KMnO4 as the oxidant, and enhanced bioremediation. Laboratory bench-scale experiments were performed to evaluate the effectiveness of this developed remedial scheme on the treatment of diesel oil contaminated soils. In the surfactant and groundwater flushing batch experiment (the first and second phases), biodegradable surfactant, Simple Green (SG) (5% by weight) was applied to flush diesel oil contaminated soils with initial total petroleum-hydrocarbon (TPH) concentration of approximately 31,500 mg kg-1. Results show that more than 90% of TPH could be removed after flushing with 40 pore volumes (PVs) of SG, followed by 25 PVs of groundwater. In the KMnO4 oxidation experiment (third phase) with initial soil TPH concentration at approximately 4,900 mg kg-1, up to 65% of TPH removal efficiency can be obtained when 1% by weight of KMnO4 was applied for oxidation. Results also reveal that the slight increase in TPH removal was observed in experiments with SG addition (0.1% by volume) owing to increased dissolution and desorption of TPH from soils. In the enhanced bioremediation (fourth phase) batch experiments, a petroleum-hydrocarbon degrading bacterium was isolated from the soil materials after the KMnO4 oxidation experiments and identified as Pseudomonas sp. via biochemical tests and further confirmation of DNA sequencing. Results from biodegradation experiments indicate that the isolated bacterium, which survived after KMnO4 oxidation process, was capable of degrading TPH caused by diesel oils, and caused the TPH to drop from 2,105 to 487 mg kg-1 within 15 days of incubation. The effectiveness of the four-phase remedial scheme was further confirmed by a semicontinuous batch experiment. Results from this study indicate that the four-phase scheme is a promising technology for the treatment of petroleum-hydrocarbon contaminated soils.

Comparison of Two Methods for Assessment of In Situ Jet-fuel Remediation Efficiency

In 1997, total petroleum hydrocarbon (TPH) remediation started at a former Air Force Base, which operated from 1940 to 1991. TPH had been released to soil and groundwater at the site by military activities. The TPH was 70% jet fuel and the affected area covered 28 ha. Remediation involved a combination of technologies, including removal of volatile organic compounds using soil vapor extraction and air sparging, free product vacuum recovery and aerobic biodegradation of organics with oxygen supplied by the air sparging system, along with nutrient addition. The primary remedial method was found to be biodegradation, which has removed 93% of the contaminants from the site to date. A significant aspect of the remedial action was performance monitoring, including documentation of remediation efficiency. The goal of the research was to assess the relative accuracy of methods commonly used for monitoring in situ TPH remediation. Two such methods were selected for the research: monitoring change in soil TPH concentration (specified as non-polar extractable substances) and monitoring respiration activity in soil with a subsequent stoichiometric mass balance to estimate the mass of TPH destroyed. The study demonstrated that both of the methods provided comparable results regarding the effectiveness of in situ TPH remediation, despite the fact that their methodologies are very different.

Effect of Petroleum‐Containing Wastewater Irrigation on Bacterial Diversities and Enzymatic Activities in a Paddy Soil Irrigation Area

Effects of petroleum contamination on bacterial diversities and enzymatic activities in paddy soils were investigated in the Shenfu irrigation area, the largest area irrigated by oil-containing wastewater for more than 50 yr in northeastern China. Bacterial diversities were determined by conventional colony morphology typing techniques and 16S rDNA polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Dehydrogenase, hydrogen peroxidase, polyphenol oxidase, urease, and substrate-induced respiration (SIR) were measured to evaluate the effects of petroleum-containing wastewater irrigation on soil biochemical characteristics. Results showed that paddy soil total petroleum hydrocarbon (TPH) concentration in the irrigation area varied from 277.11 to 5213.37 mg kg(-1) dry soil. Soil TPH concentration declined along the gradient of the irrigation channel from up- to downstream. At the current pollution level, the paddy soil TPH concentration was positively correlated with the colony forming units (CFU) of aerobic heterotrophic bacteria (AHB) (r = 0.928, p < 0.001) and the genetic diversity based on DGGE profiles (r = 0.655, p < 0.05). The bacterial diversities in the soils based on colony morphotypes of AHB also increased with TPH concentration (r = 0.598), but not significant statistically (p = 0.052). Analysis of soil enzyme activities indicated a significant positive correlation between soil TPH concentration and activities of dehydrogenases (r = 0.974, p < 0.001), hydrogen peroxidases (r = 0.957, p < 0.001), polyphenol oxidases (r = 0.886, p < 0.001), and SIR (r = 0.916, p < 0.001). On the contrary, the urease activity showed a negative correlation with paddy soil TPH concentration (r = -0.814, p = 0.002), and could be used as a sensitive indicator of petroleum contamination.

Dynamics of carbon, nitrogen and hydrocarbons in diesel-contaminated soil amended with biosolids and maize

Contamination of soil with hydrocarbons occurs frequently when petroleum ducts are damaged. Restoration of those contaminated soils might be achieved by applying readily available organic material. An uncontaminated clayey soil sampled in the vicinity of a duct carrying diesel which ruptured recently, was contaminated in the laboratory and amended with or without maize or biosolids while production of carbon dioxide (CO 2), dynamics of ammonia (NH 4 +), nitrates (NO 3 −), and total petroleum hydrocarbons (TPH) were monitored. The fastest mineralization of diesel, as witnessed by production of CO 2, was found when biosolids were added, but the amount mineralized after 100 days, approximately 88%, was similar in all treatments. Approximately 5 mg of the 48 mg TPH kg −1 found in the sterilized soil at the beginning of the experiment could not be accounted for after 100 days. The concentration of TPH in the unsterilized soil decreased rapidly in all treatments, but the rate of decrease was different between the treatments. The fastest decrease was found in the soil amended with biosolids and approximately 30 mg TPH kg −1 or 60% could not be accounted for within 7 days. The decrease in concentration of TPH at the onset of the incubation was similar in the other treatments. After 100 days, the concentration of TPH was similar in all soils and appear to stabilize at 19 mg TPH kg −1 soil. It was concluded that biosolids accelerated the decomposition of diesel and TPH due to its large nutrient content, but after 100 days the amount of diesel mineralized and the residual concentration of TPH was not affected by the treatment applied.

Enhanced land treatment of petroleum‐contaminated soils using solid peroxygen materials

AbstractA pilot field study evaluated whether adding solid peroxygen materials during land treatment could cost effectively accelerate cleanup at a site contaminated with petroleum‐related compounds. Five test cells were constructed containing approximately five cubic yards of soil contaminated with 300–400 mg/kg of total petroleum hydrocarbons (TPH). Three cells received treatment with solid peroxygen materials (either MgO2 or CaO2), while the other two cells served as controls (no peroxygen amendment). Adding solid peroxygen compounds effectively reduced the hydrocarbon contamination in the soils and decreased the treatment time. During this time, the concentration of TPH in soil in the three treatment cells decreased. In contrast, there was little loss of TPH from the two control cells simulating traditional land treatment. Adding the solid peroxygen materials reduced the total site remediation time, thereby reducing the overall costs.