Performance of carbon adsorbent derived from cathodic waste in removal of petroleum hydrocarbons from aqueous environment

Removal of emulsified fuel oils from brackish and pond water by dissolved air flotation with and without polyelectrolyte use: Pilot-scale investigation for estuarine and near shore applications

A 168-day period field study, carried out in Sisimiut, Greenland, assessed the potential to enhance soil remediation with the surplus heating from an incineration facility. This approach searches a feasible ex situ remediation process that could be extended throughout the year with low costs. Individual and synergistic effects of biostimulation were also tested, in parallel. An interim evaluation at the end of the first 42days showed that biostimulation and active heating, as separate treatments, enhanced petroleum hydrocarbon (PHC) removal compared to natural attenuation. The coupling of both technologies was even more effective, corroborating the benefits of both techniques in a remediation strategy. However, between day 42 and day 168, there was an opposite remediation trend with all treatments suggesting a stabilization except for natural attenuation, where PHC values continued to decrease. This enforces the "self-purification" capacity of the system, even at low temperatures. Coupling biostimulation with active heating was the best approach for PHC removal, namely for a short period of time (42days). The proposed remediation scheme can be considered a reliable option for faster PHC removal with low maintenance and using "waste heating" from an incineration facility.

abstractA batch pot experiment using nine herbaceous species were conducted for peat enhanced rehabilitation of contaminated soil with oily sludge in the initial contents of 0%, 1.3%, 7.4%, and 12.2%, respectively. The results showed that petroleum hydrocarbons removal, plant growth indices and enzyme activities varied depending on plant species and oil contents. Cotton, ryegrass and tall fescue were effective in the rehabilitation of oily sludge contaminated soils. The total petroleum hydrocarbon (TPH) removal ranged from 30.0% to 40.0% after 170 days of treatment. Plant biomass was shown to be the preferred indicator for screening phytoremediation plant because it was closely correlated with TPH removal and enzyme activities. Peat-enhanced plant rehabilitation could be a good strategy for the treatment of oily sludge contaminated saline soils.

This study describes the potential application of lipopeptide biosurfactants in removal of petroleum hydrocarbons and heavy metals from the soil samples collected from industrial dumping site. High concentrations of heavy metals (like iron, lead, nickel, cadmium, copper, cobalt and zinc) and petroleum hydrocarbons were present in the contaminated soil samples. Lipopeptide biosurfactant, consisting of surfactin and fengycin was obtained from Bacillus subtilis A21. Soil washing with biosurfactant solution removed significant amount of petroleum hydrocarbon (64.5 %) and metals namely cadmium (44.2 %), cobalt (35.4 %), lead (40.3 %), nickel (32.2 %), copper (26.2 %) and zinc (32.07 %). Parameters like surfactant concentration, temperature, agitation condition and pH of the washing solution influenced the pollutant removing ability of biosurfactant mixture. Biosurfactant exhibited substantial hydrocarbon solubility above its critical micelle concentration. During washing, 50 % of biosurfactant was sorbed to the soil particles decreasing effective concentration during washing process. Biosurfactant washed soil exhibited 100 % mustard seed germination contradictory to water washed soil where no germination was observed. The results indicate that the soil washing with mixture of lipopeptide biosurfactants at concentrations above its critical micelle concentration can be an efficient and environment friendly approach for removing pollutants (petroleum hydrocarbon and heavy metals) from contaminated soil.

This study was conducted to determine phosphorus sorption characteristics of five soils from contrasting parent materials in south-eastern Nigeria. The soils were collected from Ikom (basalt), Akamkpa (basement complex), Bende (shale), Amaeke (sand stone) and Umudike (coastal plain sand). The standard P requirements for the soils were calibrated from the sorption curves, and the values were very low ranging from 11.1 mg·kg-1 in Bende to 60.2 mg·kg-1 in Ikom. The P maximum sorption capacity determined by the Freundlich and Langmuir models varied with the locations, and ranged from 65.7 mg·kg-1 in Akamkpa to 516 mg·kg-1 in Bende for the Freundlich model and from 231 mg·kg-1 in Akamkpa to 369 mg·kg-1 in Bende for the Langmuir model. Similarly the P maximum buffering capacity was determined by using the two models. The values varied from 993 mg·kg-1 in Amaeke to 1180 mg·kg-1 in Akamkpa with a mean of 1087 mg·kg-1. The highest bonding energy of P was in Akamkpa with a mean value of 6.05 ml/g and lowest was in Bende with a mean value of 0.76 ml/g. From this study, the P sorption data of the soils conformed better with the Freundlich model than the Langmuir model. Freundlich model is therefore recommended for the soils.

Petroleum hydrocarbon pollutants in soil are challenging to biodegrade, negatively impacting plant growth as well as the metabolic activity and community structure of soil microorganisms. Microorganisms immobilized by seed carriers can synergistically contribute to the remediation of petroleum hydrocarbon-contaminated soil. We prepared a rape seed carrier with immobilized microorganism by seed coating (with a mixture of diatomaceous earth and bentonite as fillers) and microbial immobilization. A pot experiment was conducted with the following treatments: control (CK, neither seeds nor microorganisms added), bare rapeseed (T1), rapeseed coated with diatomaceous earth and bentonite (T2), free-living Pseudomonas aeruginosa added (T3), rapeseed coated with diatomaceous earth and bentonite plus free-living P. aeruginosa (T4), and rapeseed coated with diatomaceous earth and bentonite immobilized with P. aeruginosa (T5). We measured rape seed growth, rhizosphere microbial community structure, and petroleum hydrocarbon removal efficiency. The results showed that 1) There were no significant difference in seed germination rate among T1, T2, T4, and T5 treatments. Compared to T1, leaf length, root length, biomass, and soluble protein content of rape seed significantly increased in T4 and T5 treatments, while T2 treatment showed no significant effect. Leaf width, stem length, chlorophyll content, and superoxide dismutase activity of rape seed in T2, T4, and T5 treatments were significantly higher than T1, while malondialdehyde content was signi-ficantly lower. 2) Compared to CK, the removal rate of petroleum hydrocarbon in the T1, T2, T3, T4, and T5 treatments increased by 0.8, 1.6, 0.5, 1.8, and 2.2 times, respectively. The T5 treatment achieved the highest petro-leum hydrocarbon removal rate of 54.0%. Soil dehydrogenase activity in all treatments increased significantly, with a positive correlation with the petroleum hydrocarbon removal rate (r=0.893). 3) The T5 treatment had the highest soil microbial α diversity and the abundances of Chloroflexi and Acidobacteria. In conclusion, seed carriers with immobilized microorganisms could regulate plant growth, modify the structures of microbial communities, enhance the biological activity of soil enzymes, thereby improving petroleum hydrocarbon removal efficiency. This provides a novel environmentally friendly approach for the joint remediation of petroleum hydrocarbon-polluted soil by plants and microorganisms.

Optimization of operational parameters of supercritical fluid extraction for PHCs removal from a contaminated sand using response surface methodology

Contamination by petroleum hydrocarbons (PHs) is a great threat to environment due to the higher persistence and bio-toxicity of PHs. Therefore, removal of PHs from contaminated environment and strategies to reduce their toxic effects on living organisms are crucial for environmental safety and human health. The toxic effects of PHs from the polluted soil can be reduced by the addition of microbes and biochar. In this study, a pot trial was carried out to evaluate the effects of sugarcane bagasse (SB) biochar and Bacillus sp. MN54 addition on phytoremediation of PHs and growth of maize (Zea mays L.) in soil artificially contaminated with diesel. Maize seeds were sown in uncontaminated or contaminated (with PHs) soil, treated with biochar and Bacillus sp. MN54. The results revealed that PHs showed significant phytotoxicity to maize plants and the application of strain MN54 and biochar greatly reduced the toxic effects of PHs on plants growth and physiology by increasing the nutrients uptake in PHs contaminated soil. Interestingly, the phytotoxicity of PHs on maize plants was further reduced in the co-supplementation of strain MN54 and biochar. Plants physiological (25–48%) and agronomic (38–47%) attributes were significantly higher as compared to only PHs contaminated soil in the co-supplementation of strain MN54 and biochar. Similarly, nitrogen (41%), phosphorus (43%) and potassium (37%) concentrations were also increased in the co-supplementation of strain MN54 and biochar. Furthermore, maize plants successfully phytoremediate a considerable amount of PHs from soil particularly in the presence of strain MN54 and biochar, and this PHs removal was further enhanced in the co-supplementation of strain MN54 and biochar (i.e., 46% and 77% of initial PHs were removed in unplanted and planted treatments, respectively). The present results indicate that co-supplementation of biochar and Bacillus sp. MN54 could be effective in enhancing the degradation of PHs and improving plant growth in the hydrocarbons contaminated soil.

Effectiveness of the Zea mays-Streptomyces association for the phytoremediation of petroleum hydrocarbons impacted soils

A 2x2x3 factorial design experiment was conducted to analyze the effect of operational variables on the removal of petroleum hydrocarbons from water. The experimental variables studied included contaminant concentration, coagulant type, coagulant use, and type of source water (pond and brackish). Effectiveness of centrifugation process was evaluated in terms of petroleum hydrocarbon (PHC) and turbidity removal. The experimental results showed that centrifugation with coagulation significantly improved the PHC removal. Addition of coagulants prior to centrifugation increased the removal of PHCs by 10 to 14 percent and turbidity by 10 to 35 percent. The effectiveness of coagulation in removing PHCs and turbidity prior to centrifugation was higher at lower PHC concentrations.

Calibration analysis of chloride binding capacity for cement-based materials under various exposure conditions

The role of biodegradation in limiting the accumulation of petroleum hydrocarbons in raingarden soils

Phytoremediation continues to play an important role in the remediation of soils contaminated with hydrocarbons, as demonstrated by the ongoing influx of research articles in this field. A review of the recent literature reveals that studies on phytoremediation continue to assess the effectiveness of both existing and new plant species, particularly in treating contaminated soils. Fertilization and soil amendments are commonly incorporated into these studies. There is significant interest in microbial-assisted phytoremediation and the optimization of phytoremediation with surfactants and root exudates. Phytoremediation using plants alone often encounters limited efficiency (<65% petroleum hydrocarbon removal). However, fertilization, soil amendments, and additives like root exudates can boost efficiency to slightly above 80%, particularly with compost. Microbial-assisted phytoremediation could further increase efficiency to more than 90%, depending on the microorganisms used. Endomycorrhizal fungi and Acinetobacter sp. Tust-DM21 appear to have pronounced enhancing effects on petroleum hydrocarbon removal. Combining and optimizing good agricultural practices, fertilization, soil amendments, additives, and microbial-assisted phytoremediation could enhance overall efficiency while improving plant growth, even in saline or highly contaminated soils. Research on phytoremediation of water contaminated with petroleum hydrocarbons is significantly less prevalent. This review contributes to the identification of effective phytoremediation strategies and suggests that future research could focus on further exploring plant-microbe interactions to improve petroleum hydrocarbon removal. Artificial intelligence could also be incorporated to optimize factors that positively influence phytoremediation.

In this research the feasibility of chemical oxidation with H2O2 and Fenton's reagent for degradation of petroleum hydrocarbons before and after composting of bottom sludge from crude oil storage tanks was investigated. Results showed that total petroleum hydrocarbons removal in composting reactor was 80.2%. In chemical oxidation steps, petroleum hydrocarbons removal enhanced with increasing oxidant concentrations. Increasing oxidation time from 24 to 48 h had a little effect on petroleum hydrocarbons removal. The study showed that chemical oxidation as a pre-treatment step was more effective than post-treatment. It was also deduced that petroleum hydrocarbons in the sludge and composted mixture can be oxidized by hydrogen peroxide without adding supplementary iron.

Background: Pollution of water resources with petroleum hydrocarbons causes adverse effects on ecosystems and human health. Physico-chemical methods for removing thin layers of oil on the water surface are not cost-effective. Azolla is one of the plants that grows and reproduces on the surface of water and has many roots that can be a suitable place for microbial growth and decomposition of oil compounds. Objectives: The aim of this study was to remove petroleum hydrocarbons from water by co-culture of Azolla and bacteria. Methods: Commercial diesel fuel was used as a source of total petroleum hydrocarbon (TPH) pollution in water. Isolated bacteria from diesel fuel-contaminated soil were identified by biochemical test results according to standard methods. Experiments were conducted in separate runs, including culturing bacteria alone, Azolla alone, and co-culture of Azolla-bacteria. Concentrations of 100, 500, and 1000 mgL-1 of TPH in water and contact times of 5.0, 10.0, and 15.0 days were examined. Results: In the case of Azolla culture alone, the mean TPH removal was 40%. In the case of bacteria culture alone and TPH concentration of 1000 mgL-1, the minimum removal was 35% for Pseudomonas aeruginosa and the maximum was 60% for Alcaligenes faecalis. In the case of co-culture with TPH concentration of 1000 mgL-1, the minimum removal was 80% for P. aeruginosa-Azolla and the maximum was 100% for A. faecalis-Azolla. In the case of co-culture, the removal was 100% for TPH concentrations of 100 and 500 mgL-1 at contact times of 5.0 and 10.0 days, respectively. Conclusions: Co-culture of Azolla and bacteria was effective for the complete removal of petroleum hydrocarbons (100 and 500 mgL-1) from water. This method can be used to clean up and remove petroleum hydrocarbons from water.