Polycyclic aromatic hydrocarbons remobilization from contaminated porous media by (bio)surfactants washing.

Biosurfactants, surface-active agents produced by microorganisms, are increasingly studied for their potential use in soil remediation processes because they are more environmentally friendly than their chemically produced homologues. In this work, we report on the use of a crude biosurfactant produced by a bacterial consortium isolated from a PAHs-contaminated soil, compared with other (bio)surfactants (Tween80, Sodium dodecyl sulfate - SDS, rhamnolipids mix), to wash PAHs from a contaminated porous media. Assays were done using columns filled with sand or sand-clay mixtures (95:5) spiked with four model PAHs.

Surface volatilization modeling of (semi-)volatile hydrophobic organic compounds: The role of reference compounds.

Volatilization of hazardous hydrophobic organic compounds is often observed in many water, wastewater and soil treatment (bio)processes. Several models have been developed to quantify and predict gas-liquid pollutant transfer, being the proportionality coefficient model (PCM) one of the most commonly used, particularly in wastewater treatment. The PCM is based on the use of oxygen as a reference compound, which has a low resistance to the transfer in the gas phase.

Evaluation of trace metal accumulation in six vegetable crops intercropped with phytostabilizing plant species, in a French urban wasteland.

The extensive development of agriculture in urban and peri-urban wastelands polluted with several trace elements (TE) poses risks to human health through contaminated food products. The objective was to explore the accumulation of TE in the various parts of vegetable crop plants (tomato, French bean, radish, potato, spinach, and leek) intercropped with phytostabilizing plant species (ryegrass and white clover, respectively). Field studies were conducted in a multicontaminated French urban wasteland with Cd, Cu, Pb and Zn, and an alkaline soil pH.

Comparison of thermal and chemical enhanced recovery of DNAPL in saturated porous media: 2D tank pumping experiments and two-phase flow modelling.

Pumping experiments were performed in a 2D tank in order to estimate the recovery yield of pure heavy chlorinated organic compounds (DNAPL; dense non-aqueous phase liquids) by varying different parameters: permeability of the saturated zone, pumping flow rates, addition of surfactant and heating. Surfactant was added to decrease capillary forces involved in the entrapment of DNAPL in porous media while temperature was increased to reduce DNAPL viscosity (and hence increase its mobility). Chemical enhancement was performed with the addition of Sodium Dodecyl Benzene Sulfonate (SDBS) (at its Critical Micelle Concentration, to avoid DNAPL dissolution) and thermal enhancement was performed at 50 °C (to avoid DNAPL volatilization).

Functional potential of sewage sludge digestate microbes to degrade aliphatic hydrocarbons during bioremediation of a petroleum hydrocarbons contaminated soil.

Sewage sludge digestate is a valuable organic waste which can be used as fertilizer in soil bioremediation. Sewage sludge digestate is not only a good source of nutrients but is also rich in bacteria carrying alkB genes, which are involved in aliphatic hydrocarbons metabolism. Increase of alkB genes ratio in polluted soils has been observed to improve bioremediation efficiency.

Remediation of soils contaminated by hydrophobic organic compounds: How to recover extracting agents from soil washing solutions?

A lot of soil (particularly, former industrial and military sites) has been contaminated by various highly toxic contaminants such as petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs) or chlorinated solvents. Soil remediation is now required for their promotion into new industrial or real estate activities. Therefore, the soil washing (SW) process enhanced by the use of extracting agents (EAs) such as surfactants or cyclodextrins (CDs) has been developed for the removal of hydrophobic organic compounds (HOCs) from contaminated soils.

Electro-Fenton treatment of a complex pharmaceutical mixture: Mineralization efficiency and biodegradability enhancement.

Combination of the electro-Fenton process with a post-biological treatment could represent a cost-effective solution for application of electrochemical advanced oxidation processes. The objective of this study was to assess this treatment strategy in the case of a complex pharmaceutical mixture. First, main operating parameters ([Fe] and current) of the electro-Fenton process were optimized.

Production of biosurfactant using the endemic bacterial community of a PAHs contaminated soil, and its potential use for PAHs remobilization.

Biosurfactants are surface-active agents produced by microorganisms whose use in soil remediation processes is increasingly discussed as a more environmentally friendly alternative than chemically produced surfactants. In this work, we report the production of a biosurfactant by a bacterial community extracted from a polluted soil, mainly impacted by PAHs, in order to use it in a soil-washing process coupled with bioremediation. Nutrient balance was a critical parameter to optimize the production.

Thermal and chemical enhanced recovery of heavy chlorinated organic compounds in saturated porous media: 1D cell drainage-imbibition experiments.

Chemical and thermal enhanced recovery of pure heavy chlorinated organic compounds (DNAPL; dense non-aqueous phase liquids) was investigated by using lab-scale 1D cells. Temperature was increased to reduce DNAPL viscosity (and hence increase its mobility), while surfactant was added to decrease capillary forces involved in the entrapment of DNAPL in porous media. Laboratory scale experiments, based on mass balance and indirect monitoring methods (i.

Effect of digestate application on microbial respiration and bacterial communities' diversity during bioremediation of weathered petroleum hydrocarbons contaminated soils.

Digestate is an organic by-product of biogas production via anaerobic digestion processes and has a great potential as soil fertilizer due to concentrated nutrients. In this study, we examined digestate as a potential nutrient and microbial seeding for bioremediation of weathered (aged) petroleum hydrocarbon contaminated soils. We analysed 6 different treatments in microcosm using two industrial soils having different textures: a clay rich soil and a sandy soil.

Impact of pyrometallurgical slags on sunflower growth, metal accumulation and rhizosphere microbial communities.

Metallurgical exploitation originates metal-rich by-products termed slags, which are often disposed in the environment being a source of heavy metal pollution. Despite the environmental risk that this may pose for living organisms, little is known about the impact of slags on biotic components of the ecosystem like plants and rhizosphere microbial communities. In this study, metal-rich (Cu, Pb, Zn) granulated slags (GS) derived from Cu production process, were used for a leaching test in the presence of the soil pore solution, showing that soil solution enhanced the release of Cu from GS.

Lead sorption by biochar produced from digestates: Consequences of chemical modification and washing.

The main objectives of this work are to investigate the consequences of different chemical treatments (i.e. potassium hydroxide (KOH) and hydrogen peroxide (HO)) and the effect of biochar washing on the Pb sorption capacity.

Removal of lead and cadmium from aqueous solutions by using 4-amino-3-hydroxynaphthalene sulfonic acid-doped polypyrrole films.

Water pollution by heavy metals is a great health concern worldwide. Lead and cadmium are among the most toxic heavy metals because they are dangerous for the human and aquatic lives. In this work, the removal of lead and cadmium from aqueous solutions has been studied using electrosynthesized 4-amino-3-hydroxynaphthalene-1-sulfonic acid-doped polypyrrole (AHNSA-PPy) films as a new adsorbent.

Removal mechanisms in aerobic slurry bioreactors for remediation of soils and sediments polluted with hydrophobic organic compounds: An overview.

Hydrophobic organic compound (HOC)-contaminated soils are a great environmental and public health concern nowadays. Further research is necessary to develop environmental friendly biotechnologies that allows public and private sectors to implement efficient and adaptable treatment approaches. Aerobic soil-slurry bioreactor technology has emerged as an effective and feasible technique with a high remediation potential, especially for silt and clay soil fractions, which often contain the highest pollutant concentration levels and are usually difficult to remove by implementing conventional methods.

Bioelectro-Fenton: evaluation of a combined biological-advanced oxidation treatment for pharmaceutical wastewater.

Electro-Fenton (EF), an advanced oxidation process, can be combined with a biological process for efficient treatment of wastewater containing refractory pollutants such as pharmaceuticals. In this study, a biological process was implemented in a sequencing batch reactor (SBR), which was either preceded or followed by EF treatment. The main goal was to evaluate the potential of two sequences of a combined electrochemical-biological process: EF/SBR and SBR/EF for the treatment of real wastewater spiked with 0.

Influence of activated sewage sludge amendment on PAH removal efficiency from a naturally contaminated soil: application of the landfarming treatment.

The removal of polycyclic aromatic hydrocarbons (PAHs) from a naturally co-contaminated soil by PAHs and heavy metals with an initial concentration of 620 mg of total PAHs kg dry soil was investigated. The efficiency of landfarming in removing phenanthrene, pyrene, benzo(a)pyrene and the group of total 16 US EPA PAHs was evaluated. The process was biostimulated by adding centrifuged activated sewage sludge (SS) as an organic amendment.

Characteristics of PAH tar oil contaminated soils-Black particles, resins and implications for treatment strategies.

Tar oil contamination is a major environmental concern due to health impacts of polycyclic aromatic hydrocarbons (PAH) and the difficulty of reaching acceptable remediation end-points. Six tar oil-contaminated soils with different industrial histories were compared to investigate contamination characteristics by black particles. Here we provide a simple method tested on 6 soils to visualize and identify large amounts of black particles (BP) as either solid aggregates of resinified and weathered tar oil or various wood/coke/coal-like materials derived from the contamination history.

Bioremediation of copper-contaminated soils by bacteria.

Although copper (Cu) is an essential micronutrient for all living organisms, it can be toxic at low concentrations. Its beneficial effects are therefore only observed for a narrow range of concentrations. Anthropogenic activities such as fungicide spraying and mining have resulted in the Cu contamination of environmental compartments (soil, water and sediment) at levels sometimes exceeding the toxicity threshold.

Importance of organic amendment characteristics on bioremediation of PAH-contaminated soil.

This study investigates the importance of the organic matter characteristics of several organic amendments (i.e., buffalo manure, food and kitchen waste, fruit and vegetables waste, and activated sewage sludge) and their influence in the bioremediation of a polycyclic aromatic hydrocarbons (PAH)-contaminated soil.

Leaching and selective copper recovery from acidic leachates of Três Marias zinc plant (MG, Brazil) metallurgical purification residues.

Zinc plant purification residue (ZPR), a typical Zn-hydrometallurgical waste, was collected from the Três Marias Zn plant (MG, Brazil). ZPR was characterized for its metal content and fractionation, mineralogy, toxicity and leachability. Toxicity characteristics leaching procedure (TCLP) and European Community Bureau of Reference (BCR) sequential extraction results revealed that this ZPR displays high percentages of metals (Cd, Cu, Zn and Pb) in the highly mobilizable fractions, increasing its hazardous potential.

Citric acid- and Tween(®) 80-assisted phytoremediation of a co-contaminated soil: alfalfa (Medicago sativa L.) performance and remediation potential.

A pot experiment was designed to assess the phytoremediation potential of alfalfa (Medicago sativa L.) in a co-contaminated (i.e.

Leaching and selective zinc recovery from acidic leachates of zinc metallurgical leach residues.

Zinc (Zn) leaching yields and kinetics from three different zinc plant leach residues (ZLR) generated in different periods (ZLR1>30 years, ZLR2 5-30 years and ZLR3<2 years) were investigated. The factors affecting the Zn leaching rate such as solid to liquid ratio, temperature, acid concentration and agitation were optimized. Under optimum conditions, 46.

Impact of electrochemical treatment of soil washing solution on PAH degradation efficiency and soil respirometry.

The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil.

Fractionation and leachability of heavy metals from aged and recent Zn metallurgical leach residues from the Três Marias zinc plant (Minas Gerais, Brazil).

Various mineral processing operations to produce pure metals from mineral ores generate sludges, residues, and other unwanted by-products/wastes. As a general practice, these wastes are either stored in a reservoir or disposed in the surrounding of mining/smelting areas, which might cause adverse environmental impacts. Therefore, it is important to understand the various characteristics like heavy metal leaching features and potential toxicity of these metallurgical wastes.

Removal of hydrophobic organic pollutants from soil washing/flushing solutions: A critical review.

The release of hydrophobic organoxenobiotics such as polycyclic aromatic hydrocarbons, petroleum hydrocarbons or polychlorobiphenyls results in long-term contamination of soils and groundwaters. This constitutes a common concern as these compounds have high potential toxicological impact. Therefore, the development of cost-effective processes with high pollutant removal efficiency is a major challenge for researchers and soil remediation companies.