54 research outputs found
Batch tests for the optimization of PAH bioremediation in Mediterranean tourist port sediments
No full textPort sediments are frequently contaminated by organic or inorganic pollutants, among which polycyclic aromatic hydrocarbons (PAHs) represents a serious hazard for humans and ecosystems involving the need to treat them before disposal. In the framework of the ENPI MAPMED project (Management of port areas in the Mediterranean Sea basin), the present work aims to evaluate the best conditions of PAHs bioremediation by comparing in slurry aerobic batch tests: bioaugmentation, nutrients and different surfactants addition (saponins, Tween 80). Sediments were collected from the ports of El Kantaoui (Tunisia) and Cagliari (Italy). Fluorene, phenanthrene, fluoranthene, pyrene and benzo(a)pyrene were added at the concentration of 40mg/kgss. Parallel abiotic tests were performed. The experiments conducted without amendments showed in both sediments, after 5 days, complete fluorene and phenanthrene degradation, while pyrene and fluoranthene degradation was slower and showed a 3-day lag phase. Moreover, fluoranthene was not completely removed after 10d. Benzo(a)pyrene was only removed of about 20% in El Kantaoui sediments. Regarding the amendments, the best results were obtained with nutrient regulation (C:N:P ratio 100:10:1) and bioaugmentation, which increased removal rates and reduced the lag phase for fluoranthene and pyrene, in both sediments. Benzo(a)pyrene removal was only slightly increased in Cagliari sediments. The effect of the two surfactants differed: phytogenic saponins affected positively PAHs removal while synthetic Tween80 gave only a slight improvement in El Kantaoui sediments; for Cagliari sediments the effect of both surfactants was negative. These results are in line with previous observations suggesting a strong dependence on the specific sediments properties
HEXAVALENT CHROMIUM REDUCTION IN A BIOCATHODIC MICROBIAL ELECTROLYSIS CELL
No full textGroundwater is the environmental matrix most frequently affected by anthropogenic hexavalent chromium contamination. Due to its cancerogenicity, Cr(VI) has to be removed, hopefully using environmental-friendly and economically sustainable remediation technologies. To overcome the limits of the currently applied bioremediation technologies, an alternative strategy is the use of BioElectrochemical Systems (BESs) to stimulate bioreduction of Cr(VI). BESs include a set of technologies based on biological reactors where an electrode (anode) can function as the final electron acceptor for the oxidation of organic compounds; then electrons flow through the circuit and reach the cathode that acts as the electron donor for the bioreduction of oxidized species. In the present study, we have assessed if Cr(VI) can act as an efficient terminal electron acceptor for an anaerobic biocathode in a Microbial Electrolysis Cell (MEC).
The cathode was first inserted into the anodic compartment of a dual-chamber Microbial Fuel Cell, and inoculated with sludge from an anaerobic digester. After 50 days of acclimation, the electrode was transferred into the cathodic chamber to work at -300 mV (vs. SHE) as the biocathode in a Cr(VI)-reducing MEC. An abiotic control and an open circuit control were also operated in parallel. Hexavalent chromium dissolved concentration was analyzed at the initial, during the experiment and final time by spectrophotometric method, while the dissolved total chromium was analyzed by ICP-MS. During the whole test, the current intensity was monitored. At the end of the experiment, the microbial characterization of the communities enriched on the biocathode and in the cathodic solution was performed by 16S rRNA gene sequencing.
The acclimation phase in the MFC allowed the formation of an electroactive biofilm on the electrode. A decrease in Cr(VI) concentration was observed at the end of the tests, both in the polarized reactor and in the open circuit reactor. However, the bioelectrochemical system ensured higher removal efficiency than the pure chemical process. In addition, higher current values were measured in the BES compared to the abiotic control, thanks to the biofilm interaction with the electrode. The results from microbial characterization showed that the bacterial community on the surface of the electrode was affected by the cathodic polarization, and it was different from the biomass on graphite in the open circuit system
Nonylphenol, benzophenones and benzotriazoles in different environmental matrices and foods
No full textEmerging contaminants in sediments: a review
No full textEmerging Contaminants (ECs) are chemicals for which new concerns have recently raised in terms of occurrence, fate, adverse effects on human health and the environment. ECs include pharmaceuticals, nanomaterials, compounds used in personal care products, plastics, pesticides and flame retardants, and compounds with a large variety of uses (e.g., phenolic and perfluorinated compounds, chlorinated paraffins, etc.).
The EU Water Framework Directive 2013/39/EU deals with the status of water bodies and reports an updated list of priority substances. Some of these (e.g., nonylphenols, di(2-ethylhexyl)phthalate DEHP, perfluorooctane sulfonate PFOS, hexabromocyclododecanes, polybrominated diphenyl ethers, etc.) are emerging contaminants with high affinity towards suspended solids and sediments, due to their physicochemical properties (e.g., Koc value, etc.). The review focuses on this group of pollutants, reporting about the occurrence and distribution in sediments and biota, bioaccumulation and ecotoxicity, and the target or limit values that have been set in order to protect the aquatic environment and the human health
BIOELECTROCHEMICAL SYSTEM FOR REMOVING HEXAVALENT CHROMIUM FROM WATERS
No full textBES include a set of technologies that exploit the ability of certain microorganisms to use electrodes as the electrons acceptors/donors and to catalyze redox reactions in order to promote a flow of electrons. In the present study, we have assessed the possibility to remove Cr(VI) in a biocathodic chamber of a dual-chamber (2C) Microbial Electrolysis Cell (MEC) with cathode as the sole electron donor. The cathode was first put into the anodic compartment of a 2CMicrobial Fuel Cell (MFC) inoculated with sludge from an anaerobic digester. After the acclimation period, the electrode was transferred into the cathodic chamber to work at -300 mV (vs. Standard Hydrogen Electrode - SHE) as the biocathode in a Cr(VI)-reducing MEC with 2000 μg Cr(VI)/L. The acclimation phase in the 2C-MFC allowed to shorten the time for the electroactive-biofilm growth, and to increase the efficiency of the Cr(VI)-reducing MEC. The bioelectrochemical system ensured higher removal efficiency than the pure chemical process
Design of permeable reactive barriers and examples of full scale treatments
No full textPermeable reactive barriers (PRBs) are innovative technologies for the in situ remediation of contaminated groundwater. The technology involves the emplacement, into an excavated zone of the aquifer across the flow path of the contaminated groundwater, of a "reactive" filling material permeable to groundwater to intercept and treat the contaminants as the plume flows through under the influence of the natural hydraulic gradient.
A wide range of materials are currently available. Some of them remove contaminants through non-destructive mechanisms, such as precipitation, sorption or cation exchange (also promoted by geochemistry modifications in the treatment zone), other through destructive mechanisms, such as abiotic degradation or biological degradation (in biobarriers). The choice among these is primarily based on the contaminant to remove and the abatement required, but the hydrogeological and the biogeochemical conditions of the aquifer may have great influence as well. Sometimes, concurrently mechanisms acts in removing the pollutants. Multilayer barrier systems can be developed in order to treat groundwater affected by different kinds of pollutants
Pollutants in Groundwater
No full textGroundwater contamination generically refers to modifications in biological, physical or chemical characteristics (e.g., salinity, temperature, etc.), the presence of undesirable solutes at significant concentrations, or radioactivity. It may be: (i) of natural origin, (ii) the result of human activity; or (iii) a combination of the previous two. Naturally occurring processes, such as decomposition of organic material in soils or leaching of mineral deposits, can result in increased concentrations of several substances such as manganese, sulphate, chloride, organic matter, fluoride, arsenic, nitrate, selenium, uranium, and radon. Sources of groundwater contamination due to human activities are widespread and include diffuse sources as well as point-sources of pollution, such as land application of animal manure containing contaminants (e.g., veterinary pharmaceuticals) and agrochemicals in agriculture, leakages from sewers or sanitation systems, from waste disposal sites, landfills, underground storage tanks and pipelines, and accidental spills in mining, industry, traffic, health care facilities and military sites. The exploitation of petroleum products and the development of the industrial chemistry have given rise to a large number of organic chemicals, many of which are found in the environment. Various studies have shown that anthropogenic chemicals such as pesticides, pharmaceuticals and personal care products, industrial chemicals, and fuel additives occur in groundwater. U.S. Geological Survey (USGS) investigations have assessed the occurrence, distribution, and benchmark exceedance of various contaminants in water from public-supply wells and domestic wells, including pesticides, volatile organic compounds, pesticides and nitrate. Chemical mixtures were frequently detected, often with concentrations of individual contaminants approaching human-health benchmarks. Chemical mixtures that most frequently occurred and had the greatest potential toxicity were composed of arsenic, strontium, uranium, radon, and nitrate. Many organic chemicals are known to have potential human health impacts, and some of these may occur in groundwater at relevant concentrations. The list of those for which guideline values and national quality standards have been developed has been continually extended and revised. Among these: mono-aromatic hydrocarbons (benzene, toluene, ethylbenzene and xylenes - BTEX), volatile chlorinated hydrocarbons (tetrachloroethene - PCE, trichloroethene - TCE), and pesticides. This chapter focuses on chemical substances that have reasonable potential to contaminate groundwater and have human health impacts. It provides information about: i) the major sources of pollution; ii) inorganic contaminants, iii) organic contaminants; and iv) emerging issues
Priorities List of contaminated sites: a new relative risk assessment procedure
No full textThis paper presents a methodology (SER-APHIM) developed to prioritize efforts into investigation and/or remedial actions at contaminated sites at regional scale (Lombardy Region – Italy). The approach is a two-tiered procedure based on the "source-pathway–receptor" paradigm. Tier 1 (SER – Short Environmental Radar) is a screening tool that run with very few site-specific data and leads to a list of critical sites to sort by using Tier 2 (APHIM - Assessment of Priorities for Human health and environmental IMpacts). Tier 2 needs more detailed information about sites and their surrounding areas, including contaminant concentrations in primary sources and secondary sources, geology, hydrogeology, data from a Geographic Information System (GIS) developed for the purpose (which relates the georeferenced sites and their surrounding areas to regional cartography and census data providing climate conditions, land use, natural resources, hydrographic networks and human receptors). Tier 1 application resulted in a list of 50 sites affected by primary sources, polluted soil or groundwater; sufficient data were available only for 43 sites, which were sorted out by Tier 2
Bisphenol A, nonylphenols, benzophenones, and benzotriazoles in soils, groundwater, surface water, sediments, and food: a review
No full textContaminants of emerging concern (CECs) are not commonly monitored in the environment, but they can enter the environment from a variety of sources. The most worrying consequence of their wide use and environmental diffusion is the increase in the possible exposure pathways for humans. Moreover, knowledge of their behavior in the environment, toxicity, and biological effects is limited or not available for most CECs. The aim of this work is to edit the state of the art on few selected CECs having the potential to enter the soil and aquatic systems and cause adverse effects in humans, wildlife, and the environment: bisphenol A (BPA), nonylphenol (NP), benzophenones (BPs), and benzotriazole (BT). Some reviews are already available on BPA and NP, reporting about their behavior in surface water and sediments, but scarce and scattered information is available about their presence in soil and groundwater. Only a few studies are available about BPs and BT in the environment, in particular in soil and groundwater. This work summarizes the information available in the literature about the incidence and behavior of these compounds in the different environmental matrices and food. In particular, the review focuses on the physical-chemical properties, the environmental fate, the major degradation byproducts, and the environmental evidence of the selected CECs
Do Emerging Contaminants Translocate from Soil to Lettuce?
No full textBisphenol A (BPA), nonylphenol (4-NP), benzophenone (BP), and
benzophenone-3 (BP-3) are emerging contaminants (ECs) having the potential to enter
the soil and food, and cause adverse effects in humans, wildlife, and the environment. In
order to understand the potential translocation to edible vegetables and risk for humans
due to their consumption, lettuce was cultivated for 54 d on artificially polluted soils and
uncontaminated (blank) soil. BPA contamination in soil resulted in a very rapid
degradation and no BPA was found in the vegetable. Lettuce from the 4-NP
contaminated pot had higher concentrations compared to the vegetables from the blank
pot; p-cresol was the most frequently detected 4-NP degradation product. BP and BP-3
concentrations in lettuce from the contaminated pot and the uncontaminated pot were
similar
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