This paper investigates the electrochemical treatment of polychlorinated biphenyl (PCB) contaminated soils. The research was performed within a project co-funded by the European Regional Development Fund and for the experimental part; artificially contaminated soil with PCB was used. Two reactors of different sizes were used; the smaller designed in a Ph.D. research and the larger in a research project co-funded by the European Regional Development Fund. Specific voltage, current density, redox potential, time and pH values were considered throughout the tests. The initial PCB concentration in the test soil (3.571 mg/kgdw) exceeds the intervention threshold for sensitive use according to Romanian regulations (1 mg/kgdw). Three different tests were performed: within the first one (T1) the soil was polluted with insulating oil; within the other two tests (T2 and T3) the soil was contaminated with capacitor oil. The initial PCB concentrations within the three tests (as a sum of all PCB concentrations) were: 4.4461 mg/kgdw within T1, and 3.5710 mg/kgdw within both T2 and T3. The study showed that the electrochemical treatment could achieve up to 87 % remediation efficiency for PCB polluted soils. Therefore, this treatment is relevant and a potential solution for the remediation of PCB polluted soils.

This work evaluated surfactant-enhanced in situ chemical oxidation (S-ISCO) in a hydrocarbon-contaminated soil. Surfactants and efficacy of oxidant activation as well as the treatability of contaminated soil were assessed. The surfactant VeruSOL-3 with a critical micelle concentration (CMC) of 5.5 g/L was selected. Based on the results, activated oxidations by sodium persulphate and hydrogen peroxide were able to effectively destroy target organic compounds in emulsion and soil. The destruction of total petroleum hydrocarbon (TPH) in emulsion was completed in 14 days and polycyclic aromatic hydrocarbons (PAHs) in excess of 96 %. Green nanoiron was much more active than other activators in emulsion. The data also indicates that oxidation using activators was much less pronounced in soil matrices. However, it is expected that given sufficient dose and treatment time, a higher destruction rate in the contaminated soil can be achieved. The study showed that the remediation of target organic contaminants (TPH, PAH) in soil by S-ISCO using activated sodium persulphate is feasible. © 2013 Springer Science+Business Media Dordrecht.

Bisphenol-A (BPA) is an environmental contaminant used in the manufacturing of polycarbonate plastics and epoxy resins, which has been discovered in freshwater systemsworldwide as a result of effluent from manufacturing. This bioactive molecule is an estrogen mimic and has become a concern for exposure, especially during development, resulting in its removal from baby bottles and other consumer products. BPA is an endocrine disruptor in a variety of species and has been classified as a toxic substance in multiple countries. In this study, we examined the effect of BPA exposure on leukocyte counts in wild yellow perch, Perca flavescens. Yellow perch were exposed to either 2, 4, and 8 ppb BPA; Saprolegnia; or a blank control for a period of 7 days. Leukocyte blood counts were significantly higher in Saprolegnia, 4 ppb BPA, and 8 ppb BPA treatments compared to control. To test compound effects of BPA and Saprolegnia on leukocyte counts over a 7-day period, perch were exposed to either 4 ppb BPA, 4 ppb BPA+Saprolegnia, or control. Leukocyte counts were significantly higher in the 4 ppb BPA treatment relative to control. The 4 ppb BPA+Saprolegnia treatment was numerically elevated from the control, exhibiting a 153 % increase relative to control. BPA represents a contaminant with immunomodulatory properties that remain to be determined. © Springer Science+Business Media Dordrecht 2013.

A chitosan-graft-poly(N-allyl maleamic acid) hydrogel membrane was prepared by radical polymerization in the absence of a cross-linker. The product was characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM) to confirm the formation of hydrogels. Transparent hydrogels have been observed to exhibit as much as 223.4 % swelling capacity, following pseudo-second-order kinetic models. The synthesized hydrogel membrane was subsequently utilized for removal of copper ions from an aqueous solution in the presence of several different functional groups. The effects on adsorption efficiency of various parameters such as time, temperature, pH, initial concentration of copper (II) solution, and amount of hydrogel were also investigated. The maximum adsorption capacity and efficiency were found to be 50.75 mg g-1 and 99.91 %, respectively, by the 0.004 mg adsorbent after 12 h of immersion in copper solution. Finally, the result showed that hydrogel membrane is pH sensitive to copper (II) adsorption and has maximum adsorption efficiency near to the pH of ground water. © 2013 Springer Science+Business Media Dordrecht.

Uptake, bioaccumulation, and assimilation of ferricyanide by three different species of willows was investigated. Intact prerooted weeping willows (Salix babylonica L.), Hankow willows (Salix matsudana Koidz), and hybrid willows (S. matsudana Koidz × alba L.) were grown hydroponically and treated with ferricyanide at 25.0 ± 0.5 °C for 144 h. Willows without leaves were also investigated as a treatment to quantify effect of transpiration on transport and assimilation of ferricyanide. Dissociation of ferricyanide to free cyanide in solution in absence of light was negligible. Phytotransport of ferricyanide was apparent. The phytoremoval rate of ferricyanide obtained varied with willow species (p < 0.05). Remarkable decreases in the removal rate were detected with the trees without leaves compared with the intact trees (p < 0.01). Due to small amounts of the applied ferricyanide recovered in plant materials, ferricyanide removed from the hydroponic solution was largely assimilated by plants. Transpiration stream concentration factor (TSCF) was also estimated using the content of iron (Fe). These information suggests that phytodegradation is a major process involved in botanical assimilation of ferricyanide through an undefined degradation pathway.

There are growing concerns about the increasing trends of emerging micropollutants in the environment due to their potential negative impacts on natural ecosystems and humans. This has attracted attention from both governmental and non-governmental organisations worldwide. Pharmaceuticals, personal care products, and endocrine disruptors are continuously being released consciously or unconsciously into water sources due to poor regulatory frameworks especially in the developing countries. The effects of these contaminants are poorly known. They are not easily biodegradable and have become an environmental nuisance and public health issue. This has heightened the risk of exposure to their deleterious effects in such countries where the majority of the population are still struggling to have access to good quality drinking water supplies and better sanitation. With the rising fear of short- and long-term impacts of the ever-increasing number of persistent recalcitrant organic compounds accumulating in the environment, their removal is gradually becoming an issue to the water treatment industry. Hence, there is a need to develop functional techniques for the management of water contaminated by these emerging contaminants so as to increase the availability and access to safe and good-quality drinking water. We conducted a narrative review on these emerging micropollutants and examined their various documented sources, effects, as well as recent techniques for their effective removal. This becomes necessary due to the increasing occurrence of these pollutants in the aquatic and terrestrial environment. These levels are expected to further increase in the coming years as a consequence of the ever-increasing population density which undoubtedly characterizes developing economies. Our findings show that the present reported treatment techniques in the literature such as biological oxidation/biodegradation, coagulation/flocculation, ozonation, electrodialysis, reverse osmosis, sedimentation, filtration, and activated carbon were not designed for removal of these newly identified contaminants, and as such, the techniques are not sufficient and unable to completely degrade the compounds. We therefore recommended the need for concerted efforts to develop better techniques, especially combined advanced oxidative methods to address the shortcomings of and growing challenge to current practices.

Bioclogging extensively exists in porous media, such as permeable reactive barrier (PRB), constructed wetland, reverse osmosis, and biofilter systems and affects efficiency of sewage treatment. In this paper, variation in biochemical and hydraulic parameters under discontinuous flow condition during the clogging process was obtained. Hydraulic conductivity (K) first decreased sharply to 34.22 % of the original value during the initial 12th day and, finally, decreased to 13.70 %. Hydrodynamic dispersion (D) went through slow increase, fast increase, fast decrease, slow increase, and ultimately decreased to 44.25 %. Porosity (n) decreased obviously, especially during the initial 12 days, and total bacterial counts in the inlet of the column had more than one order of magnitude increase. The bioclogging process can be divided into four stages: (1) severe bioclogging occurred and aerobic microorganisms reproduced rapidly in the inlet, (2) bioclogging existed in the entire sand column and the hydrodynamic dispersion increased drastically as anaerobic microorganisms generated some gas, (3) aerobic and anaerobic microorganisms reproduced and hydrodynamic dispersion decreased rapidly, and (4) microorganisms multiplied continuously and the hydraulic parameters (hydrodynamic dispersion, hydraulic conductivity, and porosity) decreased steadily. Bioclogging then transformed into steady stage. Based on analysis of experimental data, hydraulic conductivity (K) follows the rule of negative exponent relationship, porosity (n) accords with power exponent relationship, and hydrodynamic dispersion (D) is polynomial equation under bioclogging process.

A novel porous biomorph-genetic composite of α-Fe₂O₃/Fe₃O₄/C (PBGC-Fe/C) with eucalyptus wood template was prepared, characterized and tested for its sorption capacity of As(V) from aqueous solution. The result indicated that the PBGC-Fe/C material retained the hierarchical porous structure of eucalyptus wood with three different types of pores (widths 70∼120, 4.1∼6.4 and 0.1∼1.3 μm) originating from vessels, fibres and pits of the wood, respectively. Its surface area was measured to be 59.2 m²/g. With increasing initial As(V) concentration from 5 to 100 mg/L, the amounts of As(V) sorbed on the pulverized PBGC-Fe/C sorbent (<0.149 mm) increased from 0.50 to 4.01 mg/g at 25 °C, from 0.50 to 4.83 mg/g at 35 °C and from 0.50 to 4.19 mg/g at 45 °C, and the corresponding removal rates decreased from 99.97 to 40.10 % at 25 °C, 99.95 to 48.40 % at 35 °C and 99.92 to 42.05 % at 45 °C. At the initial concentrations of 5, 10 and 50 mg/L, the sorption capacities for the unpulverized PBGC-Fe/C sorbent (>3 mm) were determined to be 0.50, 0.99 and 2.49 mg/g, respectively, which exhibited a similar average value to those of fine particles or nanoparticles of iron oxides. The sorption could well be described by the pseudo-second-order kinetic equation. The equilibrium data were found to follow Freundlich as well as Langmuir isotherms.

Dual-effects of adsorption and photodegradation over titania, silica embedded titania, silica and commercial Degussa P-25 samples were studied for the decolourization of methylene blue in aqueous medium. Silica embedded titania and silica were prepared using inexpensive polymeric version of ethyl silicate as a source of silica. Catalysts were characterized by X-ray diffraction, scanning electron microscopy, UV-Vis spectroscopy and low temperature (77 K) nitrogen adsorption measurements. Among all the catalysts, silica embedded titania has exhibited faster decolourization of methylene blue solution on account of the enhancement of adsorption followed by degradation. An amount of the catalyst and the initial dye concentration of MB solution were found to influence the decolourization activity. Compared to titania catalyst, silica embedded titania and Degussa P-25 have shown the red shift in their UV-Vis spectrum. The experimental data of the reaction fitted well to the pseudo first order kinetic model. In present studies, the adsorption mechanism for the decolourization of MB solution was found to be applicable for an intra particle diffusion model. © 2013 Springer Science+Business Media Dordrecht.

Water and sediment samples were collected along river transects at three artisanal gold mining areas in southern Ecuador: Nambija, Portovelo-Zaruma, and Ponce Enriquez. Samples were analyzed for a suite of major and trace elements, including filtered/unfiltered water samples and stream flow measurements to determine dissolved/particulate loads. Results show that the Q. Calixto, Calera, and Siete rivers (corresponding to Nambija, Portovelo-Zaruma, and Ponce Enriquez mining areas, respectively) have substantial trace element contamination due to mining inputs. Dissolved concentrations were elevated at Calera and Siete relative to Q. Calixto, possibly reflecting the input of soluble cyano-metal complexes in mining zones where cyanidation is used in ore processing. A negative correlation was found between MeHg:THg ratios and pH, indicating an inverse relationship of mercury methylation with cyanidation (since cyanidation increases water pH). This was the first comprehensive study to examine an extensive suite of trace elements in both water and sediment at the three main gold mining areas of southern Ecuador, including dissolved and particulate loads, and the first study to report MeHg concentrations in the mercury-contaminated rivers.