In theory, biological and physical clogging, induced as a result of potentially excessive formation of biomass from degradation of pollutants and retention of inert suspended fine particles, respectively, should result in a decrease of treatment performance. However, some wetlands are not prone to clogging in practice. The aim of this study was to compare the impact of different design (aggregate size) and operational (contact time, empty time and chemical oxygen demand [COD] loading) variables on the treatment efficiency and clogging processes. Different vertical-flow constructed wetlands were constructed and operated from June 2011 until June 2012. Data from June 2011 (setting-up period) were not used. The filter with the highest COD loading performed the worst in terms of outflow COD concentration (120 mg/l) but best in terms of COD load reduction (61 %). The wetland with the largest aggregate size had the lowest mean nitrate-nitrogen outflow concentration of 1.2 mg/l. However, the results were similar regardless of aggregate size (10 versus 20 mm) and resting time (24 versus 48 h) for most water quality variables. However, different COD inflow concentrations (COD of 146 mg/l versus COD of 312 mg/l) had a significant (p < 0.05) impact on the treatment performance for COD, ammonia-nitrogen, ortho-phosphate-phosphorus and suspended solids (SS). Serious clogging phenomena impacting negatively on the treatment performance were not observed for any columns. However, a small aggregate diameter, a short contact time, a long resting time and a low COD inflow concentration were most beneficial in reducing SS accumulation within the wetland filters. © 2013 Springer Science+Business Media Dordrecht.

Aquaculture wastewaters, with oleic acid (C18:1 ω9) as the most representative contaminant fatty acid, were used as inoculum to perform enrichment cultures in mineral medium in the presence of oleic acid as the sole carbon and energy source, allowing isolation of four bacterial strains named DG1a, DG2a, DG1b and DG2b. 16S rRNA gene sequencing analysis assigned the four isolates to the species Pseudomonas aeruginosa. Among the isolates, P. aeruginosa strain DG2a showed degradation of fatty acids, including oleic acid (C18:1 ω9). The hydrophobicity features were investigated in strain DG2a, and a constitutive hydrophobicity in the bacterial cells was highlighted. The capability to produce biosurfactants by cells of the bacterial strain P. aeruginosa strain DG2a was evidenced both in the presence of oleic acid and of aquaculture wastewaters by revealing emulsifying activity, oil spreading tests, haemolytic and cetyltrimethylammonium bromide agar tests. Bacterial cultures containing raw biosurfactant were added to native wastewaters, showing a depletion of the oleic acid content. The use of the isolated bacterial strain P. aeruginosa strain DG2a and of the produced biosurfactant in bioremediation of aquaculture wastewaters is proposed, and the valorization of aquaculture wastewaters as raw material for biosurfactant production by using the isolate is moreover suggested.

The potential risk of surface and groundwater contamination by the heavy metals and radionuclides leached from uranium waste-rock piles (UWRP) is a major environmental concern in the uranium-mining district of Northern Saskatchewan, Canada. The main objective of this study was to evaluate the nickel and uranium leaching behaviour in the UWRP lithological materials. In addition to the chemical characterization, these selected UWRP geomedia samples were also subjected to the sequential extraction procedure, availability test to quantify leaching potential and cumulative leaching test (CLT). Sequential extractions results demonstrated substantial observed differences in the Ni and U distribution patterns among various operationally defined geochemical fractions. A large fraction of total Ni concentration was associated with non-labile residual fraction while U was mainly present in the labile fractions. The observed labile Ni and U concentrations also remained relatively high in the gneissic basement materials and underlying organic-rich lake sediment. In case of basement materials, both Ni and U concentrations in solution with the first CLT fraction exceeds their maximum permissible levels in both surface and groundwater. Leaching test results confirmed that Ni and U leachability depends on their total content distribution in various solid phase fractions, and several geochemical processes are controlling the solubility of Ni and U geochemical phases in the UWRP. Our experimental data suggest the potential for a long-term risk to surface and groundwater contamination from these UWRP.

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.

The photocatalytic degradation effectiveness of six selected typical phytotoxic substances (ferulic, benzoic, gallic, salicylic, tannic, and acetic acid) by two levels of 10 nm TiO₂ (11 and 22 g/m²) immobilized on tiles under 254 nm of UV light irradiation was investigated. The results showed that the immobilized nano-TiO₂ significantly degraded all phytotoxic substances dissolved in distilled water, and the cumulative degradation rates of ferulic, benzoic, gallic, salicylic, tannic, and acetic acid reached 22.2, 33.6, 48.2, 56.9, 57.5, and 76.0 % after 6 h of treatment, respectively. Furthermore, the cumulative degradation rates of six phytotoxic substances by immobilized nano-TiO₂ were different remarkably, i.e., salicylic acid > benzoic acid, gallic acid > ferulic acid, acetic acid > tannic acid. The maximal photocatalytic degradation efficiencies of all phytotoxic substances appeared at the first 2 h in the three experiments. During the 6-h treatment period, the photocatalytic degradation efficiency of all phytotoxic substances decreased gradually. There was no significant difference in the photocatalytic degradation of benzoic acid and ferulic acid between the two levels of immobilized nano-TiO₂ treatments, whereas a significant difference was found in the photocatalytic degradation of salicylic acid, gallic acid, tannic acid, and acetic acid. In a word, nano-TiO₂ photocatalysis is an effective method to degrade phytotoxic substances. And the photocatalytic degradation effectiveness of six typical phytotoxic substances may be related to their structures.

Cr(VI) adsorption from aqueous solutions on peanut husk modified with formaldehyde (PeH-F) and peanut husk modified with formaldehyde and Fe (PeH-FFe) was evaluated as a function of shaking time, initial pH, chromium concentration, and temperature. Results showed that the Cr(VI) is preferentially adsorbed by PeH-FFe at pH 2 than pH 6. It also was found that the chromate equilibrium sorption capacity for PeH-FFe is at least six times higher than for PeH-F. The optimum pH to remove chromium is 2 for both materials; however, PeH-FFe has a higher efficiency for the chromium removal. Finally, Cr(VI) adsorption also depends on chromium concentration and temperature. The adsorption data as a function of concentration obey Linear, Freundlich, and Langmuir isotherms at pH 2 and 6. The Cr(VI) maximum capacity of PeH-FFe at pH 2 was 33.11 mg Cr(VI)/g, slightly higher than that at pH 6 (31.75 mg Cr(VI)/g). The linear isotherm shows that the pH affect the Cr(VI) distribution into the aqueous/solid phases. The negative value of ΔH and positive values of ΔG indicate that the chromium adsorption process is an exothermic and non-spontaneous process. The characterization of the peanut husk modified with formaldehyde and peanut husk modified with formaldehyde and Fe by scanning electron microscopy, Raman, and IR spectroscopies as well as the textural characteristics of the no-living biomasses were also considered in this work. © 2013 Springer Science+Business Media Dordrecht.

Although concentrations of endocrine-disrupting chemicals (EDCs) in seawaters of Japan are relatively low, vitellogenin and ovotestis inductions are still being observed in some males of mullet and flounder collected in coastal areas. These fish species are benthic and could be affected by EDCs in marine sediments. Therefore, the concentrations of EDCs in marine sediments of Osaka Bay were determined by LC-MS/MS. In addition, the estrogen receptor binding potencies as estrogenic potencies of these sediments were assessed by the medaka estrogen receptor-α binding assay. Results show that estrogenic potencies were higher in sediments of the inner part of the bay especially at station 13 (off Sakai City) where quite strong estrogenic potency was detected. Through calculation of total E2 equivalent concentration (EEQ) in sediments, it was established that approximately 50 % of estrogenic potency was due to nonylphenol (NP), estrone and 17β-estradiol, suggesting that these compounds play important roles as endocrine disruptors in coastal environments of Osaka Bay.

Petroleum hydrocarbon contamination of soil is an emerging environmental threat on the Earth due to possible toxic impact on different ecological receptors. The present study was mainly carried out to evaluate the phytotoxicity of long-term total petroleum hydrocarbon-contaminated soils by the toxicity end points obtained from three plant species Zea mays, Lactuca sativa L., and Cucumis sativus. The tested soil exerted phytotoxicity for all the evaluated end points of plants with dose-dependent relationship. The determined IC₅₀ indicates inhibition in root elongation as the most sensitive toxicity end point for L. sativa L., while inhibition in cross-section area of meristematic zone as the most susceptible and inhibition in seed germination as the least susceptible end points for both Z. mays and C. sativus. The tested root morphometric parameters confirm their applicability as novel toxicity end points. In addition, microcalorimetric analysis confirmed the applicability of inhibition in metabolic heat emission rate as a toxicity end point. Microcalorimetry can be applied to determine the exerted phytotoxic effect on seedlings. The present combined approach concludes that the phytotoxicity of the tested soil is species-specific and varies as follows: Z. mays < C. sativus < L. sativa L. The findings of this study may have implications in planning comprehensive phytotoxicity assessment for hydrocarbon-contaminated soils or screening plant species for phytoremediation program.

A novel immobilized visible light-active photocatalyst (TiO₂/polyvinyl alcohol after thermal treatment (T-PVA)/cordierite honeycomb (CHC)) was successfully prepared by a simple and convenient method combining sol–gel and thermal treatment using tetrabutyl titanate (TBOT) as the titanium source, polyvinyl alcohol (PVA) as the precursor of conjugated polymer, and CHC as the support. The synthesized photocatalyst was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, and field emission scanning electron microscopy. The results showed that PVA was dehydrated to produce conjugated unsaturated T-PVA. The T-PVA not only extended the response spectrum of TiO₂ to visible light region, but also strengthened the adhesion of TiO₂ to CHC. The TiO₂/T-PVA/CHC showed both outstanding adsorption properties and excellent photocatalytic performance under visible light on the decolorization of Rhodamine B. Over eight cycles, the photocatalyst continued to maintain perfect photocatalytic activity, showing good stability.

The fate and transport of emerging contaminants have been major concerns for ecoenvironment and human health. This study presents the adsorption behavior of an endocrine disrupting chemical estrone (E1) and its sulfate conjugate estrone-3-sulfate (E1-3S) that are released to the environment via animal waste in significant amounts and direct exposures in grazed pasture systems. Both compounds have been shown to potentially contribute to endocrine disruption in wildlife, and knowledge about the adsorption behavior of these compounds is necessary for a sound environmental risk assessment. For labile compounds such as E1 and E1-3S, however, the standard protocols might overestimate adsorption by not considering metabolite formation or allowing for equilibration that exceeds the commonly reported half-lives of these compounds. Modified batch adsorption experiments with mediator solution of 0.005 M calcium chloride (CaCl₂) and artificial urine (AU) solution were, therefore, conducted to determine the influence of these mediator solutions on the adsorption of E1 and E1-3S in three agricultural soils from Nasarawa State of Nigeria. Adsorption isotherms of both compounds were nonlinear, and the Freundlich equation was found adequate to describe the isotherms. The calculation of concentration-dependent effective distribution coefficients (K d ᵉᶠᶠ) revealed that for a range of realistic exposure concentrations in a grazed farming system, the common approach of using CaCl₂ would deliver incorrect information for a sound risk assessment.