Investigations were undertaken to study sorption of heavy metal ions from aqueous solution onto coal bottom ash. X-ray diffraction analysis of coal bottom ash indicated presence of feldspar (KAlSi₃O₈–NaAlSi₃O₈–CaAl₂Si₂O₈), mullite (Al₆Si₂O₁₃), and magnetite (Fe²⁺Fe³⁺₂O₄). Toxicity characteristics leaching procedure (TCLP) revealed that heavy metal ions such as Fe(II), Fe(III), Mn(II), Cu(II), Zn(II), As(III), As(V), Pb(II), and Cd(II) could be leached out from coal bottom ash. Continuous column test with the bottom ash showed negligible heavy metal ion leach-out at pH 6.0, although at pH 4.2 some heavy metal ion leaching, mainly of Mn(II), was observed. Batch sorption studies with individual heavy metal ions (Fe(II), Cu(II), Zn(II) and Mn(II)) revealed that the heavy metal ion sorption onto coal bottom ash could be described by pseudo-second-order kinetics. Sorption isotherm studies revealed that Langmuir isotherm could adequately describe the heavy metal ion sorption onto coal bottom ash with maximum adsorption capacity (qₘ) ranging from 1.00 to 25.00 mg/g for various heavy metal ions. Removal of heavy metal ions by coal bottom ash is attributed to both adsorption and hydroxide precipitation of heavy metals due to the presence of different oxides (i.e., SiO₂, Al₂O₃, Fe₂O₃, CaO) in coal bottom ash.

The elimination of five selected emerging contaminants (1-H-benzotriazole, N,N-diethyl-m-toluamide (DEET), chlorophene, 3-methylindole, and nortriptyline HCl) dissolved in different water matrices (surface water and secondary effluents) was carried out by sequential membrane filtration and chemical oxidation processes. First, a membrane filtration (ultrafiltration (UF) or nanofiltration(NF)) pre-treatment was conducted, and both permeate and retentate were afterwards treated by chemical oxidation, using ozone or chlorine. The application of UF and especially of NF provided a large volume of permeate, whose quality can be improved by a chemical treatment to completely remove residual contaminants except 1-H-benzotriazole. Chlorination and especially ozonation have demonstrated to be effective for the reduction of emerging contaminants in the concentrated stream, thus generating an effluent that might be recycled to the activated sludge treatment in the wastewater treatment plants (WWTP). In a second group of experiments, a chemical oxidation pre-treatment (by using ozone, chlorine, O₃/H₂O₂, ultraviolet (UV) radiation, or UV/H₂O₂) was applied followed by a nanofiltration process. Results of removals and rejection coefficients for the emerging contaminants showed that the chemical pre-treatment exerted a positive influence on the subsequent NF process, not only in terms of ECs removal but also of dissolved organic carbon content (DOC) reduction. While global removals higher than 97 % were reached for DEET, chlorophene, 3-methylindole, and nortriptyline HCl, lower values were obtained for 1-H-benzotriazole, especially for chlorine pre-treatment and in those water matrices with high content of natural organic matter. Therefore, both sequential treatments are promising to remove the selected micropollutants while reducing the chlorine doses needed to achieve final water disinfection.

Surface and groundwater are often contaminated with toxic anions such as arsenic and selenium. Because of their large surface areas, selenium adsorption on carbon sorbents is considered an attractive water treatment technique. In this present work, selenium sorption on copper-impregnated activated carbon and fly ash-extracted char carbon was evaluated. Unburned carbon was extracted from fly ash using froth floatation techniques, and the carbon sorbents were modified using copper ions. Adsorption experiments confirmed the strong influence of electrostatic forces on equilibrium uptakes of selenite (Se (IV)) and selenate (Se (VI)). Selenium sorption on virgin char carbon was maximum only at acidic pH, i.e., at pH < pHₚzc (pH at point of zero charge). Upon copper modification of the carbon surface, the pHₚzc shifted towards the alkaline region, and as a result, the positive charge density on the carbon surface increased. At pH > pHₚzc, a two- to fourfold increase in sorption coverage and threefold increase in selenium percent removal was observed. Se (IV) sorption was higher compared to Se (VI) sorption. The effect of selenium concentrations and competing anions was studied to evaluate adsorbent performance. The order of maximum surface coverage followed the order: modified char carbon > modified activated carbon > char carbon. The main mechanism of selenium (Se) sorption appeared to be (1) electrostatic attraction of the Se ions to the modified carbon surface at acidic to neutral pH; (2) complexation of Se ions with the copper ions/oxides on the carbon surface; and (3) co-precipitation with copper hydroxides at alkaline pH.

The current work reports on the degradation of glycerol aqueous solution via photocatalytic-Fenton technique. The CuFe₂O₄ photocatalyst was synthesized via sol-gel method and its physicochemical properties were characterized. The as-synthesized photocatalyst possessed Brunauer-Emmett-Teller (BET)-specific surface area of 104 m²/g. The large BET-specific surface area was also corroborated by the field-emission scanning electron microscopy (FESEM) images which showed porous morphology. In addition, the XRD pattern showed that the visible light-active component, CuFe₂O₄, was successfully formed with band gap energy of 1.58 eV determined from the UV-Vis diffuse reflectance spectroscopy. Significantly, it was determined from the blank run study that the visible light was an integral part of the photoreaction. Without the visible light irradiation, glycerol degradation was low (<4.0 %). In contrast, when visible light was present, the glycerol degradation improved markedly to attain 17.7 % after 4 h of visible light irradiation, even in the absence of CuFe₂O₄ photocatalyst. This can be attributed to splitting of H₂O₂ into hydroxyl (●OH) radical. In the presence of CuFe₂O₄ photocatalyst, the photocatalytic Fenton degradation of glycerol has further enhanced to record nearly 40.0 % degradation at a catalyst loading of 5.0 g/l. This has demonstrated that the CuFe₂O₄ was capable of generating additional hydroxyl radicals to attack the glycerol molecule. Moreover, this degradation kinetics can be captured by Langmuir-Hinshelwood model from which it was found that the adsorption constant related to H₂O₂ was significantly weaker compared to the adsorption constant of glycerol.

A serial enrichment culture has been grown in an alkaline Fe(III)-citrate-containing medium from an initial inoculum from a soil layer beneath a chromium ore processing residue (COPR) disposal site where Cr(III) is accumulating from Cr(VI) containing leachate. This culture is dominated by two bacterial genera in the order Clostridiales, Tissierella, and an unnamed Clostridium XI subgroup. This paper investigates the growth characteristics of the culture when Cr(VI) is added to the growth medium and when aquifer sand is substituted for Fe(III)-citrate. The aim is to determine how the availability and chemical form of Fe(III) affects the growth of the bacterial consortium, to determine the impact of Cr(VI) on growth, and thus attempt to understand the factors that are controlling Cr(III) accumulation beneath the COPR site. The culture can grow fermentatively at pH 9.2, but growth is stronger when it is associated with Fe(III) reduction. It can withstand Cr(VI) in the medium, but growth only occurs once Cr(VI) is removed from solution. Cr(VI) reduced the abundance of Tissierella sp. in the culture, whereas the Clostridium XI sp. was Cr(VI) tolerant. In contrast, growth with solid phase Fe(III)-oxyhydroxides (present as coatings on aquifer sand) favoured the Tissierella C sp., possibly because it produces riboflavin as an extracellular electron shuttling compound allowing more efficient electron transfer to solid Fe(III) phases. Thus, it is suggested that bacterially mediated Cr(III) reduction in the soil beneath the COPR site is dependent on Fe(III) reduction to sustain the bacterial community.

At livestock farms, the most important thing is to control odors released from manure. In this study, four commercially available microbial additives designed to control odor and NH₃emissions were applied to swine slurries stored in containers, and their effectiveness in odor reduction was statistically evaluated. Seventeen different odorous compounds in the headspace of each container were analyzed to calculate an overall odor index for slurries treated with different microbial additives over time. Of the four microbial additives tested in this study, only two were effective in reducing the odors from the swine slurry. After a 80-day storage period, the odor indexes of the slurries could be reduced by over 70 % with 50 % reduction in volatile fatty acids. In addition, a significant five orders of magnitude reduction in Escherichia coli could be achieved within 60 days. The other two microbial additives did not affect the odor characteristics of swine slurries under storage; their time profiles were statistically identical with that of the control. Results of this study imply that farmers considering applying microbial additives for controlling odors from swine manure should be careful in choosing an additive.

Stir bar sorptive extraction (SBSE) and solid phase microextraction (SPME) are well-established sample preparation methods for the analysis of polycyclic aromatic hydrocarbons in aqueous samples. However, complex matrices especially characterized by slurry particles and dissolved organic matter (DOM) can hamper the extraction of PAH with both SBSE and SPME and lead to different results. Thus, we produced aqueous eluates from PAH-contaminated soils differing in particle size distribution and organic matter content and determined the PAH concentration in the eluates with both SBSE and SPME. Furthermore, we tested the influence of filtration on the PAH analysis. The excess finding of PAH with SBSE compared to SPME ranged from −16.6 to 24.5 %. The differences increased after filtration. We found a strong positive correlation of the excess finding to the total organic carbon content (TOC) and a negative one to the pH value. The results indicate that SBSE is less affected by complex matrices than SPME.

Acidic deposition is a worldwide problem that often leads to the increase in soil available heavy metals. Liming and biochar can both raise soil pH and immobilize heavy metals. An experiment was conducted in the laboratory to study the effects of acidic deposition on soil Cd mobility and soil biological activity in a soil polluted with Cd. Biochar, prepared from poultry litter biochar (PLB) or eucalyptus biochar (EB) was added at a rate of 3 %. Liming controls, bringing the soil to the same pH as that attained with biochar, were also used. The experimental results showed a higher risk of Cd leaching and impaired biological properties under simulated acid rain. Biochar addition resulted in a reduction in the risk of leaching and in improved biological properties and could provide benefits over liming for the management of soil polluted with heavy metals, especially in areas affected by acidic deposition.

Saline stress is one of the most important abiotic factors limiting the growth and development of plants and associated microorganisms. While the impact of salinity on associations of arbuscular fungi is relatively well understood, knowledge of the ectomycorrhizal (EM) fungi of trees growing on saline land is limited. The main objective of this study was to determine the density and diversity of EM fungi associated with three tree species, Salix alba, Salix caprea and Betula pendula, growing in saline soil during two seasons, autumn and spring. The site was located in central Poland, and the increased salinity of the soil was of anthropogenic origin from soda production. The degree of EM colonisation of fine root tips varied between 9 and 34 % and depended on the tree species of interest (S. caprea < S. alba < B. pendula) and season (spring < autumn). Moreover, the ectomycorrhizal colonisation of B. pendula was positively correlated with pH and CaCO₃, while for S. caprea and S. alba, colonisation was associated with most of the other soil parameters investigated; e.g. salinity, Cₒᵣgand N. Analysis of EM fungi revealed four to five different morphotypes per each season: Tomentella sp. Sa-A, Hebeloma collariatum Sc-A, Geopora sp. Sc-A, Helotiales sp. Bp-A in the autumn and Tomentella sp. Sa-S, Tomentella sp. Sc-S and three morphotypes from the families Thelephoraceae and Pyronemataceae in the spring. In conclusion, the density of EM is related to the level of salinity (ECₑ), season and tree species. Tomentella spp., Hebeloma sp., Geopora sp. and Helotiales sp. are groups of species highly adapted to saline conditions.

Under various abiotic stresses, plants overproduce reactive oxygen species (ROS) such as superoxide anion (O₂•⁻), hydroxyl radical (OH•), and hydrogen peroxide (H₂O₂). When in excess, these highly reactive molecules cause oxidative stress, thus damaging proteins, lipids, and DNA. Therefore, plants evolved an enzymatic defense machinery that involves such enzymes as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APOX). Various plant families, species and even specimens differ in their ability to withstand the abiotic stress. A study has been undertaken to assess the differences in response to trace metals between two species: a resistant hyperaccumulator Indiana mustard (Brassica juncea) and a metal-sensitive pea (Pisum sativum). We observed that trace elements (Cu, Zn, Cd, Pb) changed the activity of antioxidative enzymes (SOD, APOX, CAT) and the rate of ROS generation. However, in the control plants and at a point 0′ of the treatment, we have noticed a large disproportion in the hydrogen peroxide level, with B. juncea maintaining naturally higher H₂O₂level (up to 40 times higher). We believe that this may be a distinguishing trait common to plants being resistant to oxidative stress.