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.

Plant peroxidases have strong potential utility for decontamination of phenol-polluted wastewater. However, large-scale use of these enzymes for phenol depollution requires a source of cheap, abundant, and easily accessible peroxidase-containing material. In this study, we show that potato pulp, a waste product of the starch industry, contains large amounts of active peroxidases. We demonstrate that potato pulp may serve as a tool for peroxidase-based remediation of phenol pollution. The phenol removal efficiency of potato pulp was over 95 % for optimized phenol concentrations. The potato pulp enzymes maintained their activity at pH 4 to 8 and were stable over a wide temperature range. Phenol solutions treated with potato pulp showed a significant reduction in toxicity compared with untreated phenol solutions. Finally we determined that this method may be employed to remove phenol from industrial effluent with over 90 % removal efficiency under optimal conditions.

In this study, 1-year greenhouse pot experiments were conducted to investigate the effect of Phyllobacterium myrsinacearum strain RC6b on the growth and phytoextraction efficiency of heavy metals by a Zn/Cd hyperaccumulator (Sedum alfredii) and alfalfa (Medicago sativa L.) in a co-cropping system. The treated soil sample was collected from a land reclamation site of Pb/Zn mine tailings in Hanzhong City, Shaanxi Province, China. Results showed that, with the inoculation of RC6b, shoot biomass yields of plants were significantly increased by 15.9–20.2 % and 17.2–19.9 % for alfalfa and S. alfredii, respectively, compared to the non-inoculated plants. Biomass yield of alfalfa was higher than that of S. alfredii. RC6b inoculation increased metal concentrations by 18.6–31.2 % (Pb), 23.8–37.5 % (Cd), and 26.4–38.3 % (Zn) in S. alfredii shoots, and by 13.8–24.7 % (Pb), 15.8–26.6 % (Cd), and 24.8–35.6 % (Zn) in alfalfa shoots, respectively. After six consecutive harvests of shoots, RC6b inoculation increased the phytoextraction efficiencies of Pb, Cd, and Zn by shoots of the co-planting system by 16.9, 46.3, and 60.9 %, respectively. Nevertheless, phytoextraction of Cu was not improved by RC6b inoculation. In the co-planting/inoculation system, the percentage removals of metals from soil by the plant shoots were 6.09, 30.97, 11.10, and 1.68 % for Pb, Cd, Zn, and Cu, respectively, after six harvests of shoots. Inoculation with RC6b significantly increased the soil microbial activity and the carbon utilization ability of the soil microbial community.

The study analyzes the presence and the origin of heavy metals in environmental compartments affected by anthropogenic activities. The paper presents the results of a field study performed on the sediments of two of the main small urban creeks of the city of Prague (Czech Republic). The aim of the survey was to verify the presence and bioavailability of heavy metals (Cu, Cr, Ni, Pb, Zn) in the aquatic environment (water as well as bottom sediments), and to assess the source of these pollutants. The results were processed to evaluate the enrichment factor and the partition coefficient, and were statistically analyzed through the analysis of variance and the principal component analysis. Comparison with relevant environmental quality standards showed that measured heavy metal concentrations were always lower than the probable effect concentration (PEC). On the contrary, the threshold effect concentration (TEC) was frequently exceeded. Sequential extraction analysis showed that the bioavailability of studied metals is quite high, suggesting that they could be easily released from the sediment to the aquatic environment. Overall, several sources of pollution, different for the different metals, were identified, all related with anthropogenic factors.

Photocatalysis is one of environment-friendly and efficient methods for municipal wastewater disinfection. In this research, two pathogens, Staphylococcus aureus and fecal coliform, were chosen to investigate the disinfection effects of several TiO₂ photocatalysts on sewage plant secondary treatment effluent, compared with UV disinfection. The results show that TiO₂ species and concentrations, light intensity, light time, and pH all have significant influences on the pathogen deactivation. It was found that the optimum operation parameters were as follows: the P25 commercial TiO₂ powder at the concentration of 0.5 g/L, the light intensity of 40 W, and the radiation duration of 20 min. The photocatalyst performed better at either acid or alkaline condition than neutral. The TiO₂ photocatalytic deactivation to S. aureus was more effective than the UV.

Arbuscular mycorrhizal fungi (AMF) can alter the dynamics of soluble nitrogen in paddy field soils by promoting nitrogen assimilation by rice. However, it is unknown whether this affects N₂O emissions from rice paddies. This study was designed to assess the effects of AMF on N₂O emissions by analyzing the relationships between AMF and the parameters affecting N₂O emissions. Path analysis was used to quantitatively partition the direct and indirect effects of different parameters on N₂O emissions. Results showed that N₂O emissions were controlled by environmental pathways (transpiration, evaporation, and precipitation affecting soil water content) and biotic pathways (soluble nitrogen assimilation by the rice, which varies according to rice biomass). Under different water conditions, the contributions of the two pathways to N₂O emissions varied strongly. During the flooding stage, the environmental pathways were dominant, but inoculation with AMF promoted the contribution of the biotic pathway to the reduction of N₂O emissions. During the draining stage, the environmental pathways were dominant in the non-inoculated treatment, but inoculation made the biotic pathways dominant by increasing the biomass of rice. During the growing stage, N₂O emissions from inoculated soil (17.9–492.9 μg N₂O-N m⁻² h⁻¹) were significantly lower than those in non-inoculated soil (22.1–553.1 μg N₂O-N m⁻² h⁻¹; p < 0.05). Consequently, inoculating with AMF has the potential for mitigating N₂O emissions from rice paddies.

The selected strains of microscopic fungi, Haematonectria haematococca (BwIII43, K37) and Trichoderma harzianum (BsIII33), decolorized the following monoathraquinone dyes with different efficiency: 0.03 % Alizarin Blue Black B, 0.01 % Carminic Acid, 0.01 % Poly R-478, and 0.2 % post-industrial lignin. The most effective was the removal of 0.03 % Alizarin Blue Black B (50–60 %) and 0.01 % Carminic Acid (55–85 %). The principal component analysis (PCA) method was applied to determine the main enzyme responsible for the biodecolorization process of the dye substrates and indicated that horseradish-type (HRP-like), lignin (LiP), and manganese-dependent (MnP) peroxidases were responsible for the decolorization of anthraquinone dyes by the strains tested. The participation of particular enzymes in the decolorization of monoanthraquinone dyes ranged from 44.48 to 51.70 % for 0.01 % Carminic Acid and from 38.46 to 61.12 % for Poly R-478. The highest precipitation in decolorization of these dyes showed HRP-like peroxidase, respectively, 54–74 and 70–95 %. The degree of decolorization of 0.2 % post-industrial lignin by the selected strains of H. haematococca and T. harzianum amounted to 58.20, 61.38, and 65.13 %, respectively. The rate of 0.2 % post-industrial lignin decolorization was conditioned by the activity of HRP-like (71–90 %) and LiP (87–94 %) peroxidases.

Sorption of four ionizable organic amines, n-hexylamine, trimethylamine, 1-naphthylamine, and phenylamine, on a soil sample were measured, and their effects on the sorption of phenanthrene (PHE) to the same adsorbent were studied. The aim of this study was to better clarify sorption mechanisms of chemicals with different polarity and ionization characteristics in a single-solute system and in a polar/nonpolar binary system. In the single system, cationic organic amines exhibited greater sorption than those in a neutral form, and the sorption increased with hydrophobicity for amines with the same form. In the binary system, the sorption of PHE was promoted in the presence of n-hexylamine and the solid-water distribution coefficient (K d) increased with increasing amine concentrations. This may be explained by the elevated amount of hydrophobic organic sites provided by the head-on adsorption of cationic n-hexylamine to the negatively charged sorbent surface, which are probably more favorable for the sorption of PHE compared with natural organic matters. Contrarily, the neutral amine, 1-naphthylamine, might compete with PHE for the mutually available hydrophobic sites and hence inhibited PHE sorption. On the other hand, both trimethylamine and phenylamine had little effects on PHE sorption due to their relatively high solubility and weak hydrophobicity. Therefore, either in single or binary system, both the form and the solubility/hydrophobicity of the compound play important roles in the sorption of ionizable organic amines and their effects on the sorption of nonpolar co-solute.

Magnetic nanoparticles of CoFe₂O₄ were synthesized by co-precipitation method. The magnetic material silicalite-2@CoFe₂O₄ (SC) was prepared by using tetrabutylammonium hydroxide as the template, tetraethoxysilane as the silica source and CoFe₂O₄ as the magnetic core. TiO₂/silicalite-2@CoFe₂O₄ (TSC) magnetic photocatalyst was prepared by sol-gel technique using SC particles as the supporter and tetrabutyltitanate as the titanium source. The samples were characterized by X-ray diffraction, scanning electron microscopy, N₂ adsorption-desorption, Fourier transform infrared spectroscopy, and ultraviolet (UV)–visible diffuse reflectance spectra. The reduction of Cr(VI) in aqueous solution by UV/TSC process was studied under various operating conditions. The results demonstrate that the as-synthesized TSC has high photocatalytic activity due to the high dispensability of TiO₂ provided by silicalite-2@CoFe₂O₄. The removal of Cr(VI) reached 72.9 % by using 0.6 g/L of TSC under the optimum conditions within 180 min. The photocatalytic reduction of Cr(VI) by TSC followed the Langmuir–Hinshelwood kinetic model. At the end of the reaction, TSC could easily be recovered and could be reused without the significant loss of the catalytic activity.

The growing pollution mainly caused by the discharge of industrial, sanitary, and agricultural wastes has become one of the main current environmental issues. Thus, the use of bioindicators has become an important tool for investigating environmental imbalance. In this context, microorganisms have shown to be important for the identification of altered environments because of their ubiquity and their ability to grow in inhospitable habitats. Yeasts of the genus Candida are potential bioindicators because of their ability to survive in contaminated freshwater environments. Besides, they are more frequently recovered than fecal coliforms. It is noteworthy that the nonspecific activity of efflux pumps, which help in cellular detoxification processes, may be associated with the presence of chemical compounds in contaminated environments. Thus, the activity of efflux pumps may be the main mechanism involved in the resistance to azole derivatives in Candida spp. and the assessment of their activity may also be a tool for environmental monitoring. As a result, the phenotypical and molecular evaluation of this antifungal resistance in Candida species has been pointed as a promising tool for monitoring the quality of aquatic environments. Hence, the objective of this study was to collect and systematize data pointing to an alternative use of Candida spp. as bioindicators by assessing the occurrence of azole resistance among environmental Candida as a strategy to monitor the quality of freshwater environments.