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.

The estimated diffusion fluxes of methane (CH₄) and carbon dioxide (CO₂) at the sediment–water interface in the Rzeszów Reservoir in southeastern Poland are presented. The relevant studies were conducted during 2009, 2010, and 2011. Calculated fluxes ranged from 0.01 to 2.19 mmol m⁻² day⁻¹and from 0.36 to 45.33 mmol m⁻² day⁻¹for methane and carbon dioxide, respectively. While the values for calculated diffusion fluxes of methane are comparable with those reported for other eutrophic reservoirs, much higher values were obtained here for carbon dioxide. The resulting values of δ¹³C-CH₄and the fractionation coefficients between methane and carbon dioxide (αCH₄-CO₂) suggest that methane in the sediment of the Rzeszów Reservoir is produced by acetate fermentation, while the hydrogenotrophic methanogenic process is of successively greater importance with increasing depth. In the top layer of the sediment, 24–72 % of CO₂came from methanogenesis, while the contribution made by the degradation of organic matter by methanogenesis to CO₂was greater in the deeper layer.

Rhizoctonia zeae SOL3 fungus was isolated from contaminated soil based on its ability to decolorize remazol brilliant blue R in solid medium. This fungus has been used to degrade pyrene a four-ring polycyclic aromatic hydrocarbon. R. zeae SOL3 could biodegrade pyrene as a sole source of carbon and energy. Different parameters were investigated to study their effect on the biodegradation rate. The highest biodegradation rate reached at 28 °C, non-agitated culture, 20 g/L glucose, 24 g/L NaCl, and 20 mg/L pyrene. The metabolites of pyrene were detected by thin layer chromatography (TLC) and confirmed by gas chromatography–mass spectrometry (GC-MS), which were identified as benzoic acid, 4-hydroxybenzoic acid and botanic acid.

We analysed nutrients and basic ions (Na, Cl, K, Mg, Si, Ca, and SO₄) for a period of 1 year, including every precipitation event, and sampled stream water every 2 weeks from a forest catchment in Shimane Prefecture, Japan. Backward-trajectory analysis revealed that some air masses originated within Japan, but did not affect the precipitation chemistry. Air masses originating from northern China were positively correlated with nutrients and all basic ions. Concentrations of ammonium and dissolved organic nitrogen were much lower in stream water than in precipitation, while those of nitrate and particulate nitrogen were similar in stream water and precipitation. Unlike nitrogen, the dissolved phosphorus concentration was much higher in stream water than in precipitation. Both phosphate and dissolved organic phosphorus (DOP) levels were higher in stream water than in precipitation. Particulate phosphorus (PP) concentrations were very similar in precipitation and stream water. PP showed stronger correlations than potassium with suspended solids (SS) and flow rate, while phosphate and DOP were more strongly correlated with potassium than with SS or flow rate. Stream silica concentrations were not correlated with phosphate but did exhibit a significant negative correlation with DOP. Neither phosphate nor DOP was correlated with calcium. These results suggest that phosphorus is not leaching with silica or calcium as a paired cation, but rather with potassium in this area. Lower nitrogen concentrations in stream water than in precipitation can be attributed to an enhanced uptake of nitrogen by forest soils owing to the increased atmospheric deposition of phosphorus.

The majority of the existing water bodies around the world are increasingly polluted with oily wastewater. The aim of this study was to investigate the role of single protozoan isolates (Aspidisca, Trachelophyllum and Peranema) and of a consortium of these three protozoan isolates in the biodegradation of fats and oils present in polluted domestic wastewater. The biomass of protozoan isolates, chemical oxygen demand (COD), dissolved oxygen (DO) and concentrations of fats and oils were determined in triplicate before and after the inoculation of isolates in oily wastewaters, using standard methods. Results revealed optimum growth of protozoan cell densities under favourable conditions of 30 °C, pH 6 and 8 (from 1.00 to 4.00, 3.96, 3.80 and 4.20 × 10²cells/ml for Aspidisca, Trachelophyllum, Peranema and a consortium of the three isolates, respectively). The average percentage uptake of DO by Aspidisca, Trachelophyllum, Peranema and their consortium was 95, 96, 96 and 100 %, respectively, for both 30 and 25 °C and at pH levels of (4, 6, 8 and 10), respectively. The results revealed that the COD removal rates of the isolates at various pH levels were ≥20 and ≤90 %, respectively, for 30 and 25 °C. At a temperature of 30 °C, the biodegradation capabilities of the isolates ranged from 3.0 to 8.0, 3.0 to 6.0, 7.0 to 11.0 and 8.0 to 22.0 %, while at 25 °C, the biodegradation rates were 3.0 to 6.0, 4.0 to 7.0, 3.0 to 8.0 and 4.0 to 15.0 % for Aspidisca, Trachelophyllum, Peranema and the consortium of these three isolates, respectively.