The feasibility of date seeds as a new low-cost natural adsorbent for the removal of dissolved organic carbon (DOC) from oily produced water was investigated. The aim of this study was to elucidate the mechanism associated with the removal of DOC and to find the best equilibrium isotherms and kinetic models for DOC removal in batch adsorption experiments. The effect of various physicochemical parameters such as initial DOC concentration (18.5–93.5 mg/L), solution pH (4–9), temperature (25–45 °C), and date seeds dosages (0.5–2.0 g) was evaluated. The equilibrium stage was attained after a contact time of 120 min. The maximum DOC removal was 82 % for 93.5 mg/L of DOC concentration. The equilibrium data were well represented by the Langmuir isotherm. The maximum monolayer adsorption capacity of date seeds was found to be 74.62 mg/g. The separation factor, R L, from the Langmuir equation and the Freundlich constant, n, indicated a favorable adsorption. The kinetic studies indicated that the adsorption process follows the pseudo-second-order kinetics. The adsorption of DOC is governed by both surface and pore diffusion. The results revealed that the DOC uptake decreases when temperature and pH increases. The adsorption process has been found exothermic in nature, and the thermodynamic parameters were determined. The Langmuir isotherm model equation was adopted to design a single-stage batch absorber for DOC adsorption onto date seeds. The study demonstrated that date seeds can be considered as a promising low-cost adsorbent for the removal of DOC from oily produced water.

Pentachlorophenol (PCP) has been used worldwide as a wood treatment agent and biocide. Its toxicity and extensive use have placed it among the most hazardous environmental pollutants. The response of a PCP-contaminated agricultural soil to the addition of solid urban waste compost and two exogenous Ascomycota fungal strains Byssochlamys nivea and Scopulariopsis brumptii was evaluated. The experiments were conducted in soil microcosms incubated for 28 days at 25 °C and 60 % moisture content. The depletion of PCP and the changes in biochemical soil properties (i.e. microbial biomass, soil respiration, dehydrogenase and fluorescein diacetate hydrolysis activities) were detected. The addition of PCP severely depressed some of the tested biochemical properties such as microbial biomass, dehydrogenase and fluorescein diacetate hydrolysis activities. By contrast, compost limited the negative effect of PCP on the dehydrogenase activity and soil respiration. When compost and fungal strains were contemporary present, a synergistic effect was observed with a reduction of more than 95 % of the extractable PCP after 28 days of incubation. No differences in PCP depletion resulted when fungi or compost were individually used. Our results indicate that many processes (i.e. microbial degradation and sorption to organic matter) likely occurred when PCP was added to the soil. The compost and the fungal strains, B. nivea and S. brumptii, showed good capability to tolerate and degrade PCP so that they could be successfully used in synergistic effect to treat PCP polluted soils.

Soil salinization is a worldwide problem of which secondary salinization is increasingly more frequent, threatening agricultural production. Salt accumulation affects not only plants but also the physio-chemical characteristics of the soil, limiting its potential use. Climate change will further increase the rate of salinization of soil and groundwater as it leads to increased evaporation, promotes capillary rise of saline groundwater as well as increased irrigation with brackish water. Episodic seawater inundation of coastal areas is likely to increase in frequency as well. This work analyzed three types of salinization: seawater inundation (by irrigating soils with a 54 dS m⁻¹NaCl solution), saline groundwater capillary rise (soil contact with a 27 dS m⁻¹NaCl solution), and irrigation with two types of brackish water with different residual sodium carbonate (RSC). Two soils were used: a mineral soil (7.0 % clay; 0.7 % organic matter) and an organic soil (2.7 % clay; 7.4 % organic matter). The tested soils had different resilience to salinization: The mineral soil had higher sodium adsorption ratio (SAR) due to low levels of calcium + magnesium but had higher leaching efficiency and more limited effects of RSC. The organic soil however was more prone to capillary rise but seemingly more structurally stable. Our results suggest that short-term inundation with seawater can be mitigated by leaching although soil structure may be affected and that capillary rise of brackish groundwater should be carefully monitored. Also, the impact of irrigation with brackish water with high RSC can be inferior in soils with higher exchangeable acidity.

Dielectric barrier discharges (DBDs) were utilized for the remediation of soil contaminated with p-nitrophenol (PNP). The effect of treatment time, applied discharge voltage, initial PNP concentration, pH of contaminated soil, and airflow rate were investigated in this study. The results showed that 63.2 % of the PNP in the contaminated soil was degraded in 50 min with a voltage of 38.2 kV with no airflow. This degradation reaction followed the first order reaction kinetics. The degradation by ozone alone was compared with the plasma treatment to identify the role of ozone. Chromatographic analysis was applied to monitor the intermediates produced during the oxidation process, and the main byproducts were maleic acid, p-benzoquinone, 4-nitrocatechol, methanoic acid, acetic acid, oxalic acid, NO₂ ⁻, and NO₃ ⁻. Possible pathways for the degradation of PNP in this system were deduced, which would provide evidence for the researches about the remediation of soils polluted by organic pollutants.

Before and after an intense wildfire in a forested area of Colorado in June 2012, river water and sediment samples were collected to study temporal and spatial trends related to the event. Water quality and soil properties were disturbed by the fire, but the magnitude was relatively small without precipitation. After precipitation, in-stream total nitrogen and total phosphorus (TP) concentrations significantly increased in the upstream section located within 10 km of the burned area. Large amounts of particulate P associated with highly correlated total suspended solids were introduced to the upstream section. Along with significantly increased in-stream concentrations of soluble reactive P (SRP) and dissolved organic P (DOP) after rain events, SRP dominated dissolved P in the river replacing DOP that was the main dissolved species before the fire event. In the riverbank, TP load increased significantly after the fire, and silt-clay and organic matter mass concentrations increased after precipitation. Riverbed TP mass concentrations decreased due to a reduced sorption capacity leading to a considerable P release from the sediments. The results indicate that fire-released P species will impact the downstream area of the watershed for a considerable time period as the bank erosion-sorption-desorption cycles in the watershed adjust to the fire-related loading.

This study aimed to decolourise different dyes using two Klebsiella strains (Bz4 and Rz7) in different concentrations and incubation conditions. Azo (Evans blue (EB)) and triphenylmethane (brilliant green (BG)) dyes were used individually and in mixture. The toxicity of the biotransformation products was estimated. Both strains had a significant potential to decolourise the dyes in the fluorone, azo and triphenylmethane classes. The type and concentration of dye affects the decolourisation effectiveness. Differences in the dye removal potential were observed particularly in the main experiment. The best results were obtained for Bz4 in the samples with EB (up to 95.4 %) and dye mixture (up to 99 %) and for Rz7 with BG (100 %). The living and dead biomass of the strain Bz4 highly absorbs the dyes. Significant effect of the process conditions was noticed for both strains. The best results were obtained in static and semistatic samples (89–99 %) for the removal of EB and a mixture of dyes and in static samples (100 %) for BG. The decrease in zootoxicity (from class IV/V) was noticed in all samples with living biomass of the strain Bz4 (to class III/IV) and in samples with single dyes for Rz7 (to class III/IV). The decrease in phytotoxicity (from class III/IV) was noticed for Bz4 in the samples with BG and a mixture (to class III) and for Rz7 in the samples with BG (to class III). The process conditions did not affect the changes in toxicity after the process.

The phenolics and high organic content present in palm oil mill effluent are the major contributors to its dark brown color, toxicity, and antimicrobial properties. In this study, ten white rot fungi were screened for their potential in the dephenolization and decolorization of treated palm oil mill effluent (TPOME) in solid and liquid state cultures. Among them, Trametes hirsuta strain AK 04 was found to be more tolerant to high TPOME concentrations and showed the highest phenolics and color removal activities. This strain was immobilized onto oil palm fibers (OPFs) and appeared more resistant to inhibitory compounds such as phenolics in TPOME than the free cell culture. The OPF-immobilized fungus was able to effectively remove phenolics and color of TPOME without effluent dilution and addition of nutrients. The activities of laccase and manganese peroxidase were found during dephenolization and decolorization processes. Moreover, the degradation rate of immobilized fungus could be accelerated by pretreatment of phenolics with phenol-degrading bacteria. This method improved the fungal dephenolization and decolorization simultaneously up to 82.2 ± 3.8 % and 87.1 ± 1.1 % after 8 days of incubation. Therefore, a two-stage biological process containing phenol-degrading bacteria and OPF-immobilized fungus could be a feasible and economical method for simultaneous improvement of dephenolization and decolorization of TPOME.

To facilitate the mapping of pollution fluxes under different flow conditions when a limited number of gauging stations are available, a method relying on geographic data was developed to estimate the mean daily stream discharge at each sampling station. It has been tested on a rural river watershed that is located in northeast France (Madon River). The stretch of 100 km is equipped with three gauging stations. Surface water samples were collected at 30 stations under different flow conditions. In a participatory research project, samples were also collected by school children at one of the stations (once a week during the school year over a 2-year period). Dissolved organic carbon and nitrogen species were measured for all samples. These data illustrate the variation in the pollution in the river that is associated with agricultural activities and discharges of untreated wastewater. This method was used to obtain localized points of nutrient discharge, to identify the zones that favor nutrient removal, and to propose remediation work.

The first uranium extraction mine of Brazil, nowadays found in decommissioning phase, has caused several negative environmental impacts in its area, as a result of mining, treatment, and beneficiation processes. The generation of acid mine drainage in waste rock pile 4 (WR-4) is one of the negative impacts with the most critical situation. The acidic water, product of this drainage, presents heavy metals and radioactive elements and it may be infiltrated by the basis of the impoundment basin, where this water is collected for treatment. The objective of this study was to investigate a typical tropical soil, located in the area of Ores Treatment Unit of Caldas in the southwestern state of Minas Gerais, Brazil, in order to use it as a mineral liner for a retention basin to minimize leakage of acidic water through the foundation of a containment dam. In this way, geotechnical, chemical, and mineralogical tests were performed in order to characterize a soil sample collected in the area. In addition, adsorption tests were conducted with solutions of aluminum (Al), manganese (Mn), and iron (Fe), and with and without adjustment of the initial pH (pHₜₒ) of the solutions. The results indicated a well-weathered soil composed of kaolinite, gibbsite, and iron oxides. The adsorption tests showed different behaviors for Al, Mn, and Fe considering or not the adjustment of the pHₜₒ. Aluminum showed low adsorption by soil; because of this, only the adsorption isotherms of Mn and Fe for test with adjustment of the pHₜ₀were determinate. The coefficient of distribution (KD) of Mn was 0.0364 L g⁻¹and Fe 0.0281 L g⁻¹. As for the retardation factor (Rd), its values ranged from 81 to 91 for Mn and from 61 to 79 for Fe, considering different behaviors of the adsorption isotherm models.

One of the most widely used carbon nanomaterials is fullerene (C₆₀), a lipophilic organic compound that potentially can behave as a carrier of toxic molecules, enhancing the entry of environmental contaminants in specific organs. Microcystins (MC) are cyanotoxins very toxic for human and environmental health. Several studies showed that exposure to MC or C₆₀generates reactive oxygen species (ROS) and changes in antioxidant levels. Also, another factor that can come to enhance the toxic potential of both MC and C₆₀is UVA radiation. Therefore, it was evaluated the effects on oxidative stress parameters of ex vivo co-exposure of MC and C₆₀(5 mg/l) in gills of the fish Cyprinus carpio under UVA radiation incidence. The results showed that (a) there was a loss of antioxidant capacity after low MC concentration (L, 50 μg/l) + C₆₀co-exposure under UVA, (b) C₆₀under UVA decreased glutathione-S-transferase (GST) activity, (c) high MC concentration (H, 200 μg/l) + C₆₀co-exposure decreased the concentrations of glutathione (GSH) under UVA or in the dark, (d) L under UVA increased lipid peroxidation, and (e) C₆₀did not cause a higher bioaccumulation of MC in gills. The lowering of GSH in H + C₆₀co-exposure should compromise MC detoxification mediated by GST, although toxin accumulation is not influenced by C₆₀.