The effect of glyphosate on richness and structure of the Rhizobiaceae and total bacterial communities in an agricultural soil after different treatments was studied. The herbicide was applied on the soil in the presence or the absence of Medicago sativa plants with or without inoculation with the Sinorhizobium meliloti reference strain RCR2011. Terminal-restriction fragment length polymorphism (T-RFLP) profiling showed that this agricultural soil has a high total microbial and rhizobial genetic diversity. To investigate the impact of the herbicide on microbial activity, fluorescein diacetate (FDA) and a panel of three enzymes (phosphatase, catalase, and protease BAA) were assessed. Depending on the type of enzyme tested, the enzymatic activities responded differently to the action of glyphosate, the presence of M. sativa, and the inoculation with RCR2011. The present work gives original insights into the effect of the herbicide on the rhizospheric area of M. sativa with or without rhizobial inoculation by the fact that glyphosate changes microbial diversity and affects soil enzymatic activities.

Detection, molecular characterization, and quantification of Norovirus (NoVs) in a semi-industrial pilot plant were performed in order to assess the efficiency of the secondary biological treatment using two different procedures: natural oxidation ponds and biodisks. A total of 102 wastewater samples were collected from two biological treatment processes in a semi-industrial pilot plant. NoVs GII and NoVs GI were detected and quantified in 65 % (n = 66) and in 1 % (n = 1) of the samples of wastewater from the plant, respectively. The average values of viral content (genome copies/μl) obtained in the effluent of the two lines of treatment showed a substantial reduction in the prevalence and in the viral content of NoVs GII detected from one basin to another of the five watersheds of the oxidation ponds and at the expiration of the biodisk line. The predominant genogroup of NoVs was NoVs GII (65 %), followed by NoVs GI (1 %). The predominant genotype of NoVs GII was GGII.12 (n = 11), followed by GGII.b (n = 1), GGII.1 (n = 1), and GGII.16 (n = 1) and two mixed combinations: GGI.2/GGII.12 (n = 5) and GGI.2/GGII.b (n = 1) were identified. The results obtained in this study represent the first documentation in Tunisia on the effectiveness of biological treatment for the removal of NoVs in the area of the capital of Tunis.

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.

The study investigated phosphate adsorption from aqueous solutions using chemical- and thermal-modified bentonite in batch system. The adsorbent was characterized by SEM, BET, and FTIR spectroscopy. Contact time, beginning phosphate concentration, pH of the solution, and the effects of the temperature on phosphate adsorption capacity were determined by a series of experimental studies. In a wide pH range (3–10), high phosphate removal yields were obtained (between 94.23 and 92.26 %), and with the increase in temperature (from 25 to 45 °C), phosphate removal increased. Langmuir and Freundlich isotherms were used to determine the sorption equilibrium, and the results demonstrated that equilibrium data displayed better adjustment to Langmuir isotherm than the Freundlich isotherm. Phosphate sorption capacity, calculated using Langmuir equation, is 20.37 mg g⁻¹ at 45 °C temperature and pH 3. Mass transfer and kinetic models were applied to empirical findings to determine the mechanism of adsorption and the potential steps that control the reaction rate. Both external mass transfer and intra-particle diffusion played a significant role on the adsorption mechanism of phosphate, and adsorption kinetics followed the pseudo-second-order-type kinetic. Furthermore, thermodynamic parameters (ΔH°, ΔG°, ΔS°) which reveal that phosphate adsorption occur spontaneously and in endothermic nature were determined. The results of this study support that bentonite, which is found abundant in nature and modified as an inexpensive and effective adsorbent, could be used for phosphate removal from aqueous solutions.

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.

In this study, BiVO₄ powder is prepared and used as a visible-light catalyst for the photocatalytic degradation of alachlor. The as-prepared BiVO₄ photocatalyst is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectra (DRS), and BET surface area analysis. Alachlor could be successfully degraded in the presence of both H₂O₂ and BiVO₄ catalyst under visible-light irradiation. With optimal operating parameters, its degradation efficiency could reach 97 % in 6 h. Factors such as solution pH, catalyst dosage, and the presence of anions are found to influence the degradation rate. To scrutinize the mechanistic details of the alachlor photodegradation, the intermediates of the process are separated, identified, and characterized by solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). Results suggest that possible transformation pathways may include oxidation of the arylethyl group, cleavage of the N-methoxymethyl group, and N-chloroacetyl moiety.

The aim of this study was to describe the mechanisms that native Bacillus cereus M6 isolated from heavy crude oilᵒAPI gravity 11.5 uses to tolerate and/or resist toxic metals. Metal tolerance and removal of Pb(II), Cr(VI), and As(V) was determined. In addition, we evidenced the subcellular distribution of metals, the efflux pump kinetics, and morphological changes in metal-tolerant bacteria. B. cereus M6 exhibited strong tolerance and resistance to the metals evaluated and efficiently removed the metal content by operating efflux pumps and accumulating mainly in membrane fraction. Also, it was found that the model that best fit the efflux corresponds to an equation for resonant oscillations. B. cereus M6 uses mechanisms, including efflux pumps, intracellular and extracellular accumulation in parallel in order to maintain metal levels below a toxic threshold and overcome the effects of high concentrations. These findings are an approach of an energy-dependent efflux system to eliminate excessive amounts of crude oil-associated metals in Bacillus. B. cereus M6 may potentially be useful in designing improved strategies for the bioremediation of soils polluted with metals. Additionally, the prediction model developed would be useful for improving the monitoring of in vitro and in vivo bioremediation processes.

High levels of marine salt deposition present in coastal areas have a relevant effect on road runoff characteristics. This study assesses this effect with the purpose of identifying the relationships between monitored water quality parameters and intrinsic site variables. To achieve this objective, an extensive monitoring program was conducted on a Portuguese coastal highway. The study included 30 rainfall events, in different weather, traffic, and salt deposition conditions. The evaluations of various water quality parameters were carried out in over 200 samples. In addition, the meteorological, hydrological, and traffic parameters were continuously measured. The salt deposition rates were determined by means of a wet candle device, which is an innovative feature of the monitoring program. The relation between road runoff pollutants and independent variables associated with weather, traffic, and salt deposition conditions was assessed. Significant correlations among pollutants were observed. A high salinity concentration and its influence on the road runoff were confirmed. Furthermore, the concentrations of the most relevant pollutants seemed to be very dependent on some meteorological variables, particularly the duration of the antecedent dry period prior to each rainfall event and the average wind speed.

In the present work, goethite (α-FeO(OH)) impregnated calcium alginate (Cal-Alg-Goe) beads were used to sorb the arsenic from groundwater without disturbing its physicochemical characteristics. Beads were formed by dropwise addition of homogenized mixer of goethite and 4 % sodium alginate solution in 0.2 M CaCl₂solution. Charge, size, and morphology of sorbents were characterized by using various techniques. The results of batch sorption experiments suggest that Cal-Alg-Goe beads are very effective for removal of arsenic in the pH range 3.0 to 7.5, and sorption was more than 95 % in the concentration range of 10–10,000 ng mL⁻¹. Beads were successfully tested for groundwater samples collected from areas having elevated levels of arsenic. Equilibrium sorption follows Langmuir isotherm model, and the maximum arsenic uptake calculated was 30.44 mg g⁻¹. The sorption kinetics could be explained by pseudo-first-order model, and the time needed for equilibrium was 24 h.

Field and laboratory studies were conducted to evaluate the effects of anaerobic digestion (AD) and solids-liquid separation on emissions during subsequent storage and land application. The lab storage tests were conducted for 21 days with manure samples obtained at the following four points in a full-scale AD system: raw manure (RM) delivery, raw manure supplemented with other substrates (AD influent), AD effluent, and AD effluent after solids-liquid separation (AD liquid effluent). Ammonia fluxes from stored AD effluent declined from 3.95 to 2.02 g m⁻² day⁻¹. Lower NH₃ fluxes, however, were observed from AD liquid effluent (1.1 g m⁻² day⁻¹) and AD influent (0.25 g m⁻² day⁻¹). Ammonia emissions from full-scale manure storages were similar to those obtained in the lab. Results also indicated significantly lower volatile fatty acid (VFA) in AD effluent and AD liquid effluent compared with that from the AD influent, indicating significant reduction in odor generation potential due to AD and solids-liquid separation processes. Two manure application methods (surface application and manure injection) for both non-AD and AD manures were simulated in the lab and studied for 9 days. Surface-applied non-AD manure exhibited the highest NH₃ flux (0.78 g m⁻² day⁻¹), while injected AD manure led to the lowest NH₃ flux (0.17 g m⁻² day⁻¹). Similar NH₃ emissions results were observed from the field studies. Overall, while AD of dairy manure resulted in significant increases in NH₃ emissions from stored effluent, the AD process significantly reduced NH₃ emissions following application of AD manure on land.