The adsorbents (such as hydrous ferric oxides, HFO) generated in the electrocoagulation (EC) processing with iron electrodes are able to remove effectively inorganic arsenic (As) present in underground water. A characterization of the HFO phases produced during the arsenic removal by the EC process from low and high arsenic concentration, by using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM), is presented. The main HFO phase produced by this process is lepidocrocite (γ-FeOOH), and that the sorption of arsenic by this solid-state phase formed as part of the EC process was effective in removing arsenic from aqueous solution.

From a storm water management perspective, not all pavements are equivalent. Pavement type can impose a strong influence on pollutant wash-off dynamics. Pollutant loads from pavement wash-off are affected by the pavements’ physical and chemical composition. However, there is a dearth of information regarding how pavement type influences atmospherically deposited pollutant loads in storm water. Therefore, experimental impermeable and permeable asphalt and concrete boards were deployed in a residential area in Christchurch, New Zealand, to quantify the influence of pavement type on storm water pollutant dynamics. Each pavement type had four replicate systems elevated 500 mm from the ground at a 4° slope. Wash-off from the pavements was collected and analysed for total suspended solids and metals (Cu, Pb, and Zn) from June to August 2014. Results show that Cu and Zn loads were lower from the concrete pavements than the asphalt pavements because the carbonates and hydroxides within the concrete adsorbed Cu and Zn. Run-off from the impermeable asphalt had the highest loads of Zn, which was attributed to Zn leaching from the asphalt. Infiltrate from permeable asphalt provided little/no retention of Cu and Zn, due to the low pH of the infiltrate causing Cu and Zn to partition into the dissolved phase and leach through the pavement. Total suspended solid (TSS) and Pb loads were the highest in run-off from the impermeable concrete, which was attributed to the smooth surface enabling particulates to be easily mobilised. TSS and Pb loads were the lowest from the permeable pavement due to the permeable material filtering out particulates.

2,3-Dihydroxybenzaldehyde modified silica gel (SGDHB) was prepared and then used for the removal of boron. Adsorption of boron on the SGDHB was examined with respect to the equilibrium adsorption, kinetics and as a function of pH. Boron is strongly retained on the SGDHB between pH 7 and pH 9. The results indicated that the adsorption equilibrium was well described by the Langmuir equation. The SGDHB exhibited an excellent sorption capacity with 3.812 mmol B/g SGDHB under experimental conditions. The material shows reasonably rapid sorption ability, with boron in 25 mL of 0.01 M H₃BO₃ solution being removed almost completely within 30 min of contact time with 0.12 g of the modified silica gel. The SGDHB was demonstrated to be an efficient sorbent for the removal of boron.

Two lakes, one from the remote high altitude on the southern slope of the Himalaya (Lake Gosainkunda) and another from the urban mid-hill area (Lake Phewa) were studied for evaluating anthropogenic inputs of the pollutants, particularly mercury (Hg) and other trace elements (TEs) (such as Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb). A total of 77 water samples, 24 from Lake Gosainkunda and 53 from Lake Phewa were collected from different depth profiles during October/November 2010. Concentrations of Hg were significantly higher in Lake Gosainkunda compared to Lake Phewa probably due to long-range transport of Hg and its deposition on high altitudes of the Himalayas, in addition to the probable natural geological sources. Some of the TEs (such as Al, V, Cr, Mn, Fe, and Co) show crustal origin in Lake Gosainkunda, whereas others such as Ni, Cu, Zn, Cd, and Pb indicate possible anthropogenic origin (enrichment factor (EF) > 4). On the other hand, Al, V, Cr, Ni, and Cu show crustal origin in Lake Phewa and the remaining TEs (Mn, Fe, Co, Zn, Cd, and Pb) showed high EF values relative to the crustal elements suggesting potential anthropogenic inputs of the pollutants. The study further indicates that two studied lakes have different potential sources for Mn, Fe, Co, Ni, and Cu regarding TE pollution. A high enrichment of Cd and Pb in high-altitude lake (with less anthropogenic activities) compared to the low-altitude lake (with high anthropogenic activities) indicates atmospheric long-range transportation of the pollutants in remote areas of the Himalayas which might be possible as air masses pass through the industrial areas and deposit in the high altitudes.

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.