Nanoparticles (NPs) are emerging as a new type of contaminant in water and wastewater. The fate of titanium dioxide nanoparticles (TiO₂NPs) in a granular activated carbon (GAC) adsorber and their impact on the removal of trichloroethylene (TCE) was investigated. Key parameters governing the TiO₂NP–GAC interaction such as specific surface area (SSA), zeta potential, and the TiO₂NP particle size distribution (PSD) were determined. The impact of TiO₂NPs on TCE adsorption on GAC was tested by conducting TCE adsorption isotherm, kinetic, and column breakthrough studies in the presence and absence of TiO₂NPs. SSA and pore size distribution of the virgin and spent GAC were obtained. The fate and transport of the TiO₂NPs in the GAC fixed bed and their impact on TCE adsorption were found to be a function of their zeta potential, concentration, PSD, and the nature of their aggregation. The TiO₂NPs under investigation are not stable in water and rapidly form larger aggregates. Due to the fast adsorption kinetics of TCE, the isotherm and kinetic studies found no effect from TiO₂NPs. However, TiO₂NPs attached to GAC and led to a reduction in the amount of TCE adsorbed during the breakthrough experiments suggesting a preloading pore blockage phenomenon. The analysis of the used GAC confirmed the pore blockage and SSA reduction.

The polysaccharidic moieties of three biosorbents (Douglas fir and argan tree barks and argan endocarp) were selectively oxidized, and the subsequent modified materials were tested for their ability to bind Pb(II) or Cd(II) from aqueous solutions. Chemical modifications consisted in two selective oxidations, alone or in combination, of the following groups: primary alcohols with NaOBr catalyzed by (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, and vicinal diols with periodate/chlorite. The sodium chlorite oxidation step induced biosorbent degradation that led to a significant decrease of mass yield. Modified materials, characterized by FT-IR spectroscopy and measurement of surface acidity, were investigated for their adsorption capabilities of Cd(II) and Pb(II). Results were compared to the capabilities of crude materials using the Langmuir adsorption model in terms of affinity (b) and maximum binding capacity (q ₘₐₓ). Ion exchange properties were found better for lead than for cadmium before and after chemical modifications. Compared to crude barks, the best results were obtained for Douglas fir barks whose oxidation resulted in significant enhancements of q ₘₐₓ up to × 10 in the case of lead.

A novel tannin-based coagulant has been synthesized at lab scale. A multiparameter optimization was performed on the production process, and up to five variables were studied according to the response surface methodology in a face-centered design of experiments which included two temperatures, two pH levels, and the reaction time in the chemical process. The coagulant involved diethanolamine, formaldehyde, and a tannin extract from Acacia mearnsii de Wild. The results revealed an average optimum combination for dye and surfactant removal which was able to remove either Alizarin Violet 3R and sodium dodecylbenzene sulfonate efficiently from water effluents.

Elevated emissions of nitrogen oxides (NOx) in the Athabasca Oil Sands Region, Alberta and higher foliar nitrogen (N) concentrations in jack pine (Pinus banksiana) needles close to major emission sources has led to concerns that the surrounding boreal forest may become N-saturated. Despite these concerns, N deposition and impacts on upland forests in the region is poorly quantified. The objective of this study was to characterize N cycling in five plots representing the two dominant upland forest types (jack pine and trembling aspen, Populus tremuloides) close (<30 km) to the largest mining operations in the region, during a 2-year period. Despite the high level of NOx emissions, bulk throughfall and deposition measured at both study sites were surprisingly very low (<2 kg N ha−1 year−1). Internal N cycling was much greater in aspen stands; annual N input in litterfall was ten times greater, and net N mineralization rates were two to five times greater than in jack pine stands. Nitrogen use efficiency (NUE) was much greater in jack pine when calculated based on N litterfall indices, but not when N pools in biomass were considered. Despite differences in internal cycling among forest types, nitrate leaching from mineral soil in both forest types was negligible (<0.1 kg N ha−1 year−1) and patterns of 15N in roots, foliage, and mineral soil were typical of N-limited ecosystems, and both sites show no evidence of N saturation.

Extraction and analysis methods have been developed for the detection of the following four antibacterial agents and two natural estrogens in treated municipal wastewater sludge and commercial compost: sulfamethoxazole (SMX), sulfadimethoxine (SDM), tetracycline (TET), oxytetracycline (OXY), estrone (E1), and 17β-estradiol (E2). The antibiotics and estrogens were extracted from secondary sludge and mixed compost using ultrasonic solvent extraction. Citric acid (pH 4.7) and methanol were used as extraction buffer, followed by tandem-solid-phase extraction cleanup, strong anion exchange + hydrophilic–lipophilic balance for antibiotics and CarboPrep/NAX for estrogens. For quantification, two different methods were employed, using HPLC–MS/MS, with an electrospray ionization source for antibiotics and an atmospheric-pressure chemical ionization source for estrogens. Recoveries were 11–31% for the sulfonamides (SMX and SDM) and tetracyclines (TET and OXY) and 30–59% for the estrogens (E1 and E2) over the entire method. Limits of detection for the extraction method were in the nanogram per gram range for dry weight sludge and compost samples. Neither of the two sulfonamide antibiotics was detected in secondary sludge or mixed compost samples. Estrogens were found in compost in amounts of 160 ± 65 ng/g (E1) and 21 ± 3 ng/g (E2), but not in sludge. The tetracyclines, as well as what is believed to be the 4-epimer of OXY, were found in both sludge and compost in amounts of 1.57 ± 0.67 and 2.95 ± 0.42 μg/g (TET), 0.56 ± 0.12 and 6.51 ± 0.52 μg/g (OXY), and 7.60 ± 1.68 and 1.35 ± 0.24 μg/g (4-epi-OXY), respectively. These results indicate that sorption-prone compounds are not removed during the wastewater treatment process and can persist through sludge digestion and that the composting process does not sufficiently eliminate these particular contaminants. Thus, biosolids (even composted) are an additional source of drug residues leaching into the environment, and it must be considered while using biosolids as fertilizer.

Titanium dioxide (TiO2)–silicon dioxide (SiO2) thin films were synthesized using the peroxo titanic acid approach (PTA) combined with the sol–gel method at low temperature around 100°C. The effects of type and amount of dopants of ferric (Fe3+) or thiourea (N-S) and co-dopants of Fe3+ and N-S on the films physicochemical properties and on the photocatalytic degradation of the methylene blue and formaldehyde under UV and visible light irradiation were investigated. Physicochemical properties of photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, wavelength-dispersive X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV–Vis spectroscopy. The results showed that the TiO2 crystal phases obtained from this method were exclusively anatase and the needle-like crystals have an average diameter of 10–25 nm. Compared with the single dopant of 1.0 wt.% Fe3+ or 0.125 wt.% N-S that was the optimal concentration for photocatalytic degradation of methylene blue and formaldehyde, the co-dopants of 0.125 wt.% N-S + 1.0 wt.% Fe3+ furthermore increased the degradation efficiency. Co-dopants of 0.125 wt.% N-S + 1.0 wt.% Fe3+ in TiO2–SiO2 films were considered to play synergistic roles in narrowing TiO2 band gap resulting in the higher methylene blue and formaldehyde degradation efficiency. Since the crystal grain size of TiO2–SiO2 films synthesized by the PTA method is small, in the visible light region, the high transmittance was attainable to 80% with no-doped and dropped to 50–60% with doped thin films.

Polybrominated diphenyl ethers (PBDEs) have been found at high levels, up to 7.6 × 106 pg/g, in biosolids commonly applied to agricultural soils. A field investigation was carried out in this study to measure concentrations of PBDEs in biosolid-amended agricultural soils in which various amounts of biosolids (20 and 80 t/ha) had been applied. Concentrations of PBDEs in surface soils that had received a single application of 80 t/ha biosolids were one to two orders of magnitude greater than that in soil, which had received a single application of 20 t/ha of biosolids. Assessment of PBDEs levels at different depths, between 0.05 and 1.05 m, in soils that received 80 t/ha biosolids, showed that PBDEs were mobilized from the surface soil to lower depths. Total PBDEs concentrations decreased from 10,250 pg/g dry weight basis (dw) in the 0.05 m soil layer to 220 pg/g dw at a depth of 1 m. The distribution of PBDEs with depth and cation exchange capacity of the soil could be described as exponential functions. The coefficients of correlation ranged from 0.47 to 0.57 and 0.47 to 0.67, respectively. Despite the deviation in the experimental measurements induced by variables, such as non-uniform biosolid application, heterogeneity of the soil, and the uneven surface of the field, variations of PBDEs along the soil profile in the biosolid-amended soil were clearly demonstrated.

The batch bioreduction of Cr(VI) by the cells of newly isolated chromium-resistant Acinetobacter sp. bacteria, immobilized on glass beads and Ca-alginate beads, was investigated. The rate of reduction and percentage reduction of Cr(VI) decrease with the increase in initial Cr(VI) concentration, indicating the inhibitory effect of Cr(VI). Efficiency of bioreduction can be improved by increasing the bioparticle loading or the initial biomass loading. Glass bioparticles have shown better performance as compared to Ca-alginate bioparticles in terms of batch Cr(VI) reduction achieved and the rate of reduction. Glass beads may be considered as better cell carrier particles for immobilization as compared to Ca-alginate beads. Around 90% reduction of 80 ppm Cr(VI) could be achieved after 24 h with initial biomass loading of 14.6 mg on glass beads. Artificial neural network-based models are developed for prediction of batch Cr(VI) bioreduction using the cells immobilized on glass and Ca-alginate beads.

Frequently, sulfonamide antibiotic agents reach arable soils via excreta of medicated livestock. In this study, accumulation and phytotoxicity indicators were analyzed to evaluate the effects of sulfonamides on plants. In a greenhouse experiment, willow (Salix fragilis L.) and maize (Zea mays L.) plants were grown for 40 days in soil spiked with 10 and 200 mg kg⁻¹ sulfadiazine (SDZ). Distribution of SDZ and major metabolites among bulk and rhizosphere soil, roots, leaves, and stems was determined using accelerated solvent extraction and LC − MS/MS analysis. Accumulation of SDZ was stronger in willow. The antibiotic was mainly stored inside roots and 4-hydroxy-sulfadiazine presence increased with the administered SDZ concentration. SDZ altered root geotropism, increased the lateral root number, and affected plant water uptake. The high concentration caused serious stress in willow (e.g., reduced C/N ratio and total chlorophyll content) and the death of maize plants. Even at environmentally relevant soil concentrations (10 mg kg⁻¹), SDZ exhibited adverse effects on root growth, while at artificially high concentrations (200 mg kg⁻¹), it showed a strong potential to impair plant performance and biomass. Willow, a fast growing tree species, showed potential for possible phytoremediation purposes.

Carbonic anhydrase (CA) has been immobilized on chitosan stabilized iron nanoparticles (CSIN) for the biomimetic carbonation reaction. CSIN was characterized using scanning electron microscope, energy dispersive X-ray, X-ray diffraction spectroscopy, and Fourier transform infrared analysis. The effect of various parameters such as pH, temperature and storage stability, on immobilized CA was investigated using a p-NPA assay. Kinetic parameters of immobilized and free CA (K ₘ and V ₘₐₓ values) were also evaluated. The K ₘ and V ₘₐₓ for immobilized CA was 1.727 mM and 1.189 μmol min⁻¹ ml⁻¹, respectively, whereas for free enzyme the K ₘ and V ₘₐₓ was 1.594 mM and 1.307 μmol min⁻¹ ml⁻¹, respectively. It was observed that the immobilized enzyme had longer storage stability and retained 50 % of its initial activity upto 30 days at room temperature. CA immobilized on CSIN has been used for hydration of CO₂, and the results were validated by using a gas chromatographic method. Proof of concept has been established for the biomimetic carbonation reaction. Immobilized CA show reasonably good CO₂ sequestration capacity of 21.55 mg of CaCO₃/mg of CA as compared to CO₂ sequestration capacity of 34.92 mg of CaCO₃/mg of CA for free CA respectively, under a limiting concentration of CO₂ (14.5 mg of CO₂/10 ml).