Specific (nitrifying, denitrifying, and methanogenic) microbial activities were measured in simplified down-flow lab-scale columns simulating subsurface horizontal flow (HF) and vertical flow (VF) constructed wetlands (CWs). Extractable volatile solid (EVS) was 6.5-fold higher in VF system than in HF system. Potential nitrification rate was similar in both systems (2.6–3.2 g N/m² day), while specific nitrifying activities were higher in the HF system (29–48 mg N/g EVS day) than in VF system (3.9–4.7 mg N/g EVS day), indicating a higher relative abundance of nitrifying bacteria in HF biofilm. Potential denitrification rates were 13–19 (HF) and 1–4 (VF) g N/m² day and specific denitrifying activities were 178–195 (HF) and 2.3–5.6 (VF) mg N/g EVS day. However, VF units exploited better the potential nitrification and denitrification rates by removing significant amounts of nitrogen. Specific methanogenic activity was null in VF units but high (0.13–0.20 g COD-CH₄/g EVS day) in HF units.

In this work, the effect of crystallite size, defects, and surface area of iron oxyhydroxide particles supported on mesoporous MCM-41 on the adsorption of hazardous β-lactamic antibiotics was investigated. Different adsorbents were prepared by impregnation of 5, 10, 20, and 50 wt% of Fe followed by treatment at 150–400 °C. Mössbauer, XRD, BET, TG, FTIR, and Raman analyses suggested that treatment at 150 °C produced a mixture of α-Fe₂O₃, FeOOH, and highly dispersed Fe³⁺ species. At higher temperatures, different phases were gradually converted to hematite with crystallite sizes varying from 1 to 5 nm. Both, Fe content and temperature, strongly affected the amoxicillin, cephalexin, and ceftriaxone adsorption at pH 5, 7, and 9, with the best results obtained for the sample 20Fe150 (20% Fe treated at 150 °C), ca. 25 mgAMX g⁻¹ which decreased to 17, 6, and 4 mgAMX g⁻¹ (AMX = amoxicillin) upon treatment at higher temperatures. These results combined with competitive adsorption using AMX/phosphate and H₂O₂ decomposition experiments suggested that the antibiotic molecules are likely adsorbing by complexation on Fe³⁺ surface species of poorly crystallized small particles of Fe oxyhydroxide phases. It was observed that below a critical crystallite size of 3 nm, the AMX adsorption was very sensitive and strongly increased.

Soil heavy metal contamination results in both huge economic loss and severe health problem. Many technologies, such as soil stabilization/solidification, soil excavation, soil washing, chemical extraction and phytoremediation, have been developed to treat soil heavy metal contamination. Among these methods, phytoremediation is usually regarded as a promising, environment-friendly, and cost-effective method. However, little information has been found to support this idea. Hence, in this study, we have conducted a cost-effectiveness analysis of three treatment methods (soil excavation and disposal, soil washing, and phytoextraction) in 16 scenarios of different soil texture, site scale, soil metal, and contamination levels with reviewed literature information. The results have showed that phytoextraction is more cost-effective when dealing with the slightly polluted soils, while soil washing is cost-effective for severely-contaminated scenarios.

As a new persistent environmental pollutant, microplastic pollution has attracted great interest recently. Microplastic particles are distributed widely throughout the world’s freshwaters, oceans, and seas, including the water column and sediments reaching as far as the deep sea. However, the practical considerations and protocols for microplastic pollution have, to the best of our knowledge, not been reviewed properly with regard to assessing their distribution, biotoxicity, sampling, and identification in the aquatic environment. In this review, the implications of microplastic pollution, including its wide distribution, biotoxicity threats, sampling, and identification challenges in the aquatic environment , were discussed and evaluated. The challenges and perspective of the related research are also presented to identify knowledge gaps and to prioritize future research needs. Graphical abstract In this review, the implications of microplastic pollution, including its wide distribution, biotoxicity threats, sampling, and identification challenges in the aquatic environment, were discussed and evaluated. The challenges and perspective of the related research are also presented to identify knowledge gaps and to prioritize future research needs.

In this study, ash samples were collected from five locations situated in the boiler of a circulating fluidised bed municipal solid waste incinerator (high- and low-temperature superheater, evaporator tubes and upper and lower economiser). These samples represent a huge range of flue gas temperatures and were characterised for their particle size distribution, surface characteristics, elemental composition, chemical forms of carbon and chlorine and distribution of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and biphenyls (PCB). Enrichment of chlorine, one of the main elements of organochlorinated pollutants, and copper, zinc and lead, major catalytic metals for dioxin-like compounds, was observed in lower-temperature ash deposits. The speciation of carbon and chlorine on ash surfaces was established, showing a positive correlation between organic chlorine and oxygen-containing carbon functional groups. The load of PCDD/F and PCB (especially dioxin-like PCB) tends to rise rapidly with falling temperature of flue gas, reaching their highest value in economiser ashes. The formation of PCDD/F congeners through the chlorophenol precursor route apparently was enhanced downstream the boiler. Principal component analysis (PCA) was applied to study the links between the ash characteristics and distribution of chloro-aromatics. The primary purpose of this study is improving the understanding of any links between the characteristics of ash from waste heat systems and its potential to form PCDD/F and PCB. The question is raised whether further characterisation of fly ash may assist to establish a diagnosis of poor plant operation, inclusive the generation, destruction and eventual emission of persistent organic pollutants (POPs).

Along the coast of Maine, USA, there are numerous wastewater treatment plants that discharge their treated effluents into a river estuary which is shared by commercial fishing and shellfish harvesting. Occasionally, there can be failures or bypasses of treatment plants that lead to untreated or partially treated sewage flowing into shellfish harvesting waters. To prevent any toxic contamination of harvested shellfish, a prohibitive zone is established around the treatment plant where shellfish harvesting is prohibited. The U.S. Food and Drug Administration has conducted numerous dye studies on both coasts of the USA to determine these prohibitive zones, based on the guidelines of the National Shellfish Sanitation Program. In May 2010, the FDA conducted such a dye study at the Yarmouth, Maine wastewater treatment plant. The results are compared with a numerical coastal model that provides the velocity field for the currents around the treatment plant. This model includes a diffusion equation to simulate dye dispersion from a point source which is used to determine the prohibitive zone. The numerical model shows good correlation with the FDA dye study report and establishes a prohibitive zone for commercial harvesting in keeping with that of the FDA study. The benefits of the numerical model include sampling at thousands of locations simultaneously, seasonal changes in river volumes, and changes in plant discharge volumes.

Mitochondria play an essential role to supply the cell with metabolic energy in the form of adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS). As a consequence, they are also the primary source of cellular reactive oxygen species (ROS) which can cause oxidative damage of individual respiratory chain complexes. Indeed, affected OXPHOS subunits result in decreases in ATP production and increases in ROS formation which generate oxidative phosphorylation deficiency leading to mitochondrial dysfunctions. It has been suggested that ROS play a vital role in the pathogenesis of mitochondrial diseases. To the best of our knowledge, this is the first study which aimed to investigate the genetic variant effect of the antioxidant enzymes GSTM1 and GSTT1 on mitochondrial disease among a Tunisian population. In this report, 109 patients with mitochondrial disease and 154 healthy controls were genotyped by multiplex PCR amplification, and data were analyzed by SPSS v20 software. The results showed that GSTM1 null genotype was found to be associated with mitochondrial disease with a protective effect; however, no significant association of GSTT1 polymorphism with mitochondrial disease risk was revealed. But, interestingly, our findings highlight that GSTM1 active and GSTT1 null genotype combination increased by three fold the risk of developing mitochondrial disease with p c = 0.020, notably mitochondrial myopathy with p c = 0.046 and Leigh syndrome with p c = 0.042. In conclusion, this study suggests that GSTM1 active and GSTT1 null genotype combination might be a risk factor in developing mitochondrial disease.

Benzotriazole (BT) and 5-methyl-1H-benzotriazole (5-MeBT) are broadly used in industrial applications, such as anti-icing fluids and dishwashing detergent, and act as the primary building blocks for UV absorbers and photostabilizers. This study examined the occurrence of these two compounds in the environment and their unique photochemical behavior affecting photosensitizers and other micro-organic pollutants in aqueous environments. BT and 5-MeBT were detected in all river water samples from the major rivers in Taipei City in the concentration ranges of 147 to 1560 ng/L and 22 to 235 ng/L, respectively, and both compounds persisted through a conventional wastewater treatment plant. The direct photolysis half-lives of BT and 5-MeBT were 56.9 and 14.0 h, respectively. The half-life of photolysis in river water for BT was 44.2 h, whereas the half-life of 5-MeBT was 24.7 h. The long half-lives in real-water matrices resulted in their prevalence in water bodies, and these compounds were also found to minimize the photosensitizing ability of nitrate and dissolved organic matter (DOM) and increase the persistence of other micro-organic pollutant. With BT present, the production of ·OH in nitrate photolysis was reduced, the degradation of DOM under sunlight was hindered, and the photodegradation of pharmaceutical residues in surface water, such as methotrexate, was completely impeded. This study suggests that in cases in which BT and 5-MeBT are highly concentrated, the effectiveness of natural attenuation process, i.e., photodegradation, in the aqueous environment is diminished, which increases the persistence of the pollutants as well as the risk of exposure.

In this study, mesoporous Fe/MCM-41 was prepared and employed as a heterogeneous Fenton catalyst for the oxidative degradation of dye rhodamine B (RhB) in aqueous solution. Structural and morphological characterizations were performed using XRD, BET, FTIR, and SEM-EDX techniques. Fe/MCM-41 exhibits high catalytic activity for degradation of RhB in the Fenton-like system consisting of solid catalyst and H₂O₂. ·OH radicals were demonstrated to be the dominant active species by using tert-butanol as a probe compound. It was suggested that dye adsorption and ·OH generation are independent of each other during the heterogeneous Fenton process at the studied initial dye and H₂O₂ concentrations. The intermediates of RhB degradation were identified by LC-MS technique in this study. It can be inferred that the destructions of the conjugated structure and N-de-ethylation happen simultaneously during the heterogeneous Fenton process.

Amine-grafted MSU-3 mesoporous silica samples were synthesized from pure and waste silica sources and their CO₂ adsorption performances were evaluated. The obtained samples were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), N₂ adsorption–desorption isotherm analysis, Fourier transform infrared (FTIR), and transmission electron microscopy (TEM). CO₂ adsorption capacities of the samples at different temperatures were determined by TGA. The amine-modified MSU-3 synthesized from waste exhibited the highest CO₂ adsorption capacity of 1.32 mmol/g at 25 °C and 1 bar, depending essentially on the porous texture and the amine content of the material. The CO₂ adsorption isotherms of the synthesized samples were measured by a static volumetric method. Adsorption isotherm indicated that the amine-modified samples presented significantly higher CO₂ adsorption capacity than the pure samples. The Avrami kinetic model fitted the experimental data well and suggested that complex reaction mechanism or the appearance of multiple reaction pathway occurred in the CO₂ adsorption. Graphical Abstract CO₂ uptake capacities and TEM images of the amine modified samples