Heterogeneous photocatalytic oxidation (PCO) is a widely studied alternative for the elimination of volatile organic compounds (VOC) in air. In this context, research on novel photoreactor arrangements to enhance PCO rates is desired. Annular fluidized bed photoreactors (AFBPR) have yielded prominent results when compared to conventional thin film reactors. However, very few works aimed at optimizing AFBPR operation. In this study, TiO₂ photocalytic agglomerates were synthesized and segregated in specific size distributions to behave as Geldart groups A, B, C, and D fluidization. The TiO₂ agglomerates were characterized by XRD, FTIR spectra, and N₂ adsorption. Photocatalyst performances were compared in a 10-mm gapped AFBPR for degrading the model pollutant methyl-ethyl-ketone (MEK), using a 254-nm radiation source. Geldart group C showed to be inadequate for AFBPR operation due to the short operation range between fluidization and elutriation. In all the cases, photocatalytic reaction rates were superior to sole UV photolysis. Group A and group B demonstrated the highest reaction rates. Considerations based on mass transfer suggested that the reasons were enhanced UV distribution within the bed at lower flow rates and superior catalyst surface area at higher flow rates. Results also revealed that groups A, B, and D perform equally per catalyst area within an AFBPR if the fluidization numbers (FN) are high enough.

The pharmaceuticals acetaminophen, sulfamethoxazole, and carbamazepine, and herbicide atrazine are among the most highly manufactured compounds in the world and are frequently detected in the aquatic environment. Much uncertainty exists regarding the impacts of the pharmaceuticals on non-target aquatic resources, while more is known about atrazine. Reduction of residues of each chemical in surface water will reduce the exposures that organisms experience in the surface water environment, thus reducing unknown risks. This project evaluated the potential use of two aquatic plant species (Acorus gramineus and Canna hybrida ‘Orange Punch’) for reducing concentrations of the chemicals in water. Concentrations of each contaminant in solution were reduced in the presence of the plants after 14 days of exposure, in (acetaminophen 64–100%, atrazine 32–51%, carbamazepine 26–49%, sulfamethoxazole 41–60%). Results indicate that these plants have potential for reducing concentrations of these chemicals in surface water, but that plant- and chemical-specific properties prevent making generalizations regarding the extent and pathways for dissipation.

The presence of polycyclic aromatic hydrocarbons, such as anthracene (AN) and benzo[a]pyrene (BaP), in water has become a problem of great concern due to the detrimental health effects caused to humans and living beings. In this work, the efficiency of the UV/H₂O₂ system for degrading the target compounds at ultra-trace levels in surface water has been evaluated. For this purpose, a previous optimization step using a face-centered central composite experimental design has been conducted, considering the effect of the UV-C irradiance and the initial concentration of H₂O₂. It was evidenced that under optimal operating conditions (11 mg L⁻¹ H₂O₂ and 0.63 mW cm⁻² irradiance), AN and BaP removal percentages were higher than 99.8%. Additionally, 69.3% of the organic matter, in terms of total organic carbon, was mineralized without the production of transformation by-products more harmful than the parent compounds. These findings demonstrate the oxidation capacity of the examined system in a natural matrix for degrading micropollutants that cannot be converted through conventional treatment processes. Consequently, new horizons are opened for the effective use of the UV/H₂O₂ system for drinking water production, providing the accomplishment of other regulated parameters related to water quality.

The increased use of heavy metals in process industries often results in the generation of large quantities of wastewater (WW) and aqueous waste (AW) containing mixtures of heavy metals such as copper and nickel. This research focuses on the electrochemical recovery of copper and nickel from acid pickling solutions used to treat metal surfaces. Using hull cells, beaker plating, and electrolytic cells in pilot scale (capacity 30 L), the most important parameters influencing the process have been identified (temperature, contact time, and current density). In total, about 60 tests were carried out on AW containing nickel and copper. The results of the tests carried out with copper-containing AW shows that removal yields are often higher than 50%; while the energy consumption is less than 15 kWh kg⁻¹ of metal deposited. The best removal efficiency (100%) was achieved by applying a current density of 6 A dm⁻² and the energy consumption was 2 kWh kg⁻¹. The tests carried out with AW containing nickel point out very low removal yields (< 20%) and very high energy consumption (even exceeding 300 kWh kg⁻¹). The best removal yield obtained, applying a current density of 3 A dm⁻², is 6.7% with an energy consumption of 40 kWh kg⁻¹ of metal removed. A costs analysis based on Metal Exchange value was carried out. The cost analysis suggests that the results, in terms of removal and recovery, obtained for these metals, in particular for copper, are very promising for an industrial application.

Sulfur-doped activated carbons (SACs) with high sulfur content and large specific surface area were synthesized from polythiophene for acetone removal. The sulfur content of carbons (3.10–8.43 at.%) could be tunable by adjusting the activation temperature. The BET surface area and pore volume of the obtained samples were 916–2020 m² g⁻¹ and 0.678–1.100 cm³ g⁻¹, with a significant proportion of microporosity (up to 84% and 72% for BET surface area and pore volume, respectively). The resulting SACs show a superior acetone adsorption capacity (i.e., 716.4 mg g⁻¹ at 15 °C and 705 mg g⁻¹ at 25 °C for SAC700). In terms of the adsorption behavior of acetone on the activated carbons, compared to the Langmuir model, the Langmuir-Freundlich model showed better agreement with the adsorption amount. The results reveal that the surface area and micropore volume are the key factors for acetone adsorption, while the sulfur-doped functional groups, especially oxidized sulfur functional groups, can enhance the acetone adsorption capacity at a certain low pressure. Temperature programmed desorption (TPD) experiments were performed to get desorption activation energy of acetone on SAC samples, and the results ranged from 23.54 to 38.71 kJ mol⁻¹. The results of the molecular simulation show that the introduction of sulfur element can increase the binding energy between acetone molecule and carbon surface, and the tri-oxidized sulfur (sulfonic acid) functional group has the highest binding energy of − 0.4765 eV. Graphical abstract

In the original publication’s Fig. 1b, the labels J and I, should be placed at approximately 2 ms and 30 ms respectively. Also, Fig. 3C y-axis title should be written as ψEₒ /(1- ψEₒ).

Erroneous information considering Chironomidae and Chaoboridae accumulation was given in Figure 4 published in Luoto et al. (2017).

To remove the extra ammonium-nitrogen (NH₃-N) and phosphorus (P) from contaminated water, a novel granular adsorbent (GAZCA) was fabricated with zeolite powders and Al–Mn binary oxide (AMBO) via the compression method. The SEM-EDS and mapping and XRD results illustrated the microstructure of GAZCA: the homogeneous aggregation of zeolite and AMBO nanoparticles with their crystal integrity and the uniform distribution of Al/Mn/Si/O elements on the adsorbent surface. FTIR and XPS results demonstrated the existence of impregnated sodium cations and hydroxyl groups, which were responsible for the removal of NH₃-N and P, respectively. The results of BET analysis and compression tests exhibited a high surface area (14.4 m²/g) and a satisfactory mechanical strength of GAZCA. Kinetic adsorption results showed a fast adsorption rate for NH₃-N and P, and mutual inference was not observed between the adsorption kinetics of NH₃-N and P in the bi-component system. The adsorption isotherm results demonstrated that the maximum adsorption capacities of NH₃-N and P were calculated as 12.9 mg/g and 9.3 mg/g via the Langmuir model, respectively. In the bi-component system, the adsorption capacities of NH₃-N and P were maintained at low and moderate concentrations and decreased at high concentrations due to the blockage effects of NH₄MnPO₄·H₂O precipitates. The removal efficiency of NH₃-N could be maintained in a wide pH range of 4~10, while P adsorption was inhibited at alkali conditions. The solution of sodium bicarbonate (0.4 M) was used for the regeneration of saturated adsorbents, which permitted GAZCA to keep 98% and 78% of its adsorption capacity for NH₃-N and P even after three regeneration and reuse cycles. Dynamic experiments illustrated that a satisfactory performance was obtained for the in situ treatment of simulated N- and P-contaminated water by using a column reactor packed with GAZCA, thus further confirming its great potential for the control of eutrophication.

The implementation of the extended producer responsibility (EPR) for e-waste is an important measure to develop an ecological civilization. In order to advance manufacturing enterprises to effectively implement resource and environmental responsibility, this study investigates the main causes of environmental regulation failure from the perspective of government and enterprises. The game theory was used to establish an evolutionary game model between government regulatory departments and electronic and electrical products’ manufacturing enterprises. A system dynamic model was utilized to construct the stock-flow graph of the game between government and enterprises, and to carry out simulation analysis under different strategies. The results found that the probability of an enterprise undertaking extended responsibility gradually increased and stabilized with the increase of government supervision and punishment intensity; the government’s regulatory probability and punishment are important factors affecting the enterprises’ compliance with regulations and responsibilities. The study suggests that government should focus on strengthening environmental regulations from the aspects of improving laws and regulations, establishing a regular monitoring system and innovating incentive and constraint mechanism.

This study was conducted to acquire novel insight into differences between bulk (16S rDNA) and metabolically active (16S rRNA) prokaryotic communities in the sediment of a hypereutrophic lake (Japan). In the bulk communities, the class Deltaproteobacteria and the order Methanomicrobiales were dominant among bacteria and methanogens. In the metabolically active communities, the class Alphaproteobacteria and the order Methanomicrobiales and the family Methanosaetaceae were frequently found among bacteria and methanogens. Unlike the bulk communities of prokaryotes, the composition of the metabolically active communities varied remarkably vertically, and their diversities greatly decreased in the lower 20 cm of sediment. The metabolically active prokaryotic community in the sediment core was divided into three sections based on their similarity: 0–6 cm (section 1), 9–18 cm (section 2), and 21–42 cm (section 3). This sectional distribution was consistent with the vertical pattern of the sedimentary stable carbon and nitrogen isotope ratios and oxidation–reduction potential in the porewater. These results suggest that vertical disturbance of the sediment may influence the communities and functions of metabolically active prokaryotes in freshwater lake sediments. Overall, our results indicate that rRNA analysis may be more effective than rDNA analysis for evaluation of relationships between actual microbial processes and material cycling in lake sediments.