This study aimed to explore the nitrogen and phosphorus removal performance of the horizontal submerged constructed wetland (HSCW) with Ti-bearing blast furnace slag (T). Another two HSCWs, with the converter steelmaking slag (G) and the stone (S) as wetland substrates, respectively, were simultaneously running as control. The results showed that the nitrogen and phosphorus removal capacities of the T-HSCW were generally better than those of another two HSCWs. When the hydraulic retention time (HRT) was 6 days, the effluent concentrations of ammonia nitrogen (NH₄⁺-N) and total nitrogen (TN) were 6.66 mg L⁻¹ and 14.02 mg L⁻¹, respectively, and the removal rates of NH₄⁺-N and TN reached 77.54% and 71.07%, respectively. The T-HSCW had better removal efficiency of phosphorus. The effluent concentration of total phosphorus (TP) was lower than 0.3 mg L⁻¹, and the maximum removal rate could reach 98%. Through the characterization of the three substrates before and after experiments, it was found that the removal of nitrogen and phosphorus by T and G mainly relied on chemical adsorption, while S mainly relied on physical adsorption. Ti could also promote the absorption of nitrogen by plants and increase the nitrogen removal capacity of T-HSCWs.

Inorganic and organic constituents present in textile effluents have a noticeable effect on the performance of Fenton processes. However, studies have been focused on simple wastewater matrices that do not offer enough information to stakeholders to evaluate their real potential in large-scale facilities. Chemical auxiliaries, commonly present in textile wastewaters (NaCl = 30 g/L, Na₂CO₃ = 5 g/L, and CH₃COONa = 1 g/L), affect both the economic and environmental performance of the process because they increase the treatment time (from 0.5 to 24 h) and the consumption of H₂SO₄ (657%) and NaOH (148%) during conditioning steps. The life cycle assessment (LCA) performed with the IPCC-2013 method revealed that dyeing auxiliaries increase from 1.06 to 3.73 (252%) the emissions of carbon dioxide equivalent (CO₂-Eqv/m³). Electricity consumption can be considered an environmental hotspot because it represents 60% of the carbon footprint of the Fenton process. Also, the presence of auxiliaries is critical for the process because it results in the increase of the relative impact (between 50 and 80%) in all environmental categories considered by the ReCiPe-2008 method. Chemical auxiliaries increased the costs of the treatment process in 178% (US$2.22/m³) due to the higher energy consumption and the additional reagent requirements. It is worthwhile mentioning that the technical simplicity of the Fenton process and its low economic and environmental costs turn this process into an attractive alternative for the treatment of textile effluents in emerging economies.

Full-scale application of heterogeneous photocatalysis for industrial wastewater treatment remains a challenge because of the complex nature of these matrices and the potential to form toxic by-products during treatment. A recent unsuccessful attempt to find adequate conditions for TiO₂/UV treatment of a cotton dyeing textile mill led to this study on the treatability of mixtures of the dyes used in the greatest amounts at the mill and therefore most likely to be present in mill effluent. Four reactive and three vat dyes were mixed in different combinations and treated (10 mg/L of each dye, 0.5 mg/L TiO₂, pH 4) to evaluate the influence of the different dyes on ADMI color, chemical oxygen demand (COD), and acute toxicity. While ADMI color removal was similar in all dye mixtures, COD removal was higher when vat dyes were absent. When treated individually, vat dyes exhibited greater recalcitrance, with no ADMI color removal and COD removals of less than 30%. Toxicity to Daphnia similis was decreased or eliminated from dye mixtures that exhibited the highest COD removals and corresponded to those in which reactive dyes were partially degraded. For raw textile mill effluent, photocatalysis reduced but did not eliminate treated effluent toxicity (EC50 = 26.8%).

With increasing metal prices and declining ore grades, new mines are getting larger and mine waste disposal and management have become more difficult, particularly from an environmental perspective. While technologies keep on improving, the available space for terrestrial mine waste disposal is limited. Thus, several coastal countries still consider deep-sea tailings placement (DSTP) as a viable option. This brief review compares the environmental impacts of DSTP versus on-land disposal and suggests several factors to consider in selecting the most suitable options for mine waste disposal.

Iron-incorporated silica (Fe/SiO₂) with different Fe/Si molar ratio was successfully prepared from rice husk pyrolytic residues (RHR) through alkali pretreatment, co-precipitation, and calcination. Various characterization methods indicated that the Fe/SiO₂ samples possessed mesoporous structure with Fe species incorporated into the framework of silica. The obtained materials were applied in the treatment of hazardous banknote printing wastewater, and under the optimal conditions, colored pollutants, humic acid-like and soluble microbial by-product-like organics were removed significantly. It was found that Fe/SiO₂ acted as both flocculant and catalyst, and the framework iron species catalyzed the oxidative degradation of refractory organics in the presence of H₂O₂. A heterogeneous Fenton-like system was formed in the wastewater treatment process.

Efficacy of activated bentonite, activated carbon, and natural phosphate under experimental conditions was tested as low-cost adsorbents for spiramycin antibiotic removal from aqueous solution. Equilibrium kinetic and isotherm adsorption process are well described by pseudo-second order and Langmuir isotherm models for activated bentonite and activated carbon, while natural phosphate follows pseudo-first order and Freundlich models, respectively. Obtained results revealed that activated bentonite has the highest adsorption capacity (260.3 mg/g) as compared to activated carbon (80.3 mg/g) and natural phosphate (1.7 mg/g). The adsorption capacity decreases for all adsorbents in the presence of NaCl. The adsorption processes are facilitated in the alkaline pH range for activated bentonite and activated carbon, whereas, for natural phosphate, the acidic pH range is favorable. They are involving ion exchange and hydrogen bond mechanisms as well as Van der Waals forces and also π interactions for activated carbon. Thermodynamic calculation shows that spiramycin adsorption is endothermic and spontaneous on all adsorbents. The activated bentonite reusability is more efficient by more than 95% in two-step desorption using NaOH and HCl eluents compared to activated carbon. Thus, activated bentonite is a promising adsorbent for spiramycin removal from aqueous solution.

Extended stochastic impact by regression on population, affluence, and technology model incorporating ridge regression was used to analyze the driving mechanism of energy-related CO₂ emissions in Kazakhstan during 1992–2014. The research period was divided into two stages based on GDP of Kazakhstan in 1991 (85.70 × 10⁹ dollars), the first stage (1992–2002), GDP < 85.70 × 10⁹ dollars, the stage of economic recovery; the second stage (2003–2014), GDP > 85.70 × 10⁹ dollars, the stable economic development stage. The results demonstrated that (1) population scale and the technological improvement were the dominant contributors to promote the growth of the CO₂ emissions during 1992–2014 in Kazakhstan. (2) Economic growth and industrialization played more positive effect on the increase of the CO₂ emissions in the stable economic development stage (2003–2014) than those in the stage of economic recovery (1992–2002). The proportion of the tertiary industry, the trade openness, and foreign direct investment were transformed from negative factors into positive factors in the stable economic development stage (2003–2014). (3) Due to the over-urbanization of Kazakhstan before the independence, the level of urbanization continued to decline, urbanization was the first factor to curb CO₂ emissions during 1992–2014. Finally, some policy recommendations are put forward to reduce energy-related carbon emissions.

Plitvice Lakes National Park presents one of the most beautiful karst complexes in the world. Its waters are supersaturated with dissolved calcium carbonate (calcite) which is released and deposited in the form of tiny crystals as a result of water splashing at tufa barriers. Sulphates, present in the particulate matter (PM), can be deposited on the surface of the calcite. In the air, sulphate particles are formed by the oxidation of SO₂ in a series of chemical reactions as reported by Li et al. (Atmospheric Chemistry and Physics 6:2453–2464, 2006). Fast oxidation of SO₂ in nature can also take place on the surface of the calcite in the presence of ozone and is significantly enhanced by high humidity as reported by Li et al. (Atmospheric Chemistry and Physics 6:2453–2464, 2006) and Massey (Science of the Total Environment 227(2–3), 109–121, 1999). The resulting sulphates can destroy the surface of the calcite and indirectly influence the composition and quality of water. Hourly concentrations of ozone, PM₁₀ and PM₂.₅ at the monitoring station Plitvice Lakes in the period from 2012 to 2014 are presented. After assessing the observed values of both PM and ozone, presently there are no significant danger for Plitvice Lakes. However, this can change in the future so continuous monitoring will be necessary in the future.

A microwave (MW) heat-activated the persulfate (PS) process was employed to treat paracetamol (PAM) in wastewater, and the powder-activated carbon (PAC) be used is used as a catalyst to accelerate this reaction process. The PAM added (100 mg) to the solution was nearly completely removed within 70 min, and the PH, temperature, PAC, and PS dosage have great influence on the degradation process; the total organic carbon (TOC) removal rate reached 98%. The PAC¹ still had a good catalytic effect after being reused six times. The radical mechanism was investigated to determine the type of dominant active species involved in PAM degradation. Sulfate radicals ([Formula: see text]) were the dominant oxidizing agent for PAM degradation under acidic conditions. The degradation mechanism was proposed based on the PAM degradation intermediates, which were identified using ultra-high-performance liquid chromatography coupled with linear trap quadrupole orbitrap mass spectrometry. Three types of possible reaction pathways for PAM were identified as follows: including hydroxylation of the benzene ring, amine group oxidation at the benzene ring, and amine (HN–C=O) functional group N–C bond cleavage.

The adsorption properties and mechanisms of methylene blue (MB) onto novel biochars produced by the fallen leaves of Magnolia grandiflora Linn (MGL), at different pyrolysis temperatures (450 °C, 500 °C, 550 °C) were explored. Results of the adsorption experiments revealed that the fallen leaf-biochar of MGL (MGLB) pyrolyzed at 450 °C (MGLB450) had the highest adsorption capacity of MB (114.15 mg g⁻¹) and MGLB pyrolyzed at 500 °C (MGLB500) was lowest (88.13 mg g⁻¹). The characterization results showed that the BET surface area (41.784 m² g⁻¹) and total pore volume (0.043 cm³ g⁻¹) of MGLB450 were low, but the contents of oxygen-containing functional groups were highest. Oxygen-containing functional group might have a greater impact on the adsorption of MB than its physical characteristics. The adsorption capacity increased with reaction temperature, indicating that the MG adsorption onto biochars was endothermic. The higher initial concentrations of MB and pH were beneficial to adsorption. The adsorption kinetics showed that the adsorption followed pseudo-second-order kinetics model. The obtained equilibrium data were fitted better by Langmuir model rather than Freundlich model.