Water, Air, & Soil Pollution最新文献

Tire wear particles (TWP), generated by the friction of vehicle tires against the road surface during driving, accelerating, and braking, are transferred to aquatic ecosystems via rainfall runoff. These particles exhibit toxicological effects on aquatic organisms and have become the focus of research in environment and health. Microalgae, as primary producers in the marine food web, play a crucial role in aquatic ecosystems and are inevitably affected by TWP. However, the toxic mechanisms by which TWP influences microalgae's normal physiological activities remain unclear. Given this, Microcystis aeruginosa, a common species in freshwater ecosystems, was selected as an experimental species in this study to investigate the effects of different concentrations of TWP (5, 25, 50, 100 mg/L) on its growth, chlorophyll a content, photosynthetic activity, extracellular polymer secretion (EPS), and oxidative stress. The results showed that TWP had a concentration-dependent inhibitory effect on the growth, chlorophyll content, and photosynthetic activity of Microcystis aeruginosa, with maximum inhibition rates reaching 89.4%, 98.44% and 92.9%, respectively. TWP stimulated the secretion of the EPS of Microcystis aeruginosa, and the secretion of the EPS increased with the increase of the concentration of TWP. TWP also promoted the polysaccharide-to-protein ratio in the EPS with a rise of 27.3–38.5%. Meanwhile, the three-dimensional fluorescence-area-integral analysis indicated that the ratio of the protein-like component was generally higher than the one of the humic-like component in the EPS of Microcystis aeruginosa. The significant increase in superoxide dismutase (SOD) activity under 50 and 100 mg/L TWP exposure predicted a substantial activation of oxidative stress. In contrast, the significant increase in the malondialdehyde (MDA) content indicated the overproduction of reactive oxygen species (ROS) and may lead to lipid peroxidation damage. These findings will help us better understand the toxic mechanisms by which TWP induces effects in microalgae.

Numerous studies highlight the potential degradation of per- and polyfluoroalkyl substances (PFAS) through advanced oxidation processes. A recent focus involves an innovative technology utilizing iron-based catalysts activated by persulfate, renowned for its exceptional PFAS removal efficiency. However, existing literature lacks a thorough comparison of various iron species catalyzing persulfate for PFAS oxidation, with limited analysis of key degradation factors. This paper conducts a comprehensive review, analyzing PFAS degradation efficiency, mechanisms, and pathways using persulfate activated by ferrous ions, zero-valent iron/nano zero-valent iron, iron-based multimetallic catalysts, and various supported iron catalysts. The influence of solution pH and Fe²⁺ concentration on the degradation process is also explored. The review reveals promising PFAS removal performance, often exceeding 90%, by iron-based materials activated with persulfate. Catalysts enhance performance through synergistic elements, optimized structural design, and diverse carriers. Acidic environments favor persulfate activation for organic pollutant degradation, while appropriate Fe²⁺ concentrations enhance removal efficiency, with Fe³⁺ regeneration being the rate-determining step. Iron-based catalyst-activated persulfate follows free radical (SO•- 4, ·OH, O₂^−•) and non-free radical pathways (Fe(IV), ¹O₂, direct electron transfer). Perfluorooctanesulfonic acid (PFOS) degradation involves desulfurization, forming the intermediate product perfluorooctanoic acid (PFOA), followed by defluorination. The critical step is removing one CF₂ unit in each round, leading to complete mineralization. The paper proposes future research directions for iron-based activated persulfate in water treatment for PFAS.

Environmental pollution by microplastics is now a global problem, as global plastic production is increasing and at the same time recycling of plastic waste is low. In recent years, a number of methods have been developed to determine the content of microplastics in soil. This study compares the efficiency of microplastic extraction in two-week and three-month incubation samples from three different soils artificially contaminated with different types of microplastics. H₂O₂ and KOH were used as agents to remove organic matter. The effects of changing the incubation time were significant in soils with a high organic matter content. A longer incubation time resulted in a lower efficiency of microplastic extraction. Compared to the results obtained with the control method after a two-week incubation, the loose sand samples achieved a similar extraction efficiency (86%), the amount of MP recovered in the uncontaminated sandy clay samples was 75%, while the sandy clay soils contaminated with heavy metals was 44%. The samples without organic matter removal showed a significantly better recovery rate of microplastics than the samples treated with H₂O₂ and KOH.

Bioleaching is a technology capable of recovering metals from polluted mine tailings. However, the process is slow and time consuming. This work studies the possible enhancement of the bioleaching rate by using different bioaugmentation strategies, i.e. single and multi-step inoculation. Slurry phase batch experiments were performed using real mine tailings containing high concentrations of Fe, Pb, Zn and Mn, and low concentrations of Cd, Ni, Cr and Cu, and a mixed microbial culture of autochthonous acidophilic bacteria grown from those tailings. The effect of the inoculum concentration added at the beginning of the batch experiments was studied in the experiments with single inoculation, while the effect of different reinoculation frequencies was analysed in the multi-step inoculation tests. The results obtained showed that bioaugmentation has a high potential for enhancing the bioleaching process. For both strategies studied, metal bioleaching rates and final removal yields increased when bioaugmentation was carried out. The best results were obtained under the multi-step approach. Average bioleaching rates were multiplied at best case approximately by 2.8 (Fe), 5.0 (Zn), 7.3 (Cu), 17.0 (Mn) and 1.5 (Pb) while removal yields at best case increased approximately 122% (Fe), 31% (Cu), 9% (Cd), 19% (Zn), 17% (Mn), 33% (Ni) and 66% (Cr), compared to reference test (without bioaugmentation). The multi-step approach was able to compensate the assumed inhibitory effect of the metal dissolution during experiments, thus maintaining the active microbial population and the bioleaching rate for longer periods of time.

Microplastics (MPs) in soil can affect soil quality, and interfere with the material cycle and energy flow of terrestrial ecosystem. To explore the migration of MPs in soil and its effect on farmland soil quality, a soil column experiment was conducted to simulate the migration of MP particles in soil under rainful condition. The results showed that at a mass ratio of 2%, the migration capacity of polystyrene, polyethylene, polypropylene, polyvinyl chloride, and polylactic acid MPs in the soil columns was similar. The presence and type of MPs had no significant effect on soil bulk density. The influence of MPs on the quantity of water stable macro-aggregates (> 0.25 mm) was more significant in the top soil layer (0–5 cm) where the MPs were added than in the middle and bottom layers (5–20 cm). Under leaching, MPs decreased the available phosphorus concentration in soil.The results of this study can improve the understanding of the effects of MPs on the soil quality and provide reference information for the environmental risk assessment of MPs in farmland soils.

Currently, bioremediation treatments are economical and eco-friendly for decolorizing toxic dyes, however, how the decolorization of triphenylmethane (TPM) dyes by endophytic fungi remains unclear. This study aimed to investigate the ability for decolorizing and detoxifying of malachite green (MG), methyl violet (MV), crystal violet (CV), and cotton blue (CB) by endophytic fungi under oligotrophic conditions. Isolate SWUNF9, was identified as Colletotrichum graminicola, which is the most promising for the four TPM dyes removal. Our findings revealed that the decolorization efficiency of isolate SWUNF9 for MG with 91% was significantly higher than other TPM dyes. The change of UV–vis peaks further suggested degradation and sorption of TPM dyes chromophores by isolating SWUNF9. Furthermore, the optimization result demonstrated the decolorization rate of four TPM dyes by isolating SWUNF9 under oligotrophic conditions could reach above 92% at 24 h. We showed that the detoxifying of TPM dyes was caused by biosorption and degradation of C. graminicola SWUNF9, respectively. Moreover, phytotoxicity tests confirmed the lower significant toxicity toward the test seeds (Vigna radiata and Zea mays) of the treatment by isolating SWUNF9 when compared to dyes before treatment. The above studies indicate that isolate SWUNF9 could be used as a potential TPM dyes adsorption and degradation agent, and enhances our understanding of endophytic C. graminicola (SWUNF9) as a promising tool for dye removal treatment of colored textile effluents.

The study summarizes the necessary revisions for initiating the nitrification process in a full-scale leachate treatment plant that operates in a warm climate including dynamic simulation and kinetic characterization studies that were conducted to determine the nitrification kinetics. Following its commissioning, the process temperature in the plant reached high temperatures during the first six months of operation and failed to achieve complete nitrification. The process temperature was lowered from 40°C to 30°C with the aid of surface aerators installed in the anoxic volume of the bioreactor. With the selection of appropriate aerator capacity, besides reducing the temperature of the activated sludge, an 80% total nitrogen removal was achieved. Furthermore, as a result of dynamic simulation and kinetic studies, the maximum specific growth rates for ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) at a process temperature of 30°C were determined to be 0.85 day⁻¹ and 0.56 day⁻¹, respectively, around neutral pH.

A one-step hydrothermal method was successfully employed to synthesize hydroxyapatite modified attapulgite composite material (HAP/ATP), which was characterized to determine physicochemical properties. Furthermore, the performance and mechanism of uranium removal by HAP/ATP were extensively investigated. Results indicated that HAP/ATP reached adsorption equilibrium for uranium at around 20 min with a maximum adsorption capacity of 387.27 mg·g⁻¹. Modern characterization techniques identified ion exchange, complexation, dissolution–precipitation, and electrostatic adsorption as the primary mechanisms for uranium removal by HAP/ATP. ATP, a type of clay mineral, possesses a large specific surface area and natural pores. When utilized as a carrier, ATP reduced agglomeration of load materials. HAP can introduce more adsorption functional groups for attapulgite, this is a synergy, exerting the complementarity of materials. HAP/ATP demonstrates promising potential as an environmentally friendly adsorbent material for the treatment of radioactive uranium-containing wastewater.

In this study, the Cr(VI) metal ions have been removed from dichromate-contaminated water using a novel Azo Dye-Sulphonated Poly (glycidyl methacrylate) nano-composite adsorbent for the first time. Crystal violet Azo dye model (CV) has been immobilized onto nano-sulfonated Poly (glycidyl methacrylate) particles (SPGMA) through the adsorption process to obtain the novel crystal violet Azo Dye-Sulphonated Poly (glycidyl methacrylate) nano-composite adsorbent (CV-SPGMA). The effect of the adsorption conditions on the removal process of Cr (VI) metal ions such as dichromate concentration, adsorption time, temperature, pH, adsorbent dose, and finally agitation speed on the Cr(VI) metal ions removal was studied. The Cr(VI) metal ions removal process has been characterized using isotherms, kinetics, and thermodynamics models. The developed novel CV-SPGMA nano-composite adsorbent chemical structure and morphology were characterized using characterization tools such as FTIR, TGA, and SEM-EDAX analyses before and after the adsorption process. The developmentof the novel CV-SPGMA nano-composite adsorbent for the removal of Cr(VI) ions from dichromate-contaminated waters under mild adsorption conditions opens a new field of multiuse of the same adsorbent in the removal of more than one contaminant.