Water, Air, & Soil Pollution最新文献

Settleability is vital important for the stability of effluent quality from the widely used activated sludge (AS) process in wastewater treatment plants. In this study, filamentous algae and seawater condition were used to build a microalgae-bacteria (MB) consortia system with the objective of improving the settleability of AS. Filamentous algae were found to flourish more in aeration seawater reactor (R2) than non-aeration (R1). During 90 days, large contents of N, P were firstly released from the biomass, but were absorbed by the algae to relatively low concentrations (N 1.1 mg/L, P 1.4–2.3 mg/L). Meanwhile, the settleability of the two types of MB consortia both significantly increased, but was superiorly enhanced in aeration condition to a low 5-min sludge volume (SV₅) (11.5%, 55 d). Filamentous algae Leptolyngbya, as the most dominant part (9.8%) of microbial community in R2, could tightly bind the bacteria cells and extracellular polymeric substances (EPS) to form larger particles, which greatly accelerated the sedimentation. This study is of interest for the potential use of sludge settleability promotion in wastewater treatment plants, which has promising prospects for preventing the sludge bulking or biomass loss in AS systems.

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Manganese (Mn) concentrations in many groundwater supplies exceed the national drinking water limit of 0.05 mg/L, exacerbating regional water scarcity and potential ecological issues. Adsorption, as an efficient process for wastewater treatment. For the adsorption process, the adsorbent was the key parameter. Manganese oxides have strong specific adsorption and catalytic oxidation capacity for Mn(II). Serpentine loading was an effective way to improve the dispersion of manganese oxides and the adsorption efficiency of heavy metals. This study aimed to remove dissolved Mn(II) from groundwater using a raw serpentine modified with manganese oxide (Srp/MO). SEM, EDS, XRD, BET and XPS were used to characterize the physicochemical properties and characteristic groups of the serpentine before and after loading. Response surface methodology (RSM) based on Box-Behnken method was used to design the experiment to optimize the effects of dosage, oscillation rate and reaction time on manganese removal. The results show that after modification, the pores of serpentine become larger, the surface becomes smooth and loose, the basic skeleton has no obvious change, the specific surface area increases, and the total pore volume decreases. The adsorption behavior of Mn(II) by Srp/MO follows Langmuir isotherm model and pseudo-second-order kinetic model. The maximum adsorption rate of Mn(II) in water by Srp/MO was 34.88 mg/g, which was 7.6 times that of the raw serpentine. The primary mechanism for Mn(II) removal by Srp/MO was based on physical adsorption and mediated by Mn³⁺/Mn⁴⁺ species. The optimal manganese removal conditions were as follows: Srp/MO dosage 80 mg/L, oscillation rate 180 r/min, reaction time 104 min. At this time, the manganese removal rate was 99.3%, which was basically consistent with 100% predicted by the model. A regeneration study over three cycles indicated that Srp/MO possessed promising reusability potential. In conclusion, Srp/MO was an excellent adsorption material for the removal of Mn(II) in groundwater, which provides a new solution for the purification treatment of manganese containing groundwater.

To evaluate the effects of ocean acidification (OA) on the shell morphology of the gastropods, three different populations of Planaxis sulcatus (Born) in the South China Sea (Coast of Borneo) were investigated. All sites are natural rocky shores sharing a very similar geologic setting of the intertidal zone including, water depth, beach topography, and wave energy. The population densities observed during sampling were similar across all three study sites. However, one population lives under low pH due to geochemical discharge from acidic soils (site E), while the other two populations live under higher pH levels (T and U sites). Quantitative analyses of the shell shape using geometric morphometrics demonstrated that OA had a significant effect on the shell morphology, demonstrating that both allometric growth and the calcification process were affected. Shells from the acidified sites were more rounded and had smaller apertures. Moreover, shell size was significantly reduced as a response to OA stress. These shell changes may have arisen to reduce the cost of shell maintenance. As there is also a significant salinity difference among sites, salinity may have influenced the shell shape of the gastropod Planaxis sulcatus and therefore, the role of OA should be examined in areas where all other physicochemical variables are the same.

Since their inception in 2011, MXenes have attracted significant attention from a range of industries due to their fascinating architectures and alluring features. Given its two-dimensional multilayered structures, high mechanical strength, outstanding electrical conductivity, and customizable surface chemistry, MXene, a new family of two-dimensional (2D) multifunctional nanomaterials, has demonstrated exceptional performance in water treatment technologies. The most recent developments in the field of MXene-based membranes, from synthesis to fabrication and application, are reviewed in this article. The manufacture of MXene membranes and their applications in membrane separation were explored in detail. The discovery and properties of MXene were briefly reviewed first, and then new developments in MXene production methods were discussed. Subsequently, the properties and methods of manufacture and integration of versatile membranes based on MXene were explored. The most recent developments in water treatment applications, such as wastewater purification, oil/water separation, and desalination, were also covered in-depth. The durability and stability of membranes based on MXene were thoroughly discussed from many perspectives, revealing that these membranes can achieve filtration efficiency of over 99% for various contaminants, such as heavy metals and organic pollutants. Additionally, Durability tests demonstrate that these membranes retain their structural integrity and performance even after extended exposure to harsh chemical environments and many filtration cycles. Comparative studies demonstrate that MXene membranes surpass unmodified membranes, in terms of both flux and pollutant removal efficiency. Lastly, research directions and prospects were discussed to enhance the use of MXene-based membranes in a variety of water treatment applications. The literature analyses revealed that, after addressing several shortcomings and challenges related to their use, MXene-based membranes could revolutionize nanostructured composite membranes.

Sodium lauryl sulfate (SLS) is an anionic surfactant used as an emulsifying detergent in personal care products (PCPs). As a pseudo-persistent pollutant, it accumulates in aquatic ecosystems with consequent adverse effects on the whole ecosystem. Most of the studies about the toxicity of SLS on non-target species were conducted before 2010, and just a bunch of recent studies focus on this topic. Due to the COVID-19 pandemic, there has been a rise in the use of PCPs, thus increasing SLS release in aquatic environments. Therefore, the present study aims to assess the impact of SLS on non-target organisms Danio rerio, Cyprinus carpio, and Xenopus laevis, through embryotoxicity tests. Embryos were exposed to different concentrations of SLS (0.1, 0.5, 1, 5, 10, 15 mg/L) for 96 h and relevant toxicity endpoints (mortality, hatching rate, and malformations) were monitored each 24 h. Additionally, heart rates along with animal length were measured. The study highlights the high sensitivity of D. rerio and X. laevis when exposed to SLS concentrations comparable to the one detected in the environment. Specifically, relevant results have been observed in the endpoint of mortality (D. rerio showed 100% mortality in the highest concentrations), hatching and malformations in both animals. Heart rate measurements showed significant differences in C. carpio and D. rerio in all the concentrations tested.

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Human activities across domestic, commercial, and industrial sectors have significantly contributed to the accumulation of pollutants, including heavy metals, inorganic and organic compounds, and dyes, in aquatic environments. To improve water quality, it is crucial to develop a sustainable treatment method for the removal of these contaminants. Modifying cellulose by adding functional groups to its structure enhances its inherent properties which improves its ability to sorb heavy metals. This study focuses on current research into the effectiveness of cellulose as a sorbent for the eradication of heavy metals from effluents. The literature review indicates that modified cellulose-based sorbents are more promising than unmodified cellulose for the heavy metal elimination process. However, to optimize the wastewater treatment process further, it is necessary to explore effective methods such as tempo-oxidation, grafting, esterification, and electrospinning for producing more effective cellulose-based adsorbents and assessing their scalability in industrial applications.

The heterogeneous photocatalyst could effectively enhance Fe(III)- activated peroxymonosulfate (PMS) to remove organic pollutants in wastewater, however, the homogeneous photocatalyst is little reported so far. In this work, the removal of organic pollutants in the Fe(III)/PMS system was developed under the both darkness and LED illumination, by the addition of phosphotungstic acid (HPW) as homogeneous photocatalyst. Important influencing factors were optimized in the both darkness and LED illumination, including Fe(III), PMS and HPW concentrations, and extra anions. The results showed that Rhodamine B removal by Fe(III)/PMS was significantly strengthened after introducing HPW. In addition, it maintained a wide pH range. The mechanism studies revealed that HPW enhancing Fe(III)/PMS achieved the physical behavior in the darkness, whereas the existence of radical and non-radical pathways were primarily contributed for removing organic pollutants by HPW boosting PMS under LED illumination. The different approaches could be easily achieved by simply switching between darkness and LED illumination. This study provided a new process for treating organic pollutants in wastewater.

Heavy metal pollution in agricultural soil is a global issue that seriously threatens agricultural production and human health. Biochar has attracted significant attention as an efficient and environmentally friendly material for remediating heavy metal pollution in soil. In this study, biochar (BC) was prepared from tobacco straw and then modified with polyethyleneimine (PEI) using a mixed co-impregnation method to create polyethyleneimine-modified biochar (PBC). The structure and surface properties of BC and PBC were analyzed, and their effects on the physiological characteristics of Chinese cabbage, as well as the accumulation of cadmium and copper in Cd and Cu-contaminated soil, were studied. The results indicated an increase in the pore volume and pore size of the modified BC, with successful impregnation of PEI on the BC surface. The introduction of functional groups, such as amine groups, enhanced the adsorption of biochar. After 70 days of cultivating young plants, the growth status of Chinese cabbage and the soil’s physical and chemical properties were determined. Compared with the control ( CK), when the addition amount of PBC was 3%, the data were analyzed by one-way ANOVA. The indicators with significant changes were as follows: the content of available Cd and Cu in soil decreased by 54.68% and 43.76%, respectively. The plant height and root length of Chinese cabbage increased by 3.1 cm and 3.5 cm, respectively. The fresh and dry weights of leaves increased by 138.07% and 98.3%, respectively. The fresh and dry weights of the roots increased by 107.3% and 140.5%, respectively. The chlorophyll content of the leaves increased by 57.68%. The absorption and accumulation of Cd in roots and leaves decreased by 48.80% and 55.88%, respectively. The absorption and enrichment of Cu in roots and leaves decreased by 33.04% and 43.41%, respectively. The enrichment coefficients of Cd and Cu in Chinese cabbage leaves decreased by 47.45% and 40.92%, respectively, and in roots by 48.80% and 33.04%. In summary, PBC serves as an effective soil heavy metal stabilizer, significantly enhancing the physiological and biochemical indexes of crops in contaminated soil and reducing heavy metal accumulation in crops. This provides a scientific basis and technical support for researching and developing efficient soil heavy metal stabilization materials.

Plastics are versatile materials whose production and use are growing on a global scale. However, inadequate plastic waste management and its degradation result in the release of small particles, namely microplastics (MPs) and nanoplastics (NPs), which have adverse effects in physical, biological, and socioeconomic aspects. United Nations (UN) Sustainable Development Goal (SDG) 2 is related to ending hunger, promoting food security and nutrition, and achieving agricultural sustainability. MPs and NPs may affect the productivity and quality of agricultural products and contaminate foods and beverages from other sources, increasing health risks for human consumers. A systematic bibliographic review was conducted using StArt 3.4 and Excel software to identify gaps and recent advances in selected publications from 2022 and 2023 regarding the impacts of MPs and NPs to UN SDG 2. Then, 310 selected studies that discussed consequences to the agricultural soil, foods, drinking water, and beverages were summarized. The review addressed the recent advances and results regarding sources, occurrence, mobility, and effects of MPs and NPs on soil properties, nutrient cycling, productivity, and quality of agricultural soils. We also explored sources and MPs/NPs contamination of different types of foods, drinking water, and beverages. Hence, we highlighted the presence of plastic particles along the whole food production and consumption, which calls attention to the imperativeness of public policies and changes on plastic waste management cycle. We also reinforce the need for assessing MPs and NPs contamination considering local particularities, such as the climate, most common species, and feeding habits.

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