Clean-soil Air Water最新文献

In this study, the treatment of chemical industry wastewater, which is used in producing auxiliary chemicals for various industries, through coagulation and Fenton oxidation was examined. Coagulation studies with alum were done at various pH levels and doses to find the best conditions for wastewater treatment, and the pre-treated wastewater was treated with Fenton oxidation using different chemical oxygen demand (COD)/Fe²⁺ and COD/H₂O₂ ratios (by weight). During coagulation (pH 5, 300 mg/L alum), COD, total suspended solids (TSS), color index (CI), and turbidity removal efficiency was obtained as 74.8%, 92.0%, 93.0%, and 93.3%, respectively. After coagulation, Fenton oxidation was achieved at a COD/Fe²⁺/H₂O₂ ratio of 1:3:7.5, resulting in 89.2% TSS removal, 97.3% turbidity removal, 97.7% CI removal, and 74.8% COD removal. As a result, the treatment of chemical industry wastewater through coagulation and Fenton oxidation processes resulted in TSS, turbidity, CI, and COD removal of 99.0%, 99.8%, 93.0%, and 93.5%, respectively. As chemical industry wastewater has high COD and TSS content and toxic properties due to various chemicals, it was thought that applying Fenton oxidation after pretreatment with coagulation process would reduce the chemicals used in Fenton oxidation and thus reduce the cost. In summary, it has been shown in this study that complex chemical industry wastewater containing various chemicals can be effectively treated by alum coagulation followed by Fenton oxidation.

Laccase exhibits low stability under UV solar radiation, which can compromise its catalytic activity in bioremediation processes. The present study shows, for the first time, an efficient, low-cost, and environmentally sustainable strategy for enhancing enzyme photostability using a naturally occurring Patagonian montmorillonite clay, without the need for surface functionalization or chemical modification. Photostability was assessed spectroscopically by comparing the enzymatic activity of free and immobilized laccase before and after UVB irradiation. Immobilization significantly improved enzyme photoprotection, retaining 95% of its initial activity after irradiation contrast to only 40% for the free enzyme. The clay's protective effect is attributed primarily to its inherent light-scattering capacity and absorbing radiation property. These results underscore the potential of Patagonian montmorillonite as a simple, scalable, reusable, and ecofriendly platform for enzyme-based bioremediation technologies. This approach opens new avenues for the practical application of microbial enzymes in open environments where photoinactivation could limit their use.

In this work, the feasibility of dye wastewater treatment was evaluated with an integrated system (IS) of bio-electrochemical system (BES), bio-contact oxidation (BCO), denitrification tank, and sand filter systems. The effects of low carbon to nitrogen ratio (C/N), current intensity, and methylene blue (MB) concentration on the reactor performance were investigated. The results demonstrated that the optimal operating conditions were an applied C/N with chemical oxygen demand (COD) of 500 mg/L, current of 20 mA and MB concentration of 25 mg/L at the BES. Under such conditions, the removal rate of the COD, MB, and total nitrogen (TIN) was approximately 94.6%, 94.8%, and 73.3%, respectively. BES played a chief part in pollutants removal and others further did contribution to nitrogen removal. It indicated that IS might be an effective strategy for improving treatment dye wastewater.

Soil is vital in supporting plant growth and maintaining a healthy ecosystem. It is also a key component of the biogeochemical cycle and significantly impacts agricultural productivity and environmental quality. However, in some regions, natural soil quality may not be sufficient to meet crop requirements. To address this issue, reconstituted soils have become a popular tool to improve plant growth conditions based on soil properties. They are fertile Technosols obtained through reconstitution, a process that combines chemical and mechanical treatments of degraded soils, sediments, and waste-derived pedomaterials to create fertile substrates. Physicochemical, biological, and toxicological parameters were measured to evaluate soil functionality and pedogenesis. The results showed that organic by-products improve soil agronomic and physicochemical properties. They can also improve the organic matter content of soil and increase crop production. Profiles containing a mixture of sludge with natural soil (volumetric ratio of 1:3) and those containing landfill soils (100%) exhibit favorable agronomic properties for plant development, such as total carbon (81.1 and 70.5 g kg⁻¹, respectively), total nitrogen (9.9 and 4.9 g kg⁻¹, respectively), and phosphorus (0.15 and 0.04 g kg⁻¹, respectively). The study also showed that for all uncultivated or cultivated studied soils, the highest levels of nutrients decrease and tend to converge with that of the control at the last period of the experiment. According to these results, reconstituted soils, made from by-product materials, can contribute to the management of degraded soils.

Soil properties and chemical elements in urban roads have been significantly affected by urbanization and traffic around the world. This study aimed to determine the concentration of major elements (Ca, K, and Mg) in urban road dust from Cancun, the main tourist city of the Mexican Caribbean, to map their spatial distribution, and shed light on the bulk chemical elemental composition. Samples were collected in streets and analyzed by ICP-OES, Perkin Elmer Optima 8300. Morphological study was performed with a Vega 3 Tescan scanning electron microscope (SEM), and chemical elemental composition was analyzed by energy-dispersive x-ray spectroscopy (EDS) with a detector coupled to the SEM. Statistical analysis was performed using Pearson correlation, principal component analysis, and k-means clustering to shed light on potential processes that control the occurrence of these elements in urban road dust. The concentrations in road dust samples follow the order Ca≫ Mg>>>K. Enrichment factor and pollution index showed that Mg and K derived from natural processes, whereas Ca had an anthropogenic origin at some sites. The data set was lowly correlated (0.4283; Ca and Mg), indicating same source, possibly dolomite (CaMg(CO₃)₂). Spatial differences exhibited higher concentrations on roads with heavy traffic, particularly in downtown. Chemical elemental analysis of urban dust confirmed the presence of particulate elements, suggesting that they originate from natural and anthropogenic sources. High concentrations of Ca, Mg, and K reflect the importance of monitoring and control measures to avoid health risks. Systematic studies on road dust need to be implemented, including atmospheric sampling.

This study analyzed particulate matter (PM_2.5 and PM₁₀) concentrations at 17 locations in Sri Lanka over 2 years (January 2021–December 2022); the effects of meteorological parameters on the PM, potential source regions for high PM, and the associated human health risk. The highest annual mean PM_2.5 (29.9 ± 19.4 µgm⁻³), PM₁₀ (55.8 ± 37.8 µgm⁻³) in 2022, and PM_2.5 (21.4 ± 7.8 µgm⁻³) and PM₁₀ (41.1 ± 14.8 µgm⁻³) in 2021 were reported in Jaffna and Kurunegala, respectively. Throughout both years, the PM concentrations were always higher than the World Health Organization guidelines. Seasonally, the Northeast monsoon experienced the highest average PM_2.5 (54.7 µgm⁻³) and PM₁₀ (104.2 µgm⁻³) in 2022, which may be attributed to low rainfall (∼4.5 mm), moderate temperature (∼26°C), and low wind speed (∼3 mph). The conditional bivariate probability function (CBPF) revealed probable sources to be motor vehicles (in Colombo, Galle, and Kurunegala), biomass burning (at all sites), textile units (in Colombo, Kurunegala), cement manufacturing plants (in Galle, Puttalam), and coal-fired power plants (in Puttalam). A period of 72-hr backward trajectories at 500, 1000, and 1500 m using the hybrid single-particle Lagrangian–integrated trajectory (HYSPLIT) revealed air mass pathways tracing back to eastern India and the Bay of Bengal, confirming transboundary pollutant movement into Sri Lanka. The health effects of PM_2.5 exposure were estimated via AirQ+, which revealed the highest mortality in Jaffna in 2022. The findings of this study provide valuable insights to local and national governments for appropriate policy intervention needed to manage air pollution in Sri Lanka, considering the health risks associated with PM_2.5 exposure.

The soil water content (SWC) and soil organic carbon (SOC) are two important factors to consider when revegetating degraded land in arid and semiarid areas. Understanding the responses of SWC and SOC to vegetation restoration as well as their coupling interaction is important for the sustainable restoration of vegetation. However, the responses of SWC and SOC are still unclear in different plantation types, especially for the deep soil layer. In this study, three common types of mature plantations containing Pinus sylvestris, Pinus tabuliformis, and Populus simonii were selected in the Loess Plateau region of China to evaluate the responses of SWC and SOC to vegetation restoration as well as their interactions, and thus determine the factors that influenced the variations in SWC and SOC. Compared with grassland, the deep soil water deficit was exacerbated in all three plantations, and the SOC increased under Populus simonii but decreased under the other types. The tradeoff relationship between SOC and SWC had the lowest root mean squared error under Populus simonii. Therefore, Populus simonii was identified as most suitable for revegetation in the study region. Soil texture had important effects on the variations in SOC in the deep soil layers (2–5 m), and SOC and the soil texture affected the variations in SWC in the whole soil profile. The results obtained in this study may facilitate the sustainable development of artificial forests in the Loess Plateau region as well as similar arid and semiarid areas.

Precise estimation of rice nitrogen (N) content is essential for optimizing fertilizer use. Traditional methods for estimating N content are time-consuming, laborious, and costly. Unmanned aerial vehicles (UAVs) are time and money efficient substitutes allowing more accurate and flexible monitoring for larger rice areas. The objectives of this study were to: (i) develop random forest (RF) and artificial neural network (ANN) models for predicting and mapping the nitrogen content (%) in rice using seven vegetation indices derived from UAV multispectral sensors and; (ii) assess the key vegetation indices (VI) and their interrelationships with the predicted nitrogen content. Experiments were conducted at two locations in Cuttack district of Odisha, India, with different nitrogen levels. The UAV images were collected synchronizing with the maximum tillering stage of rice and seven indices were generated. The rice sampling was done on the date of flying UAV images and nitrogen content was estimated in the laboratory. RF and ANN models were developed using the N content as dependent and the VIs as independent variables. Both the models exhibited robust predictive capabilities, however, the RF model exhibited better performance, compared to the ANN model. Nitrogen content prediction using the developed RF and ANN models in testing site at farmer's field ranged from 0.78% to 1.95% (R² of 0.67%) and from 0.5% to 1.78% (R² of 0.55%), respectively. Normalized difference red edge (NDRE) and normalized difference vegetation index (NDVI) turned out as significant contributors in the development of both the models.

The shadow effect is one of the major problems hindering the operation of solar energy-based systems and affects the performance of solar stills. The shade cast by the still's lateral walls on the basin reduces the solar-exposed area and reduces the daily distillation yield. This article deals with an experimental study to evaluate the shadow effect on the conventional solar still (CSS) performance. A comparative analysis was conducted between the single-slope CSS and the modified one (modified solar still [MSS]) with three glasses. Therefore, outdoor experiments were performed in hot and cold weather conditions in Adrar—Algeria. The results showed that replacing wooden walls with transparent glass is not always efficient, and the still's thermal performance depends on the weather conditions. On the summer day, the daily productivity reached 3.57 kg/m² for the CSS and 4.42 kg/m² for the MSS (a reduction of about 24% compared with the MSS). On the winter test day, the glass side walls appeared to negatively impact the MSS distillate yield, which was 5.55% lower than the CSS yield (2.57 vs. 2.71 kg/m² for CSS). Energy and exergy analysis show that the MSS is more efficient than the CSS on summer days, whereas the opposite happens on winter days.