Water, Air, & Soil Pollution最新文献

The increasing use of fly-ash particles generated from high-temperature industrial combustion in Anthropocene proxy research has increased interest in studying historical atmospheric contamination trends. Spheroidal carbonaceous particles (SCPs), a specific type of fly-ash, provide a direct anthropogenic marker preserved in stratigraphic archives, complementing isotopic approaches and strengthening chronological frameworks. Chemically robust and environmentally persistent, SCPs are widely used as indicators of industrial pollution. However, conventional SCP microscopy methods are time-consuming, motivating exploration of automated imaging systems for more efficient detection and quantification in peat records. This study develops a semi-automated SCP analysis method using a FlowCAM imaging system by creating a dedicated particle-recognition library. A FlowCAM equipped with a 10 × objective and an 80-µm flow cell was used, and SCP reference materials were incorporated to enhance classification accuracy. The resulting library was applied to peat samples spanning a concentration gradient. SCP concentrations obtained by FlowCAM were strongly linearly correlated with expected values. The method’s limit of detection was 350 g DM⁻¹, corresponding to the detection of a single SCP. Analysis of gradient samples showed that FlowCAM performs best when SCP concentrations are high, providing robust and reproducible counts when samples contain large numbers of particles. At very low concentrations, detection becomes less reliable because the standard protocol is based on a fixed sample volume, which inherently limits the probability of capturing rare particles. Although sensitivity could be increased by processing larger volumes, this was beyond the scope of this study. Overall, the method is well suited for screening and quantifying SCPs in moderately to highly contaminated samples—such as typical European industrial-era peat records—rather than targeting the detection of single or extremely sparse SCPs. This work demonstrates that FlowCAM offers a rapid, semi-automated, and cost-effective tool for analysing SCP trends in natural peat archives and represents a promising complement to conventional microscopy-based techniques.

Microplastic pollution has become a significant global environmental concern, affecting aquatic ecosystems worldwide, particularly those in inland waters. River confluences are especially important study sites because they receive inputs from multiple pollution sources and play a critical role in material transport between land and sea. This study assessed the distribution, characteristics, and ecological risks of microplastics in surface water and sediment from the Bach Hac-Red River basin in northern Vietnam. Microplastic concentrations ranged from 43.18 to 103.15 items/m³ in surface water and from 200 to 650 items/kg in sediment. A positive but statistically insignificant correlation was observed between surface water and sediment concentrations (r = 0.68; p = 0.211). Fibers and fragments were the dominant shapes in all samples. Microplastics smaller than 100 µm accounted for 48.91% of those in surface water and 65.91% in sediment. Polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and polyamide (PA) were the predominant polymer types. Ecological risk assessments using the Nemerow pollution index (NPI), pollution load index (PLI), polymer hazard index (PHI), and potential ecological risk index (PRI) indicated low bioavailability (0.024 and 1.041), low contamination (PLI: 1.60 and 1.83), moderate polymer risk (PHI: 45.46 and 48.16), and low ecological risk (PRI: 34.81 and 78.12) in surface water and sediment, respectively. These findings provide valuable baseline data for environmental protection and offer essential insights for future monitoring and management of microplastic pollution in inland aquatic systems.

The presence of phosphate and hexavalent chromium (Cr(VI), also known as chromate) in wastewater poses significant challenges for water quality management. This study investigates the effectiveness of Fe-impregnated cattle manure biochar (Fe-CMB) as an adsorbent for the simultaneous removal of chromate and phosphate from water. Fe-CMB was synthesized and characterized using various analytical techniques, including Fe-SEM, XRF, BET, XRD, and FTIR, to assess its physical and chemical properties. Batch adsorption experiments were conducted to evaluate the effects of key operational parameters, including initial concentration, contact time, temperature, and pH, on the removal efficiency of both phosphate and chromate. The adsorption kinetics closely followed the pseudo-second-order model, indicating that chemisorption was the predominant mechanism governing the removal process. The Langmuir isotherm, which suggested monolayer adsorption with maximal adsorption capacities of 31.1 mg/g for phosphate and 30.6 mg/g for chromate, provided the best fit to the equilibrium data. Thermodynamic analysis revealed that the adsorption process was endothermic and accompanied by an increase in entropy at the solid–liquid interface. Notably, while phosphate adsorption remained nonspontaneous across all temperatures, chromate adsorption became spontaneous at higher temperatures. Both phosphate and chromate adsorption were more favorable under acidic conditions, with respective adsorption capacities of 26.01 mg/g and 27.13 mg/g observed at pH 3. When chromate and phosphate were present simultaneously in the solution, the adsorption capacity for chromate (0.94 mmol/g, 48.88 mg/g) was approximately three times greater than that for phosphate (0.31 mmol/g, 9.60 mg/g). The presence of chromate significantly inhibited phosphate adsorption, reducing it by up to 62.7%, whereas phosphate had only a minor effect on chromate removal. This asymmetric inhibition suggests that chromate has a stronger affinity for Fe-CMB, underscoring the importance of considering competitive interactions in real wastewater applications. These results highlight the potential of Fe-CMB as a sustainable and eco-friendly adsorbent for the simultaneous removal of chromate and phosphate in wastewater treatment applications.

Graphical Abstract

Phosphogypsum (PG) is an industrial by-product generated during the wet process of phosphoric acid production. Currently, nearly 100 million tons of PG is produced in China annually. To prevent the main pollutants in PG, namely phosphorus and fluorine, from being leached into the soil by rainfall, this study explored the use of industrial waste carbide slag, a calcium-rich material, to immobilize these elements in the PG and soil. The results showed that the concentration of available phosphorus decreased with increasing PG particle size, while that of fluorine followed a parabolic trend, peaking at a particle size of 0.125 mm. The stabilization efficiency for both phosphorus and fluorine increased with the proportions of carbide slag. At a CS-to- PG ratio of 1:50, the leaching concentration of F in the PG was reduced by 87.4% at 15 °C and 98.2% at 25 °C. In soil column leaching experiments, under simulated rainfall conditions, a higher dosage of carbide slag (1:25) significantly reduced the leaching of water-soluble fluorine, total fluorine, water soluble phosphorus, and total phosphorus from soil affected by PG stacking—by 98.9%, 60.7%, 67.4%, and 20.9%, respectively, compared to the treatment with PG but without carbide slag. Although PG alone increased soil conductivity and lowered soil pH, the addition of carbide slag effectively neutralized acidity, stabilized soil pH, and reduced conductivity through immobilization of soluble ions. These results indicate that carbide slag is an effective and low-cost amendment for immobilizing phosphorus and fluorine and mitigating their environmental risks in PG.

In this work, a feasible conversion of mangosteen peel (MP) waste into mesoporous sulfonated hydrochar (SMP-HC) via hydrothermal assisted sulfuric acid (H₂SO₄) activation was carried out. The hydrothermal activation process was assisted by 1M H₂SO₄ for 14 h at 100 ⁰C to produce SMP-HC. The specific surface area (BET SA) analysis shows a mesoporous structure of SMP-HC with remarkable increase of ca. 576 folds (BET SA = 14,4 (m²/g) as compared to the raw MP (0.025 m²/g). Thus, SMP-HC was utilized to be a promising adsorbent for removal of toxic cationic dye namely methylene blue (MB) dye from aqueous environment. Box-Behnken design (BBD) with desirability function was applied to optimize and validate the adsorption working parameters including SMP-HC dosage (coded A:0.02–01 g/0.1L), solution pH (coded B: 4–10), and contact time (coded C:2–8 min). The optimal desirability function conditions for MB dye removal (97.5%) by SMP-HC were found to be SMP-HC dose = 0.07 g/0.1L, solution pH = 9.9, and contact time = 8 min. The maximum adsorption capacity (q_m) of SMP-HC for MB dye was found to be 203.5 mg/g at 25 ⁰C. The loading of MB dye onto SMP-HC surface can be attributed to the several possible attractions including electrostatic attraction, π-π interaction, pore filling, and hydrogen bonding. This research shows the possibility of MP waste conversion into functionalized hydrochar with preferable adsorptive performance towards MB dye removal from the contaminated water.

The parboiling process of paddy in rice mills generates wastewater characterized by a high organic load rich in lignin and phenolic compounds. Untreated discharge of this rice mill wastewater (RMW) can cause severe deterioration of soil and water quality. In this pioneering study, a nature-based treatment technology was developed and optimized for the effective remediation of RMW. An integrated constructed wetland (CW) and vermifiltration system was designed to address the limitations of CWs, such as low hydraulic capacity and high land requirement, as well as the decline in earthworm activity in vermifilters (VFs) under high organic loads. Process optimization was performed using response surface methodology with a central composite design, considering influent chemical oxygen demand (COD), CW length, and influent phenol concentration as the independent input variables. A quadratic polynomial model with high predictive accuracy (R² = 0.9884) was developed to characterize the COD removal efficiency. The model predicted an optimum COD removal of 95% (desirability = 0.949) at 2000 mg/L influent COD, 50 cm CW length, and 10 mg/L influent phenol, within the tested range. Experimental validation confirmed an overall COD removal efficiency of 94% under these conditions. Under the optimized conditions, the CW, VF1, and VF2 exhibited COD removal efficiencies of 87%, 43%, and 27%, respectively. Validation with both real and synthetic RMW presented < 5% deviation between predicted and observed values, underscoring the robustness of the model. The integrated CW and vermifiltration system demonstrated a statistically optimized and sustainable approach for high-strength agro-industrial RMW treatment.

This study evaluates the phytoremediation performance of Canna indica, Phragmites australis, and Typha latifolia in modified lab-scale constructed wetlands for decentralized wastewater treatment. Six treatment compartments (C1–C6) were developed using low-cost filter media comprising gravel, sand, charcoal, coconut coir pith, and neem powder, with configurations including aerated, planted, and unplanted systems. Wastewater collected from Pedda Cheruvu Lake, Vizianagaram, India, was treated over a 10-day cycle in two experimental runs. Key water quality parameters pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), salinity, and biochemical oxygen demand (BOD) were monitored on days 1, 6, and 10. The aerated system (C1) achieved the highest BOD removal up to 75%, while Phragmites australis (C3) showed significant improvement in DO from 0.4 to 3.6 mg/L, indicating enhanced aerobic microbial activity. Typha latifolia (C5) was most effective in reducing TDS up to 51.46% and salinity up to 55.17%. pH remained stable throughout the treatment period. The results demonstrate that hybrid constructed wetlands integrating native macrophytes and biodegradable filter media provide an efficient, sustainable, and scalable solution for decentralized wastewater treatment in semi-urban and rural regions of India.

To address the issues of prolonged composting cycles and frequent nutrient loss in traditional aerobic composting, the effects of cotton-stalk biochar addition (0% [CK], 3% [BC1], 6% [BC2], and 9% [BC3]) on the physicochemical properties and nutrient evolution of pig manure during composting were investigated using rice straw as a conditioner. Furthermore, underlying mechanisms were analyzed based on the microstructure of cotton-stalk biochar and surface properties of compost. The results showed that the biochar-treated groups entered the thermophilic phase 2 days earlier than CK, prolonging the period of high temperature. The temperature of BC3 group was always higher than that of other treatment groups. Cotton-stalk biochar improved moisture retention in compost, reduced salinization risk of compost, and enhanced the germination index (GI) of seeds, with BC3 group showing optimal performance. However, the addition of cotton-stalk biochar had little effect on the pH of pig manure. After composting, organic matter contents in CK, BC1, BC2, and BC3 were 56.60%, 58.42%, 62.63%, and 62.63%, respectively. Compared with the initial values, total nitrogen contents increased by 4.8%, 20.6%, 26.0%, and 23.8%, while NO₃⁻-N contents increased by 82.8%, 66.4%, 71.2%, and 85.7%, respectively. Similarly, total potassium contents increased by 44.6%, 70.5%, 78.7%, and 80.5%, while total phosphorus contents improved by 35.2%, 45.7%, 50.4%, and 52.9%, respectively. These results indicate that cotton-stalk biochar accelerated compost maturation and enhanced nutrient retention, while exhibiting minimal effect on the pH of compost, with BC3 achieving optimal composting efficiency. This study provides experimental data and theoretical support to optimize aerobic composting of livestock manure in Southern Xinjiang in China.

The accumulation of Fenton iron sludge (FIS) has emerged as a critical bottleneck limiting large-scale Fenton process applications. To address this challenge, we developed an integrated valorization strategy by coupling FIS amendment with anaerobic digestion of pharmaceutical wastewater. Experimental results demonstrated that FIS addition stimulated dissimilatory iron reduction (DIR) pathways, enhancing organics depolymerization efficiency through Fe(III)-mediated electron transfer. This process promoted macromolecular cleavage and EPS solubilization (S-EPS, 3.38 → 10.32 mg/g-VS), while modulating microbial consortia structure. Notably, Proteobacteria (7.3% → 15.4%) and Firmicutes (23.1% → 36.2%) enrichment enhanced hydrolytic enzyme secretion, while Desulfobacterota emergence (0% → 3.7%) established syntrophic networks via direct interspecies electron transfer (DIET). These biochemical cascades synergistically improved anaerobic performance: COD removal increased by 23.3% (66.39% → 81.86%) and methane yield surged 91.7% (136.58 → 261.83 mL/g-COD). Furthermore, iron sludge amendment reduced capillary suction time (CST) by 29.6% through dual mechanisms – TB-EPS reduction and bioflocculation enhancement. This work demonstrates a sustainable approach for FIS recycling through AD integration, achieving synergistic benefits in waste management and energy recovery.

The spread of organic waste-derived amendments such as compost, anaerobic digestate and biosolids has been identified as a major source of microplastics in agricultural soil, with potential negative environmental and human health effects. Due to lacking regulatory frameworks and standard monitoring procedures, the extent of microplastic contamination in Scottish organic waste-derived soil amendments is still poorly understood. This study investigated the presence, quantity and characteristics (morphology, density and colour) of microplastics in anaerobically digested biosolids, green-waste-derived compost and food-waste-derived anaerobic digestate produced in Scotland. Microplastics (100—5000 µm) were present in all analysed samples in concentrations ranging from 34 to 160 particles g⁻¹ dw, with the highest levels found in biosolids, followed by digestate and compost. High-density fibres represented 55.8—66.4% of microplastics in biosolids, likely polyester from the domestic washing of textiles. In addition to microplastics, > 20,000 cellulosic microfibres g⁻¹ dw, likely textile-derived natural fibres, were detected in biosolids, and were absent in other samples. Microplastic fibres of a wider-density-range represented 72% of microplastic in compost, while high-density microplastic fragments (34%) and fibres (24%) were the most abundant microplastics in digestate. Based on the results, it was estimated that compost, anaerobic digestates and biosolids could respectively introduce 3.17 × 10¹², 5.9 × 10¹¹ and 7.2 × 10¹² microplastic particles measuring 100—5000 μm to Scottish land, annually. These findings highlight the extent of microplastic contamination in terrestrial environments across Scotland, underscoring the need for standardised routine monitoring, enhanced waste management practices, and stricter regulatory measures.