Biological wastewater treatment technologies following sustainable techniques is extensively moving towards resource recovery and circular economy approaches. Aerobic granular sludge (AGS) technologies are widely used in this research area, owing to their enhanced potential in terms of nutrient removal, settling properties, microbial diversity, and resistance to shock loading. However, slow granulation and rapid post-formation disintegration remain major challenges limiting the large-scale application of AGS technology. This review summarizes the fundamental mechanisms of granulation, morphological characteristics, and key factors influencing granule stability. It further highlights the growing importance of sewage sludge valorization for recovering energy and value-added products within a circular economy framework. Furthermore, widely incorporated resource recovery pathway and biorefinery-based approaches are critically discussed. Special emphasis is given to sludge-based biorefineries as integrated platforms for simultaneous waste treatment and resource recovery. Overall, this review provides a comprehensive overview of current developments and future directions in AGS-based sludge valorization approaches toward establishing a sustainable and economically viable circular bioeconomy.
Mangrove microbes, including bacteria and fungi, play a crucial role in leaf-litter decomposition, and organic matter recycling. A consortium of Serratia marcescens HL2215 and Trichoderma sp. CNSC-2, isolated from Indian mangroves, was evaluated for their litter degradation potential. The tannin content of Excoecaria agallocha and Heritiera fomes leaf litter, was investigated, which measured 343.23 ± 8.42 µg/mL and 290.53 ± 14.00 µg/mL, respectively. Tannin dynamics during decomposition were monitored, and litter leachates were characterized using ATR-FTIR and ¹H NMR spectroscopy, revealing the presence of bioactive compounds including caffeic acid, catechin, gallic acid, p-coumaric acid, and taxifolin. The microbial consortium exhibited enhanced biofilm biomass (35.05 ± 0.73 μm³/µm²) and thickness (47.08 ± 2.58 μm), showing minimal changes following tannin exposure. A comparative analysis of planktonic and biofilm modes demonstrated significantly higher upregulation of lignocellulose-degrading genes, including the cellulose-degrading (bcsZ, bglB, GH5, and GH31) and lignin-degrading genes (cueO, dyP, Lac1, and mcuO), under planktonic conditions. CMCase activity increased over time, with the consortium exhibiting the highest activity under planktonic conditions, reaching 3.00 ± 0.08 U/mL in the H. fomes set-up, followed by 2.79 ± 0.15 U/mL in the E. agallocha set-up on day 28. Further, microcosm experiments demonstrated higher leaf-litter degradation efficiency in the planktonic mode, achieving a C/N ratio of 9.94
Cadmium (Cd) is a toxic heavy metal often present in soils, and in saline soils, it becomes more mobile, creating significant risks to food safety, the environment, and ecosystems. Recycling waste, such as eggshell and pine sawdust, into useful products like calcium oxide nanoparticles (CaO-NPs) and biochar (BC) is an innovative and eco-friendly approach to improve food safety, food security, and environmental sustainability. The current study involved the preparation of CaO-NPs and BC, the application of BC to soil and foliar application of CaO-NPs, their combined use, and the effectiveness of both in reducing Cd toxicity in maize (Zea mays L.) plants. BC was applied to soil at 1
Ammonia (NH3) and greenhouse gas (GHG), such as carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4), emissions from slurry storage constitute an environmental problem and reduce the sustainability of its use. We studied the effect of untreated and acidified (H2SO4) biochar applied as a cover to reduce NH3 and GHG emissions (along with nitric oxide, nitrogen dioxide, and carbon monoxide from slurry digestate in a 50-day incubation experiment). Three hay and two wood biochars produced at different temperatures (ranging from 300 to 1000 °C) were used in the experiment. On average, untreated biochar applied as a cover did not reduce NH3 emissions. Acidification of the digestate and the use of acidified biochar applied as a cover significantly reduced NH3 emissions, but increased N2O emissions, following digestate drying. However, for one of the biochars, a reduction of NH3 and an increase of N2O emissions was observed when applied untreated. No single property of the biochar explained this finding; however, the interaction of pH, specific surface area, and hydrophobicity explained a large part of the variability in NH3 and N2O fluxes. No statistically significant differences in CO2 and CH4 cumulative emissions were found between the treatments. The outcomes of this study can inform the design of more effective and targeted mitigation strategies for gaseous emissions from slurry storage, supporting both future research and practical implementation in livestock systems.
This study constructs “production-ecology-landscape” analytical framework for cultivated land multifunctionality and employs cold/hot spot analysis, Spearman rank correlation, bivariate spatial autocorrelation, and K-means clustering to examine the trade-offs and synergies in cultivated land functions across the North China Plain from 2000 to 2020. Key findings are as follows: (1) From 2000 to 2020, cultivated land area declined, with multi-functional trends exhibiting pronounced spatial differentiation. The production function showed an inverted U-shaped trajectory, ecological function showed a progression of gradual decline in the initial stage, a significant drop during the middle stage, and a gradual recovery in the later stage, demonstrating a pattern of “higher values in the south and lower values in the north”, landscape function exhibited fluctuating declines. (2) Significant synergistic relationships were observed among production, ecological, and landscape functions. The production-ecology and production-landscape synergies both rose first and then declined, while the ecology-landscape synergy progressively intensified. (3) Spatial aggregation of cultivated land functions was statistically significant, with temporal-spatial differentiation evident across functional dimensions. (4) The North China Plain was divided into five functional zones: functional synergy zone, grain main producing zone, ecological agriculture zone, landscape agriculture zone, and balanced development zone.
This study investigates the preparation and characterization of activated carbon derived from the native Iraqi plant white wormwood (Artemisia herba-alba, AHA). The synthesized material is evaluated as a sustainable adsorbent for removing organic contaminants and reducing the chemical oxygen demand (COD) in real oil refinery wastewater collected from the Siniya refinery in the Salah al-Din Governorate, Iraq. The adsorbent is characterized using BET, XRD, FTIR, and SEM. Batch adsorption experiments are conducted to evaluate COD removal efficiency and determine optimal operating conditions. The highest removal efficiency is 98
Domestic-source contaminated soil (DSCS) generates substantial organic acids during degradation, leading to soil acidification and deterioration of mechanical properties, which consequently impairs its potential for engineering reuse. This study proposes a novel approach to achieve the transformation of gaseous carbon (CO2) into liquid and solid phases within the soil, thereby regulating the hydrochemical environment of DSCS and facilitating carbon sequestration. Four carbonate-alkaline solutions were prepared by absorbing CO2 into solutions of sodium aluminate (NaAlO2), sodium hydroxide (NaOH), potassium hydroxide (KOH), and ammonia water (NH3·H2O), which were then individually injected into DSCS. The pH, electrical conductivity, redox potential, ion concentration, calcium carbonate content, and carbon phase transformation patterns at different degradation stages after treatment were evaluated. The mechanism of hydrochemical environment alteration and carbon phase transformation was revealed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. The results demonstrated that all four carbonate-alkaline solutions can effectively regulate the hydrochemical environment and transform the carbon phase. NaAlO2 exhibited optimal performance, significantly increasing the soil pH to 8.5–9.5 and enhancing calcium carbonate precipitation (with a maximum content increase of 42.42
Managing limited water resources among competing agricultural and industrial sectors remains a major challenge in arid regions due to the lack of integrated approaches for simultaneously evaluating biophysical and economic impacts of water deficits. Water scarcity poses a critical threat to sustainable development, especially in basins where agriculture and industry compete for limited water resources. This study develops an integrated framework to assess Water deficit impact, Agricultural vulnerability, Industrial sensitivity, and Economic loss in the Zayandeh-Rud Basin, Iran. The framework applies sector-specific indicators, including the Total Water Deficit Allocation Impact (TWDAI) and Total Water Deficit Industrial Impact (TWDII), alongside economic metrics such as the Total Economic Impact of Water Deficit (TEIWD) and marginal loss metrics (MELUUW-AB and MELUUW-D), to evaluate multiple water shortage scenarios and support Water allocation optimization. Results show substantial agricultural vulnerability, particularly for orchard crops, such as red apples and apricots with TWDAI values reaching 0.84 and 0.82 respectively, under complete deprivation. Thermal power plants and paper production exhibited the highest industrial sensitivity, with TWDII values of 0.337 and 0.253 at 100
Increasing population, rapid urbanization, sustained economic growth, exponential rise in industrialization, and an overwhelming number of upcoming megacities have increased the volume and complexity of waste generated worldwide. Global waste generation has reached 2.01 billion tons, and urban management planners are facing major challenges in disposing of this huge quantum of waste in a financially viable and environmentally sustainable manner. All of this has made solid waste management (SWM) more complex, thus necessitating advanced and superior optimization strategies that can reduce cost and enhance the efficiency of any SWM model. This review paper comprehensively analyzes the optimization techniques researchers have used for SWM while evaluating their employment, advantages, and limitations. Research papers from 2010 to 2024 have been reviewed, and optimization models have been categorized into deterministic, probabilistic, hybrid, and Internet of Things (IoT)-based models, with the collection and transportation stages of SWM assessed in detail. Models have been compared considering cost minimized, distance reduced, greenhouse gas emission (GHGE) cut down, and social sustainability. Some advances have been made in optimizing SWM through innovative routing procedures, advanced waste bin placements, and adjusting the timing of collection vehicles. The review highlights major research gaps and proffers viable recommendations for future research in optimization techniques in SWM, which can enable urban management planners to adopt methods that can produce efficient SWM models for upcoming mega cities. These directions will assist managers, researchers, and waste management professionals in producing financially viable and environmentally sustainable SWM models. The review synthesizes 66 high quality studies (2010–2014) using PRISMA 2020 guidelines. A comparative analysis indicates that hybrid and IoT integrated models achieve up to 20-40
This study investigates the factors influencing Bangladeshi farmers’ behavioural intentions to adopt biogas technology using an integrated approach combining PLS-SEM, ANN, and fsQCA. Based on data from 397 farmers, the findings show that perceived trust, social norms, facilitating conditions, environmental responsibility, perceived consumer effectiveness, and perceived environmental concern significantly influence adoption intentions, with perceived trust as the strongest predictor. Utilization attitude further strengthens the effects of social norms and perceived trust on adoption. The study recommends strengthening farmers’ trust through certification and quality assurance, improving facilitating conditions through financial incentives and technical support, promoting community engagement to reinforce positive social norms, and integrating environmental responsibility into agricultural extension services. Together, these measures can accelerate biogas adoption, ease rural energy shortages, reduce environmental pollution, and advance Bangladesh’s renewable energy goals and UN Sustainable Development Goal 7 (Affordable and Clean Energy).
Biochar, a sustainable material derived from underutilized biomass, shows excellent potential for wastewater treatment. In this study, it was produced from peanut shells, an abundant agricultural residue, through a pyrolysis process. Subsequently, a thermo-chemical activation with KOH was carried out, resulting in activated carbon (AC) with a significantly increased surface area (from 30 to 1171.53 m2/g). Cu (3, 6, and 10
Over the past few decades, extensive research has focused on variations in land-use and land-cover (LULC) and their potential environmental impacts. However, there has been relatively limited investigation into their effects on air quality. This study aims to utilize advanced geospatial technologies, specifically GIS and remote sensing big data, to evaluate the impacts of LULC changes on particulate matter (PM2.5) emissions and to analyze the subsequent effects on air quality from 2000 to 2020. To achieve these objectives, LULC data from 2000 to 2020 were obtained from the GlobeLand30 dataset, while PM2.5 concentration data was sourced from the Global Annual PM2.5 dataset provided by the Socioeconomic Data and Application Center (SEDAC). We employed fragmentation modeling for morphological image analysis to understand structural changes in the landscape. Additionally, the GeoDetector model was used to statistically assess the impact of LULC changes on PM2.5 concentrations, quantifying the influence of different land-use types on air quality. Our findings reveal that both natural and socioeconomic factors significantly influenced landscape patterns throughout the study period. LULC changes occur more rapidly at lower altitudes, which are more favorable for human habitation. Notably, the least sloping regions, such as the plains and areas along the Yi River, experienced the most significant changes. In contrast, the steep and hilly regions in the northeast and west exhibited minimal fragmentation risk. The increase in industrial and commercial activities, coupled with rising population density and traffic flow, directly contributed to escalating air pollution levels. Integrating agricultural practices with development initiatives is essential for promoting sustainable urbanization. Further research is needed to fully understand the complex interactions shaping landscape patterns. Geospatial-remote sensing big data used to link LULC dynamics with PM₂.₅ trends. Fragmentation modeling and GeoDetector quantified spatial heterogeneity impacts. Urban expansion and socioeconomic growth increased PM₂.₅ in low-slope regions. Integrating land-use planning and green infrastructure can improve air quality.
To resolve two main drawbacks of Fe(II/III)/peroxydisulfate (PDS) system, i.e., sluggish Fe(II) regeneration and strongly acidic operating environment, hydroxylamine (HAm) and nitrilotriacetic acid (NTA) were introduced simultaneously to Fe(III)/PDS system to degrade orange G (OG) under neutral condition in this study. The results shown that Fe(III)-NTA/HAm/PDS system could effectively remove OG at pH 7.0 and the removal ratio of OG reached 86.4
The effect of organic modification on the toxicological properties of nanostructured organically-modified clays has not been fully explored. In this study, we investigated the toxic effects of cetyltrimethylammonium bromide CTA-modified bentonite inorganic/organic composite (Ben-CTA) on Chlamydomonas sp. In vitro mechanistic toxicity assessment was performed using cells of Chlamydomonas sp., which resulted in a loss of viability after 72 h of exposure, with an IC50 value of 149.648 ± 9.4 mg/L. The analysis of various growth parameters showed that Ben-CTA had significant toxic effects on Chlamydomonas sp. Moreover, the toxicity of Ben-CTA to Chlamydomonas sp. was confirmed by increased total phenolic content, increased MDA and GPX levels, and decreased growth parameters as well as photosynthetic pigment levels. Fluorescence microscopy images of the treated cells revealed morphological changes. Additionally, infrared spectroscopy indicated chemical surface interactions between the algal cells and the organic/inorganic composites. A transcriptomic analysis revealed various patterns expression of eight genes in Chlamydomonas sp. exposed to Ben-CTA. The analysis showed the upregulation of genes coding for cytochrome b(N-terminal)/b6 (petB), caspase (Casp), ribulose bisphosphate carboxylase large chain (rbcL), phosphoglucomutase glucose (PGQ1), β-carotene hydrolase (Q2CHY), β-carotene ketolase (Q2BKT), superoxide dismutase (SOD) and peroxidase (PerchL).
Metolachlor is one of the most frequently detected herbicides in drinking water sources, posing a significant environmental risk. In this study, an L-arginine functionalized magnetic Fe₃O₄/activated carbon nanocomposite (Fe₃O₄/L-Arg@AC) was synthesized and its metolachlor removal performance was evaluated. The kinetic and equilibrium adsorption mechanisms of Fe₃O₄/L-Arg@AC for metolachlor removal were investigated comparatively with pure activated carbon (AC-Puriss), nitric acid modified activated carbon (AC-HNO₃), and Fe₃O₄/L-Arg. Although Fe₃O₄-based, L-arginine functionalized, and activated carbon-containing systems have been studied in the literature for different pollutants, the use of Fe₃O₄/L-Arg@AC composite for metolachlor removal is limited. FTIR analyses confirmed successful binding of L-arginine functional groups to the surface, while SEM images revealed that the composite exhibited a more homogeneous distribution and an improved porous surface morphology. Kinetic analyses showed that adsorption process was not limited to diffusion alone but was based on a multi-stage mechanism where liquid film and intraparticle diffusion processes acted together. The functionalized structure exhibited faster mass transfer and more efficient adsorption behavior compared to Fe₃O₄/L-Arg. Equilibrium data indicated that Freundlich model was more suitable for the composite structure and that heterogeneous surface properties were dominant. Metolachlor adsorption capacity remained stable under neutral and slightly basic pH conditions, while it was only minimally affected under acidic conditions. In addition, the synthesized adsorbent exhibited good reusability with a regeneration efficiency of 93.2
This study evaluated the potential of biocoagulants produced from four types of prickly pear peels to remove turbidity and chemical oxygen demand from domestic wastewater. The optimal conditions of wastewater pH and coagulant dosages were defined using a D-optimal design for each biocoagulant. The biocoagulants showed potential to remove turbidity and chemical oxygen demand with ranges of 0–58.8
In the last few decades, intensive groundwater extraction for irrigation in India has severely depleted aquifers, with growing concerns over groundwater quality. This study the first national-scale assessment linking hydrochemical evolution with extraction intensity, integrating depth-to-water levels (DTWs), groundwater recharge (GWR), and water quality parameters with the stage of groundwater extraction (SoGE) across alluvial (ALV) and hard-rock (HR) aquifers. Results show that increasing groundwater stress is associated with rising pH, declining DTWs, reduced GWR, and overall water quality deterioration, particularly within over-exploited, critical, and semi-critical (OCS) units. Within critical SoGE ranges ( 60–140
Reliable natural capital accounting is essential for achieving the Sustainable Development Goals (SDGs) amid rapid environmental change. However, high-resolution, national-scale assessments of ecosystem service value (ESV) in the tropics are offen hindered by persistent cloud interference, seasonal phenological fluctuations, and valuation parameters that are not locally calibrated. Leveraging the Google Earth Engine platform and 10-m Dynamic World data, this study proposes a Temporal Probability Aggregation (TPA) framework to eliminate observational noise and seasonal biases, enabling high-precision, probabilistic land use/land cover (LULC) mapping at the national scale. Taking Tanzania (2016–2024) as a case study, we developed spatio-temporally consistent annual ESV indicators by coupling a benefit transfer model calibrated with multi-source socio-economic and ecological factors. The results indicate that rapid cropland and urban expansion occurred at the expense of forests and wetlands, driving significant spatial trade-offs between provisioning and regulating services alongside pronounced spatial heterogeneity. By providing a high-resolution and scalable monitoring framework, this research fills a critical gap in natural capital accounting for data-scarce tropical regions and offers precise decision support for regional spatial planning.
In this study, the environmental and human health risks associated with heavy metals (HMs) in different land uses in a dust-prone area of the Jazmurian Basin, southeastern Iran, were investigated. The samples included 51 surface soil samples (0–10 cm) and 14 subsurface samples (50 cm) from agricultural lands (AL), rangelands (RL), barren lands (BL), and riverbeds (RB), collected during the summer season of 2024. The concentrations of arsenic (As), lead (Pb), nickel (Ni), chromium (Cr), manganese (Mn), cobalt (Co), copper (Cu), aluminum (Al), and iron (Fe) were measured using ICP-OES. The enrichment factor (EF), Nemerow Integrated Pollution Index (NIPI), Improved Weighted Index (IWI), Hazard Index (HI), and Total Cancer Risk (TCR) were used to assess the ecological and health risks of HMs. Uncertainty and sensitivity analyses were performed using Monte Carlo simulation. Although all metals fell into the low enrichment class across all land uses, the highest mean EF values of As, Cr, Co, and Pb were observed in AL, while the highest mean EF values of Fe, Mn, and Cu were observed in RL. The highest pollution levels were recorded by the NIPI for AL (1.70) and in the IWI for RB (3.63). Both indices showed the lowest pollution levels in RL (NIPI = 0.92; IWI = 2.37). The NIPI indicated pollution levels ranging from low to warning, whereas the IWI indicated moderate to severe pollution levels in the study area. The highest HI values were observed for Pb in BL, with values of 1.74 × 10⁻3 for adults and 3.6 × 10⁻1 for children, indicating no significant non-carcinogenic risk. The highest CR values were obtained for As (5.26 × 10⁻⁷) in the RL, indicating a negligible carcinogenic risk in the study area. The TCR ranged from 4.75 × 10⁻⁷ in BL to 7.6 × 10⁻⁷ in RL, remaining below the acceptable risk threshold. The sensitivity analysis showed that Pb had the greatest impact on the non-carcinogenic risk, while As was the main contributor to carcinogenic risk. Finally, although the IWI indicated moderate to severe contamination in some land uses, the non-carcinogenic and carcinogenic health risks associated with HMs in the study area remained low. Therefore, continuous monitoring, especially for RB and AL, is recommended to prevent future spread and potential environmental and health impacts.
Indoor dust is an important exposure medium for potentially toxic elements in urban environments, particularly in densely populated areas with mixed residential and industrial activities. This study investigated heavy metal contamination in indoor dust collected from 40 residential dwellings in the Ümraniye district of Istanbul. Elemental concentrations, multivariate statistical analyses, enrichment factors, and human health risk assessments were applied to determine source contributions and exposure risks for adults and children. The mean abundance of metals followed the order Ca > Na > Al > Fe > K > Mg > P > Zn > Ti > Cu > Mn > Ni > Ba > Cr > Pb > Sb > V > Co > A > Cd > Hg Multivariate analyses (correlation, clustering, and PCA) revealed a multi-source structure dominated by lithogenic inputs with significant traffic-related and anthropogenic contributions. Enrichment factor results confirmed strong enrichment of Cd, Zn, Cu, and Sb. Health risk assessment indicated ingestion as the dominant exposure pathway. While no non-carcinogenic risk was observed for adults, the hazard index exceeded acceptable limits for children, with Cr identified as the major contributor. Carcinogenic risk levels remained within acceptable ranges but were higher in children. The results highlight the coupled outdoor–indoor nature of indoor dust contamination and emphasize the increased vulnerability of children. This study provides a robust framework for exposure assessment and environmental health management in urban residential environments.
