Municipal solid waste (MSW) is rising globally, and improper management harms the environment and public health. As a result, there is heightened interest in finding effective solutions, and identifying research trends helps determine the best management and valorization pathways. However, the existing reviews often focus narrowly on specific technologies or regional case studies, lacking a comprehensive analysis of global research trends. This study addresses this significant gap by conducting a large-scale trend analysis based on 15,646 relevant articles screened from 25,068 Scopus-indexed publications from 1904 to 2023 using title, abstract, and keyword analysis. Literature-based comparative assessments were conducted to critically evaluate the pathways through TEE (techno-economic and environmental), SWOT (strengths, weaknesses, opportunities, and threats), and PESTEL (political, economic, social, technological, environmental, and legal) frameworks. Since 1990, article publication has increased by about 10% annually, consistently concentrating on thermochemical conversion and, more recently, on sustainability and circular economy perspectives. Seven distinct pathways for MSW management were identified, with recycling and material recovery, followed by thermochemical conversion for high-calorific waste and biochemical conversion for high-organic waste, showing the most promise. The findings aim to help researchers understand MSW research trends and assist planners in identifying effective management and valorization strategies.

Pharmaceuticals and personal care products (PPCPs) in wastewater pose significant threats to both human health and aquatic ecosystems. Wastewater discharge from various sources is the primary cause of these contaminants, and proper treatment is essential for protecting the environment. Traditional treatment technologies are often too expensive and ineffective in removing PPCPs. Constructed wetlands (CWs) offer a sustainable, cost-efficient alternative for wastewater treatment, though their capability to eliminate PPCPs can vary based on multiple aspects. Recent studies highlight biochar—a carbon-rich material resultant from biomass pyrolysis—as a promising amendment to improve CW performance. However, there is a deficiency of proper literature reviews on using biochar in CWs specifically for PPCP removal. This review focuses on biochar's role in CWs and its effectiveness in removing PPCPs and enhancing microbial activity and nutrient cycling. A bibliometric analysis using Vosviewer software was used to assess the current research trends in the biochar-amended CWs to attenuate PPCPs. While biochar shows potential in eliminating PPCPs, challenges, such as optimizing its application and addressing long-term operational concerns for treating emerging pollutants like PPCPs. Future research should enhance biochar production and low-cost techniques for diverse groups of PPCPs and perform field trials to validate laboratory results under actual conditions exploring microbial–biochar and plant-biochar interactions. Addressing these challenges is crucial to advancing biochar-amended CWs and enhancing wastewater treatment on a global scale.

The infrastructure of water, sanitation, and hygiene (WASH) systems in Nepal is highly vulnerable to frequent natural disasters, endangering both socio-economic well-being and public health. This study employs a literature review approach to examine the intricate relationships between WASH systems and natural and human-induced disasters, including landslides, floods, and earthquakes. The results reveal severe consequences, including contaminated water sources, deteriorated sanitary infrastructure, and an increase in illness, disproportionately affecting marginalised populations. This research also sheds light on Nepal's remarkable resilience, showcasing innovative recovery programmes that combine indigenous knowledge with scientific approaches to enhance long-term preparedness. Key strategies include fortifying infrastructure resilience, distributing redundant facilities, enhancing institutional synergies through comprehensive emergency planning, localising capacity building, and incorporating disaster mitigation into land-use policies. Despite its contributions, this study is limited by its reliance on secondary data sources, which may include biases in reporting disaster impacts and resilience strategies. However, future research should aim at incorporating field studies and empirical analysis to enhance the accuracy and applicability of resilience frameworks. Despite these limitations, this study further proposes incorporating WASH resilience into sustainable development paradigms through multi-sectoral collaboration, strategic resource allocation, and ongoing implementation of the best practices. Globally, natural disasters pose a significant challenge to WASH infrastructure; however, in Nepal, the exceptional frequency and severity of disasters, such as landslides, floods, and earthquakes, necessitate a unique focus on innovative, context-specific strategies to enhance resilience and ensure long-term sustainability.

A rural catchment stream, Roshi (Nepal), is experiencing pollution loads from non-point pollution sources: agricultural runoffs and stone quarry sediment loads requiring immediate concern. This study is focused on developing a well-calibrated and validated water quality model to determine the pollution load capacity of Roshi River at peak rainfall periods using software QUAL2kW concerning pH, Temperature, DO, FSS, NO3-, NH4+, TP, BOD, and Turbidity. A pollution-dominant stretch of 1.95km was selected and segmented into three segments. RMSE values showed the model satisfactory in predicting actual in-field scenarios. Scenario analysis showed that in the existing pollution source flow and streamflow, the pollution load capacity is 275 mg/L for BOD, 33 mg/L for NH4+, 1250 mg/L for NO3-, 10 mg/L for TP, and 0 mg/L for DO. The FSS in the Headwater must be limited to 55 mg/L to maintain the stream water quality within standards signifying the immediate need to reduce the upstream stone quarry load. Policymakers are urged to implement stringent regulations on upstream quarries concerning sediment load discharge into the stream. The developed model can be a valuable tool for predicting the stream's response to potential emissions from future development activities during the monsoon period.

This study synthesizes polycyclic aromatic hydrocarbon (PAHs) contamination across the Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation (BIMSTEC) region which includes Bangladesh, India, Bhutan, Myanmar, Nepal, Sri Lanka, and Thailand. The analysis revealed extreme spatial heterogeneity within the PAHs concentrations across environmental matrices, like the atmospheric levels ranged from 2.3 ng/m³ (Nepal) to 5,578 ng/m³ (Bangladesh). It has further been reported that aquatic contamination exhibits considerable variability, ranging from 878.7 to 47,366 ng/g in water and sediments across the study region, while urban soils exhibited concentrations between 830 and 3,880 ng/g. It has been found that biomass combustion significantly contributes to PAHs, with Bangladesh showing the highest burden in the BIMSTEC region. The research distribution further revealed significant knowledge gaps, with India contributing nearly 40% of regional studies, while lower-income countries such as Myanmar accounted around 4%. Along with it, the behavior and persistence of PAHs has been shaped by a complex interplay of physicochemical properties, meteorological conditions, seasonal variations, and the exacerbating role of climate change. Such complexity calls for in-depth research, coordinated regional efforts, and the implementation of effective mitigation measures to safeguard environmental integrity and public health in the BIMSTEC region. Graphical abstract