The rise in population, urbanization, and industrial developments have led to a substantial increase in waste generation and energy demand, posing significant challenges for waste management as well as energy conservation and production. Bioenergy conversions have been merged as advanced, sustainable, and integrated solutions for these issues, encompassing energy generation and waste upcycling of different types of organic waste. Municipal solid waste (MSW) and agricultural residues (AR) are two main resources for bioenergy conversions. Bioenergy production involves feedstock deconstruction and the conversion of platform chemicals to energy products. This review provides a detailed overview of waste sources, biofuel, and bioelectricity production from fermentation and microbial fuel cell (MFC) technology, and their economic and environmental perspectives. Fermentation plays a critical role in liquid biofuel production, while MFCs demonstrate promising potential for simultaneous production of electricity and hydrogen. Fermentation and MFCs hold a significant potential to be integrated into a single pipeline, enabling the conversion of organic matter, including a variety of waste material and effluent, into diverse forms of bioenergy via microbial cultures under mild conditions. Furthermore, MFCs are deemed a promising technology for pollutant remediation, reducing COD levels while producing bioenergy. Importantly, the consolidated fermentation–MFC system is projected to produce approximately 7.17 trillion L of bioethanol and 6.12 × 10⁴ MW/m² of bioelectricity from MSW and AR annually, contributing over USD 465 billion to the global energy market. Such an integrated system has the potential to initiate a circular economy, foster waste reduction, and improve waste management practices. This advancement could play a crucial role in promoting sustainability across the environmental and energy sectors.

Hydrogen demand is rapidly increasing, intensifying concerns over the environmental impacts of fossil-derived hydrogen production. This review critically examines the environmental impact reduction potential of hydrogen production from biobased resources by synthesizing current literature on feedstock availability, conversion technologies, and life cycle environmental performance. Biobased feedstocks, including agricultural and forest residues, and algae, are considered promising alternatives that can support diversified and regionally adaptable hydrogen supply chains. This review compares thermochemical, biological, and electrochemical hydrogen production pathways, highlighting their respective advantages and limitations. Emerging technologies, such as plasma catalysis, photoelectrochemical water splitting, and photobiological systems, are discussed for their potential to further reduce emissions, despite their early-stage development. Reported life cycle assessment results indicate that biochemical conversion pathways exhibit carbon footprints ranging from 1.0 to 5.59 kg CO₂-eq/kg H₂, approximately 60% lower than those of thermochemical processes (13.7 kg CO₂-eq/kg H₂). Moreover, integrating low-emission energy sources into hydrogen production is essential for further reducing environmental impacts and production costs. A comparative evaluation indicates that biobased hydrogen production achieves carbon footprint as low as 0.4 kg CO₂-eq/kg H₂, substantially lower than that of conventional steam methane reforming (10 kg CO₂-eq/kg H₂). Overall, biobased hydrogen production offers a lower-carbon alternative to fossil-based routes, particularly when coupled with low-carbon energy inputs. Furthermore, regions such as Idaho present favorable opportunities for large-scale hydrogen production through its robust hydropower and nuclear energy capacity, enabling efficient and affordable hydrogen production. Integrating sustainable feedstock with advanced conversion technologies can support the transition toward resilient hydrogen infrastructure. AbstractSection Graphical abstract

Fe₄₂Mn₂₈Cr₁₅Co₁₀Si₅ is a highly strain-hardenable high-entropy alloy (HEA) that is challenging to machine with traditional metal cutting tools. The electrochemical behavior of this HEA was examined in nitrate- and chloride-based electrolytes to understand the electrochemical machining (ECM) process. Potentiodynamic and potentiostatic tests were conducted on this alloy in 1 M and 2.35 M NaNO₃ solutions, with and without additions of 0.01 M nitric acid and 0.01 M citric acid. A 20% NaCl solution was also tested as an electrolyte. Nitrate solutions caused passivation of the HEA, while no passivation was observed in chloride solutions. Surface analysis with X-ray photoelectron spectrometry (XPS) indicated that adding citric acid helped reduce surface passivation. The Faradaic efficiency of ECM increased with higher applied voltage. The chloride solution showed higher Faradaic efficiency than nitrate-based solutions. Specifically, the Faradaic efficiency of 20% NaCl at 10 V is 57.4%, compared to 21.9% for 20% NaNO₃ + 0.01 M citric acid at 10 V. Electrochemical parameters, including anodic and cathodic exchange current densities, Tafel slopes, and corrosion current densities, were calculated from the experimental data. The corrosion current densities in the 20% nitrate solutions ranged from 2.35 to 3.2 × 10⁻⁵ A/cm², while the 20% chloride solution had a lower corrosion rate at 1.45 × 10⁻⁵ A/cm². These electrochemical parameters can help predict the dissolution behavior of the HEA in nitrate and chloride solutions and aid in optimizing the ECM process.

In this study we have designed and fabricated a household solar water desalination unit for the arid regions of rural areas of Sindh like Tharparkar district. Drought conditions, shortage of drinking water and relying on saline water in arid regions of Sindh is a serious problem. In areas under these tracts, it is difficult to obtain drinkable water. This study focuses on the development of a cost effective and affordable desalination unit having simple construction, easy to use, repair, maintain and can be operated by an unskilled man. The solar desalination unit comprises of a solar oven, condenser, and collector pot. In this research various water samples were collected from three arid regions of Tharparkar district i.e., Islamkot, Diplo and Mithi. The performance of solar water desalination unit was assessed by analysing the Total Dissolve Solids (TDS), pH and Electrical Conductivity (EC) of all samples. The sample collected, before treatment had maximum TDS, conductivity, and pH values as 10421 mg/L, 20842 μS/cm and 8 respectively. Those sample after treatment reduced to TDS of 230 mg/L, conductivity of 460 μS/cm and pH of 7.4. This portable solar desalination unit showed remarkable results and found as effective in the removal of TDS from all water samples. The efficiency of unit was calculated as 35.2% with maximum daily output of 5 litres. This unit was constructed at very low cost of PAKPKR 4500/- and its complete rely on solar energy which makes it quite affordable for those which cannot afford expensive treatment techniques. This unit has very minimal maintenance cost and does not require electricity. The values for pH, TDS, and EC achieved from this unit are satisfying the World Health Organization (WHO) guidelines for drinking water quality.

Rapid urbanization and the intensifying pressures of climate change have elevated solid waste management (SWM) as a critical public service challenge. Evidence on the joint mediating effects of digital transformation and environmental governance between municipal SWM and climate sustainability remains questionable. This study examines the role of SWM in promoting climate sustainability by evaluating environmental management practices and AI-enabled digitalization. Data were collected from 406 employees across seven Water and Sanitation Service Companies (WSSCs) in Khyber Pakhtunkhwa, Pakistan, using a cross-sectional survey with a structured and validated instrument. The analytical approach involved Confirmatory Factor Analysis (CFA) and Structural Equation Modeling (SEM) with bootstrapped mediation analysis (5000 resamples), executed in SPSS and AMOS software. The study measured waste management effectiveness, environmental practices, AI-enabled digital systems, and sustainability outcomes across economic–environmental–social nexus. Findings reveal a significant positive relationship between effective SWM and climate sustainability (β = 0.41, p < 0.001). Environmental practices including regulatory compliance, pollution control, and workforce training along with AI-driven digital capabilities including real-time tracking, route optimization, electronic service reporting, and data dashboards play a strong mediating role (indirect effects: ENV = 0.13; DIG = 0.12; joint = 0.21). The results suggest that municipal waste systems achieve greater climate benefits when routine operations are supported by integrated environmental management and smart digital technologies. The study contributes to the research on sustainable models, circular economy, and smart urban governance, offering policy guidance for municipal authorities in Pakistan, through AI-enabled tools and solutions, environmental governance practices, and SDG-aligned incentives.