This study investigates an energy-efficient and environmentally sustainable approach to enhancing bioethanol production from sugarcane leaves through synergistic pretreatment using low-power ultrasound and an organic acid co-solvent system. To reduce the energy demand and environmental impact associated with conventional pretreatment methods, methanesulfonic acid (MSA) and formic acid (FA) were combined under low-power ultrasonic conditions. A Box–Behnken design (BBD) based on response surface methodology (RSM) was employed to optimize the FA concentration, ultrasonication time, and ultrasound power. The optimal conditions were identified as 29.17% FA, 18.70 min of ultrasonication, and an ultrasound power of 16.61 W, with the MSA concentration maintained at 5%. These conditions promoted the disruption of the lignocellulosic structure through acoustic cavitation and acid-assisted modification, thereby enhancing cellulose accessibility while minimizing energy consumption. Subsequent simultaneous saccharification and fermentation (SSF) using Saccharomyces cerevisiae at 32 °C with an enzyme loading of 50 FPU/g achieved an ethanol yield of 73.22% of the theoretical yield (on a cellulose basis), corresponding to an ethanol concentration of 12.602 mg/mL after 48 h. Extending the fermentation time to 72 h resulted in only a marginal increase in ethanol yield of 0.8%, suggesting that a 48 h incubation period represents a potentially techno-economically optimal operating window by reducing processing time and associated production costs. Compared with separate hydrolysis and fermentation (SHF), SSF achieved a comparable ethanol concentration while shortening the overall processing time and eliminating the need for a separate hydrolysis step at 50 °C. These findings demonstrate that low-power ultrasound-assisted MSA–FA co-solvent pretreatment is a promising strategy for converting sugarcane leaf residues into bioethanol under mild and potentially cost-effective operating conditions.
The objective of this study was to develop and evaluate a hybrid smart-bin system integrating solar power, ozone disinfection, and Internet of Things (IoT)-based monitoring to improve urban waste management at the source. The compact, scalable prototype was designed to operate autonomously using solar energy while reducing waste volume and microbial contamination. Performance tests demonstrated a waste-volume reduction factor of 3.15 compared with conventional waste handling. Following a six-hour solar-powered charging cycle, the system remained operational for 168 h, enabling approximately one week of operation without grid electricity. A 10-min ozone treatment reduced the microbial count to 1.25 ± 0.22 log CFU/mL, representing an approximately six-log reduction relative to untreated waste. These findings highlight the system's potential to reduce waste-collection frequency and landfill demand while improving resource efficiency and minimizing exposure to pathogens, leachate, unpleasant odors, and disease vectors. However, potential reductions in transport-related carbon emissions require further verification through a life-cycle assessment (LCA). A multi-year techno-economic assessment incorporating operating and battery-replacement costs indicated that the projected cash flows were insufficient to recover the initial capital investment of 300,000 THB within a 10-year evaluation period at a 10% discount rate, yielding a base-case net present value (NPV) of approximately −139,000 THB. A positive financial return was achieved only under optimistic assumptions of zero maintenance costs and a service life exceeding 20 years. Therefore, the current justification for deployment rests primarily on the system's observed volume-reduction and microbial-reduction performance and its potential public-health benefits. Achieving economic feasibility will require lower capital costs, higher annual net benefits, or a combination of both.
Indonesia faces a severe air pollution crisis, with average PM2.5 concentrations exceeding WHO guidelines by more than sevenfold and contributing to an estimated 13% of annual deaths nationwide. Emerging evidence further links PM2.5 exposure to increased vulnerability to viral infections, including COVID-19 and influenza, compounding the country's public health burden. Conventional personal protective equipment, predominantly petroleum-based polypropylene masks, offers only short-lived electrostatic filtration and generates substantial non-biodegradable waste, undermining both protective efficacy and environmental sustainability. Electrospinning has emerged as a promising alternative, enabling the fabrication of nanofiber membranes with diameters from 10 nm to the submicron scale that achieve high particulate filtration efficiency at low pressure drop through mechanisms including interception, inertial impaction, Brownian diffusion, and electrostatic capture. This review synthesizes recent advances across single- and multi-spinneret fabrication techniques, bead-on-string architectures, and post-treatment strategies for optimizing filtration performance. It further examines the development of biodegradable polymer membranes, upcycled waste-derived nanofibers, and multifunctional designs incorporating antimicrobial, antiviral, and humidity-resistant properties tailored to tropical urban conditions. These innovations collectively achieve filtration efficiencies exceeding 99% while addressing plastic waste accumulation. This review proposes a practical roadmap toward sustainable, multifunctional electrospun membranes capable of mitigating both urban air pollution and airborne pathogen transmission in Indonesia's rapidly urbanizing tropical cities.
Conventional plastic has become an essential element in the manufacturing of nearly all consumer products. However, it has emerged as a major contributor to environmental pollution and is difficult to biodegrade. This research therefore synthesizes composite films from jackfruit seed (JSF) reinforced with bacterial cellulose (BC) for a sustainable alternative. The structural, physical, chemical, and mechanical properties of Jackfruit Seed Starch-based composite films (JSF/BC) were investigated. The incorporation of BC fiber into the JSF composite film matrix significantly enhanced the water resistance, UV blocking, and thermal stability. By loading BC at 40 wt.%, the mechanical properties, such as tensile strength and elongation, were 0.74 MPa and 10.21%, respectively. JSF/BC composite films had a thermal stability at temperatures up to approximately 270 °C. JSF/BC composite films also exhibited a biodegradability of 72.1 - 100% within 15 days. The experimental results indicate that the composite film offers a green, high-performing alternative to conventional plastics, suitable for packaging and other short-term plastic products.
Microalgal systems are receiving significant attention for wastewater treatment because of their effective treatment performance while simultaneously generating valuable biomass for energy recovery. This study compares the performance of three biological systems - green microalgae, diatoms, and aerobic bacteria for the treatment of real domestic wastewater. Each system was operated in semi-continuous mode at different solid retention times (SRTs) of 2, 4, 6, 8, 10, and 12 days. Reactor performance was evaluated based on the removal of organic carbon, nutrients, and micropollutants. The maximum dissolved organic carbon removal efficiencies were 89% for aerobic bacteria, 84% for green microalgae, and 87% for diatoms. On the other hand, the microalgal systems outperformed the aerobic bacterial system in terms of nutrient and micropollutant removal. The microalgal systems achieved higher nutrient removal efficiencies, with maximum total nitrogen (TN) removal of 71% for green microalgae and 67% for diatoms, compared with 40% for aerobic bacteria. Diatoms exhibited a higher maximum lipid content of 21.2% at an SRT of 8 days, compared with 15.6% for green microalgae at an SRT of 6 days. Fatty acid analysis revealed the presence of palmitic, palmitoleic, stearic, and elaidic acid esters, which are suitable for biodiesel production. Overall, the results demonstrate that aerobic bacteria were effective for organic carbon removal, whereas green microalgae and diatoms exhibited enhanced nutrient and micropollutant removal while simultaneously generating lipid containing biomass with potential for biodiesel production.
