Abstract Hydrogen sulfide (H 2 S) is a highly toxic gas often encountered in various industrial settings, including the construction industry. When H 2 S is encountered in construction environments, it not only poses severe health risks to workers but also causes project delays and economic losses. In this study, a quantitative survey was conducted to assess construction professionals’ awareness of H 2 S hazards, evaluate the impacts of regulatory measures on project performance, and identify effective mitigation measures. A structured online survey was administered to 59 construction engineers and professionals in Kuwait, and the responses were analyzed using descriptive and inferential statistics in SPSS. The results revealed significant gaps in hazard awareness, with 41.1% of the respondents incorrectly identifying H 2 S as a harmless gas. While 61.4% reported preemptive testing of H 2 S concentrations during groundwater pumping, nearly half of the participants reported no regular training on H 2 S management. H 2 S emissions negatively impact safety (81.0%), cost (79.3%), and schedule (75.9%). Effective mitigation measures identified include implementing water treatment systems (59.6%), installing on-site gas monitoring labs (49.1%), and utilizing exhaust ventilation in confined spaces (54.4%). The findings underscore the need for enhanced training protocols, stricter enforcement of safety regulations, and the integration of proactive engineering controls to reduce occupational hazards, protect worker health, and ensure project delivery in H 2 S-prone environments.
Abstract Chlorpyrifos (CPF) is a widely used organophosphate pesticide that poses environmental issues. Nanobiochar has garnered significant scientific interest because of its higher adsorption capacity. However, despite its potential for pesticide retention, the influence of biochar on CPF transport remains poorly understood. This study investigates the influence of fertilizers and organic matter on the fate and transport of CPF in nanobiochar (NBC)-amended porous media. The transport behavior of CPF in NBC-amended and unamended sand, together with the effects of humic acid and fertilizers (nitrate and phosphate), was investigated through soil column experiments. Breakthrough curves were simulated using the dual-porosity nonequilibrium model in HYDRUS-1D. The results showed that the incorporation of one percent NBC reduced C/C o from 0.45 to 0.30, indicating enhanced sorption resulting from the high surface area and microstructure of NBC. Correspondingly, the simulated sorption coefficient increased from 1.64 to 1.968 Lg −1 , indicating improved retention of CPF. Humic acid increased CPF mobility by approximately 44 percent, whereas nitrate and phosphate enhanced CPF retention by 20 percent, reducing the C/C o ratio to 0.20 in NBC-amended sand compared with 0.45 in unamended sand. The enhanced retention in the presence of fertilizers was due to electrical double-layer compression. Furthermore, pH-dependent sorption behavior indicated greater CPF retention under acidic conditions following NBC incorporation. Overall, the results demonstrate that NBC effectively reduces CPF mobility in porous media. However, its effectiveness is influenced by coexisting environmental factors. Therefore, a comprehensive investigation of additional environmental factors is required to optimize biochar-based remediation strategies.
Abstract A heat recovery and management system for municipal solid waste decomposition in an open dumpsite is crucial for preventing urban heat island effects and reducing greenhouse gas emissions. The temperature rise has reached the ignition point in open dumpsites, increasing serious environmental issues. The present study systematically evaluated heat output from the Ariyamangalam dumpsite in Tiruchirappalli, using landfill degradation and transport equations combined with thermodynamic principles, and estimating smoldering potential for different waste fractions. The results indicate that the existing physical composition produces 1,348 MJ per tonne of waste. A combined approach of remote sensing and machine learning was adopted to investigate surface thermal characteristics and predict future surface temperatures. Thermal infrared sensor data and high-resolution satellite images were used to derive the spatial distribution of temperature. The thermal footprint mapping was conducted in ArcGIS (version 10.4.1), and variations in surface temperatures were correlated with biomining activities, which increased temperatures by 2°C–5°C across seasons. At the same time, the random forest algorithm identified surface temperature trends using Landsat imagery from 2004 to 2024. The random forest executed well with an out-of-bag error of 9.5% and an R 2 of 0.81. The outcomes highlight the significant thermal load caused by waste decomposition and biomining. Without efficient recovery, heat accumulation at the dumpsite is a growing concern, intensifying fire risks and local climate stress.
Abstract Anaerobic digestate obtained from a digester operated on food waste was further treated in a dual-chamber microbial fuel cell (D-MFC) for nutrient recovery. Digestate was fed to the D-MFC at different dilutions [chemical oxygen demand (COD): 1,000–5,000 mg/L] in fed-batch mode and at different organic loading rates (OLRs) (0.85–1.70 kg/m 3 /day) in continuous mode. Peak power densities of 2.02 and 1.72 W/m 3 were achieved at a COD concentration of 3,000 mg/L and OLR of 1.35 kg/m 3 /day, respectively, due to strengthened metabolic activity of exoelectrogens. However, at an excessively high OLR, reactor performance declined due to variation in the microbial community structure, facilitating the dominance of non-exoelectrogens over exoelectrogenic microorganisms. Based on D-MFC operation over 80 days, the average COD and ammonia ( NH 4 + - N ) removal efficiencies were 96 ± 1 percent and 62 ± 3 percent, respectively, while phosphorus release increased the average PO 4 3 − - P concentrations to 33 mg/L in anode effluent. Further, struvite precipitation led to NH 4 + - N and PO 4 3 − - P recovery of 87 percent and 94 percent, respectively, thus yielding 3.17 kg struvite/m 3 of treated digestate. Technoeconomic analysis for a 2,000 L D-MFC indicated a payback period of six years for the initial capital expenditure based on revenue generation from recovered nutrients and wastewater treatment. Overall, the long-term operational stability and enhanced nutrient recovery prove this approach to be a promising solution for AD effluent management on a large scale.
Abstract The current study introduces a novel cross-linked biopolymer (BP) blend of chitosan and sodium alginate at concentrations of 1%, 2%, and 4% for immobilizing Cr 6+ and Cd 2+ (at concentrations of 300 and 500 mg/kg) in clayey soil. This research aims to develop a biopolymer blended clay liner for landfills and contaminated sites by enhancing sorption while preserving geotechnical integrity. The objective includes evaluating BP's efficacy in heavy-metal immobilization and enhanced geotechnical performance through pH, electrical conductivity, 1-D consolidation, and sorption tests on control (metal-spiked) and BP-treated soils prepared at 70% maximum water-holding capacity. Results show a reduction in void ratio and compressibility, predominantly in the 500-mg/kg Cr 6+ -spiked soil, primarily due to the adsorption and surface complexation of the predominant aqueous hydrogen chromate ( HCrO 4 4 − ) species under acidic conditions, resulting in enhanced particle aggregation and pore volume reduction. Up to 2% BP, all samples meet the linear hydraulic conductivity criteria (≤10 −7 cm/s) and exhibit an increase in sorption capacity. However, 4% BP slightly increases compressibility and conductivity and reduces sorption due to uneven mixing and metal-induced flow paths. Fourier transform infrared spectroscopy confirmed coordination bonds via adsorption and metal chelation in the BP matrix. Optimally, 1% and 2% BP balances superior sorption with geotechnical stability, offering an eco-friendly innovation over conventional stabilizers for heavy-metal containment in clayey soil.
