In order to reduce global warming, new energy fuels that use waste biomass to replace traditional coal are rapidly developing. The main purpose of this study is to investigate the feasibility behavior of different biomass materials such as spent coffee grounds (SCGs) and spent tea grounds (STGs) as fuel during combustion and their impact on the environment. This study involves using fuel shaping and co-firing methods to increase the fuel calorific value and reduce the emissions of pollutants, such as NO_X and SO₂, and greenhouse gas CO₂. The produced gas content was analyzed using the HORIBA (PG-250) laboratory combustion apparatus. The results indicate that, among the measured formed particles, SCG:STG = 8:2, 6:4, and 4:6 had the lowest post-combustion pollutant gas emissions. Compared to using only waste coffee grounds as fuel, the NOx emissions were reduced from 166 ppm to 102 ppm, the CO emissions were reduced from 22 ppm to 12 ppm, and the CO₂ emissions were reduced from 629 ppm to 323 ppm. In addition, the emission of SO₂, the main component of acid rain, was reduced by 20 times compared to the combustion of traditional fuels. The SO₂ emission of five different proportions of biomass fuels was 5 ppm, which is much lower than that of traditional coal fuels. Therefore, SCG and STG mixed fuels can replace coal as fuel while reducing harmful gasses.

Polycyclic aromatic hydrocarbons (PAHs) are a matter of deep concern as they pose significant environmental and health hazards due to their persistence, bioaccumulation, and toxic effects. In soils, PAHs accumulate, contaminating ecosystems, entering food chains, and posing threats to plant and human health. This study conducted a comprehensive assessment of PAH contamination in agricultural soils (particle size < 20 µm) across various land-use categories and depths to determine contamination levels and associated health risks, as such comprehensive studies are very rare in Bangladesh. Soil samples were investigated using gas chromatography–mass spectrometry (GC–MS). The findings revealed that the concentrations of ∑16PAH ranged from 299 to 1928 µg/kg, with the lowest levels observed in research areas and the highest in industrial soils. Concentration trends were as follows: industrial areas > coastal areas > local market areas > rural areas > research areas. Higher concentrations were noted for individual PAHs such as Nap, Phe, BbF, and BkF (313.14 µg/kg ± 62.01 to 546.97 µg/kg ± 146.76), while the lowest concentrations were recorded for BghiP, DBahA, and Ind (1.25 µg/kg ± 1.10 to 5.74 µg/kg ± 3.77). PAH levels were highest in surface soils, following a depth sequence of 0–5 cm > 5–10 cm > 10–15cm. The results also showed that low-, intermediate-, and high-molecular-weight PAHs comprised 46.06–83.18%, 16.47–48.68%, and 0.23–6.51% of total PAHs, respectively. The source of PAHs was identified as integration of pyrogenic petrogenic. Children were found to have higher exposure through ingestion compared to adults, with lower exposure through inhalation and dermal pathways. The total incremental lifetime cancer risk (ILCR) for children ranged from 2.03 × 10⁻⁸ to 9.07 × 10⁻⁷, and for adults from 1.96 × 10⁻⁸ to 8.04 × 10⁻⁷. Both groups exhibited no carcinogenic risk, as per the USEPA threshold. These findings underscore the need for ongoing monitoring and management strategies to mitigate PAH contamination in agricultural soils, thus protecting environmental and public health concerns.

Spent coffee grounds (SCGs), a waste product of the coffee industry, present a significant untapped resource for fuel production. This study aims to optimize the gasification of SCG using various metal catalysts (NiO, MnO₂, Al₂O₃, and Fe₂O₃) to maximize syngas yield. SCG samples were gasified at different temperatures (800 °C, 900 °C, 1000 °C) and analyzed using Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TG-DTA), and Fourier Transform Infrared (FTIR) spectroscopy to evaluate catalyst performance and reaction mechanisms. The findings indicated that utilizing mixing techniques for physical contact to introduce catalysts led to a uniform distribution of catalyst particles throughout the sample. The decomposition rate of the gasification experiment after adding the catalyst was 24% faster than that of the pure SCGs. In the gasification experiment, the MnO₂ catalyst showed the highest CO production, which was 71% higher than that of NiO under the same conditions. At this temperature, MnO₂ generated around 171% more CO than at 800 °C, surpassing the yields observed with other catalysts. The study concludes that Mn emerged as the most promising catalyst, significantly improving both CO and CH₄ yields. Selecting the appropriate metal catalyst and optimizing operational temperatures are crucial for enhancing the efficiency of SCG gasification.

Water pollution caused by fluoranthene (FLN), phenanthrene (PHE), and pyrene (PYR) has become an increasingly serious issue in recent years. Consequently, finding effective methods to remove these pollutants from aquatic environments is of paramount importance. This study investigated the removal rate of FLN, PHE, and PYR from simulated wastewater using persulfate (PS) and explored the effects of PS catalyzed by three different forms of schwertmannite (sch): sch-1, sch-2, and sch@BC (schwertmannite-biochar composite), and the BET of sch-1, sch-2, sch@BC has been detected, which were 1.09 cm³/g, 11.30 cm³/g, and 6.10 cm³/g. The results showed varying removal rates after a 1 h reaction time for different treatments: For FLN: sch-1+PS (98.5%), sch-2+PS (54.2%), sch@BC+PS (21.1%), and PS alone (14.8%). For PHE: sch-1+PS (94.3%), sch-2+PS (44.1%), sch@BC+PS (28.4%), and PS alone (7.6%). For PYR: sch-1+PS (97.2%), sch-2+PS (52.5%), sch@BC+PS (14.2%), and PS alone (1.7%). Among the catalysts tested, sch-2 (added 0.36 mL H₂O₂ five times) demonstrated excellent catalytic ability in enhancing the PS removal of FLN, PHE, and PYR. This research provides theoretical support for treating polycyclic aromatic hydrocarbon (PAH)-containing wastewater via persulfate oxidation catalyzed by schwertmannite.

Water pollution caused by fluoranthene (FLN), phenanthrene (Phe), and pyrene (Pyr) has become an increasingly serious issue in recent years. Consequently, finding effective methods to remove these pollutants from aquatic environments is of paramount importance. This study investigated the removal of FLN, Phe, and Pyr from simulated wastewater using persulfate (PS) and explored the effects of PS catalyzed by three different forms of schwertmannite (sch): sch-1, sch-2, and sch@BC (schwertmannite-biochar composite). Results showed varying removal rates after a 1-hour reaction time for different treatments: For FLN: sch-1+PS (98.5%), sch-2+PS (54.2%), sch@BC+PS (21.1%), and PS alone (14.8%). For Phe: sch-1+PS (94.3%), sch-2+PS (44.1%), sch@BC+PS (28.4%), and PS alone (7.6%). For Pyr: sch-1+PS (97.2%), sch-2+PS (52.5%), sch@BC+PS (14.2%), and PS alone (1.7%). Among the catalysts tested, sch-2 (added 0.36 mL H2O2 five times) demonstrated excellent catalytic ability in enhancing PS removal of FLN, Phe, and Pyr. This research provides theoretical support for treating polycyclic aromatic hydrocarbon (PAH)-containing wastewater via persulfate oxidation catalyzed by schwertmannite.