Muhammad Waqas

Despite growing interest in valorizing agricultural waste through anaerobic digestion (AD), full-scale implementation in developing countries remains insufficiently explored. This study evaluates the development, performance, and technological characteristics of agricultural waste AD plants in Türkiye between 2011 and 2024, identifying key drivers and barriers to the biogas sector. Data were collected through surveys, regulatory databases, and operator interviews covering all 103 AD facilities. During the study period, 102 electricity-generating AD plants and one biomethane facility were commissioned, reaching a total installed electrical capacity of 301 MW in Türkiye. In 2024, these plants generated 1,244 GWh electricity (average power: 142 MW), corresponding to a 47% capacity factor. Although most facilities had capacities between 1 and 4 MW, larger plants (>3 MW) generated 68% of total electrical output. Cattle manure as the dominant feedstock accounted for 64% of energy production, followed by poultry manure (24%) and agro-industrial wastes (12%). Regionally, 70% of capacity is concentrated in Central Anatolia and the Aegean. Beyond energy recovery, the widespread use of AD in Türkiye contributes pollution mitigation by reducing uncontrolled manure disposal, greenhouse gas emissions, and nutrient pollution. Nationwide, approximately 11% of cattle manure and 18% of poultry manure undergo AD treatment. All plants operate as wet, mesophilic systems, with 97 using CSTR digesters and 5 employing plug-flow lagoons. The findings highlight the role of policy incentives and livestock distribution in shaping the development of the biogas sector, providing practical insights for sustainable agricultural waste management in developing countries.

TThe study aimed to analyze the effect of different plastic waste, including Polystyrene (PS), Polyethylene (PE), Polypropylene (PP), and their mixture at 50:50% on the yield and quality of liquid oil through pyrolysis. A small-scale batch pyrolysis reactor with a total capacity of 10kg was commissioned and operated at 550°C with a retention time of 90minutes. Results revealed that the highest conversion (51%) of feedstock to liquid oil was recorded for PS in comparison to other types of plastic waste, whereas among the mixed plastics, PE:PS produced the highest quantity (39%) of liquid oil. The physicochemical analysis demonstrated that the obtained oils comprised mostly aromatic compounds with some alkanes and alkenes. Moreover, liquid oils from all types of plastic waste showed a range of density between 0.734 to 0.892g ml-1, viscosity (1.99 to 3.1mm2 s-1), flash point (29 to 48°C), and high heating value (37.2 to 42.4MJ kg-1). Based on the obtained results, in-depth discussion has been made on the utilization of the produced liquid oil and gases in several energy-related applications, including transportation fuel, heating, and electricity production, along with the applicability of resultant char for several energy and environmental applications. Moreover, it has been emphasized that the key bottleneck in commercializing the plastic-based circular economy concept requires a continuous supply of feedstock, characterization and pretreatment of feedstock to eliminate toxicity, approaches for reducing wax formation, technological advancements to enhance the quality and yield of pyrolysis, and detailed life cycle assessment to achieve maximum environmental and human health benefits.

Zinc oxide nanoparticles (ZnO NPs) are becoming an innovative agent in biological and environmental applications due to its unique characteristics, biocompatibility, low cost and toxicity. In this study, the composite ZnO NPs using Rhododendron arboreum (R. arboreum) stem bark were synthesized and characterized for UV–visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The biomedical assessment of the synthesized nanoparticles showed zones of inhibition of 23 ± 0.09, 18 ± 0.1 and 16 ± 0.05 mm, against the Klebsiella pneumoniae (K. pneumoniae), Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains, respectively. Likewise, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against K. pneumoniae, S. aureus, and E. coli were found to be 34 ± 0.21 and 72.71 ± 0.47, 47 ± 0.11 and 94.86 ± 0.84 and 94 ± 0.18 and 185.43 ± 0.16 µg/mL, respectively. The biosynthesized ZnO NPs resulted in significant eradication of the outer and inner membranes of the tested bacterial cells. In addition, the environmental application of the synthesized ZnO NPs also showed time-dependent photocatalytic degradation activity and revealed 65% methyl orange dye degradation with an irradiation period of 6 h. The findings of this study suggest the suitability of the novel R. arboreum stem bark-based ZnO NPs as an effective ameliorant against bactericidal activities and photocatalytic potential for the removal of potentially toxic substances from water.

Zinc nanoparticles (ZnNPs) open new opportunities for biomedical applications as a strategy against microbes and dye removal in an efficient way. The composite ZnNPs using Rhododendron arboreum (R. arboreum) stem bark were synthesized and characterized for UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The synthesized nanoparticles showed zones of inhibition of 23±0.09, 18±0.1 and 16±0.05 mm, against the Klebsiella pneumoniae (K. pneumoniae), Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli strains. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values against K. pneumoniae, S. aureus, and E. coli were found to be 34±0.21 and 72.71±0.47, 47±0.11 and 94.86±0.84 and 94±0.18 and 185.43±0.16 µg/mL, respectively. The biosynthesized ZnNPs resulted in significant eradication of the outer and inner membranes of the bacterial cells. Likewise, the synthesized ZnNPs showed time-dependent photocatalytic degradation activity and revealed 65% methyl orange dye degradation with an irradiation period of 6 hours. The findings of this study suggest the suitability of the novel R. arboreum stem bark-based ZnNPs as an effective ameliorant against bactericidal activities and photocatalysts for the removal of hazardous water contaminants.