Resource depletion and climate changes due to human activities and excessive burning of fossil fuels are the driving forces to explore alternatives clean energy resources. The objective of this study was to investigate the potential of potato peel waste (PPW) at various temperatures T15 (15 degrees C), T25 (25 degrees C), and T35 (35 degrees C) in anaerobic digestion (AD) for biogas generation. The highest biogas and CH4 production (117 mL VS-g and 74 mL VS-g) was observed by applying 35 degrees C (T35) as compared with T25 (65 mL VS-g and 22 mL VS-g) on day 6. Changes in microbial diversity associated with different temperatures were also explored. The Shannon index of bacterial community was not significantly affected, while there was a positive correlation of archaeal community with the applied temperatures. The bacterial phyla Firmicutes were strongly affected by T35 (39%), whereas Lactobacillus was the dominant genera at T15 (27%). Methanobacterium and Methanosarcina, as archaeal genera, dominated in T35 temperature reactors. In brief, at T35, Proteiniphilum and Methanosarcina were positively correlated with volatile fatty acids (VFAs) concentration. Spearman correlation revealed dynamic interspecies interactions among bacterial and archaeal genera; facilitating the AD system. This study revealed that temperature variations can enhance the microbial community of the AD system, leading to increased biogas production. It is recommended for optimizing the AD of food wastes.

Arctic wetlands are currently net sources of atmospheric CH4. Due to their complex biogeochemical controls and high spatial and temporal variability, current net CH4 emissions and gross CH4 processes have been difficult to quantify, and their predicted responses to climate change remain uncertain. We investigated CH4 production, oxidation, and surface emissions in Arctic polygon tundra, across a wet-to-dry permafrost degradation gradient from low-centered ( intact) to flat-and high-centered ( degraded) polygons. From 3 microtopographic positions ( polygon centers, rims, and troughs) along the permafrost degradation gradient, we measured surface CH4 and CO2 fluxes, concentrations and stable isotope compositions of CH4 and DIC at three depths in the soil, and soil moisture and temperature. More degraded sites had lower CH4 emissions, a different primary methanogenic pathway, and greater CH4 oxidation than did intact permafrost sites, to a greater degree than soil moisture or temperature could explain. Surface CH4 flux decreased from 64 nmol m(-2) s(-1) in intact polygons to 7 nmol m(-2) s(-1) in degraded polygons, and stable isotope signatures of CH4 and DIC showed that acetate cleavage dominated CH4 production in low-centered polygons, while CO2 reduction was the primary pathway in degraded polygons. We see evidence that differences in water flow and vegetation between intact and degraded polygons contributed to these observations. In contrast to many previous studies, these findings document a mechanism whereby permafrost degradation can lead to local decreases in tundra CH4 emissions.