The aqueous leaf extracts of Datura stramonium and Ricinus communis were analyzed for phytoconstituents, including alkaloids, steroids, flavonoids, terpenoids, phenolic compounds, tannins, cardiac glycosides, anthraquinone glycosides, saponins, and triterpenes. The extracts revealed promising compounds in both plants. Given the toxicity of these compounds, it is recommended to eradicate these species or find beneficial uses for them. This research explores waste elimination and biogas generation through anaerobic digestion, providing a sustainable renewable energy option. Biogas production was evaluated via co-digestion of cow manure (CM) with Datura stramonium leaves (DSL) and Ricinus communis leaves (RCL) in three ratios (60% DSRC: 40% CM, 50% DSRC: 50% CM, 40% DSRC: 60% CM) under mesophilic conditions at 38ºCover 30 days. Physicochemical factors such as pH, total solids, volatile solids, organic carbon, nitrogen, and the carbon-to-nitrogen ratio were measured before and after digestion. Results showed significant increases in pH and total nitrogen, with notable decreases in volatile solids and organic carbon. Biogas yield was higher when substrates were co-digested with cow dung compared to leaves alone, with the 60% DSRC: 40% CM ratio yielding the most biogas. The study concludes that the co-digestion of cow manure with Ricinus communis and Datura stramonium leaves in a 60%:40% mix ratio significantly enhances biogas yield and reduces volatile and total solids.