Sustainable management of Alternanthera philoxeroides by anaerobic digestion: optimization of food to microorganism ratio and kinetic study

Alternanthera philoxeroides (A. philoxeroides) is a noxious aquatic weed that is classified as one of the most destructive weeds in the world since it invades both aquatic and terrestrial habitats. The current study focused on the anaerobic digestion of A. philoxeroides, and aimed to identify the optimal ratio of food to microorganisms among 1.5, 2, 2.5, and 3 A. philoxeroides weed successfully optimized by producing a considerable amount of biogas through anaerobic digestion. The highest cumulative biogas production was obtained from food to microorganism ratio 2.5 (2696.31 ± 31.87 mL) followed by ratio 3 (2387.5 ± 96.87 mL), ratio 2 (1844.05 ± 15.15), and ratio 1.5 (1758.8 ± 21.4 mL) and lowest cumulative biogas was found in control (658.28 ± 38.35 mL). Management of A. philoxeroides weed by anaerobic digestion to fulfill the Sustainable development goal is also addressed. X-ray diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to analyze both undigested and digested A. philoxeroides. According to the batch investigation, A. philoxeroides with food to microorganism ratio of 2.5 has significant potential for biogas generation as it yields 4.09-fold higher biogas productions than the control. The modified Gompertz model and logistic function model precisely depicted the degradation process and the kinetic behavior of cumulative biogas. Anaerobic digestion is supposed to be a cost-effective alternative for the management of the noxious weed A. philoxeroides.