Biswanath Saha

This study evaluated the influence of four thermal pretreatment techniques—autoclaving, hot-air oven treatment, hot-water immersion, and microwave irradiation—on Parthenium hysterophorus biomass to improve its biodegradability and biogas generation potential under batch anaerobic digestion. Among the investigated methods, hot-air oven pretreatment at 110 °C for 90 min exhibited the most significant enhancement in biomass solubilization, as indicated by a 51.5% rise in soluble chemical oxygen demand (sCOD) and an increase in volatile fatty acids (VFAs) compared with the untreated control. These compositional improvements facilitated faster hydrolysis and led to a 25.73% higher cumulative methane yield in biochemical methane potential (BMP) assays. Structural analysis revealed pronounced alterations in the lignocellulosic matrix, with reductions in hemicellulose and partial delignification improving substrate accessibility. Complementary characterisation using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) confirmed the disruption of crystalline cellulose regions and modification of functional groups, supporting the observed biochemical improvements. Collectively, the results demonstrate that hot-air oven pretreatment is a practical and energy-efficient approach for enhancing the digestibility of P. hysterophorus biomass, promoting its utilisation as a sustainable feedstock for renewable biogas production and environmental management of this invasive weed.

Invasion of Lantana camara all over the world and its management is a global problematic issue. Its rapid growth and competition with natural resources such as space, water, and nutrients of other plants, reasons for the demand to manage this noxious weed. This study was done to optimize the ideal food to microorganism (F/M) ratio. Different food to microorganism (F/M) ratios of 1, 1.5, 2 and 2.5 were studied along with one control where only cow dung was kept. Highest methane production was obtained from the F/M ratio of 1.5 (195.5 ± 8 mL CH₄/g VS) and cumulative methane production from it was 4801.5 mL followed by ratios 2 and 2.5 respectively. In control, methane production was relatively low as compared to all the F/M ratios (2151.5 ± 8 mL). 20 L capacity batch reactor was performed with a working volume of 15.5 L where substrate and cow dung were fed according to the best ratio found during biochemical methane potential trial (BMP). Maximum methane yield was observed on the 19^th day (2650 ± 18 ml CH₄/g VS). Maximum volatile solids (VS) reduction was observed in the F/M ratio 1.5 (49.63%) followed by 2 and 2.5 respectively. The maximum amount of volatile fatty acid (VFA) was produced in F/M ratio 1.5 (715 ± 10) and 2 (715 ± 15) followed by ratios 2.5 and 1 respectively. Maximum soluble chemical oxygen demand (sCOD) was found in F/M ratio 1.5 (8000 `mg/L). Morphological changes were captured in FESEM and XRD. Highlights