Optimization of biomethanation of water hyacinth (Eichhornia crassipes) using biocatalyst

Since water hyacinth (WH) spreads quickly and adversely affects the development of both animals and plants by robbing water bodies of their nutrients and oxygen, WH is widely regarded as a noxious weed around the world. Therefore, turning this undesirable weed into valuable chemicals and fuels aids in developing countries' ability to sustain themselves. Hence, the present work aims to optimize average biogas production (ABP), cumulative methane yield (CMY), and methane concentration (MC) during biomethanation of WH using cow dung. The investigations were conducted in a semi-batch digester at various pH (6–8), temperature (30–50 °C) and cow dung dosage (0.0143–0.0429 m3/m3 WH slurry). The central composite design (CCD) of response surface method was used to optimize the pH, temperature, and cow dung dosage. The effects of studied process parameters on the ABP, CMY and MC were significant. The predicted and experimental responses showed goodness of quadratic fit. The optimum ABP of 0.058 m3/kg WH, CMY of 0.055 m3/kg WH, and MC of 83.38% were achieved at the pH, temperature and cow dung dosage of 7.2, 47.5 °C and 0.0428 m3/m3 WH slurry. In addition, anaerobic biodegradability was found to be between 14.7 and 72.6% in all tests. Hence, Eichhornia crassipes could be a potential substrate to produce maximum biogas using cow dung.