Harnessing water hyacinth for biogas and bioslurry generation: experimental insights on biomass characterization and crop yield enhancement

This study explored the physicochemical characterization of several components of water hyacinth and its biogas potential in batch and semi-continuous mode.The effect of the bioslurryfrom the continuous digesters were evaluated on the crop biomass yield. In the batch studies, several portions of water hyacinth, such as complete fresh biomass leaf stem and root, were evaluated to identify the most effective components for biogas and bioslurry generation.

The semi-continuous trials used two stainless steel digesters, each with a capacity of 650 L, to produce biogas and bioslurry.The anaerobic digestion process required semi-continuous feeding of substrate and other materials, as well as regular monitoring of gas flow rate, temperature, total solid, volatile solid, and pH levels.The generated biogas and bioslurry were thoroughly characterised.

The results reveal that the whole fresh biomass has substantial potential for biogas and bioslurry generation. The fresh stem produced the highest biogas and methane yields, with values of 597 and 326 LN/kgVS (litres normalised per kilogramme of volatile solids), respectively.The biogas exhibited an average methane and carbon dioxide quality of 59.2 ± 0.2 % and 38.9 ± 0.2 %, respectively, with a minimum concentration of 1.0 ± 0.8 ppm for hydrogen sulphide.Bioslurry application yields the highest yield (169.43 kg/ha± 3.5) for Teff crops, followed by mineral fertiliser (159.43 kg/ha± 5.03) from a 0.0006 hectare area. As a result, our findings provide useful insights into the practical application of water hyacinth as a sustainable source of biogas generation and bioslurry as an organic fertiliser to increase agricultural productivity.