Valorization of Water Hyacinth to Biomethane and Biofertilizer Through Anaerobic Digestion Technology

•Cow and poultry manures were used as co-substrates to promote methane production and digestate quality.•Codigestion and the pretreatment method increased the methane production and improved the digestate quality.•Codigestion of the aerial part of water hyacinth resulted in the highest methane production at 25% poultry waste.•A low concentration of KOH pre-treatment (1.5%) improves break down of lignocellulosic materials and reduces retention times.•The Alkali-thermal pretreatment increased the concentration of calcium and the assimilable (P2O5) and reduces heavy metals in the digestate.