An expanded granular sludge bed (EGSB) and modified continuous stirred tank reactor (MCSTR) were investigated with respect to the treatment of water hyacinth juice (WHJ) and water hyacinth residue (WHR), to promote the utilisation of water hyacinth as a resource and control its excessive growth. The results revealed that EGSB and MCSTR can efficiently manage WHJ and WHR. The energy recovery efficiency of water hyacinth was 21.10 m(3) biogas/t, wherein the WHJ in EGSB produced 0.190 m(3) biogas/kg chemical oxygen demand, and the WHR in MCSTR generated 397 mL biogas/g total solid. Highthroughput sequencing analyses indicated that the MCSTR and EGSB had similar dominant microbial composition in the hydrolytic acidification phase, while genus norank_o__NB1-n was unique to the MCSTR. The methanogenesis metabolic pathways of WHR contained both acetoclastic methanogenesis and hydrogenotrophic methanogenesis, where the dominant functional microorganisms were Methanosaeta and Methanobacterium, respectively. However, the methanogenetic metabolic pathways of WHJ involved only acetoclastic methanogenesis, with Methanosaeta as the dominant functional microorganism. A novel processing technology for the sustainable utilisation of water hyacinth was successfully established. This technology allowed for substance circulation and energy exchange in the ecosystem and is suitable for industrial applications owing to its performance, cost, and environment-friendly characteristics. (C) 2020 Elsevier Ltd. All rights reserved.