Cogeneration of H_2 and CH_4 from water hyacinth by two-step anaerobic fermentation

摘要

A novel reaction mechanism of H_2 and CH_4 cogeneration from water hyacinth (Eichhornia crassipes) was originally proposed to increase the energy conversion efficiency. The glucose and xylose hydrolysates derived from cellulose and hemicellulose are fermented to cogen-erate H_2 and CH_4 by two-step anaerobic fermentation. The total volatile solid of hyacinth leaves can theoretically cogenerate H_2 and CH_4 yields of 303 ml-H_2/g-TVS and 211 ml-CH_4/ g-TVS, which dramatically increases the theoretical energy conversion efficiency from 19.1% in only H_2 production to 63.1%. When hyacinth leaves are pretreated with 3 wt% NaOH and cellulase in experiments, the cogeneration of H_2 (51.7 ml-H_2/g-TVS) and CH_4 (143.4 ml-CH_4/ g-TVS) markedly increases the energy conversion efficiency from 3.3% in only H_2 production to 33.2%. Hyacinth leaves, which have the most cellulose and hemicellulose and the least lignin and ash, give the highest H_2 and CH_4 yields, while hyacinth roots, which have the most ash and the least cellulose and hemicellulose, give the lowest H_2 and CH_4 yields.