Anaerobic Fermentative Hydrogen Production From Glucose And Apple Residue

Hydrogen is a clean and renewable energy with many advantages, e. g. the higher combustion value and the several storage forms. With the development of economy, the traditional resource is facing with exhaustion and the demand of the new energy has become more and more imminent, so people expect to find new substitute energies. Fermentative hydrogen production resolves the organic waste by biological technology to realize the aim of preparing bioenergy and reducing waste. The key of the technology is to increase the cumulative hydrogen yield and the average hydrogen production rate of the substrate.The hydrogen productions of glucose and apple residue were investigated through anaerobic fermentation by using natural sludge obtained from the bed of a local river as inoculant. One-step method (the cultivation of hydrogen-producing bacteria and the process of fermentative hydrogen production carried on continuously in the same reactor) which was different from the method adopted by most studies was used in this study. The effects of the substrate concentration and the pH value on hydrogen production from glucose and the effects of hydrochloric acid concentration, enzymatic time, enzymatic temperature and substrate concentration on hydrogen production from apple residue were also discussed in this paper.Substrate concentration and pH value were the key factors influencing on the hydrogen production through the anaerobic fermentation of glucose. (1) Under the condition of pH changing naturally with the time increasing, an ideal hydrogen production with great efficiency, a cumulative hydrogen yield of 1.85 mol-H₂·mol^-1 -glucose and an average hydrogen production rate of 0.086 mol-H₂·mol^-1-glucose·h^-1, was reached when the initial pH value was 7.0 and the substrate concentration was 7.5 g-glucose·l^-1. (2) When the pH value was kept constantly during the fermentation process, an optimal hydrogen-producing condition for the glucose fermentation, the substrate concentration of 7.5 g-glucose·l^-1 at a constant pH value of 6.0, was obtained, under which the corresponding cumulative hydrogen yield was 1.83 mol-H₂·mol^-1 -glucose and the average hydrogen production rate was 0.22 mol-H₂·mol^-1-glucose·h^-1.Comparison of the experimental results, related apple residue fermentation showed that the concentration of hydrochloric acid to pretreatment apple residue, the temperature and time of enzyme hydrolysis to apple residue and the substrate concentrations had a great influence on the hydrogen production from the fermentation of apple residue. An ideal hydrogen production with a cumulative hydrogen yield of 3.84 mmol-H2·g^-1-TS and an average hydrogen production rate of 0.30 mmol-H2·g^-1-TS·h^-1 was reached and the optimal hydrogen production condition was proposed as follows: 1 Firstly, the substrate was heated by an aqueous solution of 0.6% HCl for 2 hours at 70℃(the ratio of solid to liquid was 1 g:10 ml), and then hydrolyzed for 48 hours by enzyme catalyst (the ratio of substrate to enzyme was 100:1) at a pH value of 5.0 and a temperature of 45℃; 2 The substrate after enzyme hydrolysis, i. e., the enzyme converted apple residue with a substrate concentration of 15 g·l^-1 was fermented at an initial pH of 7.0 and a temperature of 37℃.