Effects of substrate components on hydrogen fermentation of multiple substrates

Abstract

As is well known, carbohydrate is the most appropriate organic material for hydrogen fermentation, and its hydrogen yield is significantly larger than that of protein. The fermentation of protein began with hydrogen production followed by hydrogen consumption, which helps overall hydrogen recovery. Both carbohydrate and protein are basic components of organic material, and yet carbohydrate is known to be a better substrate than protein in terms of hydrogen yield during hydrogen fermentation. This study used multiple substrates containing different ratios of glucose and peptone as multiple substrates to investigate the roles played by carbohydrate and protein in hydrogen fermentation. The experimental results demonstrated that suitable ratios of glucose and peptone improved the growth of hydrogen producing bacteria. Additionally, a maximum hydrogen yield of 6.4 mmole-H2/g-COD was obtained from the multiple substrate containing 40% peptone and 60% glucose. Most of the produced hydrogen came from fermentation of glucose, not peptone. During hydrogen fermentation, the pH dropped by 1.0 and 1.9 units in 80% and 20% of peptone content in the substrate. Ammonia produced due to peptone degradation neutralized the acids produced from hydrogen fermentation.

Biological hydrogen production of the genus Clostridium: Metabolic study and mathematical model simulation

“…The estimated kinetic parameters for different Clostridium species suggest that C. beijerinckii L9 possessed a kinetic advantage in competing glucose with the other three strains because of its highest q max G and relatively low K Glu values. The estimated biomass yield coefficients (Y ) were within the range of reported values for acid producing bacteria (0.239-0.68) [33][34][35][36][37], but were higher than that of ADM1 (0.083 mmol/mmol), probably due to the biomass yield contributed by peptone metabolism [29,38]. Using bioenergetic calculations according to McCarty [39] and assuming glucose as the sole substrate, a theoretical true yield of 0.278 mmol/mmol for acid producing bacteria was obtained and the value was comparable to the estimated values listed in Table 3.…”

“…Corresponding to VFA production, the medium pH decreased from 7.2 to a value between 4.6 and 5.0. Release of ammonia nitrogen was insignificant during the BHP test, indicating that peptone was primarily utilized for biosynthesis of biomass [28,29]. The patterns of BHP test results for C. acetobutylicum M121 and C. tyrobutyricumi FYa102 isolates were very similar to those observed for C. butyricum ATCC19398 and C. beijerinckii L9 as shown in Fig.…”

Evaluation of biohydrogen production from glucose and protein at neutral initial pH

“…The electrons produced by oxidation of amino acids would be consumed by the reduction of others amino acids, thereby leading to few available electrons for the production of hydrogen via ferrodioxin and hydrogenase [24]. In other words, hydrogen may be produced and/or consumed during the anaerobic degradation of protein [18,25]. Additionally, initial pH is an important factor that influences hydrogen consumption in the anaerobic fermentation of protein.…”

Hydrogen and methane potential based on the nature of food waste materials in a two-stage thermophilic fermentation process

“…In addition, the existence of protein in the substrate is important for biohydrogen production since it provides a nitrogen source that enhances the growth and activity of H 2 -producing bacteria [7]. Kim et al [8] indicated that adding sewage sludge to enrich protein enhances the H 2 production potential, and obtained a 111.2 ml H 2 /g VSS/h specific H 2 production rate with the codigestion of food waste and sewage sludge.…”