Hydrogen is regarded as a promising fuel in the future since it is renewable and non-pollution. Utilization of food waste as substrate for dark fermentative hydrogen production could not only solve the food waste problem, but also generate the clean energy. However, nutrients stored in the food waste are in the form of macromolecules (such as starch and protein) which have to be degraded into utilizable forms (such as glucose and free amino nitrogen) before used by microorganisms for dark fermentative hydrogen production (Han et al., 2015a). Although some reported pretreatments are able to convert the macromolecules into micromolecules, various inhibitory products (such as furfural) could also be generated.
In our previous study, we have successfully developed a novel combined bioprocess based on solid state fermentation for dark fermentative hydrogen production from food waste (Han et al., 2015b). Food waste is first used to produce glucoamylase and protease by Aspergillus awamori and Aspergillus oryzae via solid-state fermentation. The produced gluoamylase and protease are utilized to hydrolyze food waste to get the food waste hydrolysate rich in glucose and free amino nitrogen (FAN). Subsequently, the food waste hydrolysate is used as substrate for dark fermentative hydrogen production by heat pretreated sludge.
Obviously, more hydrogen yield could be achieved using glucose solution (food waste hydrolysate) rather than direct food waste solid as substrate. Furthermore, other reported pretreatments could solubilize part of the starch contained in the food waste, while a large amount of starch remains in the solid phase. In our previous study, the starch conversion efficiency of the food waste could reach 82.8-87.2% by using enzymatic hydrolysis within 24 h. The proposed bioprocess could effectively accelerate the hydrolysis rate of food waste, improve raw material utilization and enhance hydrogen yield (Han et al., 2015c).
In this study, the techno-economic evaluation of fermentative hydrogen production from food waste via the novel combined bioprocess was investigated. The total capital investment of US$583092 and the total production cost of US$88298.1/year were calculated, respectively. The total revenue was US$234771.7/year, which included the sales of 42858 m3 H2/year, 547500 kg solid biomass/year and the received waste treatment charge (US$17644/year). The return on investment was 26.75%, the breakeven of the capital investment was 5 years and the internal rate of return was 24.07%. The production plant reached shutdown point when the food waste feed was less than 0.3 ton/day. The results exhibited that the combined bioprocess for hydrogen production from food waste was feasible. This is an important study for attracting investment and industrialization interest for hydrogen production from food waste in the industrial scale.
The previous studies stated above
Han, W., Lam, W.C., Melikoglu, M., Wong, M.T., Leung, H.T., Ng, C.L., Yan, P., Yeung, S.Y., Lin, C.S.K., 2015a. Kinetic analysis of a crude enzyme extract produced via solid state fermentation of bakery waste. ACS Sustain. Chem. Eng. 3, 2043-2048.
Han, W., Liu, D.N., Shi, Y.W., Tang, J.H., Li, Y.F., Ren, N.Q., 2015b. Biohydrogen production from food waste hydrolysate using continuous mixed immobilized sludge reactor. Bioresour. Technol. 180, 54-58.
Han, W., Ye, M., Zhu, A.J., Zhao, H.T., Li, Y.F., 2015c. Batch dark fermentation from enzymatic hydrolyzed food waste for hydrogen production. Bioresour. Technol. 191, 24-29.
Figure Legend: The proposed bioprocess flow of the fermentative hydrogen production from food waste. The mass balance of the plant in each unit was marked (Red: input; Green: output).
Wei Han, Jun Fang, Zhixiang Liu, Junhong Tang.
College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China
In this study, the techno-economic evaluation of a combined bioprocess based on solid state fermentation for fermentative hydrogen production from food waste was carried out. The hydrogen production plant was assumed to be built in Hangzhou and designed for converting 3 ton food waste per day into hydrogen. The total capital cost (TCC) and the annual production cost (APC) were US$583092 and US$88298.1/year, respectively. The overall revenue after the tax was US$146473.6/year. The return on investment (ROI), payback period (PBP) and internal rate of return (IRR) of the plant were 26.75%, 5 years and 24.07%, respectively. The results exhibited that the combined bioprocess for hydrogen production from food waste was feasible. This is an important study for attracting investment and industrialization interest for hydrogen production from food waste in the industrial scale.Go To Bioresource Technology