Bio hydrogen generation from kitchen waste in an inclined plug flow reactor

https://doi.org/10.1016/j.ijhydene.2009.08.048Get rights and content

Abstract

The performance of inclined plug-flow reactor of 0.15 m3 for hydrogen generation from kitchen waste using 100 °C heat treated biogas plant slurry as inoculum under solid phase anaerobic digestion was studied. The reactor pH stabilized at 5.6 after 21 days of its operation. 40% VS degradation was obtained and it generated 72 mL H2/gVS added. The soluble metabolites in the reactor were predominantly butyric acid (45–50%), acetic acid (20–30%) and propionic acid (10–20%).

Introduction

Waste materials such as food wastes, industrial wastes, wastewater treatment plant wastes and municipal solid wastes having higher fraction of biodegradable as well as carbonaceous materials are used for anaerobic digestion to generate methane [14]. The use of methane as a fuel could be debatable, due to its global warming potential. This calls for study of alternate eco friendly, high efficiency future energy options such as biohydrogen. Hydrogen is a clean fuel since its combustion does not generate polluting emissions. According to energy experts, hydrogen is safe, versatile and has high-energy content as well as high utilization efficiency [1].

Much recent interest has been expressed in the biological generation of hydrogen from waste materials by dark fermentation, due to its potential importance in economy [2], [3], [4], [5]. Though the conventional low solid anaerobic digestion is a proven technology for methane generation from Municipal Solid Waste (MSW) the technology for solid phase anaerobic digestion system has not yet been developed. This paper presents the feasibility of solid phase anaerobic digestion for generating hydrogen from kitchen waste using an inclined plug flow reactor.

Section snippets

Characterisation of kitchen waste

The kitchen waste used as the feedstock was collected from kitchen of a hostel with around 1000 inhabitants. The composition of the kitchen waste was studied by manual segregation. The kitchen waste was analysed for moisture content, pH, carbon, nitrogen, total solids and volatile solids as per standard methods [6].

Inclined plug flow reactor

A pilot scale Inclined plug flow reactor was used for the hydrogen generation study. The principal objective of developing such a design was to achieve a low initial investment, high

Characteristics of kitchen waste

The average composition and characteristics of kitchen waste used for this study is depicted in Table 1, Table 2 respectively. The waste consisted of about 96% of biodegradable organics, which were suitable for anaerobic digestion system [7]. The food waste was around 66% of the total waste. Vegetable waste was around 27% of the total waste. The egg shell, packing material and ash content were around 1.1%, 1.4% and 3.6% of the total waste respectively.

The optimal pH reported in literature for

Conclusion

The yield of hydrogen was observed around 72 mL H2/gVSadded in the pilot scale inclined plug-flow reactor. Hydrogen concentration of around 46 ± 7% was found in the biogas and the rest was CO2. The maximum hydrogen generation from kitchen waste was observed in the pH of 5.5–6.0. TVFA generated contains only butyric acid, acetic acid and propionic acid. The hydrogen generation was followed the butyric acid pathway. From the findings it is evidenced that the inclined plug-flow reactor is suitable

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