Co-Digestion of Kitchen Waste with Grass and Leaves after Hyperthermophilic Pretreatment for Methane and Hydrogen Production

Przemysław Liczbiński,Sebastian Borowski

doi:10.3390/en14185880

Przemysław Liczbiński, Sebastian Borowski

Open Access

https://doi.org/10.3390/en14185880

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Journal: Energies	Publication Date: Sep 17, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Lodz University of Technology

Abstract

The study investigated co-digestion batch experiments using kitchen waste (KW) and garden waste (GW) collected from individual households. Grass and leaves were first subjected to a 3-day hyperthermophilic pretreatment at 70 °C and 80 °C and then co-digested with kitchen waste at 35 °C and 55 °C. The hyperthermophilic pretreatment resulted in the solubilization of organic material with the release of fatty acids, whereas the biogas yield was negligible. In the second stage, the greatest methane yield of 387 NmL/gVS was achieved for the mono-digestion of leaves, whereas the co-digestion of grass with 50% KW gave the highest hydrogen production of 88 NmL/gVS. Considering the overall process performance, the best operating conditions were established using a 3-day hyperthermophilic pretreatment at 70 °C, followed by co-digestion at 55 °C in the second stage for the mixture of 25% garden waste with 75% KW.

Highlights

With the depletion of fossil fuels and their impact on the environment, the share of energy produced from renewable sources, including biomass, increases every year.On 2 December 2015, the European Commission implemented the concept of CircularEconomy (CE) [1], which assumes the longest possible use of products and resources in order to reduce waste generation at all stages of the production process
Mainly grass and leaves, consists of lignocellulosic materials that are cheap and widely available; they are potentially attractive for methane and hydrogen production [8,9,10]
The concentrations of phosphorus and sulfur in the grass were much greater than the corresponding values for the leaves, making the former substrate more suitable for biological treatment

Summary

Introduction

With the depletion of fossil fuels and their impact on the environment, the share of energy produced from renewable sources, including biomass, increases every year.On 2 December 2015, the European Commission implemented the concept of CircularEconomy (CE) [1], which assumes the longest possible use of products and resources in order to reduce waste generation at all stages of the production process. According to the Central Statistical Office, in 2018, more than 12 thousand tons of municipal waste were generated in Poland, and this amount was 4.3% greater than in the previous year This corresponds to 325 kg of municipal waste produced per person in 2018 [5]. Mainly grass and leaves, consists of lignocellulosic materials that are cheap and widely available; they are potentially attractive for methane and hydrogen production [8,9,10]. This waste is traditionally treated by composting, in which actinomycetes and fungi provide enzymes that degrade the lignocellulosic structures. Considering the above, the codigestion of kitchen waste with hyperthermophilically pretreated grass and leaves seems to be an attractive approach to utilizing both waste types produced in individual households

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Results

Conclusion