Biogas production by co-digestion of sodium hydroxide pretreated Napier grass and food waste for community sustainability

ABSTRACT

Community agricultural waste-to-energy management, especially in developing countries, can respond to sustainable development goals by the United Nations. Co-digestion techniques for waste from phytomass in fields as Napier grass (NP) and debris from consumption in the community as food waste (FW) into biogas production by conventional anaerobic digestion technology contribute to sustainable energy communities. However, lignocellulose requires proper pretreatment of the material type. Therefore, low sodium hydroxide (NaOH) concentration for Napier grass pretreatment and varying the co-digestion ratio with food waste from the community under conventional batch conditions were optimized to be economically cost-effective with elementary technology. The results showed the highest methane yield at 0.285 m³/kg VS_added at the 4% concentration of sodium hydroxide pretreatment with significant content of FW added with biomass. The best conditions of co-substrates can increase methane yields by up to 3.54 times compared to a single substrate. The energy and cost estimation based on energy consumption and chemical input cost showed that co-digestion with NaOH pretreatment could achieve the net benefits by increasing the biogas production (242 US$/tonne TS). This study confirms the application of waste management in agricultural communities that can be used as fuel in households to increase biogas and economic value. The authors expect this work to be a successful case study for further results that lack government financial support and limitations of advanced technology for a sustainable community.

Graphical abstract

KEYWORDS:

• Waste to energy
• Napier grass
• food waste
• sodium hydroxide pretreatment
• biogas production
• co-digestion

Highlights

• Napier grass and food waste are high potential materials for biogas production.

• Methane yield was improved after alkaline pretreatment with NaOH concentration of 4% and 60 min

• Co-digestion substrates enhance to improve the potential of biogas production between Napier grass and food waste.

• The optimal mixing ratio of NP-NaOH and FW was 1:3.

Acknowledgments

This research was financially supported by the Technology Clinic Fund 2019–2021 (Platform: Building Community Enterprise and VC Community Incubator). The authors are thankful for the support received from the Faculty of Engineering of Rajamangala University of Technology Thanyaburi (RMUTT) and Ayutthaya Elephant Palace, and Royal Kraal for their facilities and materials. Sincere appreciation also goes to Miss Ratchadaphon Rudtee, Mr Nipithpon Panon, Miss Apichaya Wanchai, and Miss Kaewsiri Chotikarn for technical assistance. The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper. The authors have fully disclosed those interests to Taylor & Francis and have an approved plan to manage any potential conflicts arising from this arrangement.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

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