Exploring biorefinery alternatives for biowaste valorization: a techno-economic assessment of enzymatic hydrolysis coupled with anaerobic digestion or solid-state fermentation for high-value bioproducts

ABSTRACT

Enzymatic hydrolysis of organic waste is gaining relevance as a complementary technology to conventional biological treatments. Moreover, biorefineries are emerging as a sustainable scenario to integrate waste valorization and high-value bioproducts production. However, their application on municipal solid waste is still limited. This study systematically evaluates the techno-economic feasibility of the conversion of the organic fraction of municipal solid waste (OFMSW) into high-value bioproducts through enzymatic hydrolysis. Two key variables are examined: (a) the source of the enzymes: commercial or on-site produced using OFMSW, and (b) the treatment of the solid hydrolyzate fraction: solid-state fermentation (SSF) for the production of biopesticides or anaerobic digestion for the production of energy. As a result, four different biorefinery scenarios are generated and compared in terms of profitability. Results showed that the most profitable scenario was to produce enzymes on-site and valorize the solid fraction via SSF, with an internal rate of return of 13%. This scenario led to higher profit margins (74%) and a reduced payback time (6 years), in contrast with commercial enzymes that led to an unprofitable biorefinery. Also, the simultaneous production of higher-value bioproducts and energy reduced the economic dependence of OFMSW treatment on policy instruments while remaining energetically self-sufficient. The profitability of the biorefinery scenarios evaluated was heavily dependent on the enzyme price and the efficiency of the anaerobic digestion process, highlighting the importance of cost-efficient enzyme production alternatives and high-quality OFMSW. This paper contributes to understanding the potential role of enzymes in future OFMSW biorefineries and offers economical insights on different configurations.

RESEARCH HIGHLIGHTS

• Techno-economic analysis to assess enzyme origin and solid hydrolysate fate.

• The viability of enzymatic hydrolysis depends on the cost and origin of enzymes.

• On-site produced enzymes cut payback time to 6 years, elevating profits by 74%.

• Anaerobic digestion and solid-state fermentation can be complementary technologies.

• High-value bioproducts are key to making organic waste biorefineries profitable.

KEYWORDS:

• Techno-economical assessment
• biorefinery
• organic fraction of municipal solid waste
• valorization
• enzymatic hydrolysis
• anaerobic digestion
• solid-state fermentation
• biopesticide
• sensitivity analysis

Acknowledgments

Esther Molina thanks Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) for her postdoctoral grant (INVESTIGO 2023).

Disclosure statement

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

Author contributions statement

Esther Molina-Peñate, Adriana Artola and Antoni Sánchez were involved in the conception and design of the study. Esther Molina-Peñate performed the data acquisition, data analysis and drafting of the manuscript. Adriana Artola and Antoni Sánchez revised it critically for intellectual content. All authors approved the final version and agreed to be accountable for all aspects of the work.

Data availability statement

The data supporting the findings of this study are available within the article and its supplementary material.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21655979.2024.2307668

Additional information

Funding

This work was supported by the Spanish Ministerio de Ciencia e Innovación (Project PID 2020-114087RB-I00).