Economic and environmental assessment of bacterial poly(3-hydroxybutyrate) production from the organic fraction of municipal solid waste

Jon Kepa Izaguirre,José A L Santos,Carlos Garbisu,Itziar Alkorta,M Manuela R Da Fonseca,Leire Barañano,M Teresa Cesário,Sonia Castañón

doi:10.1186/s40643-021-00392-4

Abstract

The management of municipal solid waste is a major logistic and environmental problem worldwide. Nonetheless, the organic fraction of municipal solid waste (OFMSW) is a valuable source of nutrients which can be used for a variety of purposes, according to the Circular Economy paradigm. Among the possible applications, the bioproduction of a biodegradable polyester, poly(3-hydroxybutyrate) [P(3HB)], using OFMSW as carbon platform is a promising strategy. Here, an economic and environmental assessment of bacterial P(3HB) production from OFMSW is presented based on previously published results. The SuperPro Designer® software was used to simulate P(3HB) production under our experimental parameters. Two scenarios were proposed depending on the fermentation medium: (1) enzymatic hydrolysate of OFMSW supplemented with glucose and plum waste juice; and (2) basal medium supplemented with glucose and plum waste juice. According to our results, both scenarios are not economically feasible under our experimental parameters. In Scenario 1, the low fermentation yield, the cost of the enzymes, the labour cost and the energy consumption are the factors that most contribute to that result. In Scenario 2, the cost of the extraction solvent and the low fermentation yield are the most limiting factors. The possibility of using process waste as raw material for the generation of other products must be investigated to enhance economic feasibility. From an environmental viewpoint, the photochemical oxidation potential (derived from the use of anisole as extraction solvent) and the generation of acid rain and global warming effect (caused by the burning of fuels for power generation) are the most relevant impacts associated to P(3HB) production under our experimental parameters.

Highlights

Due to the development of science and technology, many industrial and commercial activities have undergone great growth and innovation in the last decades.Regrettably, such growth has been accompanied in many cases by an adverse environmental impact and, in particular, the generation of extremely large volumes of wastes
Glucose and sugar-rich plum waste juice were added as feed to enhance productivity; (2) in Scenario 2 (Additional file 2: Fig. S2B), the enzymatic hydrolysate from OFMSW was not used as fermentation medium
Total equipment cost was US$ 1,066,000 and US$ 764,000 for Scenario 1 and 2, respectively. This difference is due to the fact that, in Scenario 2, the thermo-chemical pre-treatment and the enzymatic hydrolysis steps were not performed, as this scenario did not include the use of OFMSW hydrolysate as fermentation medium

Summary

Introduction

Due to the development of science and technology, many industrial and commercial activities have undergone great growth and innovation in the last decades.Regrettably, such growth has been accompanied in many cases by an adverse environmental impact and, in particular, the generation of extremely large volumes of wastes. Relatively recently, the concept of Bioeconomy, based on the utilization of renewable biological resources and waste streams to produce food, feed, materials and energy has been emphasized and supported as a way to achieve a more sustainable, greener economic model which can boost the creation of new value chains, while protecting biodiversity and the environment The merging of these two “Guiding Principles” (Circular Economy and Bioeconomy) in the current economy arena has led to the term Circular Bioeconomy focused on a sustainable, resourceefficient valorization of biomass in integrated production chains and chain networks, while making use of wastes and optimizing (ideally, considering the three pillars of sustainability) the value of biomass over time via cascading, in an attempt to retain resource quality by adhering to the bio-based value pyramid and the waste hierarchy where feasible and suitable (Stegman et al 2020)

Methods

Results

Conclusion