Dark fermentation biorefinery in the present and future (bio)chemical industry

Abstract

Dark fermentation, also known as acidogenesis, involves the transformation of a wide range of organic substrates into a mixture of products, e.g. acetic acid, butyric acid and hydrogen. This bioprocess occurs in the absence of oxygen and light. The ability to synthesize hydrogen, by dark fermentation, has raised its scientific attention. Hydrogen is a nonpolluting energy carrier molecule. However, for energy generation, there is a variety of other sustainable alternatives to hydrogen energy, e.g. solar, wind, tide, hydroelectric, biomass incineration, or nuclear fission. Nevertheless, dark fermentation appears as an important sustainable process in another area: the synthesis of valuable chemicals, i.e. an alternative to petrochemical refinery. Currently, acetic acid, butyric acid and hydrogen are mostly produced by petrochemical reforming, and they serve as precursors of ubiquitous petrochemical derived products. Hence, the future of dark fermentation relies as a core bioprocess in the biorefinery concept. The present article aims to present and discuss the current and future status of dark fermentation in the biorefinery concept. The first half of the article presents the metabolic pathways, product yields and its technological importance, microorganisms responsible for mixed dark fermentation, and operational parameters, e.g. substrates, pH, temperature and head-space composition, which affect dark fermentation. The minimal selling price of dark fermentation products is also presented in this section. The second half discusses the perspectives and future of dark fermentation as a core bioprocess. The relationship of dark fermentation with other (bio)processes, e.g. liquid fuels and fine chemicals, algae cultivation, biomethane-biohythane-biosyngas production, and syngas fermentation, is then explored.

Development of an Energy Biorefinery Model for Chestnut (Castanea sativa Mill.) Shells

“…This is equivalent to 18.9 mg butyrate/g CS and would correspond to a potential daily production of 0.4 mmol/g day. Bastidas-Oyanedel et al [52] referred butyric acid as the highest valuable compound produced in DF. The reason for this are the numerous applications for butyric acid in the chemical, textile, plastic, food, beverage, dairy and pharmaceutical industries [53].…”

Evaluación del potencial acidogénico para producción de AGV de melaza de la industria azucarera como valorización de este subproducto

“…Resumo O potencial acidogênica de melaço da indústria de cana de açucar foi avaliado em 4 diferentes OLR (13,96 ± 7,11; 15,81 ± 4,83; 6,02 ± 4,33; 26,94 ± 13,27kg DQO/m 3 .d) num reator de fluxo ascendente com lodo granular. O sistema não tinha controle de pH e também nao inibição da fase metanogênica.…”

“…Una de las etapas de la digestión anaerobia poco explorada es la acidogénesis, la cual consiste en la conversión de compuestos complejos, como los aminoácidos, glucosa y ácidos grasos de cadena larga, por medio de la fermentación, en ácidos grasos volátiles (C2-C5) [2]. Los sistemas de fermentación de sustratos complejos que existen actualmente para la producción de ácidos grasos volátiles (AGV) involucran diferentes tipos de microorganismos y rutas bioquímicas [3]. En años recientes, la producción de los diferentes AGV (acético, butírico, propíonico, valérico) se ha venido estudiando por sus aplicaciones innovadoras, ya que ha sido considerada como la principal plataforma para el desarrollo de las biorefinerías debido a que son la materia prima para la obtención de biocombustibles, biomateriales y bioquímicos [1].…”

“…Las biorefinerías combinan la tecnología necesaria para convertir materias primas renovables en productos intermediarios y finales (biomateriales, biocombustibles y bioquímicos) [4]. A escala industrial, el ácido acético es ampliamente utilizado en la síntesis de una variedad de productos, como el acetato de vinilo, el cual hace parte de la producción de textiles, PVC, aditivos de cemento, pegamento blanco, bolsas de papel, entre otros [3]. Las principales aplicaciones industriales del ácido butírico son la manufactura del plástico acetato-butirato y la producción de un tipo de polímero biodegradable, que recientemente ha venido siendo explotado y es conocido como polihidroxibutirato (PHB) [4].…”

Acidogenic fermentation of Scenedesmus sp.-AMDD: Comparison of volatile fatty acids yields between mesophilic and thermophilic conditions

“…Instead, AD can be limited to the acidogenic fermentation and the VFA mix separated from the culture broth can serve as a resource for the production of valuable products such as ketones, esters or alcohols (Agler et al, 2011;Bastidas-Oyanedel et al, 2015).…”