Valorisation of digestate from biowaste through solid-state fermentation to obtain value added bioproducts: A first approach

Abstract

Digestate from biowaste was assessed as a potential source of bioproducts of commercial and industrial interest through solid-state fermentation. The targeted bioproducts were hydrolytic enzymes (cellulases and proteases from autochthonous microbiome), biosurfactants (sophorolipids produced from Starmella bombicola) and biopesticides (produced from Bacillus thuringiensis). Low cellulase production was observed within the range of 0.5-1.5 FPU g -1 DM while protease production showed two discrete peaks of 66±8 and 65±3 U g -1 DM at 3.5 and 48h, respectively. Low sophorolipids production was also obtained, with a maximum yield of 0.02 g g -1 DM using hygienised digestate supplemented with external sugar and fat sources. Biopesticides produced by B.thuringiensis were successfully at 72h of operation, reaching a maximum spore production of 8.15±0.04 (10 7 ) CFU g -1 DM and 2.85±0.22(10 7 ) CFU g -1 DM using sterile and hygienised digestate, respectively. These biopesticides could contribute to the substitution of chemically produced pesticides, moving towards a sustainable digestate management in a circular economy scheme.

Process Waters from Hydrothermal Carbonization of Sludge: Characteristics and Possible Valorization Pathways

“…Moreover, depending on the size of the biogas plant, on the transportation costs and on the type of initial feedstocks, application of digestate on the field is not always economically feasible or allowed. In this sense, the importance of digestate management has been recognized by research and policy institutions, requiring a more sustainable approach to be adopted, mainly considering this waste as a feedstock for further bio-transformation [ 8 ] and thermal transformation [ 9 ] in a circular economy framework.…”

Pathogen Reduction Potential in Anaerobic Digestion of Organic Fraction of Municipal Solid Waste and Food Waste

“…AD reduces the abundance of pathogens, contributing to more hygienic crops. Pre-sanitation is also important when the digestate is used as a feedstock for further biotransformation through SSF [20], torrefaction, or pyrolysis [21].…”

“…Due to the emerging limits of using digestates the fertilizer, a novel approach which uses digestate as a feedstock for further biotransformation through solid-state fermentation (SSF) is currently under consideration [20]. SSF can be an attractive technology.…”

“…SSF can be an attractive technology. It allows the use of solid substrates for biotransformation into value-added bioproducts, such as: Hydrolytic enzymes, biosurfactants, aromas, biopesticides, or bioplastics [20]. Moreover, application of torrefaction or the pyrolysis for recycling biowaste formed during AD, is currently considered as another digestate management path [21].…”

Innovative Production of Bioproducts From Organic Waste Through Solid-State Fermentation

“…Another studied bioproduct are biopesticides, especially those derived from Bacillus thuringiensis. There are several reports on this subject, using many different organic wastes as the substrates such as soy fiber (Ballardo et al, 2017), biowaste (Ballardo et al, 2017) or even biowaste digestate (Cerda et al, 2019). The most interesting are those using complex substrates such as those derived from biowaste.…”