1,721,017 research outputs found
H2S-laden biogas triggers sulfur amino acids production in microbial protein synthesized during mixed culture fermentation by methane and sulfur oxidizing bacteria
No full textValorisation of industrial hemp (Cannabis sativa L.) biomass residues through acidogenic fermentation and co-fermentation for volatile fatty acids production
No full textIn line with the emerging circular bioeconomy paradigm, the present study investigated the valorisation of abundant hemp biomass residues (HBRs) such as hurds (HH) and a mix of leaves and inflorescences (Mix), and other organic wastes (i.e., cheese whey and grape pomace) through the volatile fatty acid (VFA) production in mono- and co-acidogenic fermentation. The highest VFA yields, measured as acetic acid (HAc) per unit of volatile solids (VS), were obtained with the untreated Mix in mono-fermentation (185±57 mg HAc/g VS) and with the combination of Mix and CW in co-fermentation (651±65 mg HAc/g VS), while the highest HAc percentage reached up to 94% of total VFAs. Finally, a preliminary techno-economic evaluation revealed that the mono-fermentation of alkali pretreated HH could lead to the highest revenues among HBRs, reaching up to 710-1810, 618-1577 and 766-3722 €/ha∙year for the production of HAc, single cell protein and polyhydroxybutyrates, respectively
From residue to resource: The multifaceted environmental and bioeconomy potential of industrial hemp (Cannabis sativa L.)
No full textIn the emerging context of circular bioeconomy, industrial hemp (Cannabis Sativa L.) biomass is a valuable resource for the sustainable implementation of second-generation biorefineries. Potentially, all the main hemp components can find application within different biorefinery approaches, adding value to the conventional production of hemp fibres and seeds. Hurds, leaves and inflorescences, constituting most of the hemp plant biomass, and often considered as low-value residues, can indeed play a key role in the sustainable production of both bioenergy and high-value bioproducts. The present article reviews the advances and outlines the potential future perspectives of hemp-based biorefineries. After critically overviewing some of the most established applications of hemp, spanning from soil bioremediation to bioenergy and biofuel production, particular attention is given to novel valorisation schemes to synthetize highly demanded bioproducts such as microbial protein and biopolymers. Our preliminary calculations show that hemp biomass can sustain high biodiesel yield (1.6 g/g VS (volatile solids)) and related revenues (510–868 €/ha•year), while bioethanol production can yield 0.10–0.33 mL/g VS, profiting between 75–325 €/ha•year. Moreover, hemp suits biomethane production by yielding and profiting 98–426 mL/g VS and 60–380 €/ha•year, respectively. High yields of polyhydroxybutyrate (0.13 g/g VS) can be obtained, albeit high production costs might restrain their marketability. Finally, the biomethane-to-microbial protein pathway can yield and profit 0.03–0.15 g/g VS and 141–893 €/ha•year, respectively, while the volatile fatty acids-to-microbial protein pathway 0.04 g/g VS and 91–362 €/ha•year
Sulfur-containing microbial protein production from sulfide-rich biogas in hollow fiber membrane bioreactors
No full textAnaerobic digestion of organic waste can unlock the upcycling of waste resources through the valorization of biogas into value-added products. This study proposed the conversion of sulfide-rich biogas into microbial protein (MP) through a microbial fermentation process carried out in hollow fiber membrane bioreactors by means of a consortium of methane- and sulfur-oxidizing bacteria, characterized by the dominance of Methylocystis spp. and Chryseobacterium spp. The efficiency of the gas-to-liquid mass transfer and the effects of biofilm formation on gas diffusion, as well as the effects of gas loading rate (10 L/d and 15 L/d) and sulfide content of the biogas (1500, 3000 and 4000 ppm of H2S) on the fermentation performance were evaluated. Biomass concentrations up to 768.5 (± 17.2) mg of volatile suspended solids (VSS) per liter were achieved when treating biogas containing 1500 ppm of H2S. Increasing sulfide concentrations (up to 4000 ppm of H2S) had negligible effects on the biomass productivity and yield. The biomass had a high protein (up to 64.7 %) and amino acids (up to 510.3 mg/g VSS) content, with beneficial effects of H2S on the content of sulfur-containing amino acids. Switching from 1500 ppm to 4000 ppm of H2S increased the content of methionine and cysteine by 57 % and 39 %, respectively
Biowaste upcycling into second-generation microbial protein through mixed-culture fermentation
No full textSecuring a sustainable protein supply at the global level is among the greatest challenges currently faced by humanity. Alternative protein sources, such as second-generation microbial protein (MP), could give rise to innovative circular bioeconomy practices, synthesizing high-value bioproducts through the recovery and upcycling of resources from overabundant biowastes and residues. Within such a multi-feedstock biorefinery scenario, the wide range of microbial pathways and networks that characterize mixed microbial cultures, offers interesting and not yet fully explored advantages over conventional monoculture-based processes. In this review, we combine a comprehensive analysis of waste recovery platforms for second-generation MP production with a critical evaluation of the research gaps and potentials offered by mixed culture-based MP fermentation processes
Exploring the biomethane potential of different industrial hemp (Cannabis sativa L.) biomass residues
Full text linkIndustrial hemp stands out as a promising candidate for clean and sustainable biomass-to-bioenergy systems due to its multipurpose, high biomass yield and resource efficiency features. In this study, different hemp biomass residues (HBRs) were evaluated as a potential feedstock for renewable biomethane production through anaerobic digestion (AD). The biochemical methane potential (BMP) of the raw and pretreated fibers, stalks, hurds, leaves and inflorescences was investigated by means of batch anaerobic tests. The highest BMP was obtained with the raw fibers (i.e., 422 ± 20 mL CH4·g VS-1), while hemp hurds (unretted), making up more than half of the whole hemp plant dry weight, showed a lower BMP value of 239 ± 10 mL CH4·g VS-1. The alkali pretreatment of unretted hurds and mechanical grinding of retted hurds effectively enhanced the BMP of both substrates by 15.9%. The mix of leaves and inflorescences and inflorescences alone showed low BMP values (i.e., 118 ± 8 and 26 ± 5 mL CH4·g VS-1, respectively) and a prolonged inhibition of methanogenesis. The latter could be overcome through NaOH pretreatment in the mix of leaves and inflorescences (+28.5% methane production)
Protein from microscopic sources—a realistic scalable solution?
No full textAmong the different possible alternative protein sources, a microbial protein (MP) obtained from bacteria, fungi (filamentous fungi and yeast), and microalgae, represents a highly efficient and potentially abundant protein source for both animal and human nutrition. The present chapter overviews and discusses the main aspects of MP production from various microorganisms, including their positioning in the nascent and fast-growing alternative protein industry. The chapter further explores and discusses the possibilities offered by the MP platform in relation to the nascent circular bioeconomy framework, particularly in relation to the European context. Finally, the main issues and obstacles that must be faced and overcome to bring MP to commercialization are evaluated in terms of technological, regulatory, and social aspects
Novel photo-chemoautotrophic system combining microalgae and hydrogen oxidizing bacteria for microbial protein production from carbon dioxide
Full text linkThis study investigated the production of microbial protein (MP) using a novel microbial consortium composed of microalgae and hydrogen-oxidizing bacteria (HOB). This photo-chemoautotrophic consortium was aimed at capturing and valorising carbon dioxide (CO2) while overcoming typical limitations of each microbial group. Batch tests were run under varying gas mixtures of oxygen (O2), CO2 and hydrogen (H2) to assess process performance in terms of biomass growth, nitrogen assimilation, gas consumption, final biomass and microbial community composition. The consortium was compared to the single microalgae and HOB cultures grown under photo- and chemoautotrophic conditions, respectively. The consortium achieved significant growth (5.5 g VSS/L) under a non-explosive gas mixture, reaching a protein content of 40.3 ± 8.5 %. The consortium achieved up to 1.8- and 10-times higher biomass growth compared to the single microalgae and HOB cultures, respectively, showing a higher CO2 consumption and stimulating photosynthetic O2 production
Ammonia stripping from buffalo manure digestate for future nitrogen upcycling into bio-based products
No full textMitigating ammonia emissions from the livestock sector offers the opportunity to combine environmental protection with resource recovery through emerging circular bioeconomy approaches. In this work, we tested the potential of low-rate stripping techniques to enable techno-economically feasible nitrogen recovery and valorization from buffalo manure digestate. The proposed process achieved more than 80% ammonia stripping at mild temperatures (35-55 °C) and without the need of caustic agents to increase pH. Coupling such low-rate ammonia stripping with innovative biological resource valorization processes could offer interesting future perspectives
Biovalorization of Lignocellulosic Waste
Full text linkThe swift and successful transition towards a fossil fuel-free economy is amongst the most complex challenges ever faced by humanity, implicating intricate connections and trade-offs with the so-called water–energy–food nexus [...
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