How do scholars approach the circular economy? A systematic literature review

Waste biorefinery models towards sustainable circular bioeconomy: Critical review and future perspectives

The circular economy (CE) requires companies to rethink their supply chains and business models. Several frameworks found in the academic and practitioner literature propose circular economy business models (CEBMs) to redefine how companies create value while adhering to CE principles. A review of these frameworks shows that some models are frequently discussed, some are framework specific, and some use a different wording to refer to similar CEBMs, pointing to the need to consolidate the current state of the art. We conduct a morphological analysis of 26 current CEBMs from the literature, which includes defining their major business model dimensions and identifying the specific characteristics of these dimensions. Based on this analysis, we identify a broad range of business model design options and propose six major CEBM patterns with the potential to support the closing of resource flows: repair and maintenance; reuse and redistribution; refurbishment and remanufacturing; recycling; cascading and repurposing; and organic feedstock business model patterns. We also discuss different design strategies to support the development of these CEBMs. (Less)

A Review and Typology of Circular Economy Business Model Patterns

Food waste biorefinery: Sustainable strategy for circular bioeconomy.

Biorefineries in circular bioeconomy: A comprehensive review

Short chain carboxylic (volatile fatty) acid (VFA) production in mixed microbiomes is majorly limited by the prevalence of methanogenic bacteria and the availability of substrate from waste to the biocatalyst during the fermentation process. To enhance the VFA production from food waste, the present study evaluates a strategy for selective enrichment of the biocatalyst by exposing it to acid-shock, followed by operation under alkaline conditions (pH 10). A comprehensive system based analysis was carried out during the bio-based platform chemical synthesis from waste, in conjugation with microbial profiling and bio-electrochemical analysis. After the selective enrichment of the biocatalyst, enhanced VFA synthesis was conducted with pretreated biocatalyst (PT; 11.1 g L−1) and compared with untreated parent biocatalyst (UT; 6.1 g L−​1). In both systems biohydrogen was the co-product. Variations in the VFA profiles were documented with respect to the biocatalyst used, which influenced the degree of acidification (DOA – PT: 37% and UT: 11%). A high fraction of acetic acid (6.9 g L−1) was observed, followed by butyric acid (2.6 g L−1) and propionic acid (1.3 g L−1) in PT operation, contrary to the control system (acetic acid, 3.9 g L−1, butyric acid, 1.6 g L−1; propionic acid, 0.9 g L−1). Specifically, the PT system showed the biosynthesis of iso-valeric acid: 0.15 g L−1 (C5) and caproic acid: 1.9 g L−1 (C6), which indicates the possibility for chain-elongation through the selective enrichment of the microbial community. The PT system showed Epeak at −0.415 V on the cyclic voltammogram, which corresponds to the involvement of the redox couple, H+/H2, correlating with the enhanced acidogenic process, unlike UT. Tailoring of the parent inoculum (pretreatment) resulted in the enrichment and enhancement of the capabilities of the biocatalyst in secreting the redox mediators, which were not detected in the UT system. Acidogenic firmicutes (spore formers) and fatty acid producing bacteroides were enriched in the PT system along with saccharolytic and proteolytic bacteria (Bacillus cellulosilyticus (alkalophile), Soehngenia saccharolytica, etc.). The presence of Clostridium autoethanogenum and Propionibacterium freudenreichii in the PT system supports effective utilization of complex carbohydrates, facilitating acidification.

A. Naresh Kumar

Papers

Waste biorefinery models towards sustainable circular bioeconomy: Critical review and future perspectives

Food waste biorefinery: Sustainable strategy for circular bioeconomy.

Regulation of acidogenic metabolism towards enhanced short chain fatty acid biosynthesis from waste: metagenomic profiling

Highly efficient sulfonated polybenzimidazole as a proton exchange membrane for microbial fuel cells

Waste derived bioeconomy in India: A perspective.