Bio-based circular economy

Developing a treatment technology which minimizes the production of by-product (waste) is need of an hour. In this study, municipal yard waste (primary raw material) was microwave-pretreated before anaerobic digestion (AD) to improve biogas production. The anaerobically digested, Pretreated Yard Waste (PTY) and the Untreated Yard Waste (UTY) (waste/secondary raw material) was Hydrothermally Carbonized as a downstream treatment technique to produce energy rich hydrochar. The Hydrothermal carbonization (HTC) was conducted at a temperature of 180 °C and 200 °C for 6 h to produce carbon-rich hydrochar. Physicochemical, structural and combustion properties of PTY and UTY hydrochar were characterized and compared using a range of techniques to gain detailed insight into individual hydrochar samples. Microwave pretreatment of yard waste enhanced the biogas production from 264 ± 11 mL/g VS to 370 ± 14 mL/g VS. The carbon content and higher heating value of digestate increased considerably from 44 to 44.35% to 53–56% and15–16 MJ/kg to 21–23 MJ/kg, respectively after HTC. Thermal gravimetric analysis of the prepared hydrochar showed that the high-temperature carbonization increased the combustion properties of hydrochar. The hydrochar prepared from PTY showed enhanced physicochemical, structural and combustion properties as compared to hydrochar prepared from UTY. The finding asserted that the pretreatment of yard waste before AD not only improved biogas production but also improved yield with better quality hydrochar when its resulting digestate was hydrothermally carbonized.AD of yard waste yields biogas and HTC of the resulting digestate yields hydrochar; both are biofuel, hence, augmenting HTC as a downstream treatment process along with AD would result in the creation of near-zero loss process.

Food waste (FW) is difficult to manage during thermal treatment. In this study hydrothermal carbonization (HTC) of FW was carried out at increasing temperatures and retention times using the approach of reaction severities (logR0 = 5.31–7.09). The hydrochar sample with the best-obtained energy yield was further pelletized using molasses as a binder at different ratios (5%, 10%, 20% and 30%). A conceptual framework was proposed using the circular economy concept. As severity increases, hydrochar yield declines while its fuel properties improve. Decarboxylation and dehydration allow functional groups to become impaired, including C-O and –OH. Carbon microspheres were observed on the hydrochar surface due to extensive FW carbonization. The pellets with 30% molasses as binder showed the highest mass density (1683.24 kg/m3), while the energy density for it was 37.54 GJ/m3. Food waste management will generate local employment and new business prospects by integrating HTC and pelletization.

In this paper we inquire into the fundamental assumptions that underpin the ideal of the Bio-Based Economy (BBE) as it is currently developed. By interpreting the BBE from the philosophical perspective on economy developed by Georges Bataille, we demonstrate how the BBE is fully premised on a thinking of scarcity. As a result, the BBE exclusively frames economic problems in terms of efficient production, endeavoring to exclude a thinking of abundance and wastefulness. Our hypothesis is that this not only entails a number of internal tensions and inconsistencies with regard to the ideal of BBE, but ultimately undermines the ideal itself, by pushing purported regen-erativity into a cataclysmic and terminal discharge. We here point to the strategies that the BBE employs in this exclusion, the fundamental assumptions regarding the relation between energy and economy that underpin this endeavor, as well as to the resulting inconsistencies and their catastrophic consequences. We finally argue for the introduction of the presently excluded question of abundance and wastefulness and explore the implications of such a question for the ideal of a zero-waste humanity.

Microbial C1 gas conversion technologies have developed into a potentially promising technology for converting waste gases (CO2, CO) into chemicals, fuels, and other materials. However, the mass transfer constraint of these poorly soluble substrates to microorganisms is an important challenge to maximize the efficiencies of the processes. These technologies have attracted significant scientific interest in recent years, and many reactor designs have been explored. Syngas fermentation and hydrogenotrophic methanation use molecular hydrogen as an electron donor. Furthermore, the sequestration of CO2 and the generation of valuable chemicals through the application of a biocathode in bioelectrochemical cells have been evaluated for their great potential to contribute to sustainability. Through a process termed microbial chain elongation, the product portfolio from C1 gas conversion may be expanded further by carefully driving microorganisms to perform acetogenesis, solventogenesis, and reverse β-oxidation. The purpose of this review is to provide an overview of the various kinds of bioreactors that are employed in these microbial C1 conversion processes.

RESUMO
Para o atingimento dos objetivos do desenvolvimento sustentável o agronegócio, por uma série de questões históricas e conjunturais, pode ser apontado como vilão, vítima e solução. Este trabalho defende que é preciso alterarmos o paradigma econômico para um modelo que não exaure os recursos naturais. Para isso o agronegócio precisa reforçar suas qualidades e promover a conservação dos recursos hídricos, da biodiversidade, das matas nativas, utilizando biotecnologia, técnicas agronômicas e práticas de manejo mais avançadas, contribuindo, assim, para o desenvolvimento econômico e social das comunidades locais. O rumo é a produção de biomassa para comida, ração, fibras, combustíveis com uso de tecnologia para reaproveitar todos os resíduos e com isso também sequestrar os gases de efeito estufa na atmosfera. 
Palavras-chave
Bioeconomia circular sustentável; Agronegócio; Objetivos do desenvolvimento sustentável; Agenda 2030

RESUMEN
Para lograr los objetivos de desarrollo sostenible, la agroindustria, debido a una serie de cuestiones históricas y conjeturaes, puede ser señalada como villana, víctima y solución. Este artículo sostiene que es necesario cambiar el paradigma económico a un modelo que no agote los recursos naturales. Para ello, la agroindustria necesita reforzar sus cualidades y promover la conservación de los recursos hídricos, la biodiversidad, la manutencion de los bosques nativos en pied, utilizando biotecnología, técnicas agronómicas y prácticas de manejo más avanzadas, contribuyendo así al desarrollo económico y social de las comunidades locales. La dirección es la producción de biomasa para alimentos, piensos, fibras, combustibles con el uso de tecnología para reutilizar todos los desechos y, por lo tanto, también el secuestro de gases de efecto invernadero en la atmósfera.
Palavras-clave
Bioeconomía circular sostenible; Agronegocios; Metas de desarrollo sostenible; Agenda 2030

ABSTRACT
In order to achieve the sustainable development goals, agribusiness, due to a series of historical and conjectural issues, can be appointed as villain, victim and solution. This paper argues that it is necessary to change the economic paradigm to a model that does not exhaust the natural resources. For this, agribusiness needs to reinforce its qualities and promote the conservation of water resources, biodiversity, native forests, using biotechnology, agronomic techniques and more advanced management practices, thus contributing to the economic and social development of local communities. The direction is the production of biomass for food, feed, fibers, fuels with the use of technology to reuse all waste and with that also to sequestrate greenhouse gases from the atmosphere.
Keywords
Sustainable circular bioeconomy; Agribusiness; Sustainable development goals; 2030 agenda