Production of biopolymers from renewable carbon sources provides a path towards a circular economy. This review compares several existing and emerging approaches for polyhydroxyalkanoate (PHA) production from soluble organic and gaseous carbon sources and considers technologies based on pure and mixed microbial cultures. While bioplastics are most often produced from soluble sources of organic carbon, the use of carbon dioxide (CO₂) as the carbon source for PHA production is emerging as a sustainable approach that combines CO₂ sequestration with the production of a value-added product. Techno-economic analysis suggests that the emerging approach of CO₂ conversion to carboxylic acids by microbial electrosynthesis followed by microbial PHA production could lead to a novel cost-efficient technology for production of green biopolymers.

The influence of operating conditions on the yield and quality of bio-oil obtained from black spruce wood mixture was studied using an auger reactor. Fast pyrolysis optimization through response surface analysis was carried out with four variables: pyrolysis temperature, solids residence time, nitrogen flow, and temperature of first stage of condensation. The optimal conditions obtained for bio-oil production were 555°C, 129 s, 6.9 L/min, and 120°C, respectively. The product yields were 38.61 wt.% of biochar, 25.39 wt.% of liquid, and 36.52 wt.% of non-condensable gases. Two liquid products were produced at the exit of the two condensers, following the concept of fractional condensation. The oily phase yield recovered in the first condenser was 10.59 wt.%, with a 16.86 wt.% of moisture content. Physical properties of the oily phase were analyzed and compared with the ASTM standard D7544-12. Qualitative identification of chemical compounds was carried out for the oily phase which helped in pyrolysis optimization for the bio-oil production targeted towards its use as fuel in commercial burners. In addition, the oil produced here is one of the lowest in water and solids content, attributable to the unique feature of auger reactors without the need for additional treatments. Biofuel; Research; Journal; Biodiesel; Bioethanol; Biogas; Application

Microwave-assisted hydrothermal (MHT) treatment of biomass has received significant attention owing to energy efficiency during internal energy transfer and the additional benefits to the hydrochar produced in terms of physicochemical composition. Therefore, this study proposes the combination of MHT pretreatment with the fast pyrolysis process, to evaluate and optimize the effect of this treatment on the quality of the hydrochar and, consequently, on the quality of the bio-oil. The optimization of MHT treatment using black spruce was carried out, followed by fast pyrolysis of the hydrochar produced under optimal conditions in an auger reactor at 550 °C to obtain a high-quality bio-oil. As a result, the pretreated biomass showed on the one hand a significant decrease in the ash content by 58% and 43% in the content of the extractives. While on the other hand, the obtained hydrochar showed an increase in the availability of cellulose by 18.5% as a consequence of the reduction in the content of hemicellulose. Accordingly, hydrochar showed an increase in thermal stability during pyrolysis and it produced a higher total bio-oil yield, increasing by 24%. Most importantly, the oil obtained showed a 35% reduction in moisture content. Chemical composition of the oil was qualitatively examined through GC-MS analysis. It was observed that the bio-oil showed a dramatic increase in the relative content of levoglucosan, by 127%. A bio-oil with the characteristics obtained would be a suitable candidate for use in boilers for heating purposes or chemical extraction.