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The production of polyhydroxyalkanoates using submerged cultures of Cupriavidus necator DSM 428 was evaluated using low-cost substrates from agroindustry: (i) dextrose from cassava starch and (ii) a mixture of sugarcane vinasse from the bioethanol industry and dextrose from cassava starch. The effects of vinasse composition (2.5, 5.0, 7.5, 25, 50, and 75% v/v) and the use of raw and activated carbon-pre-treated vinasse were assessed. The results indicate that cultivations using only cassava starch dextrose reached 4.33 g/L of biomass as the dry cell weight and a poly(3-hydroxybutyrate) (PHB) production of 47.1%. Raw vinasse proportions of 25, 50, and 75% in the culture medium resulted in total inhibition. Vinasse treated at the same ratios led to biomass production in the range 1.7–4.44 g/L. The higher PHB production scenario was obtained in a medium containing dextrose and treated vinasse (7.5%), yielding 5.9 g/L of biomass and 51% of PHB accumulation. The produced PHB was characterized by XRD and FTIR for an analysis of crystalline structure and chemical functional groups, respectively. EDS was employed for a semi-quantitative analysis of the chemical composition, and SEM was used to analyze the morphology of the microgranules. The results of DSC and TGA analyses demonstrated the thermal stability of the obtained PHB. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) relies on the cooperation of specific microbial communities, making it susceptible to process disruptions that could impact biogas production. In this regard, this study presents a technological solution based on the Arduino platform, in the form of a simple online monitoring system that can track the produced biogas profile, named as biogas analyzer module (BAM). The applicability of the BAM focused on monitoring the biogas produced from sugarcane vinasse inoculated with sewage sludge biodigestion processed in mesophilic conditions (38 oC), in a pH range of 6.5–7.5, and following a three-stage operational model: (i) an adaptation (168 h), (ii) complete mixing (168 h), and (iii) bio-stimulation with glycerol (192 h). Then, the lab-made BAM was used to trace the produced biogas profile, which registered a total biogas volume of 8,719.86 cm3 and biomethane concentration of 95.79% (vol.), removing 90.8% (vol) of carbon dioxide (CO2) and 65.2% (vol) of hydrogen sulfide (H2S). In conclusion, the results ensured good accuracy and efficiency to the device created by comparisons with established standards (chromatographic and colorimetric methods), as well as the cost reduction. The developed device would likely be six times cheaper than what is available in the market. [ABSTRACT FROM AUTHOR]

The production of polyhydroxyalkanoates using submerged cultures of Cupriavidus necator DSM 428 was evaluated using low-cost substrates from agroindustry: (i) dextrose from cassava starch and (ii) a mixture of sugarcane vinasse from the bioethanol industry and dextrose from cassava starch. The effects of vinasse composition (2.5, 5.0, 7.5, 25, 50, and 75% v/v) and the use of raw and activated carbon-pre-treated vinasse were assessed. The results indicate that cultivations using only cassava starch dextrose reached 4.33 g/L of biomass as the dry cell weight and a poly(3-hydroxybutyrate) (PHB) production of 47.1%. Raw vinasse proportions of 25, 50, and 75% in the culture medium resulted in total inhibition. Vinasse treated at the same ratios led to biomass production in the range 1.7–4.44 g/L. The higher PHB production scenario was obtained in a medium containing dextrose and treated vinasse (7.5%), yielding 5.9 g/L of biomass and 51% of PHB accumulation. The produced PHB was characterized by XRD and FTIR for an analysis of crystalline structure and chemical functional groups, respectively. EDS was employed for a semi-quantitative analysis of the chemical composition, and SEM was used to analyze the morphology of the microgranules. The results of DSC and TGA analyses demonstrated the thermal stability of the obtained PHB.

• Performance evaluation of a hermophilic anMDBR for sugarcane vinasse treatment. • Overall COD removal efficiencies were above 94% during operation for both effluents. • Ultrafiltered vinasse affected the anMDBR performance by lower COD/SO 4 2- ratios. • The dissociation of VFAs in the mixed liquor hampered their recovery in the distillate. • Low methane contents in the biogas were mainly attributed to H 2 S production. This study presents the first feasibility evaluation of a lab-scale thermophilic anaerobic membrane distillation bioreactor (AnMDBR) for treating sugarcane vinasse, considering the use of waste heat from vinasse which comes from ethanol distillation at high temperatures (80–90 °C). This research focuses mainly on evaluating the VFA production and recovery from anaerobically digested sugarcane vinasse in a single-stage An-MDBR system, alongside monitoring the generation of bioCH4, another bioproduct. The AnMDBR was fed with raw vinasse (phase I) and with ultrafiltered vinasse (phase II). The ultrafiltration of the sugarcane vinasse as pre-treatment stage resulted in a reduction in the COD/SO 4 2- ratio, adversely impacting process performance. The system achieved high removal efficiencies of COD (98 ± 1 % when fed with raw vinasse, and 94 ± 4 % with ultrafiltered vinasse), phosphorus (almost 100 %) and ammonia nitrogen (∼91 %). Regarding byproducts, the system showed low efficiencies in the VFAs recovery in the distillate and low methane content of the biogas formed. To enhance the VFA recovery, the pH of the solution should be kept below the pKa values favoring the VFA transport across the membrane. The permeate flux exhibited a decline throughout operation (from 4.4 to 0.5 L/(m2·h)), attributed to the fouling layer formation. Thus, strategies to mitigate membrane fouling are crucial for improving permeate flux and, consequently, enhancing the feasibility of full-scale MDBR for sugarcane vinasse treatment. [ABSTRACT FROM AUTHOR]

There is an emerging interest of use biological processes for vinasse treatment generally because they are able to produce interesting metabolites from living cells. Additionally, the production of yeasts with weakened cell wall without modifying its physiological performance would be of great technological value not only to facilitate the extraction of intracellular metabolites but also to increase the biomass digestibility. This study explored the remediation of a glycerol-fortified sugarcane vinasse using Rhodotorula glutinis or Rhodotorula mucilaginosa coupled with the production of valuable residual biomasses displaying a tailor-made weakened cell wall. Firstly, the biomass-bound ß- d -glucosidase activity was selected as a proper cell wall lytic potential marker. Secondly, in vitro -dose response assays with several metal ions showed that the presence of 6 mM of MnCl 2 and FeCl 3 increased the ß- d -glucosidase activity in R. glutinis and R. mucilaginosa , respectively. Thirdly, the supplementation of those salts to either YPD or vinasse-based media was evaluated. As a result, cells were bigger or even rounder than the corresponding controls (without metal ions supplementation) suggesting a weakening of the cell wall. Finally, as proof of concept, after 6 days of vinasse treatment at 30 °C under stirred conditions, the reduction of COD value for R. glutinis and R. mucilaginosa was 81.3% and 80.8%, respectively. The final biomass, lipid and protein concentrations for R. glutinis were 15.1 g/L, 31.1% and 48.12%, respectively. The final biomass, lipid and protein concentrations for R. mucilaginosa were 15.7 g/L, 31.5% and 48.12%, respectively. Potential technological applications of residual biomass were also discussed. [Display omitted] • Remediation of a glycerol-fortified vinasse by oleaginous yeasts was proposed. • R. glutinis or R. mucilaginosa with a tailor-made weakened cell wall was used. • Treatment of vinasse was coupled with the production of valuable residual biomass. • The reduction of COD value for both biotreatments was about 80%. • Residual biomasses showed a valuable content of lipids (31%) and proteins (48%). [ABSTRACT FROM AUTHOR]