The gasification of biomass in supercritical water is a promising technology for hydrogen production and the paper reports a thermodynamic analysis, based on minimization of Gibbs free energy, of the gasification with supercritical water of different biomass and agro-food residues: almond shells, digestate from wastewater treatment, algae and manure sludge. Numerical simulations were performed in order to assess the effect of temperature, pressure and biomass-to-water ratio on gas-phase yield and composition.A partial energy integration was also discussed, by considering the energy recovery from a turbine expansion of the gas-phase stream leaving the gasifier. The proposed thermodynamic approach allows predicting not only gasification efficiency of gasifier but also energy balance on the entire gasification process. Results showed that the dry substrates (almond shells and algae more than digestate and sludge) tend to form more carbon monoxide. Besides, data comparison revealed that the produced hydrogen comes from biomass and water for high process temperature, while when temperature decreases, the thermodynamic path tends to promote water formation from the hydrogen of the dry biomass.

A near-zero waste treatment system for food processing wastewater was developed and studied. The wastewater was treated using an anaerobic membrane bioreactor (AnMBR), polished using an outdoor photobioreactor for microalgae cultivation (three species were studied), and excess sludge was treated using hydrothermal carbonization. The study was conducted under arid climate conditions for one year (four seasons). The AnMBR reduced the total organic carbon by 97%, which was mostly recovered as methane (~57%) and hydrochar (~4%). Microalgal biomass productivity in the AnMBR effluent ranged from 0.25 to 0.8 g·L⁻¹·day⁻¹. Nitrogen (N) and phosphorous (P) uptake varied seasonally, from 18 to 45 mg·L⁻¹·day⁻¹ and up to 5 mg·L⁻¹·day⁻¹, respectively. N and P mass balance analysis demonstrated that the process was highly efficient in the recovery of nitrogen (~77%), and phosphorus (~91%). The performance of the microalgal culture changed among seasons because of climatic variation, as a result of variation in the wastewater chemistry, and possibly due to differences among the microalgal species. Effluent standards for irrigation use were met throughout the year and were achieved within two days in summer and 4.5 days in winter. Overall, the study demonstrated a near-zero waste discharge system capable of producing high-quality effluent, achieving nutrient and carbon recovery into microalgae biomass, and energy production as biogas and hydrochar.

Air-nanobubble water (NBW) was applied to pre-acclimate anaerobically digested sludge that was then used as the inoculum in the two-stage anaerobic digestion (AD) of high saline (20 g NaCl/L) food waste (FW) to optimize NBW application in the AD of high saline FW. K⁺ was simultaneously supplemented during the methanogenic stage to resist the inhibition of salt on methanogens. Results showed that after the second pre-acclimation cycle, the inoculum activity was increased 27% in the Air-NBW supplemented reactor in comparison to the deionized water (DW) supplemented one. In the first-stage AD, H₂ yield was enhanced by 46% in the Air-NBW pre-acclimated sludge reactor compared with the DW pre-acclimated sludge reactor. Besides, supplementation of KOH in the methanogenic stage could enhance methane production by 17–25% in the DW reactors at initial pH 7.5, 8.0, and 9.0 when compared to the control reactor (using NaOH adjusted initial pH to 7.5), respectively.

[ES] La OMS ha declarado que la resistencia a los antimicrobianos es una de las 10 principales amenazas de salud pública a las que se enfrenta la humanidad. La presencia de bacterias resistentes a antibióticos es un problema de salud y seguridad mundial, cada año se identifican cada vez más bacterias resistentes a antibióticos presentes en alimentos, las cuales ofrecen una alta resistencia a los antibióticos de uso común en clínica. Es por ello, que el objetivo de nuestro trabajo pasa por identificar y evaluar la presencia de estas bacterias en distintas muestras de lodos, aguas residuales y aguas de las acequias de agua de riego anexas al Campus de Vera de la Universitat Politècnica de València (UPV). Para llevar a cabo los análisis en primer lugar se hará una determinación de la presencia de patógenos como Salmonella y la calidad higiénico-sanitaria de las aguas y lodos, mediante el recuento de coliformes y E. coli como organismo indicador de contaminación fecal. Seguidamente se procederá a aislar bacterias resistentes a antibióticos en medios selectivos con antibióticos betalactámicos y carbapenémicos y se identificarán mediante pruebas bioquímicos y moleculares en caso de no ser concluyentes los resultados. Posteriormente se realizarán los antibiogramas para evaluar la resistencia fenotípica y se procederá a detectar mediante PCR la presencia de determinados genes de resistencia. | [EN] The World Health Organization (WHO) has proclaimed that antimicrobial resistance constitutes one of the top ten major threats to global public health. The presence of antibiotic-resistant bacteria poses a challenge to global health and security. Each year, an increasing number of antibiotic-resistant bacteria are identified in food, which exhibit a high level of resistance to antibiotics commonly used in clinical practice. In this study, bacterial strains from various sources were investigated, and their resistance to different antibiotic families was analyzed, in addition to exploring the existence of multidrug-resistant strains. Several multiplex PCR assays were conducted to detect resistance genes (to beta-lactam, carbapenem, or quinolone antibiotics) from extracted DNA of isolated strains as well as directly from samples. These assays revealed that samples with the highest prevalence of these genes corresponded to water from irrigation canals adjacent to the campus of Universitat Politècnica de València. Overall, this work highlights the presence of bacteria with antibiotic resistance in agricultural irrigation waters and in sludge used as fertilizers. This finding underscores the need to expand the scope of the research and to enhance the hygienic and sanitary measures implemented during the utilization of the studied sludge and water samples. | Fernandez De Peñaranda Alejandre, A. (2023). Estudio de la presencia de bacterias multi-resistentes en lodos y aguas de uso agrícola de la Comunidad Valenciana en el contexto de la seguridad alimentaria. Universitat Politècnica de València. http://hdl.handle.net/10251/197798