Comprehensive ADM1 Extensions to Tackle Some Operational and Metabolic Aspects in Anaerobic Digestion.

Modelling in anaerobic digestion will play a crucial role as a tool for smart monitoring and supervision of the process performance and stability. By far, the Anaerobic Digestion Model No. 1 (ADM1) has been the most recognized and exploited model to represent this process. This study aims to propose simple extensions for the ADM1 model to tackle some overlooked operational and metabolic aspects. Extensions for the discontinuous feeding process, the reduction of the active working volume, the transport of the soluble compound from the bulk to the cell interior, and biomass acclimation are presented in this study. The model extensions are included by a change in the mass balance of the process in batch and continuous operation, the incorporation of a transfer equation governed by the gradient between the extra- and intra- cellular concentration, and a saturation-type function where the time has an explicit influence on the kinetic parameters, respectively. By adding minimal complexity to the existing ADM1, the incorporation of these phenomena may help to understand some underlying process issues that remain unexplained by the current model structure, broadening the scope of the model for control and monitoring industrial applications.

[Microbiological air quality in a Community Family Health Center of Talcahuano, Biobío Region, Chile]. / Calidad microbiológica del aire en un Centro Comunitario de Salud Familiar de Talcahuano, Región del Biobío, Chile.

BACKGROUND: Indoor air quality in health centers is essential to protect the health of people. In Chile, the Community Family Health Centers (CECOSF) are places with large attendance of people, favoring the dissemination of microorganisms, and there are no reports of the microbial air loading these health centers. AIM: To evaluate the microbiological indoor air quality in CECOSF-Centinela in Talcahuano, Biobío Region. METHODS: Air samples were taken in 6 rooms of the CECOSF, every 15 days between July 2018 and June 2019, with the MAS-100 NT equipment using trypticase and Sabouraud agars. Different morphotypes of bacteria and fungi were identified by PCR. RESULTS: The bacterial and fungal counts varied between 9.1 × 101 - 2.4 × 103 cfu/m3 and 10 - 1.5 × 102 cfu/m3, respectively. The air in the waiting room presented the highest counts, both for bacteria and fungi (P < 0.05). Staphylococcus, Enterococcus, Pseudomonas, Acinetobacter were identified, highlighting the species Staphylococcus aureus and Pseudomonas oryzihabitans, the latter described as a nosocomial pathogen. Among the fungi, Aspergillus, Meyerozyma and Rhodotorula were identified. CONCLUSION: The indoor air of the CECOSF-Centinela presents microorganisms of importance in human health. Therefore, it is necessary to formulate more regular monitoring programs for the control of air quality inside these health centers.

Calidad microbiológica del aire en un Centro Comunitario de Salud Familiar de Talcahuano, Región del Biobío, Chile / Microbiological air quality in a Community Family Health Center of Talcahuano, Biobío Region, Chile

INTRODUCCIÓN: La calidad del aire en centros de salud es fundamental para resguardar la salud de las personas. En Chile, los Centros Comunitarios de Salud Familiar (CECOSF) son lugares de gran concurrencia de personas, favoreciendo la diseminación de microorganismos. OBJETIVO: Evaluar la calidad microbiológica del aire al interior del CECOSF-Centinela en Talcahuano, Región del Biobío. METODOLOGÍA: Se tomó muestras de aire en seis salas del CECOSF, quincenalmente, entre julio de 2018 y junio de 2019, con el equipo MAS-100 NT, empleando agar tripticasa y agar Sabouraud. Diferentes morfotipos de bacterias y hongos fueron identificados mediante RPC. RESULTADOS: Los recuentos de bacterias y hongos variaron entre 9,1 × 101 - 2,4 × 103 ufc/m3 y 10 - 1,5 × 102 ufc/m3, respectivamente. El aire de la sala de espera presentó los recuentos más altos, tanto para bacterias como hongos (P < 0,05). Se identificó Staphylococcus, Enterococcus, Pseudomonas, Acinetobacter, destacando las especies Staphylococcus aureus y Pseudomonas oryzihabitans, microrganismo este último, descrito actualmente como patógeno nosocomial. Entre los hongos se identificó Aspergillus, Meyerozyma y Rhodotorula. CONCLUSIÓN: Las muestras de aire del CECOSF-Centinela presentan microrganismos de importancia en salud humana. De ahí la necesidad de formular programas de monitoreo más regulares para controlar la calidad del aire al interior de estos establecimientos.

BACKGROUND: Indoor air quality in health centers is essential to protect the health of people. In Chile, the Community Family Health Centers (CECOSF) are places with large attendance of people, favoring the dissemination of microorganisms, and there are no reports of the microbial air loading these health centers. AIM: To evaluate the microbiological indoor air quality in CECOSF-Centinela in Talcahuano, Biobío Region. METHODS: Air samples were taken in 6 rooms of the CECOSF, every 15 days between July 2018 and June 2019, with the MAS-100 NT equipment using trypticase and Sabouraud agars. Different morphotypes of bacteria and fungi were identified by PCR. Results: The bacterial and fungal counts varied between 9.1 × 101 - 2.4 × 103 cfu/m3 and 10 - 1.5 × 102 cfu/m3, respectively. The air in the waiting room presented the highest counts, both for bacteria and fungi (P < 0.05). Staphylococcus, Enterococcus, Pseudomonas, Acinetobacter were identified, highlighting the species Staphylococcus aureus and Pseudomonas oryzihabitans, the latter described as a nosocomial pathogen. Among the fungi, Aspergillus, Meyerozyma and Rhodotorula were identified. CONCLUSION: The indoor air of the CECOSF-Centinela presents microorganisms of importance in human health. Therefore, it is necessary to formulate more regular monitoring programs for the control of air quality inside these health centers.

Copper-Polyurethane Composite Materials: Particle Size Effect on the Physical-Chemical and Antibacterial Properties.

In this work, thermoplastic polyurethane (TPU) composites incorporated with 1.0 wt% Cu particles were synthesized by the melt blending method. The effect of the incorporated copper particle size on the antibacterial, thermal, rheological, and mechanical properties of TPU was investigated. The obtained results showed that (i) the addition of copper particles increased the thermal and mechanical properties because they acted as co-stabilizers of polyurethane (PU) (ii) copper nanoparticles decreased the viscosity of composite melts, and (iii) microparticles > 0.5 µm had a tendency to easily increase the maximum torque and formation of agglomerates. SEM micrographics showed that a good mixture between TPU and copper particles was obtained by the extrusion process. Additionally, copper-TPU composite materials effectively inhibited the growth of the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus. Considering that the natural concentration of copper in the blood is in the range of 0.7-0.12 mg/L and that the total migration value of copper particles from TPU was 1000 times lower, the results suggested that TPU nanocomposites could be adequately employed for biomedical applications without a risk of contamination.

Characterization of a hyperthermophilic sulphur-oxidizing biofilm produced by archaea isolated from a hot spring

Background: Sulphur-oxidizing microorganisms are widely used in the biofiltration of total reduced sulphur compounds (odorous and neurotoxic) produced by industries such as the cellulose and petrochemical industries, which include high-temperature process steps. Some hyperthermophilic microorganisms have the capability to oxidize these compounds at high temperatures (N60°C), and archaea of this group, for example, Sulfolobus metallicus, are commonly used in biofiltration technology. Results: In this study, a hyperthermophilic sulphur-oxidizing strain of archaea was isolated from a hot spring (Chillán, Chile) and designated as M1. It was identified as archaea of the genus Sulfolobus (99% homology with S. solfataricus 16S rDNA). Biofilms of this culture grown on polyethylene rings showed an elemental sulphur oxidation rate of 95.15 ± 15.39 mg S l-1 d-1, higher than the rate exhibited by the biofilm of the sulphur-oxidizing archaea S. metallicus (56.8 ± 10.91 mg l-1 d-1). Conclusions: The results suggest that the culture M1 is useful for the biofiltration of total reduced sulphur gases at high temperatures and for other biotechnological applications.

Thiosulphate oxidation by Thiobacillus thioparus and Halothiobacillus neapolitanus strains isolated from the petrochemical industry

Sulphur Oxidizing Bacteria (SOB) is a group of microorganisms widely used for the biofiltration of Total Reduced Sulphur compounds (TRS). TRS are bad smelling compounds with neurotoxic activity which are produced by different industries (cellulose, petrochemical). Thiobacillus thioparus has the capability to oxidize organic TRS, and strains of this bacterium are commonly used for TRS biofiltration technology. In this study, two thiosulphate oxidizing strains were isolated from a petrochemical plant (ENAP BioBio, Chile). They were subjected to molecular analysis by real time PCR using specific primers for T. thioparus. rDNA16S were sequenced using universal primers and their corresponding thiosulphate activities were compared with the reference strain T. thioparus ATCC 10801 in batch standard conditions. Real time PCR and 16S rDNA sequencing showed that one of the isolated strains belonged to the Thiobacillus branch. This strain degrades thiosulphate with a similar activity profile to that shown by the ATCC 10801 strain, but with less growth, making it useful in biofiltration.