Composition and ecology of bacterial and archaeal communities in anaerobic reactor fed with residual glycerol.

Glycerol, the main residue of biodiesel production, can be used to produce organic acids and energy through anaerobic digestion. This study aimed to assess microbial structure, diversity, productivity, and stability and the influence of these parameters on the performance of an anaerobic reactor. The experimental setup consisted of an upflow anaerobic sludge blanket (UASB) reactor fed residual glycerol and nutrients. The organic loading rate (OLR) was gradually increased through five stages, and sludge samples were collected at each, followed by DNA extraction and PCR denaturing gradient gel electrophoresis (PCR-DGGE). The resulting bands were excised, amplified, and purified. The results showed increased bacterial diversity and richness from the inoculum (Rr 38.72 and H 2.32) and along stages I and II, reaching the highest populational parameters (Rr 194.06 and H 3.32). The following stages promote decreases in richness and diversity, achieving the lowest populational parameters on this study (Rr 11.53 and H 2.04). Biogas production increased along with functional organization due to the specialization of the bacterial community and a decrease in the methanogenic population, both promoted by the increase in OLR.

Evaluation of different air dosing strategies to enhance H2S removal in microaerobic systems treating low-strength wastewaters.

This study aimed to evaluate different air dosing strategies such as microaeration flow rates and air dosing points to enhance H2S removal in microaerobic systems treating low-strength wastewaters. Efficiency and stability of the reactors, as well as biogas quality, were assessed, and microbial community changes were evaluated using the PCR-DGGE technique. The results showed that the air dosing point affected the H2S concentration and that air dosing at the headspace promoted the highest H2S removal efficiency. The airflow rate also affected the process, since H2S concentration in the biogas was higher at 0.1 mL air.min-1 than at 0.3 mL air.min-1. The methane concentration in the biogas was also affected by both air dosing point and flow rate, since the lowest value was observed at the highest airflow rate of the headspace dosing point, due to dilution by the N2 influx applied to the system. The highest productivity and operational efficiency were observed at this air dosing point, with this airflow (HD0.3), which corroborates with the operational results and the ecological parameters, since the microaeration at this stage promoted high bacterial and archaeal species richness and diversity, optimum functional organization, high COD and H2S removal efficiencies.

Fermentative H2 production from residual glycerol: a review.

The fermentative production of H2 from residual glycerol is an attractive alternative for clean energy production from a waste product. Selection of operational variables for microbial populations with an adequate diversity in order to improve H2 yields is an issue faced during optimization of biological production of H2. Operational and environmental factors affect both microbial diversity and the activity of specific enzymes. Therefore, these variables must be controlled to obtain the best H2 yields. This review covers the main variables involved in the fermentative production of H2 from crude glycerol and the biochemistry of the anaerobic digestion of glycerol, with a focus on the microbial diversity involved in this process.

Influência da temperatura de secagem e da concentração de Aerosil®200 nas características dos extratos secos por aspersão da Schinus terebinthifolius Raddi (Anacardiaceae) / Influence of the drying temperature and the Aerosil®200 concentration on the characteristics of Spray-dried extracts from Schinus terebinthifolius Raddi (Anarcadiaceae)

A Schinus terebinthifolius Raddi é muito usada na medicina popular e atualmente como fitomedicamento pelas propriedades antimicrobiana, cicatrizante e antiinflamatória. O objetivo deste trabalho foi avaliar a influência da temperatura de entrada e a concentração de Aerosil®200 nas características de extratos secos por aspersão da Schinus terebinthifolius Raddi. Os extratos preparados com etanol 70 °GL foram secos em Mini-spray dryer, Buchi B191, com adição do adjuvante tecnológico numa proporção de 20:80; 25:75 e 30:70 (p/p) Aerosil®200: resíduo seco, variando a temperatura de entrada de 120 °C a 160 °C. A umidade residual, o rendimento final do produto e o aumento da massa frente à umidade relativa controlada de 90 por cento foram usados como critério de avaliação. A análise de superfície de resposta revelou que à medida que a temperatura e a concentração de Aerosil aumentam, diminui a umidade residual dos extratos, bem como sua higroscopicidade. As melhores condições de secagem foram a temperatura de entrada de 140 °C e 30 por cento do adjuvante, resultando em rendimento acima de 80 por cento.

Schinus terebinthifolius Raddi has been used in the Brazilian folk medicine since a long time and now as phytopharmaceutical because of its antimicrobial, cicatrizant and anti-inflammatory properties. The aim of this work was to evaluate the influence of the inlet temperature and the Aerosil concentration on the characteristics of the spray-dried extracts from Schinus terebinthifolius Raddi by spray-drying method. The extracts were prepared from a 70 °GL ethanolic extract with a Buchi B 191 Mini-spray dryer with technological adjuvant into a ratio of 20:80; 25:75 and 30:70 (w/w) Aerosil®200: dried residue, in the inlet temperature range from 120 °C to 160 °C. The residual humidity, final yield and the moisture uptake profile at 90 percent Relative Humidity (RH) were used as evaluation criteria. The response surface analysis showed that increasing the temperature and the Aerosil®200 concentration, lead to lower residual humidity and moisture uptakes. The best drying parameters were the inlet temperature of 140 °C and 30 percent of Aerosil®200 concentration, resulting in yields over 80 percent.