Removal of ammonia by immobilizaed Nitrosomonas europaea in a biotrickling filter packed with polyurethane foam

[Abstract] A chemolithoautrotrophic microorganism Nitrosomonas europaea has been utilized to remove gaseous ammonia in a biotrickling filter packed with polyurethane foam. The optimal pH for removing was 7.5 and the biological removal efficiency was zero at pH 6.5. Empty bed residence time of 150, 100, 50, 25, 20, 11 and 5 seconds were tested; the removal efficiency was of 100% in all range for a constant load of 8 gN.m-3.h-1. The critical elimination capacity was 270 gN.m-3.h-1 while the nitrite concentration was below of 100 mM (EBRT of 11 second, pH 7.5-7.6). Therefore, these results demonstrate that is possible to reach a high removal of ammonia using polyurethane foam, as solid support for Nitrosomonas europaea, and a biotrickling filter system

Optimization of culture media for etanol production from glicerol by Escherichia coli

http://dx.doi.org/10.1016/j.biombioe.2011.12.002The culture media for glycerol to ethanol biotransformation by Escherichia coli under anaerobic conditions was optimized. A Plackett-Burman screening design was used to determine which factors were significant with a 95% confidence interval. A full factorial 22 and response surface model were employed to determine the optimum conditions for the selected response variable. The response variable considered in this work was biomass productivity (QX). Profiles for biomass growth, glycerol consumption and ethanol production were obtained at optimum conditions and fermentation parameters were calculated. Glycerol to ethanol yield and ethanol specific productivity were determined to be 845 g kg 1 of glycerol and 212 g kg 1 h 1 of cell mass respectively. Optimized culture media is presented along with the main results and experimental profiles obtained from this work

Operational conditions for start-up and nitrate-feeding in an anoxic biotrickling filtration process at pilot scale

A real biogas effluent was desulfurized using an anoxic biotrickling filter at pilot scale. Guidelines and recommendations have been proposed to achieve the correct inoculation and biofilm development. The hydrogen sulfide inlet concentration (4100–7900 ppmV) was not controlled. The operational variables studied were the hydrogen sulfide inlet load (37–149 gS m−3 h−1), biogas flow rate (1–3.4 Nm3 h−1) and pH (6.8–7.4). Moreover, three nitrate-feeding modes were studied: manual, continuous and automated. Without the addition of nutrients to the nitrate solution, a removal efficiency greater than 95% was obtained for loads in the range 33–55 gS m−3 h−1 along with an elemental sulfur percentage of 85 ± 5%. The nitrate solution was mainly composed of NaNO3 (500 g L−1), the macronutrients KH2PO4 (10 g L−1), NH4Cl (5 g L−1) and MgSO4·7H2O (4 g L−1), and trace elements. The critical elimination capacity was 94.7 gS m−3 h−1 (RE > 99%) on day 119 and the maximum elimination capacity was 127.3 gS m−3 h−1 (RE = 92.6%) on day 122. The recommended operational conditions for start-up are an inlet load of 100 gS m−3 h−1, a pH set-point of 6.8 to reduce sulfide accumulation and nitrate-feeding automated by oxide reduction potential

Modeling and control strategies for anoxic biotrickling filtration in biogas purification

BACKGROUND Anoxic biotrickling filters have been used to 'sweeten' biogas. Nevertheless, the cost and availability of large amounts of nitrate could limit the use of this technology in comparison with aerobic biotrickling filters. The development of a dynamic mathematical model would be useful for the design of control strategies with regard to nitrate dosage. RESULTS A dynamic model has been developed to describe the performance of an anoxic biotrickling filter for biogas desulfurization. The model considers the most relevant phenomena involved in biotrickling filter operation: advection, absorption, diffusion and biodegradation. Moreover, a fraction of the liquid phase is stagnant – an assumption that increases the importance of diffusion phenomena for low liquid flow rates. Once the model had been validated, six control strategies were analyzed for different scenarios and purposes: i.e. to minimize nitrate consumption and/or to maximize H2S removal efficiency. CONCLUSION The mathematical model developed from the description of the phenomena involved in the process is a powerful tool to evaluate all possible strategies when considering and quantifying the savings and improvements in different operating modes

Estadio de madurez sexual en toros de la raza nelore

La presente investigación se planteó con el objetivo de determinar el estado de madurez sexual de toros jóvenes de la raza nelore y su relación con el perímetro escrotal y las características seminales. Se estudiaron 1985 animales con edades comprendidas entre los 19 y los 23 meses de edad, alimentados con pasturas tropicales (Brachiaria brizantha, Brachiaria decumbes y Panicum maximun) y evaluados a través de examen andrológico. Se valoraron las características físicas del eyaculado, la morfología espermática y el perímetro escrotal (PE). Tras el examen andrológico, los animales se clasificaron como aptos para la reproducción (clase andrológica 1) aptos para la reproducción en régimen de monta natural (clase 2) no aptos para la reproducción temporalmente (clase 3) y descartados (clase 5). Para comparar las medias encontradas entre las clases andrológicas se utilizaron dos pruebas: la de Tukey, con probabilidad del 5 % de error, y la de correlaciones simples de Pearson, para verificar las relaciones entre las características estudiadas. Se encontró que el 84,5 % de los toros son sexualmente maduros. El 39,75 % de los animales aptos para la reproducción presentó un PE mayor a 34 cm, y solo el 71 % de la población estudiada exhibió una circunferencia escrotal inferior a 28 cm. Se registraron correlaciones altas favorables entre PE y las características físicas del semen. Se concluye que el PE es una excelente característica para evaluar y seleccionar toros jóvenes de la raza nelore

Biofiltration of reduced sulphur compounds and community analysis of sulphur-oxidizing bacteria.

http://dx.doi.org/10.1016/j.biortech.2010.12.018The present work aims to use a two-stage biotrickling filters for simultaneous treatment of hydrogen sulphide (H2S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS). The first biofilter was inoculated with Acidithiobacillus thiooxidans (BAT) and the second one with Thiobacillus thioparus (BTT). For separate feeds of reduced sulphur compounds (RSC), the elimination capacity (EC) order was DMDS > DMS > MM. The EC values were 9.8 gMM-S/m3/h (BTT; 78% removal efficiency (RE); empty bed residence time (EBRT) 58 s), 36 gDMDS-S/m3/h (BTT; 94.4% RE; EBRT 76 s) and 57.5 gH2S-S/m3/h (BAT; 92% RE; EBRT 59 s). For the simultaneous removal of RSC in BTT, an increase in the H2S concentration from 23 to 293 ppmv (EBRT of 59 s) inhibited the RE of DMS (97–84% RE), DMDS (86–76% RE) and MM (83–67% RE). In the two-stage biofiltration, the RE did not decrease on increasing the H2S concentration from 75 to 432 ppmv

Hydrogen sulphide removal from biogas by an anoxic biotrickling filter packed with Pall rings

Hydrogen sulphide (H2S) is one of the most problematic contaminants in biogas. In this study, a biotrickling filter with a working volume of 2.4 L and packed with polypropylene Pall rings was tested for its ability to remove H2S from biogas under anoxic conditions. The influence of the H2S inlet concentration, nitrate feeding regime (manual and controlled) and liquid flow rate on the elimination capacity of the biotrickling filter was studied. The results indicate that 99% of the H2S was removed for H2S inlet loads lower than 120 g S m"3 h"1 when using controlled nitrate feeding by ORP

Development of a remote sensing and control system for greenhouse applications

Real-time monitoring provides reliable, timely information of crop and soil status, important in taking decisions for crop production improvement. This work presents a real-time monitoring and control system for climatological variables in greenhouse. The system has wireless communication capabilities, which allow it to cover extensive surfaces in real-time, without extra resources. The system implementation is based on the micro controllers “PIC18F4550” and “DSPIC 30F5011”, user interface was programmed under LINUX. The proposed system performance was compared with commercial Data Loggers, readings present a linear adjustment with R2=0.9656

Stereoselective preparation of quaternary 2-vinyl sphingosines and ceramides and their effect on basal sphingolipid metabolism

The dicyclohexylborane-mediated addition of allene 1 to (E)-2-tridecenal affords a quaternary protected 2-amino-2-vinyl-1,3-diol in good yield as a single diastereomer. This compound is readily transformed into the four stereoisomers of the quaternary (E)-2-vinyl analogs of sphingosine. The metabolic fate and the effect of these compounds on the basal sphingolipid metabolism in human A549 lung adenocarcinoma cells has been studied, together with the ceramide analog of the most relevant vinylsphingosine derivative

Development of a remote sensing and control system for greenhouse applications

Real-time monitoring provides reliable, timely information of crop and soil status, important in taking decisions for crop production improvement. This work presents a real-time monitoring and control system for climatological variables in greenhouse. The system has wireless communication capabilities, which allow it to cover extensive surfaces in real-time, without extra resources. The system implementation is based on the micro controllers “PIC18F4550” and “DSPIC 30F5011”, user interface was programmed under LINUX. The proposed system performance was compared with commercial Data Loggers, readings present a linear adjustment with R2=0.9656