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W Borzani

Publications and source records attributed to W Borzani.

11 recordsLinked to original sources
PubMed2004

Stirred anaerobic sequencing batch reactor containing immobilized biomass: a behavior study when submitted to different fill times.

The effect of the filling stage on the behavior of a mechanically stirred anaerobic sequencing batch reactor containing biomass immobilized on 1 cm polyurethane foam cubes was investigated. The reactor was made of acrylic with a capacity of 6.3 L, treating per cycle 2.5 L synthetic low-strength wastewater with a concentration of 500 mgCOD/L, at 30+/-1 degrees C. Eight-hour cycles (tC) and agitation of 500 rpm were utilized. At the beginning of each cycle 60% of the wastewater volume was treated, sufficient to completely cover the bed. The remaining volume was added at different fill times (tF) of 10, 120, 240, 260 and 480 min. The results obtained showed that ratios of tF/tC < or = 0.5 enabled organic matter removal higher than 75% and 70% for filtered and non-filtered samples, respectively. Ratios of tF/tC > 0.5, despite operation stability, resulted in loss of efficiency and formation of viscous material, similar to extra-cellular polymeric substances.

Bacteria, Anaerobic↗
PubMed2001

Anaerobic sequencing batch reactors for wastewater treatment: a developing technology.

This paper describes and discusses the main problems related to anaerobic batch and fed-batch processes for wastewater treatment. A critical analysis of the literature evaluated the industrial application viability and proposed alternatives to improve operation and control of this system. Two approaches were presented in order to make this anaerobic discontinuous process feasible for industrial application: (1) optimization of the operating procedures in reactors containing self-immobilized sludge as granules, and (2) design of bioreactors with inert support media for biomass immobilization.

Anaerobiosis↗
PubMed2001

Influence of agitation rate on the performance of a stirred anaerobic sequencing batch reactor containing immobilized biomass.

The present work reports on the influence of the mechanical agitation rates on the performance of a stirred anaerobic sequencing batch reactor containing immobilized biomass on polyurethane foam, as inert support, treating synthetic domestic wastewater. The reactor was operated at 30 degrees C and an 8-hour cycle was used to treat approximately 0.5 L of the synthetic substrate with a COD concentration of nearly 500 mg/L. The studied agitation rates ranged from no agitation to 750 rpm. The system attained non-filtered substrate removal efficiency greater than 83% when agitation was employed. A very short start-up period and good solid retention could be observed. The use of agitation increased the efficiency of the reactor and enabled reduction of the total cycle time. An empirical equation and a first-order kinetic model are proposed to analyze the influence of agitation rates on the reactor's performance.

Bacteria, Anaerobic↗
PubMed1983

Measurement of invertase activity of cells of Saccharomyces cerevisiae.

The determination of the invertase activity of intact yeast cells presents a critical point, that is, the blockage of the enzyme action at a given moment. In this paper seven blockage methods were compared: the addition of 0.010 M sodium hydroxide solution, addition of 0.010 M sodium carbonate solution, addition of 0.010 M sodium carbonate solution followed by centrifugation (9750g; 10 min), immersion of the reacting mixture in a boiling water bath, immersion of the mixture in a -15 degrees C bath, filtration through a Millipore membrane, and addition of the first Somogyi's reagent followed by immersion in a boiling water bath. Only the last two methods lead to a rapid and effective blockage of the invertase activity.

Chemical Phenomena↗
PubMed1977

Some observations on oscillatory changes in the growth rate of Saccharomyces cerevisiae in aerobic continuous undisturbed culture.

Oscillatory changes in the growth rate were observed in undisturbed continuous culture of Saccharomyces cerevisiae on sugar-cane molasses media when nitrogen sources (2.56 to 6.17 g/liter of ammonium sulfate or 1.22 g/liter of urea) were added to the feeding mash and when the air rate was 1.3 to 1.6 v/v/m. The oscillations were not affected by the addition of yeast extract. The suppression of the nitrogen source during the continous test leads to a nonoscillatory transient state. No oscillations occured at all when no nitrogen source was added to the medium and/or the air rate was equal to zero or equal to about 3.3 v/v/m. The oscillatory responses of the system were affected by a previous anaerobic continuous cultivation of the yeast.

Aerobiosis↗