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Diego Rosso

Publications and source records attributed to Diego Rosso.

5 recordsLinked to original sources
PubMed2006

Surfactant effects on alpha-factors in aeration systems.

Aeration in wastewater treatment processes accounts for the largest fraction of plant energy costs. Aeration systems function by shearing the surface (surface aerators) or releasing bubbles at the bottom of the tank (coarse- or fine-bubble aerators). Surfactant accumulation on gas-liquid interfaces reduces mass transfer rates, and this reduction in general is larger for fine-bubble aerators. This study evaluates mass transfer effects on the characterization and specification of aeration systems in clean and process water conditions. Tests at different interfacial turbulence regimes show higher gas transfer depression for lower turbulence regimes. Contamination effects can be offset at the expense of operating efficiency, which is characteristic of surface aerators and coarse-bubble diffusers. Results describe the variability of alpha-factors measured at small scale, due to uncontrolled energy density. Results are also reported in dimensionless empirical correlations describing mass transfer as a function of physiochemical and geometrical characteristics of the aeration process.

Air↗
PubMed2006

Economic implications of fine-pore diffuser aging.

Aerobic biological treatment, such as the activated sludge process, is commonly used for municipal wastewater treatment. Fine-pore diffusers have virtually replaced coarse-bubble diffusers in such operations, but most of the plant's energy expenditure is still consumed by aeration. Therefore, the performance of diffusers will critically affect plant economics. This paper analyzes and quantifies the consequences of aging processes on fine-pore diffusers. Datasets from 94 field measurements were analyzed and showed a clear pattern of performance decline with time in operation. Efficiency declines rapidly during the first 24 months of operation when the rate of decline decreases and efficiency stabilizes at a low value. For example, cost analysis scenarios were performed using the measured rate of decline in diffuser performance. The analyses include loss of transfer efficiency and elevated headloss, which both increase operating cost. Cleaning the diffusers within 12 months of operation is generally economically favorable, restores efficiency, and reduces power overhead. Periodic cleaning prolongs the economically viable lifespan for the aeration system.

Bioreactors↗
PubMed2005

Comparative economic analysis of the impacts of mean cell retention time and denitrification on aeration systems.

Biological nutrient removal is practiced in various modifications of the activated sludge process (ASP) throughout the world. This paper compares conventional, nitrifying-only and combined nitrifying/denitrifying (NDN) processes. The authors performed 113 oxygen transfer efficiency measurements with the off-gas method over 20 years. This dataset was analysed and used to perform an economic analysis for three example scenarios, one for each layout (conventional, nitrifying-only and NDN). Field oxygen transfer efficiency and relevant plant operative costs and credits were considered (i.e., aeration cost, sludge disposal cost, methane production credit). The conclusion is that NDN operations always have lower aeration costs, and generally have the lowest combined operating cost. Reduced aeration costs result because of improved aeration efficiency at higher mean cell retention times and the use of nitrate as an electron acceptor. The improved aeration efficiency overcomes the increased oxygen required at higher cell retention time due to cell decay.

Biodegradation, Environmental↗
PubMed2004

Outcome in children with pulmonary Langerhans cell Histiocytosis.

BACKGROUND: The aim of this study was to evaluate features and outcome of children with Langerhans cell Histiocytosis (LCH) and pulmonary involvement. PROCEDURE: Retrospective evaluation of LCH patients was performed from 1987 to 2001. Multisystem patients were classified according to the pattern of organ system involvement into Groups: A (no pulmonary, hematologic, or hepatic involvement), B (pulmonary involvement), C (pulmonary and hematologic or hepatic involvement), and D (hematologic or hepatic involvement). All had skin, bone, or lymph node involvement. Chest X-ray was performed in all patients and computed tomography (CT) in 21. Diagnostic lung biopsy was performed in five patients. RESULTS: Pulmonary involvement was found in 36/220 patients studied. Two patients had isolated pulmonary involvement. Multisystem involvement was present in 83 patients, 34 of whom had pulmonary involvement. In 20/36 patients, tachypnea, cough, and thoracic pain occurred. Diffuse interstitial involvement was found in all cases. Pulmonary function tests were performed in nine patients, six of whom revealed mild to moderate restrictive respiratory involvement. The two patients having isolated pulmonary involvement survived 2 and 2.7 years after diagnosis. Median follow-up of all multisystem patients was 2.1 years, with a 5-year survival probability of 0.59. The 5-year survival probability of Groups A-D was 0.94, 0.83, 0.23, and 0.40, respectively. The survival difference between Groups B and C was statistically different (P < 0.0071). CONCLUSIONS: According to our data, pulmonary compromise without other risk organ involvement does not appear to be a negative prognostic factor in our study.

Adolescent↗