RESUMEN
Performance of an electrocoagulation (EC) process in batch and continuous operating modes was thoroughly investigated and evaluated for enhancing wastewater phosphorus removal under various operating conditions, individually or combined with initial phosphorus concentration, wastewater conductivity, current density, and electrolysis times. The results revealed excellent phosphorus removal (72.7-100%) for both processes within 3-6 min of electrolysis, with relatively low energy requirements, i.e., less than 0.5 kWh/m3 for treated wastewater. However, the removal efficiency of phosphorus in the continuous EC operation mode was better than that in batch mode within the scope of the study. Additionally, the rate and efficiency of phosphorus removal strongly depended on operational parameters, including wastewater conductivity, initial phosphorus concentration, current density, and electrolysis time. Based on experimental data, statistical model verification of the response surface methodology (RSM) (multiple factor optimization) was also established to provide further insights and accurately describe the interactive relationship between the process variables, thus optimizing the EC process performance. The EC process using iron electrodes is promising for improving wastewater phosphorus removal efficiency, and RSM can be a sustainable tool for predicting the performance of the EC process and explaining the influence of the process variables.
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Fósforo/análisis , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/análisis , Contaminantes Químicos del Agua/análisis , Electrólisis , Eliminación de Residuos Líquidos/instrumentaciónRESUMEN
The purpose of this paper is to provide a green technology that can clean turbine engine oil filters effectively in ships using ultrasound, with ultrasonic devices having a frequency of 25kHz and different powers of 300W and 600W, respectively. The effects of temperature, ultrasonic cleaning times, pressure losses through the oil filter, solvent washing, and ultrasonic power devices were investigated. In addition, the cleaning efficiency of three modes (hand washing, preliminary washing and ultrasonic washing) were compared to assess their relative effectiveness. Experimental results revealed that the necessary ultrasonic time varied significantly depending on which solvent was used for washing. For instance, the optimum ultrasonic cleaning time was 50-60min when the oil filter was cleaned in a solvent of kerosene oil (KO) and over 80min when in a solvent of diesel oil (DO) using the same ultrasonic generator device (25kHz, 600W) and experimental conditions. Furthermore, microscopic examination did not reveal any damage or breakdown on or within the structure of the filter after ultrasonic cleaning, even in the filter's surfaces at a constantly low frequency of 25kHz and power specific capacity (100W/gal). Overall, it may be concluded that ultrasound-assisted oil filter washing is effective, requiring a significantly shorter time than manual washing. This ultrasonic method also shows promise as a green technology for washing oil filters in turbine engines in general and Vietnamese navy ships in particular, because of its high cleaning efficiency, operational simplicity and savings.
RESUMEN
A specifically designed pilot-scale hybrid wastewater treatment system integrating an innovative equalizing reactor (EQ), rotating hanging media bioreactor (RHMBR) and submerged flat sheet membrane bioreactor (SMBR) was evaluated for its effectiveness in practical, long-term, real-world applications. The pilot system was operated at a constant flux, but with different internal recycle flow rates (Q) over a long-term operating of 475 days. At 4 Q internal recycle flow rate, BOD5, CODCr, NH4(+)-N, T-N, T-P and TSS was highly removed with efficiencies up to 99.88 ± 0.05%, 95.01 ± 1.62%, 100%, 90.42 ± 2.43%, 73.44 ± 6.03%, and 99.93 ± 0.28%, respectively. Furthermore, the effluent quality was also superior in terms of turbidity (<1 NTU), color (<15 TCU) and taste (inoffensive). The results indicated that with providing only chemically cleaned-in-place (CIP) during the entire period of operation, the membrane could continuously maintain a constant permeate flux of 22.77 ± 2.19 L/m(2)h. In addition, the power consumption was also found to be reasonably low (0.92-1.62 k Wh/m(3)).
Asunto(s)
Ciudades , Membranas Artificiales , Aguas Residuales/química , Purificación del Agua/métodos , Biodegradación Ambiental , Análisis de la Demanda Biológica de Oxígeno , Reactores Biológicos/microbiología , Costos y Análisis de Costo , Electricidad , Diseño de Equipo , Concentración de Iones de Hidrógeno , Nitrógeno/aislamiento & purificación , Oxígeno/análisis , Permeabilidad , Fósforo/aislamiento & purificación , Proyectos Piloto , Presión , Temperatura , Factores de Tiempo , Aguas Residuales/microbiología , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/economíaRESUMEN
This paper evaluated a novel pilot scale hybrid treatment system which combines rotating hanging media bioreactor (RHMBR), submerged membrane bioreactor (SMBR) along with electrocoagulation (EC) as post treatment to treat organic and nutrient pollutants from municipal wastewater. The results indicated that the highest removal efficiency was achieved at the internal recycling ratio as 400% of the influent flow rate which produced a superior effluent quality with 0.26mgBOD5L(-1), 11.46mgCODCrL(-1), 0.00mgNH4(+)-NL(-1), and 3.81mgT-NL(-1), 0.03mgT-PL(-1). During 16months of operation, NH4(+)-N was completely eliminated and T-P removal efficiency was also up to 100%. It was found that increasing in internal recycling ratio could improve the nitrate and nitrogen removal efficiencies. Moreover, the TSS and coliform bacteria concentration after treatment was less than 5mgL(-1) and 30MPNmL(-1), respectively, regardless of internal recycling ratios and its influent concentration.
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Reactores Biológicos , Ciudades , Electrocoagulación/métodos , Aguas Residuales/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/instrumentación , Purificación del Agua/métodos , Amoníaco/aislamiento & purificación , Análisis de la Demanda Biológica de Oxígeno , Nitratos/análisis , Nitrógeno/aislamiento & purificación , Fosfatos/aislamiento & purificación , Fósforo/aislamiento & purificación , Proyectos Piloto , Reciclaje , República de Corea , VolatilizaciónRESUMEN
OBJECTIVE: Hemodynamic abnormalities and refractory atrial arrhythmias in patients late after the Fontan operation result in significant morbidity and mortality. We reviewed our experience with Fontan conversion and concomitant arrhythmia surgery. METHODS: Between January 1996 and February 2004, 16 patients underwent Fontan conversion and arrhythmia surgery. Mean age at the initial Fontan operation was 5.1+/-3.5 (range: 2-15) years and mean age at Fontan conversion was 17.0+/-5.8 (range: 6-30). The initial Fontan operations were atriopulmonary connections in 14 patients, extracardiac lateral tunnel in 1, and intracardiac lateral tunnel in 1. The types of arrhythmia included atrial flutter in 10 patients and atrial fibrillation in 3. Fontan conversion operation was performed with intracardiac lateral tunnel in 5 patients and extracardiac conduit in 11. Arrhythmia surgery included isthmus cryoablation in 10 patients and right-sided maze in 3. RESULTS: There has been no mortality. At Fontan conversion operation, 7 patients required permanent pacemaker. All patients have improved to New York Heart Association class I or II. With a mean follow-up of 26.9+/-30.6 (range:1-87) months, 16 patients had sinus rhythm, 2 patients had transient atrial flutter which was well controlled, and 2 patients required permanent pacemaker during follow-up. CONCLUSIONS: Fontan conversion with concomitant arrhythmia surgery and permanent pacemaker placement is safe, improves New York Heart Association functional class, and has a low incidence of recurrent arrhythmias. In most patients, concomitant permanent pacemakers are needed.
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Arritmias Cardíacas/cirugía , Procedimiento de Fontan/métodos , Cardiopatías Congénitas/cirugía , Adolescente , Adulto , Arritmias Cardíacas/etiología , Arritmias Cardíacas/mortalidad , Aleteo Atrial/etiología , Aleteo Atrial/mortalidad , Aleteo Atrial/cirugía , Niño , Preescolar , Femenino , Atrios Cardíacos/fisiopatología , Cardiopatías Congénitas/complicaciones , Cardiopatías Congénitas/mortalidad , Humanos , Masculino , Marcapaso Artificial , Complicaciones Posoperatorias/etiología , Enteropatías Perdedoras de Proteínas/complicaciones , Enteropatías Perdedoras de Proteínas/cirugía , Embolia Pulmonar/complicaciones , Embolia Pulmonar/cirugía , Reoperación , Resultado del TratamientoRESUMEN
1. Neurogenin1 (Ngn1) is a basic helix-loop-helix (bHLH) transcription factor that is expressed in neuronal precursors during development of the nervous system. 2. In the present work, we investigated a instructive potential of Ngn1 in pluripotent embryonal carcinoma P19 cells. Treatment with retinoic acid (RA) induced expression of Ngn1 as well as NeuroD in P19 cells in early period of neuronal differentiation. P19 cells contained endogenous E47, a heterodimeric partner of neurogenic bHLH factors, and overexpression of Ngn1 alone was sufficient to induce the maximum activation of the E-box-mediated gene expression. 3. Sustained expression of Ngn1 in the absence of RA was sufficient to induce substantial expression of neuronal markers. The data indicate that Ngn1 is able to commit pluripotent P19 cells to adopt a neural cell phenotype in the absence of RA, which may finally lead to enhanced neuronal differentiation. The results also suggest that RA may induce neuronal differentiation of P19 cells by promoting a bHLH cascade including Ngn1.