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F Benítez

Publications and source records attributed to F Benítez.

11 recordsLinked to original sources
PubMed2006

Production of biomass (algae-bacteria) by using a mixture of settled swine and sewage as substrate.

This paper presents the use of a mixture of settled swine and sewage as substrate for biomass production, mainly constituted by microalgae Chlorella vulgaris and aerobic bacteria, growing outdoor at different dilution rates in a continuous mode. The experiments were carried out in 16-litre volume laboratory ponds operating at hydraulic retention times (HRT) in a range of 4-14 days equivalent to dilution rates (D) in a range of 0.250-0.071 d(-1). Total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), total biochemical oxygen demand (TBOD(5)), total suspended solids (TSS), volatile suspended solids (VSS), total Chlorophyll (S C), total Kjeldahl nitrogen (TKN), ammonia nitrogen, total phosphorous, orthophosphate and pH were monitored. An empirical relationship between the dilution rate (D) and the removal efficiencies of TCOD, SCOD, TBOD(5), TKN and total phosphorous was found. The occurrence of an inhibition process for TCOD, TBOD(5), TKN and total phosphorous removals was observed. The Andrews kinetic model was successfully applied to these experimental data, while the Monod model was more suitable for studying the variation of the SCOD removal rate with the effluent SCOD concentration. The maximum microalgal biomass productivity was found to be in the range of 93-98 mg VSS(A)/L d (37.2-39.2 g/m(2)d) at dilution rates in the range of 0.167-0.250 d(-1), where VSS(A) is the concentration of microalgae expressed in VSS. In the case of the bacteria, the productivity increased linearly with the dilution rate being maximum at a D value of 0.25 d(-1). It was concluded that the mixture of pre-treated swine and sewage used as substrate, contributed to the obtention of a high biomass (microalgae-bacteria) production, providing a simple technology feasible to be applied in developing countries.

Animals↗
PubMed2004

Evaluation of a laboratory and full-scale microalgae pond for tertiary treatment of piggery wastes.

Piggery wastes tertiary treatment in laboratory and full-scale microalgal ponds was evaluated. COD, BOD, inorganic nitrogen and orthophosphate removals of up to 57%, 69%, 79% and 74%, respectively, were obtained. The effect of the hydraulic retention time (HRT) on removal efficiencies followed an exponential relationship. COD, BOD and orthophosphate removal rate decreased with increased effluent concentration while the inorganic nitrogen removal rate increased with an increasing effluent substrate concentration at inorganic nitrogen concentration values lower than 0.07 g l(-1). Values of maximum substrate removal rate, half rate constant, cell yield coefficient, endogenous constant and maximum specific growth rate were 7.1 +/- 0.5 d(-1), 0.21 +/- 0.02 g l(-1), 0.26 +/- 0.01 g VSS g(-1) COD, 0.012 +/- 0.001 d(-1)and 1.9 +/- 0.9 d(-1), respectively. At full-scale, effluent COD, BOD, MPN, inorganic nitrogen and orthophosphate decreased while pH and Chlorophyll a increased with the operation time. It was found that the use of the final effluent as drinking water did not affect pigs growth.

Animals↗
PubMed2003

Population dynamic of algae and bacteria in an oxidation channel.

A study on algae and bacteria population changes, as a function of time, was carried out in a pilot scale oxidation channel bioreactor using a carrousel system. Total Coliforms, Pseudomonas aeruginosa, and Streptococcus faecalis, the most common bacteria found in sewage, Scenedesmus obliquus and Chlorella vulgaris were the microalgae considered in this work. Physicochemical parameters such as COD, BOD, Chlorophyll a, nitrogen, and phosphorous compounds were studied and determined during the experiments. It was demonstrated that the level of wastewater contamination could be predicted based on the bacterial and algae composition. The relationships between the algae and bacteria population, and the variation of these microorganism populations as a measurement of the level of purification were established. The oxidation channel was able to remove a considerable amount of organic matter and pathogenic microorganisms in a relatively short time. The nitrification process could not be measured. The increase in the relative concentration of microalgae contributed toward improving the global efficiency of the system as well as reducing the pathogenic bacteria population.

Bacteria↗
PubMed1999

[Forestier's disease. Ear, nose and throat manifestations].

Forestier's disease is a skeletal pathology that sometimes affects the head and neck as a consequence of hyperostotic involvement of the cervical spine. We report the case of a 73-year-old man who had progressive difficulty in swallowing solids. Gastrointestinal endoscopy revealed a bony mass in the hypopharynx. The case is described and the disease manifestations in head and neck are discussed.

Aged↗
PubMed1997

In-laboratory removal of femoral sheath following protamine administration in patients having intracoronary stent implantation.

Two hundred twenty-eight patients with successful coronary stent implantation were randomized either to protamine administration and femoral sheath removal (group I, n = 117) or no heparin neutralization and delayed sheath removal (group II, n = 111). The hospital stay after treatment was shorter in patients receiving protamine; therefore, protamine use for neutralizing circulating heparin may be safely administered immediately after stent implantation.

Anticoagulants↗
PubMed1997

[Primary stent treatment in the acute phase of myocardial infaction].

INTRODUCTION: Although direct balloon angioplasty has emerged as an alternative to thrombolytic therapy in patients with acute myocardial infarction, reocclusion and restenosis rates are limiting factors. We postulated that these limitations could be partly overcome by primary stenting of the responsible lesion. MATERIAL AND METHODS: Since January/94 we have studied 59 patients with acute myocardial infarction who were treated in the early phase (3.1 +/- 2 hours since the onset of symptoms) by elective Palmaz-Schatz stent implantation. No adjunctive thrombolytic therapy was associated. Two patients were in cardiogenic shock and were treated under percutaneous cardiopulmonary support. At cardiac catheterization a left ventriculography and coronary angiograms were obtained. Then, mechanical recanalization of the responsible lesion was performed. If the angiographic anatomy was considered suitable, a stent was implanted at the lesion. RESULTS: The infarct related artery was the left anterior descending in 29 patients, the circumflex in 14 and the right coronary artery in 16. At baseline conditions, 40 patients had a totally occluded artery and 19 showed a TIMI-grande 1 antegrade flow. One patient had an early clinical recurrence 4 days later, which required an additional divided Palmaz-Schatz stent at the distal portion of the lesion, in order to seal a residual dissection. All remaining patients had a favourable clinical course without major complications. Immediately after treatment the minimal lumen diameter was 3.2 +/- 0.4 mm and no residual stenosis was detectable at the treated segment. Six-month angiographic reevaluation was performed in all 29 (49%) eligible patients. Restenosis (> 50% stenosis) was detected in 6 out of the 29 evaluated patients (21%). CONCLUSIONS: Primary stent implantation in selected patients with an evolving myocardial infarction provides good initial and 6-month results.

Acute Disease↗
PubMed1996

[Long-term clinical course of acute myocarditis. Prospective study of a series of 99 patients (1987-1995)].

BACKGROUND: The natural history of acute myocarditis is not well known. The aim of our study was to assess the spontaneous outcome of patients with this disease and its possible relation with progression to chronic dilated cardiomyopathy. METHODS: With this aim, we have carried out a prospective study of 99 patients consecutively diagnosed with acute myocarditis in our hospital from 1987 to April 1995, with a mean follow-up of 34 +/- 25 months. Acute myocarditis was diagnosed by clinical, echocardiographic and isotopic (detection of myocite damage) data, in absence of any other cardiac lesion. RESULTS: Mean age was 26 +/- 17 years; 70% of the patients were male. Initial symptoms were dyspnea in 58% of the patients, chest pain in 33% and arrhythmias in 9%. Severe heart failure was present in 62% of the patients, ventricular arrhythmias in 16% and supraventricular arrhythmias in 16%. Cardiothoracic index was 0.50 +/- 0.07. Left ventricular ejection fraction was 0.40 +/- 0.18, although in 44% of the patients it was lower than 0.30. Immunosuppressive therapy was not used in any case. Outcome was favorable in 70% of the patients, who had a normal ejection fraction, while 13% died or needed heart transplantation during follow-up and 17% progressed to stable chronic dilated cardiomyopathy. Final ejection fraction was 0.53 +/- 0.17, significantly higher than the initial, 0.40 +/- 0.18 (p < 0.05); this improvement in ejection fraction was mainly observed during the first month after diagnosis (0.49 +/- 0.18). The proportion of patients with an ejection fraction of less than 0.30 decreased from 44% to 21% at the end of follow-up. CONCLUSIONS: Spontaneous outcome of acute myocarditis is good in the majority of patients, although an unfavourable evolution was observed in almost 30% of the patients (death, need of heart transplantation or chronic dilated cardiomyopathy). Improvement in ventricular function mainly occurs at short-term, during the first month of evolution in our study.

Acute Disease↗