Biomedical subjects

Fernando Beltrán

Publications and source records attributed to Fernando Beltrán.

3 recordsLinked to original sources

PubMed2004

Stabilized leachates: sequential coagulation-flocculation + chemical oxidation process.

The combined sedimentation-chemical oxidation treatment of medium-stabilized landfill leachates has been investigated. The sequence of stages implemented was: (a) coagulation-flocculation by pH decrease (pH 2) to acidic conditions (COD removal approximately 25% related to COD0 approximately 7500 ppm); (b) coagulation-flocculation by Fe(III) addition (0.01 M) at pH 3.5 (COD removal approximately 40% related to COD of supernatant after step (a); (c) Fenton (Fe(III) = 0.01 M; H2O2 = 1.0 M) oxidation (COD removal approximately 80% related to COD of supernatant after step (a); and (d) coagulation-flocculation of Fenton's effluent at pH 3.5 (COD removal approximately 90% related to COD of supernatant after step (a). The use of Kynch theory allows for the design of clarifiers based on the amount of solids fed. For a general example of 1000 m3 day(-1) of a feeding stream, clarifier area values of 286,111 and 231 m2 were calculated for compacting indices of 3.7, 2.67 and 2.83 corresponding to the first, second and third consecutive sedimentation processes, respectively, (steps (a), (b) and (d)).

Environmental Pollution↗

PubMed2003

Stabilized leachates: ozone-activated carbon treatment and kinetics.

Ozone has been used as a pre-oxidation step for the treatment of stabilized leachates. Given the refractory nature of this type of effluents, the conversion of some wastewater quality parameters has been moderate after 1 h of ozonation (i.e. 30% chemical oxygen demand (COD) depletion). Ozone uptake was calculated in the interval 1.3-1.5 g of ozone per gram of COD degraded. An optimum dose of ozone has been experienced in terms of biodegradability of the processed effluent (60 min of treatment, 1 x 10(-3) mol L(-1) ozone inlet feeding concentration and 50 L h(-1) gas flow-rate). pH and other typical hydroxyl radical generator systems exerted no influence on the efficiency of the process, suggesting the negligible role played by the indirect route of oxidation (generation of hydroxyl radicals). The ozonated effluent was thereafter treated in a second adsorption stage by using a commercial activated carbon. Removal levels up to 90% of COD in approximately 120 h were experienced for adsorbent dosages of 30 g L(-1). Both steps, the single ozonation and the adsorption stage have been modelled by using different pseudoempirical models.

Carbon↗

PubMed2003

Fenton-like oxidation of landfill leachate.

The treatment of stabilized leachates by means of Fenton's like reagent [Fe(III)-H2O2] has been studied. It has been demonstrated that the oxidation state of the catalyst does not influence the efficacy of the process in terms of chemical oxygen demand depletion profiles. The abrupt increase in temperature experienced in oxidation experiments involves a wastage of hydrogen peroxide diminishing the fraction of this reagent addressed at removing COD. If temperature is kept constant, the hydrogen peroxide uptake is 10 mg of H2O2 consumed per mg of COD abated (from 15 to 30 degrees C). Working temperatures above 30 degrees C does not lead to additional COD conversion, contrarily, the percentage of wasted H2O2 is increased. A rough economic analysis of the process indicates that this treatment can be a suitable alternative to deal with this type of effluents.

Hydrogen Peroxide↗