Dispersion model to describe the carbon removal from wastewater in a fixed bed up flow pilot bioreactor with a hexagonal feldspar packing
Modelo de dispersión para describir la remoción de carbono de aguas residuales en un reactor de flujo ascendente de lecho fijo con un empaque hexagonal de feldespato
S. A. Martínez–Delgadillo1*, M. Rodríguez–Cruz2 and M. G. Rodríguez–Rosales1,3
1 Departamento de Energía, Universidad Autónoma Metropolitana —Azcapotzalco. Av. San Pablo 180. Azcapotzalco. CP.02200. México D.F. * Corresponding author. E–mail: samd@correo.azc.uam.mx
2 Área de Física, Universidad Autónoma Chapingo. Km 38.5 Carretera México–Texcoco. México
]]> 3 Depto. Ingeniería en Sistemas Ambientales, ENCB, IPN, Av. Wilfrido Massieu s/n Unidad Profesional Adolfo López Mateos, México D.F.
Received 3rd of December 2007
Accepted 10th of October 2008
Abstract
In this work the modeling of carbon removal from wastewater in a fixed bed up flow pilot bioreactor with a hexagonal feldspar packing was carried out. The performance of a hexagonal feldspar packing was evaluated in an aerated biological pilot reactor. The feldspar packing was obtained by direct extrusion followed by sintering at 1100°C, during 4 hours, conditions at which the highest porosity and specific surface area were obtained. In addition to its easy preparation and low cost, the packing presented chemical resistance to different acids. The biological fixed bed up flow reactor with a total volume of 30.7 L was randomly packed with the hexagonal pieces of feldspar. Dispersion test were performed with a tracer (KCl), to estimate the dispersion number (Nd) in the reactor, with and without aeration. It was found that the dispersion increased due to the aeration and exerts a strong influence on reactor performance. A plug flow reactor model with axial dispersion and Monod kinetic was used to describe the carbon removal (COD) in the reactor at different hydraulic loading rates. The wastewater used during the tests was sampled at the exit of the primary settler of a Mexican wastewater treatment plant, being a mixture of industrial and urban effluents, with a COD = 650 mg/L. Four ascendant flow hydraulic loadings (L) from 1.08 x 10–4 (m3/s m2) to 4.32 x 10–4 (m3/s m2) were tested. The COD removal was about 95%, higher than the 85% reported in other studies.
Keywords: dispersion, modeling, feldspar packing, wastewater secondary treatment.
Resumen
]]> En el presente trabajo se modeló la remoción de carbono de aguas residuales en un bioreactor piloto de lecho fijo de flujo ascendente con un empaque hexagonal de feldespato. El desempeño del empaque hexagonal de feldespato fue evaluado en el reactor piloto aireado. El empaque fue obtenido mediante extrusión seguida de un proceso de sinterizado a 1100°C durante 4 horas, en la cual se obtuvo la mayor porosidad y área superficial especifica. Además de su fácil preparación y bajo costo, el empaque de feldespato resultó ser resistente a diferentes ácidos. El reactor piloto, con volumen total de operación 30.7 L, fue empacado al azar con el soporte hexagonal de feldespato. Se realizaron pruebas con y sin aireación, para estimar el número de dispersión (Nd), utilizando como trazador KCl. Se encontró que la dispersión se incrementa con la aireación y ejerce una fuerte influencia en el desempeño del reactor. Para describir la remoción de carbono (DQO) se utilizo un modelo que considera la dispersión axial en el reactor, así como una reacción de remoción de tipo Monod que fue validado a diferentes cargas hidráulicas. Durante los experimentos se utilizó agua residual muestreada a la salida del sedimentador primario de una planta mexicana de tratamiento de aguas residuales. El agua residual es una mezcla de agua residual industrial y de agua residual domestica con una demanda química de oxigeno (DQO) de 650 mg/L. Las pruebas se realizaron con flujo ascendente y se probaron 4 cargas hidráulicas (L); desde 1.08 x 10–4 (m3/s m2) hasta 4.32 x 10–4 (m3/s m2). La remoción DQO alcanzó un 95 % lo cual es mayor a lo reportado (85%) en otros estudios.Palabras clave: dispersión, modelo, lecho fijo, feldespato, empaque, reactor, flujo ascendente, agua residual.
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References
APHA, AWWA, WPCF. (1995). Standard Methods for the Examination of Water and Wastewater. 19th ed. American Public health Association, Washington, D.C., U.S.A. [ Links ]
Bruckschen B., Seitz H., Buzug T. M, Tille C., Leukers B., Irsen S. (2005). Comparing Different Porosity Measurement Methods for Characterisation of 3D Printed Bone Replacement Scaffolds. Biomedizinische Technik 50, 1609–1610. [ Links ]
]]>Dochain, D.; Vanrolleghem, P. (2001). Dynamic modeling and estimation in wastewater treatment process. IWA Publishing. U.K. [ Links ]
Eckenfelder, W.W. (1989). Industrial Water Pollution Control, 2nd Edition, McGraw–Hill, New York. [ Links ]
Levenspiel, O. (1999). Chemical reaction Engineering. 3rd Ed. John Wiley & Sons. [ Links ]
Logan, B. E., Hermanowicz, S.W., Parker, D.S. (1987). Engineering implication of a new trickling filter model. Water Pollution Control Federal 59 (12), 1017–1028. [ Links ]
Peixoto, J., Mota, M. (1998). Biodegradation of toluene in a trickling filter. Bioprocess Engineering 19, 393–397. [ Links ]
]]>Raj, S.A. and Murthy, D.V.S. (1999). Comparison of the trickling filter models for the treatment of synthetic dairy wastewater. Bioprocess Engineering 21,51–55. [ Links ]
Ramalho, R. (1996). Tratamiento de Aguas Residuales. Ed. Reverté, Spain. [ Links ]
Richard, U., Edgehill. (1999). Mathematical analysis of trickling filter response to pentachlorophenol shock load. Biochemical Engineering Journal 3, 55–60. [ Links ]
Rodríguez, M., Hernández, R. T. (1999). Supports tubular ceramics. Revista Mexicana de Física 45, 61–63. [ Links ]
Sá, C.S.A., Boaventura, R.A.R. (2001). Biodegradation of phenol by Pseudomonas putida DSM 548 in a trickling bed reactor. Biochemical Engineering Journal 9, 211–219. [ Links ]
]]>Tchobanoglous, G., Metcalf, E. (Eds.). (1991). Wastewater Engineering Treatment, Disposal and Reuse. 3rd Edition, McGraw–Hill, Singapore. [ Links ]
Tekerlekopoulou A.G., Vasiliadou I.A., Vayenas D.V. (2008) Biological manganese removal from potable water using trickling filters Biochemical Engineering Journal 38, 292-301. [ Links ]
Wang, Q.H., Zhang, L., Tian, S., Sun, P.T.C., Xie, W. (2007). A pilot–study on treatment of a waste gas containing butyl acetate, n–butyl alcohol and phenylacetic acid from pharmaceutical factory by bio–trickling filter. Biochemical Engineering Journal 37, 42–48 [ Links ]
Wang, C., Zeng, Y., Lou, J., Wu, P. (2007) Dynamic simulation of a WWTP operated at low dissolved oxygen condition by integrating activated sludge model and a floc model. Biochemical Engineering Journal 33, 217–227 [ Links ] ]]>