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Biofilm reactors: An experimental and modeling study of wastewater denitrification in fluidized‐bed reactors of activated carbon particles
Author(s) -
Coelhoso Isabel,
Boaventura Rui,
Rodrigues Alírio
Publication year - 1992
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260400510
Subject(s) - activated carbon , plug flow , denitrification , residence time distribution , fluidized bed , moving bed biofilm reactor , chemistry , tracer , bioreactor , biofilm , plug flow reactor model , carbon fibers , wastewater , diffusion , biomass (ecology) , adsorption , continuous stirred tank reactor , environmental engineering , materials science , mineralogy , environmental science , nitrogen , thermodynamics , composite material , ecology , inclusion (mineral) , bacteria , composite number , biology , nuclear physics , physics , organic chemistry , genetics
A fluidized‐bed biofilm reactor using activated carbon particles of 1.69 mm diameter as the support for biomass growth and molasses as the carbon source is used for wastewater denitrification. The start‐up of the reactor was successfully achieved in 1 week by using a liquor from garden soil leaching as the inoculum and a superficial velocity u 0 = 5 u mf . Typical biofilm thickness is 800 μm; therefore covered activated carbon particles have 3.3 mm in diameter. Reactor hydrodynamics was studied by tracer (KCl solution) experiments. The analysis based on residence time distribution theory involved a model with axial dispersion flow and tracer diffusion with linear adsorption inside the biofilm. Peclet numbers higher than 100 were found, allowing the plug flow assumption for the reactor model. Experimental profiles of nitrate and nitrite species were explained by a kinetic model of two consecutive zero‐order reactions coupled with substrate diffusion inside the biofilm. Under the operating conditons used thick biofilms were obtained working in a diffusion‐controlled regime. Comparison is made with results obtained in the same reactor with sand particles as the support for biomass growth. Activated carbon as the support has the following advantages: good adsorptive characteristics, homogeneous biofilm thickness along the reactor, and easy restart‐up of the reactor. © 1992 John Wiley & Sons, Inc.