a b s t r a c t
In order to apply a spout–fl uid bed reactor with a draft tube for the nitrifi cation process of wastewater
treatment, the infl uence of fl uid-mechanical parameters on volumetric mass transfer coeffi cient was
analyzed. Experiments were carried out in a 10 0 0 mm high 2D semi-column with a draft tube. The draft
tube had a cross section of 50 50 mm2 and the annular region of the reactor had a cross section of
50 140 mm2. The work described in this paper reports the influence of several fluid-mechanical
parameters including liquid and gas flow rates, particle diameters and particle circulation on volumetric
mass transfer coefficient, kLa. The liquid flow ranged from 3.5–4.5 m3/h and gas flow ranged from 300 to
800 L/h. The particles used were glass spheres with diameters of 3, 4, 5 and 6 mm. Tap water and air
were used as the liquid and gas phase, respectively. The experimental results have shown that particle
circulation through the draft tube contributes to kLa increase as well as the increase in the particle
diameter, the gas and liquid flow rates