Comparative bioparticle and hydrodynamic characteristics of conventional and tapered anaerobic fluidized-bed bioreactors

Abstract

By maintaining the same operational conditions of one conventional¯uidized-bed bioreactor (CFB) and two tapered¯uidized-bed bioreactors (TFBs), the performance of the TFBs with taper angles of 5°and 2.5°were found to be superior to that of the CFB with a taper angle of 0°. Experimental results together with statistical analyses showed that the bioparticle and hydrodynamic characteristics of the TFBs were signi®cantly different from those of the CFB. Also, bioparticle strati®cation occurred in the three bioreactors. The bio®lm thickness (d) and the speci®c biomass (b) of the three bioreactors varied in the following decreasing order 5°b 2.5°b 0°under the same volumetric loading. Meanwhile, the speci®c energy dissipation rate (v) and the bioparticle washout rates (W = 0.214 AE 0.219; 0.537 AE 0.493 g BAC dm

Influence of medium composition on the characteristics of a denitrifying biofilm formed by Alcaligenes denitrificans in a fluidised bed reactor

“…This figure shows that the biofilms formed have low densities. The values obtained are very small compared with the results referred to in the literature for biofilms formed by other microorganisms using reactors with higher shear stresses, or different configurations [2,3].…”

“…The density of the wet biofilm (z f , g/cm 3 ) can be calculated using the biofilm density z biofilm (g TVS /cm 3 wet biofilm ), the relationship TVS/ TS and the amount of water in the biofilm, according to…”

“…In order to prevent washout of the bioparticles, as frequently reported for fluidised bed reactors [3,6] it was necessary to remove the excess of biomass formed on the carriers. After the removal of the biofilm from the supports, the biofilm accumulated was very low (Fig.…”

“…However, during continuous operation, the performance and stability of the reactor depends on the structure of the biofilm formed around the support. Hence, parameters such as biofilm thickness, biofilm density and shape [2,3] and the overall density of the particles covered with biofilm should be controlled to obtain a stable reactor operation.…”

“…Relatively few studies have been carried out in denitrifying fluidised bed reactors with the purpose of studying in detail the biofilm properties formed during reactor operation [3,6]. Research regarding pure culture biofilms in fluidised bed reactors is not common in spite of the fact that it can give a good insight on the influence that several parameters have on the structure of the biofilms.…”