Oxygen transfer rate and acetone uptake rate in the airlift reactor using bacteria immobilized on solid particles creating the inverse fluidized bed
Special Symposium - Environmental Protection & Sustainability
Environmental Protection & Sustainability (EPS - Poster)
Keywords: waste water, ketone, aerobes, immobilization
The inverse fluidized bed airlift reactor seems to be an interesting proposal for the waste water treatment. An expansion of the fluidized bed to accomodate the generated cells allows to avoid problems of clogging. Additionally an inverse fluidized bed in the downcomer of the airlift reactor ensures a keeping of a bioparticle bed separated from a higher shearing in the riser.
The aim of the presented work is to investigate the oxygen transfer rate and the consumption course of the acetone in the presence of the Acinetobacter calcoaceticus aerobic bacteria immobilized on solid particles creating the inverse fluidized bed in the downcomer of the external loop airlift reactor.
It is found that the minimum fluidization velocity diminishes during the biodegradation process because of an increase of the density of the carrier particle - biomass layer agglomerates. An experimental equation for prediction of the minimum fluidization velocity is obtained. The lowest and approximately constant value of the biodegradation time is observed for gas flow rates slightly higher than the minimum fluidization velocity value i.e. up to about double minimum fluidization velocity value. The highest rate of the biodegradation with bacteria A. calcoaceticus and thus the lowest biodegradation time is obtained for pH value slightly above 7. Biodegradation time increases with an increase of the initial acetone concentration. It was found that the biodegradation time decreases with an increase of the initial bed height with immobilized bacteria. It is because more solid particles mean the larger bacteria amount as well as the longer contact time of the bacteria and the biodegradated substance in the case of the higher fluidized bed. The oxygen transfer coefficient values in the inverse fluidized bed reactor are found to be higher than values obtained in the suspension airlift reactor as well as in the airlift reactor with the fluidized bed in the riser for the same solid concentration. Therefore experimental values of the biodegradation time in the inverse fluidized bed reactor are lower than those obtained in the reactor with the immobilized bacteria fluidized bed in the riser.
The disappearance of the organic compounds in the solution and the new cell synthesis occur simultaneously. The uptake rate of the substrate depends on the biomass amount and simultaneously the microorganism proliferation rate is dependent on the substrate concentration. It means that both variables influence each other. Therefore the equation of the substrate uptake rate includes a dynamics of the biomass growth. The Monod equation presenting the mathematical correlation of the substrate concentration with the growth kinetics of microorganisms including the biomass growth is presented taking into account the simplest models of two first order process rate equations i.e. the simultaneous substrate consumption rate and the biomass growth rate were used.
See the full pdf manuscript of the abstract.
Presented Monday 17, 13:30 to 15:00, in session Environmental Protection & Sustainability (EPS - Poster) S-7P.
