Biological denitrification by pseudomonas denitrificans in a tapered fluidized bed reactor

Abstract

A new reactor system using tapered fluidized bed has been employed for biological denitrification, in which a facultative and heterotrophic denitrifier, Ps. $\mbox{\underline{denitrificans}}$ (ATCC. 13867) adhering on 25/35 mesh activated carbon was used. This reactor system may have a much wider range of optimal operating condition with many advantages of fluidized bed. The environmental parameters affecting denitrification by $\mbox{\underline{Ps}}$. $\mbox{\underline{denitrificans}}$ was investigated. It has been found that optimum pH was between 7.0 and 8.5, and optimum temperature between 25 and 35 ℃. The rate of nitrate reduction was almost constant irrespective of nitrate concentration, zero order reaction. As a rational basis of reactor design, mathematical model of biological denitrification in tapered fluidized bed was derived ; $So^{0.55} = - K \mbox{\overline{t}}`` + Si^{0.55}$ $where K=1.657 (1.0-ε_{avg}) (ρk)^{0.55} D^{0.45} (rp)^{-0.9}$ In this experiment, the rate coefficient, K was 0.024 but it was impossible that general conclusion regarding the magnitude of the K value could be made due to the limited amount of data available.