CONDUCTIVITY TRACER STUDIES FOR A FLUIDIZED-BED BIOREACTOR

摘要

An automated conductivity tracer test was developed to measure the residence time distribution (RTD) of a cometabolic fluidized-bed bioreactor (FBBR). The FBBR contained sand-core bioparticles grown with phenol and it provided high (70% to 80%) removal of trichloroethene (TCE) at short (3 minute) detention times. The tracer test apparatus was constructed with "off-the-shelf components controlled with a PC-based data acquisition system. Non-disruptive hydrodynamic testing was obtained during normal operation of the FBBR. The conductivity of injected brine (sodium chloride) pulses was monitored at the reactor inlet and outlet. Dispersion numbers and detention times were computed by fitting the advection-dispersion model to the tracer curves. Typical dispersion numbers attributed to the fluidized-bed of bioparticles ranged from 0.07 to 0.11. In simplified modeling of the FBBR, dispersion was found to have little effect on TCE removal. Based on the dispersion of brine pulses, it was determined that phenol feed pulses injected at inhibitory concentrations over 2 g/L would be rapidly dispersed in the biological bed to non-inhibitory concentrations.