Mathematical analysis of trickling filter response to pentachlorophenol shock load

Abstract

The response of a laboratory trickling filter to a step increase in pentachlorophenol (PCP) feed concentration was analyzed using continuous stirred tank (CSTR) and plug flow reactor (PFR) models. The CSTR model provided a slightly better fit to experimental data than the plug flow model when specific growth rate, μ, and PCP-degrading biomass concentration before the shock load, X 0, were variable parameters but was clearly superior when the mean residence time, τ, was added as a third parameter. The three-parameter CSTR model accurately represented six of seven concentration response curves corresponding to step increases in PCP feed concentration of 12–165 mg l −1 and 20–150 mg l −1. The continuing improvement in system response to repetitive 20–150 mg l −1 shock loads was reflected by a monotonic increase in the optimal estimates of initial rate of biomass production.