Abstract

Phenolic wastewater was treated in a three-phase draft tube fluidized bed reactor containing biofilm. Phenol removal rate with biofilm was evaluated both theoretically and experimentally. The results indicate that biodegradation of phenolic wastewater by biofilm process could be treated as a zero order reaction. The volumetric biological removal rate with biofilm is proportional to the specific surface area of the biofilm with characteristic constant (k) 0.74 x 10^-2 kg PhOH/m²biofilm/d. It is proven here that almost 100% phenol removal could be attained at a specific biofilm surface area per volumetric phenol loading rate exceeding 132 m²/(kg-PhOH/d). The bioparticle diameter and the bioparticle hold-up in the three phase draft tube fluidized bed bioreactor are the decisive factors for the efficiency of the phenol treatment.

Key words: Phenol degradation, draft tube fluidized bed reactor, kinetics.

Abbreviation

a_s, Specific surface Area of Bioparticle m^-1; k, first order rate constant m.d; k = r_ddm_m/y, characteristic constant kg/m².d; K_s, half saturation constant mgl^-1, kg m^-3; n, number of tanks (reactors); S, substrate (phenol) concentration, mgl^-1, kgm^-3; s_i, initial or inlet substrate (phenol) concentration, mgl^-1. kgm^-3; S_o, outlet substrate (phenol) concentration, mgl^-3, kg m^-3; L_v, volumetric substrate loading rate kg/m³/d; PhOH, phenol; R_B, rate of degradation due to biofilm, kg/d; V, volume of reactor, 1, m³; Y, yield coefficient (kg of biomass/kg of phenol); m_m, maximum specific growth rate, h^-1; d, effective biofilm thickness for biodegradation, m; and r_d, density of biofilm, kg/m³.