Biodegradation of benzene and a BTX mixture using immobilized activated Sludge

Abstract

Aerobic biodegradation was studied using activated sludge immobiized in calcium alginate gel. Hydrogen peroxide provided the dissolved oxygen source in a recirculation reactor that was operated batchwise and continuously. Responses to changes in benzene concentrations, flow rates, and biomass loadings were measured. Sixty percent of the benzene was biologically degraded in batch tests after 24 h using an initial concentration of 100 mg/L. A residence time of 17.14 h was required to biologically reduce benzene concentrations from 600 ppm to below the detection limit (1 ppm) during continuous operation. The system was modeled using Monod kinetics for substrate utilization. The apparent k_m values changed with biomass loadings, but were independent of the initial benzene concentrations. The aromatic species in BTX mixtures (i.e., benzene, toluene and o‐, m‐ and p‐xylene) can all be degraded at the same time.