Biodegradation dynamics of aromatic compounds from waste air in a trickle-bed reactor

Abstract

Biodegradation of polyalkylated benzenes from waste air was investigated experimentally in a laboratory-scale trickle-bed reactor. The study focussed on the description of process dynamics with regard to its behavior during quasi-steady-state, the start-up of the reactor, the influence of the nitrogen source and the response to cyclical starvation periods. A stable long-term operation of the bioreactor could be achieved by maintaining a sufficient nitrogen source at any time and by removing excess biomass, i.e. mainly extracellular polymeric substances, from the system from time to time. The start-up period of the bioreactor using an adapted mixed population was as short as 48 h and reproducible. A clear dependence of the biodegradation on the available nitrogen concentration in the liquid phase was observed with experiments where ammonium was added as pulses. A dynamic operation mode with cyclical starvation periods was applied simulating a two-shift operation of a waste-air purification plant over 7 days a week. This cyclical operation led to an increase of the integral biodegradation performance. The characteristic bioreactor response time to the dynamic operation with starvation periods was about 6–7 h and conformed with the observations of other studies.