Modeling of Biological Removal of H2S from Gas Flows in Biotrickling Filters

Wastewater treatment, oil and gas facilities along with the other industrial sections such as food, pulp and paper industries are the main sources of hydrogen sulfide emission to the atmosphere. Hydrogen sulfide is a toxic, flammable and corrosive gas, so several methods have been used for its removal. The physical and chemical methods are not cost effective and cause secondary pollution. The biological methods have recently received increasing interests as they can overcome the process and disposal costs. In this work a Biotrickling filter with counter-current flows of gas and liquid was modeled. In this dynamic model, it was assumed that hydrogen sulfide transferred from the gas phase to the liquid bulk, then to the biofilm. The effects of gas flow rate, liquid velocity, column height, and residence time on the performance of the bioreactor were investigated. The model showed that by increasing the gas flow rate up to 1.8 m3h-1, elimination capacity was increased, whereas removal efficiency was decreased. Moreover, by increasing the velocity of the trickling liquid from 2 to 15 m/s, removal efficiency increased from 26% to 99.7%. Higher heights of bioreactor resulted in higher removal efficiency of hydrogen sulfide and its effect was more significant at lower residence times.