Hydrogen sulphide and volatile fatty acid removal from foul air in a fibrous bed bioreactor

Abstract

Odour control in Hong Kong has been addressed as an important issue by the authorities, since odour pollution is generated from many sources including wastewater treatment plants. Although a number of existing technologies are available for odour abatement and control, biological technique is still more attractive due to its low operating cost and ease of maintenance. A newly innovated fibrous bed bioreactor with twin columns was specially designed and constructed in our laboratory, in which an inner column was centred in an outer column. The bioreactor was fully filled with water in order to absorb the odorous components from foul gas and also contained both suspended and attached biomass to degrade the absorbed odorous pollutants. In this study, hydrogen sulphide (H2S) and butyric acid (C4H8O2) were used as odorous components and successfully removed from synthetic foul gases. Many factors affecting the H2S and butyric acid removal efficiency and maximum elimination capacity, such as pH of water solution, gas flow rate and its fluctuation, and sulphate content in solution have been studied. The experimental results demonstrated that the reduction rates of 97.8% for H2S and 99.9% for butyric acid were achieved in this experimental condition. It is proved that this bioreactor was a compact odorous gas treatment system with an application potential for treating foul air with high odour strength and low airflow rate such as the offensive gases from sludge treatment processes in a wastewater treatment plant.