Biofiltration performance and kinetic study of hydrogen sulfide removal from a real source

Biofiltration is one of the most accepted technologies in odor control in wastewater facilities. A biofilter system consists of a bed of organic material providing both as the carrier for the active microorganisms and as nutrient supply. This study was aimed to evaluate and model a biofilter performance operated under real conditions of odor emission from a wastewater pump station located in Khorramabad, Iran.

The media was a mixture of compost and wood chips with a weight ratio of 5:1. The treatment performance of the biofilter was assessed during a 90-day operation period and the gathered data were utilized to develop and determine the best fit kinetic model based on Michaelis-Menten and Ottengraf models. The best fit model was used in the analysis of scenarios defined based on inlet H₂S loading fluctuations. Also, the effectiveness of the main parameters in biofilter performance was evaluated using a dimensionless sensitivity coefficient.

The best fit model was found the Ottengraf zero-order type limited by diffusion based on the values of R-square (0.98) and mean square error (MSE) (0.002). The results demonstrated a high H₂S removal efficiency of about 98% in an EBRT (empty bed residence time) of 60 s. despite high fluctuations of inlet concentration under real conditions. The system was able to meet the effluent standard limit of 10 ppm even if the inlet H₂S loading increases up to two times the base level. According to the results of the defined sensitivity coefficient, the system performance was more sensitive to the inlet concentration than EBRT with a ratio of 1.4.

In addition to the acceptable efficiencies of biofilter in odor removal, the results proved the worth of using a kinetic model in forecasting the system performance which is a useful tool in the design and operation of such systems.