Simultaneous biofiltration of H₂S, NH₃, and toluene using compost made of chicken manure and sugarcane bagasse as packing material

Offensive odors from wastewater treatment plants (WWTP) are caused by volatile inorganic compounds such as hydrogen sulfide and ammonia and volatile organic compounds (VOCs), such as toluene. To treat these pollutants, biofiltration is an effective and economical technology used worldwide due to its low investment and environmental impact. In this work, a laboratory-scale prototype biofilter unit for the simultaneous biofiltration of hydrogen sulfide, ammonia, and toluene was evaluated by simulating the emission concentrations of the El Salitre WWTP Bogotá, Colombia, using a compost of chicken manure and sugarcane bagasse as packing material for the biofilter. The prototype biofilter unit was set to an operation flow rate of 0.089 m³/h, an empty bed residence time (EBRT) of 60 s, and a volume of 0.007 m³ (6.6 L). The maximum removal efficiency were 96.9 ± 1.2% for H₂S, at a loading rate of 4.7 g/m³ h and a concentration of 79.1 mg/m³, 68 ± 2% for NH₃, at a loading rate of 1.2 g/m3 h and a concentration of 2.0 mg/m³, and 71.5 ± 4.0% for toluene, at a loading rate of 1.32 g/m³h and a concentration of 2.3 mg/m³. The removal efficiency of the three compounds decreased when the toluene concentration was increased above 40 mg/m³. However, a recovery of the system was observed after reducing the toluene concentration and after 7 days of inactivity, indicating an inhibitory effect of toluene. These results demonstrate the potential use of the prototype biofilter unit for odor treatment in a WWTP.