Treatment of waste gas containing ammonia by biofilter

A laboratory-scale biofilter was used to treat waste gas containing NH₃. Its performance, transformation mechanisms and microbiological characteristics were investigated in this study. The inlet concentration of ammonia varied from 20~300mg/m³, and the air flow rate were 0.61m³/h, 0.85m³/h and 1.06m³/h, equivalent to empty bed residence time of 35s, 25s and 20s. The experimental results showed that the influent ammonia can be efficiently removed in the biofilter and elimination capacity of 29.62g/m³-h can be obtained. NH₃ could be removed effectively in. However, the removal mechanisms of NH₃ in the biofilter were different at various influent loads. NH₃ was mainly removed by bio-nitration in the conditions of low influent loads, while more NH₃ was transferred to aqueous phase by dissolution with the increase of influent loads. The results in microbial analyses had proven that the dominant ammonium oxidizing bacteria strains were Nitrosomonas and Nitrosococcus, while the dominant nitrite oxidizing bacteria were Nitrococcus, Nitrobacter and Nitrospira.