The treatability of butyrate in aerated lagoon was investigated in continuous laboratory-scale aerated reactors at 35°C. The effects of cell retention time, organic loading rate and pH on cellular growth and oxidation rate of butyrate were investigated. The cell retention time was varied in series of bioreactors from 1.5 to 8.0 days and influent pH was varied from 4.0 to 7.0. Butyrate loading rate of up to 3 kg/m3/d as soluble organic carbon was investigated. The analysis showed that the maximum specific growth rate of heterotrophic bacteria was 2.1 d-1, yield coefficient was 0.51, bacterial decay coefficient was 0.133 d-1 and cell maintenance coefficient was 0.262 d-1. The maximum specific substrate utilization rate, half-rate saturation constant and substrate inhibition constant were 1.22 mg SOC/mg POC/d, 7.8 mg SOC/L, and 5900 mg SOC/L, respectively. Butyrate removal rate was influenced by loading rate, but was independent of the mode of variation of butyrate loading rate. No evidence was found to support the view that total butyrate concentration influenced the density of heterotrophic bacteria. However, the concentration of undissociated butyrate was found to significantly affect the density of heterotrophic bacteria. In the alkaline pH range, heterotrophic bacteria increased as butyrate concentration increased. Densities of heterotrophic bacteria as high as 1.1×1010 cfu/mL were observed when effluent pH was 8.4, but decreased to 3×103 cfu/mL when effluent pH decreased to 4.3.