Influence of temperature on removal efficiency of ammonia, iron and manganese in biological purification biofilter

Temperature is one of the most critical operational parameters for biological purification filter. In order to investigate the removal efficiency of ammonia, iron and manganese in the process of water temperature dropping from about 25℃ to 6℃, the biological purification filter was used to treat the simulated groundwater containing ammonia, iron and manganese. The results showed that the concentration of ammonia, total iron and manganese in the effluent was lower than 0.15mg/L, 0.1mg/L and 0.05mg/L, respectively, which were all lower than the national standards. Total iron and manganese in the effluent were not adversely affected by the decrease of water temperature, but ammonia in the effluent gradually increased from about 0.02mg/L to about 0.12mg/L. Further analysis showed that iron was mainly removed in 0-0.4m of the filter layer, and iron removal was not affected by the variation of water temperature. Ammonia and manganese were mainly removed in 0-0.8m of the filter bed, and their concentrations along the filter bed obviously increased with the decrease of water temperature. Biological ammonia and manganese removal were observed to follow a first-order kinetic reaction. When the water temperature was 24.6℃, 15.3℃ and 6.7℃, the kinetic constants k were 0.154min-1, 0.186min-1; 0.143min-1, 0.175min-1; 0.103min-1 and 0.163min-1, respectively, and the half reaction times t1/2 were 4.51min, 3.72min; 4.83min, 3.96min; 6.72min and 4.24min, respectively. With the decrease of water temperature, the removal efficiency of ammonia and manganese was obviously and adversely affected. © 2020, Chemical Industry Press Co., Ltd. All right reserved.