Removal of ammonium and manganese from surface water using a MeO_x filter system as a pretreatment process

Residual aluminium from the coagulation-sedimentation process in the treatment of surface water can decrease the catalytic activity of a manganese co-oxide filter film (MeO_x) used for ammonium and manganese removal. To solve this problem, a MeO_x filter was used as a pretreatment process to filtrate source water directly before the coagulation and sedimentation treatment. The removal performance and the mechanism of change in the activity of MeO_x were investigated. The experimental results indicated that the MeO_x filter removed ammonium and manganese from surface water sources effectively, and its manganese removal activity was enhanced. The characteristics of MeO_x were investigated via SEM, EDS, XPS, and the BET surface area. Analysis of the experimental results showed that the increase in the content of Al under this condition was much lower than that under treatment with the coagulation-sedimentation process. After long-term operation, the amount and surface area of MeO_x coated on the filter sand increased significantly, leading to an increase in the catalytic activity. However, in cold water, the catalytic activity of MeO_x decreased, and more Mn(II) was obtained on the surface of MeO_x. Thus, the morphology of MeO_x changed. Fortunately, when water temperature increases, the removal activity can recover immediately. By inactivating microorganisms and comparing the removal performance with that under other conditions, the MeO_x activity of the pretreatment process is preserved effectively and no strengthening measures are required. This study will provide a new strategy for the use of the MeO_x catalytic technology.