| 摘要 |
<p>PURPOSE:To always keep a denitrifying ratio high and to obtain stable treated water quality by connecting two biological filter tanks in series or in parallel and removing a suspended substance in the front stage biological filter tank and performing denitrifying treatment in the post stage biological filter tank and performing the alteration of a passage accompanied by washing operation at every predetermined time. CONSTITUTION:Two biological filter tanks 1, 2 are arranged to front and post stages and, after the post stage biological filter tank 2 is washed, the passage from an upstream part is connected to the post and front stage biological filter tanks 2, 1 to perform water treatment operation. Immediately after denitrification is performed in the front stage biological filter tank 1, the suspended substance in inflow raw water can be caught in the post stage biological filter tank 2. Therefore, the advance of breakthrough can be suppressed and the denitrifying ratio of the front stage biological filter tank 1 can be kept. After the front stage biological filter tank 1 is washed, the passage from the upstream part is connected to the front and post stage biological filter tanks 1, 2 to perform water treatment operation. By this constitution, the suspended substance in raw water can be removed in the front stage biological filter tank 1 and denitrification can be performed in the post stage biological filter tank 2. Therefore, the treated water is kept in good quality.</p> |
