Multistage fiber filtering apparatus capable of selectively filtering

A multistage fiber filtering apparatus comprising:

• an enclosure configured to include an upper box and a lower box communicating with the upper box
• a strainer configured to be installed in the upper box along a longitudinal direction;
• a plurality of fiber yarn media configured to surround an outer circumferential surface of the strainer to form a first filtering layer;
• a plurality of fiber ball media configured to be built in the lower box to form a second filtering layer;
• a first pipe configured to be formed on one side wall of a lower portion of the upper box and to introduce the raw water;
• a second pipe configured to be formed on one side wall of a lower portion of the lower box and to discharge filtered water;
• a third pipe configured to be formed on one side wall of an upper portion of the lower box and to introduce the raw water or discharge the filtered water;
• and
• a controller configured to selectively introduce the raw water into the first pipe or the third pipe depending on a turbidity of the raw water in a filtering mode, and selectively introduce a washing water into the second pipe or the third pipe depending on the turbidity in a backwashing mode.