Suspended-matter removing method utilizing biofilm and suspended-matter removing apparatus utilizing biofilm

A suspended-matter removing apparatus utilizing a biofilm, comprising:

• a filtering part having a filter layer formed by filling a solid filter material;
• a water-to-be-treated feeding part that feeds water to be treated to a first side of the filtering part to pass the water to be treated through the filter layer;
• a protrusion-element feeding part that feeds a protrusion element to the first side of the filtering part;
• a water-quality inspection part that inspects water quality of filtrate that has come out from a second side of the filtering part;
• a determination part that, based on a preset standard, determines whether or not a protrusion has been added to the surface of the solid filter material;
• and
• a control part that, when the determination part determines that the protrusion has not been formed, controls the protrusion-element feeding part to feed the protrusion element to the filtering part so as to add a protrusion to the surface of the solid filter material, and when the determination part determines that the protrusion has been added, controls the protrusion-element feeding part to reduce a feeding amount of the protrusion element as compared with when it is determined that the protrusion has not been formed.