Abstract: Disclosed herein is a structure for fixing screen bars of a screening apparatus, which is installed in a wastewater treatment plant to remove impurities contained in wastewater and includes a screen panel formed by arranging the screen bars parallel to each other to have gaps ranging from 1 mm to 10 mm therebetween. The screen bar fixing structure of the present invention is constructed such that screen bars, which are thin and long shapes, can maintain the straightness and gaps therebetween constant even though the screen bars are not welded to support bars provided on the rear surfaces of the screen bars, thus solving the problem in which impurities such as hairs, which are relatively long, are wound around the support bars, with the result that rakes undesirably flip or are damaged, or the gaps between the screen bars become clogged.

Abstract: A grit chamber for a wastewater treatment plant. A vertical floodgate is installed on a partitioning wall and is driven in a vertical direction to be opened downwardly from a top toward a bottom. A floodgate driving motor is coupled to one end of the vertical floodgate to directly drive the vertical floodgate. An inflow amount measurement sensor functions to stepwisely measure a flow amount of wastewater which passes through a wastewater tank. A control section is connected to the floodgate driving motor and the inflow amount measurement sensor to control the floodgate driving motor in response to a measurement result of the inflow amount measurement sensor. A wastewater level is adjusted within a predetermined range through operation of the vertical floodgate to maintain a constant flow velocity of wastewater which passes through a sand sedimentation zone, thereby preventing organic material which is contained in the wastewater and is other than sand, from sedimenting.