Optimum placement of thin-layer elements in a horizontal sedimentation tank purification of drinking water

Experimental studies of the effectiveness of water distribution methods in a thin-layer sump were carried out on model and semi-industrial installations. When designing sedimentation tanks, it is usually recommended to take η = 0.03-0.07. According to our data, when η > 0.05, it is not possible to ensure uniform operation of all slots (holes), which worsens the hydrodynamic conditions in the settling zone. Experiments have also established that double gratings with a relative area of holes of 2n provide almost the same flow distribution as single gratings. In this case, the experimental values of β 1 were 2.6 and 2.7, respectively, i.e. differed by no more than 5%. With this in mind when installing double gratings with reflectors, the relative area holes with a sufficiently efficient flow distribution can be accepted and η = 0.06-0.1 instead of η = 0.03-0.05 recommended for single grates, which is essential to reduce the risk of clogging them and improve the reliability of sewer sedimentation tanks. The obtained dependences with sufficient accuracy for practice can be used to calculate double gratings and gratings with reflectors at values η=2η1 , where η1 is the relative area of the slots in a single grating, as well as when calculating partitions with round (square) holes, taking into obtained formulas bs = r holes, and ns = n holes.