Rectangular sludge sedimentation tank for waste water treatment plant

摘要

Waste water velocity is no less than 0.5 times and at most 2.0 times the scraper velocity. Water velocity is measured just over the swept thickening zone near the start of the tank. The initial section extends from the inlet up to 20% of the length of the tank. Waste water supply is at the height of the sludge layer. Preferred features: The initial section of the tank is at most 10% of its total length. The inlet discharges at the tank base and comprises an optionally nonuniform gap or slot, extending over the width of the tank. Supply velocity is 20 cm/s at most; preferably 5-10 cm/s. A separation zone lies at the base. This extends longitudinally up to 3 m. Tank depth is reduced in comparison with similar prior art units, by at least 20% for the same loading. The tank base is inclined or rises. Gap width is up to 50 cm, preferably up to 20 cm.