Sewage purification plant with partial agitation and aeration - combining vertical flow settling tank with denitrification and flocculation

摘要

A sewage purificn. installation has, combined with the partial agitation and aeration tank, a long, flat bottomed settling tank through which the liq. flows vertically, and in which an inclined partition forms a denitrification and flocculation zone. The partition carries a gutter with outlet holes the spacing of which diminishes towards the aerating tank inlet, and above the gutter a device lowers a plate profiled to suit, into the gutter to ensure that the flow of water in it is at the same speed as that of the carriage as it runs forward, and lifts up the plate as the carriage runs back. The pump on the arating carriage sets up turbulence in the flocculation zone, as it sucks up the sludge on the bottom of the funnel shaped settling tank and ejects it in a jet into the aerating tank, whilst the clear water runs off via a gutter fed by a series of tubes with holes which regulate the flow relatively to the water level. As sewage flows from the aerating tank as much sludge as possible is carried to the far end of the settling tank, and its surface loading is kept as uniform as possible. In the zone formed by partition the turbulence set up makes it possible to flocculate the fine sludge and rid the denitrified sludge of gas, before they enter the actual settling zone.