Sewage treatment using percolation unit with pre- and post-clarification tanks - in which water is recycled from buffer space downstream of percolation tank to stabilise rate of flow through percolation unit

摘要

A percolation sewage treatment plant has one or more pre-clarification tanks (1), a percolation tank (3) with packing material (2) and a post-clarification tank (4). An inlet pipe (5) brings the waste water to the pre-clarification tank, and a second pipe (6) transfers it to the percolation tank. The post-clarification tank has an outlet pipe (7), and a return pipe (8) leads from the outlet section of the percolation tank back to the pre-clarification tank. The novel feature is that a buffer space (9) is provided downstream of the percolation tank. From this space the water returns to the pre-clarification tank via the pipe (8) or to the percolation tank via a return pipe (10). Also claimed is procedure for operating this plant, in which the liquid leaving the percolation material (2) is collected in the buffer space and is periodically returned in part to the percolation chamber. Once a required minimum liquid level in the buffer space has been reached liquid is delivered from the buffer space to the post-clarification tank. USE/ADVANTAGE - Used in sewage treatment esp. for e.g. individual dwellings, hotels etc.. The construction of the plant is simple and it provides reliable and effective waste water treatment even in the case of varying water flow rates.