| 摘要 |
<p>A sewage treatment system includes a pair of substantially identical unitary fluid treatment modules (15, 17), each having a central sedimentation tank surrounded by a peripheral wetland. The sedimentation tanks are coupled through a dosing device (13) to an input source of sewage (19) and, as an outlet (21), to a leaching field. The dosing device (13) includes a switching mechanism (contained within 13) isolated from the fluids, which mechanism provides in one cycle for one treatment module to be filled with the incoming sewage while maintaining its outlet closed. When the liquid level in the sedimentation tank in the first treatment module (15) reaches a predetermined level the dosing device (13) switches the sewage input (19) to the other treatment module (17), while opening the outlet (22) from the first treatment module (15) to the leaching field. The dosing device switching mechanism (contained within 13) which is actuated in response to sensed liquid levels in the sedimentation tanks in the two treatment modules (15, 17), employs pinch valves.</p> |
