| 英文摘要 |
For economic reason and operation convenience, the river water treatment plant is better siting by the location of polluted stream as near as possible. However, the surroundings of some polluted streams in Taiwan have no available lands for construction of conventional water treatment facilities. This study is attempted on developing the feasible treatment methods for polluted river water in case of land-limited condition. The removal of BOD, suspended solids, and NH3-N in the influent of river water, with hydraulic retention time of 8 hours, are up to 60% by a gravel-contact oxidation process and more than 90% removal (HRT is 2 days) by the oxidation ditch system. The gravel-contact oxidation chamber is selected with a shallow bed in two patterns that is 50 and 60 cm in depth, respectively. Natural gravels sizing from 10 to 20 cm are filled in the gravel-contact bed with porosity around 40%. To overcome the land-limited problem, the gravel-contact oxidation chamber is designed a long-and-narrow tank for availably placing it along the riverbank. 1 to 1.5 m in width of the chamber is designed to be constructed on a platform supported by particular cantilever steel-beams. One end of the cantilever beam is fixed to the retaining wall, while the other end is free above the river. The influent flowrates of gravel-contact oxidation system are designed from 1500 to 10000 cmd. This study also provides another conventional treatment system－oxidation ditch. It consists of an oval-shaped channel in 1.5 m deep with rotor aerators across the ditch. Due to the limitation of land area surrounding the river, the oxidation ditch is constructed on a special decking system across over the river. The oxidation ditch can treat polluted water in this study with a loading of BOD up to 300 mg /L and SS up to 200 mg /L, and designed flowrates are from 5000 to 10000 cmd.
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