| Summary: | 碩士 === 大葉大學 === 環境工程學系碩士在職專班 === 96 === This study was aimed to estimate river assimilative capacity for the non-tidal section of the Old Jhuoshei River at Changhua County using QUAL2K water quality model. Furtheremore, pollution reduction strategies and remediation alternatives were proposed.
The results of assimilative capacity simulation showed: (1) biochemical oxygen demand needs to be cut down 25% at Headwater (Jhongliao Bridge), 65% at Haifonglun Drainage Extension, and 20% at Sihu Drainage Extension; (2) ammonia nitrogen needs to be cut down 50% at the Headwater (Jhongliao Bridge), 35% at Cingshueisi Drainage Extension, 70% at Haifonglun Drainage Extension, and 40% at Sihu Drainage Extension; (3) dissolved oxygen needs to be increased 30% at the Headwater (Jhongliao Bridge).
Accordingly, feasible strategies used in this study are as follows: (1) the installation of the surface aeration machines: surface aeration machines are set up in the section between Headwater (Jhongliao) and the intersection of Cingshueisi Drainage Extension. Moreover, dissolved oxygen will be expected to increase 35% (from 2.38 mg/L to 3.09 mg/L); (2) the construction of sewage systems: the effect of the construction of sewage systems to reduce pollution load is insignificant. However, if this method is combined with a pseudo natural remediation method, the remediation strategy is still feasible; (3) the use of pseudo natural remediation methods: the flow rates at Headwater (Jhongliao bridges), Cingshueisi Drainage Extension, and Sihu Drainage Extension need to be adjusted to 0.35, 0.25, and 0.20 CMS, respectively. The biochemical oxygen demand and ammonia nitrogen removal rates must be maintained at 60%. Furtheremore, the flow rate at Haifonglun Drainage Extension flow must be adjusted to 0.18 CMS, and biochemical oxygen demand and ammonia nitrogen removal rates must be maintained at 80%. These are all required for the simulation results to meet the limitation of intermediate-level pollution.
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