| 摘要: | 基隆河為淡水河的重要支流，流域橫跨臺北市、新北市與基隆市，在水資源管理與環境保護上扮演關鍵角色。分流式下水道系統尚未全面建置前，政府設置多座截流站以截取生活污水並抽送至污水處理廠。隨著接管率提升，截流站退場的可行性及其對水質影響成為重要議題。此外，濱江與民生污水處理廠放流水將直接排入河川中下游，對水質可能產生壓力，特別是下游的感潮河段，易因潮汐與流量變動導致污染物累積與再釋放。
本研究應用 Water Quality Analysis Simulation Program (WASP) 建立基隆河水質模式，模擬三項情境：
1.評估「污水部分排入(截流站依現況操作)」、「污水完全分流(截流站退場)」以及「尚未接管污水全部排入(截流站未操作)」三種截流站操作條件下，生活污水排放對河川污染的影響。
2. 分析濱江與民生污水處理廠放流水排入河川後對河川水質的影響。
3. 探討上游補注流量變化對感潮河段污染物稀釋與傳輸的影響。
模擬結果顯示，在「尚未接管污水全部排入(截流站未操作)」情境下，百齡橋DO由3.19降至2.85 mg/L，BOD由5.43升至5.6 mg/L，氨氮由2.96升至3.59 mg/L，RPI 由4.75升至5.75，水質惡化明顯。而在「污水完全分流(截流站退場)」情境下，百齡橋DO濃度可升至3.6 mg/L，BOD 與氨氮降至4.91 mg/L與2.42 mg/L，RPI 雖維持在4.0，但各水質指標皆有改善趨勢；在污水處理廠放流水模擬中顯示，即便水質符合排放標準，總放流量大仍對下游造成壓力。百齡橋DO濃度由3.19mg/L降至3 mg/L，BOD與氨氮分別由5.43 mg/L升至5.67 mg/L、2.96 mg/L升至3.18 mg/L，RPI由4.75增至5.75，反映污水處理廠放流水會造成水質惡化；在上游補注流量模擬結果顯示，相較現況Q75基流(6.43 CMS)，補注25%(8.03 CMS)與50%(9.65 CMS)皆有助於改善水質，以補注50%效果最為顯著。百齡橋DO濃度由3.19 mg/L升至3.76 mg/L，BOD與氨氮分別從5.43 mg/L下降至4.97 mg/L、2.96 mg/L下降至2.62 mg/L，江北橋RPI由2.75降至2(稍受污染)、南湖及成美橋由4降至3.25，整體水質明顯改善。
此外，本研究也針對模式參數進行敏感度分析，結果顯示BOD衰減速率常數及其溫度修正係數為最敏感參數，對BOD與DO濃度變化影響可達5.5%與4.9%。相對而言，硝化反應相關參數與再曝氣係數調整對結果影響不大，推測因氨氮濃度偏低與再曝氣效果有限所致；BOD氧限制半飽和常數因溶氧充足，影響亦極小。整體而言，BOD衰減相關參數為關鍵參數，應作為優先考量之參數。
;The Keelung River, an important tributary of the Tamsui River, flows through Taipei City, New Taipei City, and Keelung City, playing a vital role in regional water resource management and environmental protection. Before the full implementation of a separated sewer system, the government constructed multiple interceptor stations to divert domestic sewage to wastewater treatment plants. With the increasing sewer connection rate, the feasibility of phasing out these interceptor stations and their impact on water quality has become a key issue. Additionally, the effluent from the Binjiang and Minsheng wastewater treatment plants will be directly discharged into the mid-to-lower reaches of the river, potentially imposing additional pressure on water quality, especially in the tidal downstream section where pollutants tend to accumulate and re-release due to tidal and flow variations.
This study applied the Water Quality Analysis Simulation Program (WASP) to develop a water quality model for the Keelung River and simulate the following three scenarios:
1.Evaluate the impact of domestic sewage discharge under three interceptor station operation conditions: partial discharge (current operation), complete diversion (interceptor decommissioned), and full discharge without interception (no operation).
2.Assess the impact of effluent from the Binjiang and Minsheng wastewater treatment plants on river water quality.
3.Investigate the effect of upstream flow augmentation on pollutant dilution and transport in the tidal section.
Simulation results show that under the “no interceptor operation” scenario, water quality at Bailing Bridge deteriorated significantly, with DO decreasing from 3.19 to 2.85 mg/L, BOD increasing from 5.43 to 5.6 mg/L, NH₃-N rising from 2.96 to 3.59 mg/L, and RPI increasing from 4.75 to 5.75. Under the “interceptor decommissioned” scenario, DO improved to 3.6 mg/L, BOD and NH₃-N decreased to 4.91 mg/L and 2.42 mg/L, respectively, and RPI remained at 4.0, with overall improvement in water quality indicators.
Simulations of treated effluent discharge, despite meeting discharge standards, showed that the large total volume still posed pressure on downstream water quality. At Bailing Bridge, DO decreased from 3.19 to 3.0 mg/L, BOD and NH₃-N increased to 5.67 mg/L and 3.18 mg/L, respectively, and RPI rose from 4.75 to 5.75, indicating potential degradation caused by the added effluent.
Under upstream flow augmentation scenarios, compared to the current Q75 base flow (6.43 CMS), increases of 25% (8.03 CMS) and 50% (9.65 CMS) improved water quality, with the 50% augmentation being the most effective. DO at Bailing Bridge rose to 3.76 mg/L, BOD and NH₃-N decreased to 4.97 mg/L and 2.62 mg/L, respectively. RPI at Jiangbei Bridge dropped from 2.75 to 2.0 (slightly polluted), and RPI at Nanhu and Chengmei Bridges decreased from 4.0 to 3.25, showing notable water quality improvements.
Additionally, sensitivity analysis revealed that the BOD decay rate constant and its temperature correction coefficient were the most sensitive parameters, with effects up to 5.5% and 4.9% on BOD and DO concentrations, respectively. In contrast, nitrification-related parameters and the reaeration coefficient had limited influence, likely due to low ammonia concentrations and limited reaeration efficiency. The BOD oxygen half-saturation constant had minimal effect due to sufficient DO levels. Overall, BOD decay-related parameters were identified as key factors and should be prioritized during model calibration. |
