Fan Chihhao, Wang Wei-Shen
Department of Safety, Health, and Environmental Engineering, Ming Chi University of Technology, Taishan, Taipei County, Taiwan.
Ann N Y Acad Sci. 2008 Oct;1140:78-85. doi: 10.1196/annals.1454.031.
Water-quality modeling has been used as a support tool for water-resources management. The Streeter-Phelps (SP) equation is one often-used algorithm in river water-quality simulation because of its simplicity and ease in use. To characterize the river dissolved oxygen (DO) sag profile, it only considers that the first-order biological oxygen demand (BOD) degradation and atmospheric reaeration are the sink and source in a river, respectively. In the river water-quality calculation, the assumption may not always provide satisfactory simulation due to an inappropriate description of BOD degradation. In the study, various patterns of BOD degradation were combined with the oxygen reaeration to simulate the DO sag profile in a river. Different BOD degradation patterns used include the first-order decay, mixed second-order decay, and oxygen-inhibition decay. The results shows that the oxygen-inhibition SP equation calculates higher BOD and DO concentration, while the mixed second SP equation calculates the least among the three tested models. In river-water calculation of Keelung River, the SP and oxygen-inhibition SP equations calculate similar BOD and DO concentrations, and the mixed second SP equation calculates the least BOD and DO concentration. The pollution loading of BOD and atmospheric reaeration constant are the two important factors that have significant impacts on aqueous DO concentration. In the field application, it is suggested that the mixed second SP equation be employed in water-quality simulation when the monitoring data exhibits a faster trend in BOD decay. The oxygen-inhibition SP equation may calculate the water quality more accurately when BOD decay is slower.
水质模型已被用作水资源管理的一种支持工具。斯特里特-菲尔普斯（SP）方程是河流水质模拟中常用的一种算法，因其简单易用。为了描述河流溶解氧（DO）下垂曲线，它仅考虑一级生物需氧量（BOD）降解和大气复氧分别是河流中的汇和源。在河流水质计算中，由于对BOD降解的描述不当，该假设可能并不总是能提供令人满意的模拟结果。在本研究中，将各种BOD降解模式与氧复氧相结合，以模拟河流中的DO下垂曲线。所使用的不同BOD降解模式包括一级衰减、混合二级衰减和氧抑制衰减。结果表明，氧抑制SP方程计算出的BOD和DO浓度较高，而混合二级SP方程在三个测试模型中计算出的结果最小。在基隆河的河水计算中，SP方程和氧抑制SP方程计算出的BOD和DO浓度相似，而混合二级SP方程计算出的BOD和DO浓度最小。BOD的污染负荷和大气复氧常数是对水体DO浓度有显著影响的两个重要因素。在实际应用中，建议当监测数据显示BOD衰减趋势较快时，在水质模拟中采用混合二级SP方程。当BOD衰减较慢时，氧抑制SP方程可能会更准确地计算水质。
