Settling basin design in a constructed wetland using TSS removal efficiency and hydraulic retention time

• Published in: Journal of environmental sciences (China) 2014-09, Vol.26 (9), p.1791-1796
• Main Authors: Lee, Soyoung, Maniquiz-Redillas, Marla C., Kim, Lee-Hyung
• Format: Article
• Language: English
• Subjects: Basins; Constructed wetland; Construction; Flow rate; Hydraulic retention time; Particle Size; Particle size distribution; Sedimentation; Sediments; Settling; Settling basin design; Time Factors; TSS; TSS removal efficiency; Waste water; Water Purification; Wetlands; 人工湿地; 去除效率; 去除率; 平均流速; 水力停留时间; 沉沙池; 设计参数
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2014.07.002

Using total suspended solid （TSS） removal efficiency and hydraulic retention time （HRT） as design parameters a design guideline of a settling basin in a constructed wetland （CW） was suggested; as well as management of sediment and particle in the settling basin. The CW was desiEned to treat the piggery wastewater effluent from a wastewater treatment plant during dry days and stonnwater runoff from the surrounding paved area during wet days. The first settling basin （FSB） in the CVV was theoretically designed with a total storage volume （TSV） of 453 ms and HRT of 5.5 hr. The amount of sediment and particles settled at the FSB was high due to the sedimentation and interception of plants in the CVV. Dredging of sediments was performed when the retention rate at the FSB decreased to approximately 80%. Findings showed that the mean flow rate was 21.8 m3/hr less than the designed flow rate of 82.8 m3/hr indicating that the FSB was oversize and operated with longer HRT （20.7 hr） compared to the design HRT. An empirical model to estimate the length of the settling basin in the CW was developed as a function of HRT and desired TSS removal efficiency. Using the minimum tolerable TSS removal efficiency of 30%, the length of the FSB was estimated to be 31.2 m with 11.8 hr HRT.