title: Phosphorus removal from lagoon-pretreated swine wastewater by pilot-scale surface flow constructed wetlands planted with Myriophyllum aquaticum.
abstract: Although constructed wetlands (CWs) are used as one relatively low-cost technology for livestock wastewater treatment, the improvement of phosphorus removal in CWs is urgently needed. In this study, a three-stage pilot-scale CW system consisting of three surface flow CWs (SFCWs; CW1, CW2, and CW3) in series from inlet to outlet was constructed to treat swine wastewater (SW) from a lagoon. The CWs were planted with Myriophyllum aquaticum. Considering different inlet loading rates, three strengths of swine wastewater (low: 33% SW, medium: 66% SW, and high: 100% SW) were fed to the CW system to determine total phosphorus (TP) removal efficiency and clarify the important role of plant harvest. Results from the period 2014-2016 indicate that the three-stage CW system had mean TP cumulative removal efficiencies and removal rates of 78.2-89.8% and 0.412-0.779gm-2d-1respectively, under different inlet loading rates. The TP removal efficiency and removal rate constant had temporal variations, which depended on temperature condition and the annual growth pattern of M. aquaticum. The harvested phosphorus mass was 15.1-40.9gm-2yr-1in the CWs except for CW1 with high strength SW, and contributed 22.5-59.6% of TP mass removal rate by the SFCWs. The TP removal was mainly by adsorption and precipitation in the substrate in CW1 but by uptake and multiple harvests of M. aquaticum in CW2 and CW3. The results suggest the three-stage CW system planted with M. aquaticum is suited for removing high TP concentrations from swine wastewater with a high removal efficiency. However, TP removal in high strength SW amounted to 70.1±23.3%, and the outflow concentration of 17.0±14.9mgL-1was still high. Optimal loading rates for high strength SW still need to be investigated for the CW system presented here.
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China.
authors: Pei
authors: P
authors: Luo
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China. Electronic address: liufeng@isa.ac.cn.
authors: Feng
authors: F
authors: Liu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China.
authors: Xinliang
authors: X
authors: Liu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China; College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors: Xiao
authors: X
authors: Wu
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Ran
authors: R
authors: Yao
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China.
authors: Liang
authors: L
authors: Chen
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China.
authors: Xi
authors: X
authors: Li
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China.
authors: Runlin
authors: R
authors: Xiao
authors: Key Laboratory of Agro-ecological Processes in Subtropical Regions, Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China.
authors: Jinshui
authors: J
authors: Wu
keywords: Constructed wetland; Harvest management; Myriophyllum aquaticum; Phosphorus removal; Swine wastewater