Four small-scale gravel-based integrated vertical-flow constructed wetlands (IVCWs) were established to treat domestic and secondary wastewater (SW) in parallel under two loading rates (LRs) for an operational period of about two years and the total phosphorus (TP) removal performances were investigated and compared. Highly effective TP elimination sustained for about 10d, with remarkable declines followed to relatively stable efficiencies for both types of wastewater. Significant difference of TP removal performance for the two types of wastewater was observed. In period 1, under high LR, the IVCWs performed better when treating domestic wastewater (DW), achieving average removal efficiency and rate of 51.6% and 0.389gm(-2)d(-1), respectively, compared to those of 30.1% and 0.233gm(-2)d(-1) for SW. However, in the operational period 2 fed with a low LR, better TP removal performance was achieved for SW, with reduction efficiency and rate of 41.5% and 0.057gm(-2)d(-1) on average, while the corresponding value for the treatment of DW was just 12.5% and 0.023gm(-2)d(-1). Significant correlations between TP removal efficiency and plant growth detected during this period and better developed vegetation in systems fed with SW might suggest the considerable role of plant growth, which could be influenced by inlet properties, on P retention and lifespan extending of constructed wetland. Gravel-based IVCW could be employed to remove low load of phosphorus and wastewater properties, and plant growth cycle should be taken intoconsideration in future IVCW design and application.
HORIZONTAL SUBSURFACE FLOW
; NUTRIENT REMOVAL
1.Yunnan Univ, Res Inst Engn & Technol, Kunming 650091, Peoples R China 2.Chinese Acad Sci, Inst Hydrobiol, State Key Lab Freshwater Ecol & Biotechnol, Wuhan 430072, Peoples R China 3.Jiangxi Acad Environm Sci, Nanchang 330029, Peoples R China 4.Chinese Acad Fishery Sci, Yangtze River Fisheries Res Inst, Minist Agr China, Key Lab Freshwater Biodivers Conservat, Wuhan 430223, Peoples R China 5.Chinese Acad Fishery Sci, Freshwater Fisheries Res Ctr, Wuxi 214081, Peoples R China