Influence of clogging on flow pattern and wastewater treatment efficiency of constructed wetland

The hydraulic retention time(HRT) distribution of a constructed wetland and a control system without plants was studied using a NaCl tracer.The influence of the wetland plants on the flow pattern in subsurface flow constructed wetlands(SFCW) and vertical flow constructed wetlands(VFCW) before and after clogging are discussed.The results show that the HRT is shortened by wetland plants before clogging,and after clogging the result is the contrary in SFCW.In VFCW,the influence of wetland plants on the flow pattern is not observed before clogging,while after clogging HRT increases due to wetland plants.The influence of clogging on the flow pattern in constructed wetlands is obvious.Because of clogging,the HRT increases 12.3% in SFCW and 22.6% in VFCW.The constructed wetland after clogging has higher purification efficiency than the constructed wetland before clogging,but the wastewater treatment capacity of the constructed wetland will decrease and even reach zero if clogging is serious.