Abstract:

Spatiotemporal variation of redox potential (Eh) in the integrated verticalflow constructed wetland (IVCW) and purification efficiency of pollutants in different function units have been studied.The results showed that the Eh of downflow surface strata,bottom strata and upflow surface strata in IVCW were 402～585 mV,-87～-130 mV and 308～432 mV,respectively.The IVCW system could be divided into three function units along the water flow direction—oxic A unit,anaerobic unit and oxic B unit.Oxic A unit is the predominant area for pollutants removing,of which the removal efficiency of BOD5、CODCr、NH+4N were 430%,484%,541%,respectively,especially the NH+4N,accounting for 79% of the total removal efficiency.Denitrification and anaerobic decomposition of organic matters primarily occurred in anaerobic unit.The further removal of organic matters after anaerobic decomposing and further nitrogen removal occurred in oxic B unit.It was also observed that there was significant correlation between the removal efficiency of NH⁺₄-N and Eh of different function units in the system（p＜001）,but the correlation between the removal efficiency of BOD₅、COD_Cr、NO^-₃-N and Eh of different function units were not significant.