Treatment efficiency of integrated vertical-flow constructed wetland for saline wastewater

Abstract

The integrated vertical-flow constructed wetland (IVCW) was simulated with three suits of designed experiment columns planted with Kandelia candel. Units A, B and C were irrigated with sewage of different salinity (A: 10‰ B: 20‰, C: 30‰), respectively. The removal rates of dissolved organic carbon (DOC), NH3-N and NO3−-N dropped 90.4%–48.6%, 80.2%–40.3% and 84.8%–60.9%, respectively, when salinity increases from 10‰ to 30‰. The removal rate of TP increased 14%–31.2%, oppositely. A 20-day inflow salinity drastic change shock affective trial was done on units D and E. Unit D was used as a control and irrigated with saline sewage (20‰). Unit E was irrigated with sewage with low salinity (5‰) as a salinity drastic change shock on the third and fourth days. DOC, NH3-N and NO3−-N removal efficiency of unit E showed a three-stage process of change, “rapidly decrease, increase beyond the normal standard, and then back to the normal standard”. TP removal value was negative during the 2-day shock period.