| Effects of plant absorbing such as Canna generalis, Zizania cadaciflora, Ipomoea aquatica, Pistia stratiotes in the ecological oxidation ditch were studied. The results showed that removal efficiency of organic matter and suspended solid was steady in the system,and the average removal rates of COD and SS were 51.02% and 58.92% respectively, but the removal efficiency of TP, NH4+-N and TN were comparatively low. The capacities in pollutant uptake and degradation were varied among different plant species. The contribution of plant uptake to the TN and TP removal of C. generalis was the best, because of its higher biomass and the average value were up to 152.3 and 22.6 g/m2, followed by the Pistia stratiotes, the Z. cadaciflora and I. aquatica were the poor. Proportion of quantity of removal nitrogen and phosphorus of C. generalis to the total removal quantity were 0.24% and 0.18% in the ecological oxidation ditch. Proportion of quantity of removal nitrogen and phosphorus of Zizania cadaciflora to the total removal quantity were 0.11% and 0.03% in the ecological
oxidation ditch. Proportion of quantity of removal nitrogen and phosphorus of I. aquatica to the total removal quantity were 0.09% and 0.06% in the ecological oxidation ditch. Proportion of quantity of removal nitrogen and phosphorus of P. stratiotes to the total removal quantity were 0.12% and 0.09% in the ecological oxidation ditch. In addition, the production of residual activated sludge can be reduced by the plant in the system. |
