Study On Key Technologies And Application Of Domestic Wastewater Purification By Macrophytes

During the course of the research,nine macrophytes(Elodea,Potamogeton maackianus, Potamogeton malaianusMiq,Potamogeton cripus,Acorus tatarinowii Schott, Juncus effuses, Iris germanica L.,Oenanth ejavanica, Ranunculus sceleratus)species were selected,planted and treated the domestic wastewater.Through the test of potted plant, comparisions of the wastewater treatment efficiency between nine macrophyte species. The ecological treatment system is studied in Tangquan town of Nanjing city.The treatment efficiency of each mange unit was investigated in the combined system and the TN and TP in different organs were measured in order to research the time when the accumulations of nitrogen and phosphorous achieve a peak value.It help to ascertain the best harvest time and method.The conclusions are as follow: (1) On the low temperature weather condition,all the selected macrophytes can help to remove the pollutant in wastewater in different extent. The average remove rates of NH₄⁺-N are 87.64%,80.13%,61.40% under three concentrations,that of the comparison are 32.58%,18.18%,19.32%。The emergent plant has a stronger ability to remove and resist the pollutant than the submergent plant. Different plant species had different absorption features of nitrogen and phosphorus. (2)Different plant species in Tangquan pond-wetland system had different accumulation features of nitrogen and phosphorus, The plant nitrogen and phosphorus contents were in the order of floating-leaved macrophyte > submersed macrophyte > emerged macrophyte. Hydrophytes could absorb more nitrogen and phosphorus, and the nitrogen absorption by various kinds of plant in the wetland was greater than that of phosphorus absorption. In the late of autumn and the early of the winter accumulation of nitrogen and phosphorus in the Hydrophytes achieve a peak value and it accumulates in leaves . Therefore,we should pick them up to wipe off nitrogen and phosphorus in the wastewater. (3)The average removal efficiency of COD_Cr,TNand TP in the regulate pond are 9.34%, 44.56 %, 68.56 %,and contact oxidation pond are 46.77%,35.63%,18.1%. Simultaneou- sly ,the temperature is higher, treatment efficiency is better. The system has higher nitrogen and phosphorus removal efficiencies between July and September.