Study On Purification Of Domestic Wastewater By Aquatic Macrophytes

The research content in this dissertation is under the jurisdiction of the cleaning technology of the macrophytes. The aim of research is to provide gist to exploit the new technology used in municipal wastewater treatment which possessing some advantages, such as lower investment, running cost and management expectancy, little sludge. During the course of research, nine macrophytes (typha latifolia, Canna flaccida, Juncus effuses, Cyperus alternifolius, Potamogeton malaianus Miq, Myriophyllum spicatum, Ceratophyllum demersum, Vallisneria, Egeria densa) 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 and the impact factors on efficiency were studied in this paper. The research results are only phasic achievements of the project because biologic tests usually need a long period, and these conclusions would still accept to be farther proved. These results can conclude as follows. (1) All the selected macrophytes can help to remove the pollutant in wastewater in different extent. The emergent plant has a stronger ability to remove and resist the pollutant than the submergent plant. So the emergent plant should be located in front of the submerged plant. (2) For aquatic plants, The suitable input COD loading is between 80-120mg/L , NH3-N is 12~15mg/L and TP is 1.2~1.5mg/L. (3) The good treatment effect of domestic wastewater by macrophyte can be obtained in 5 days. (4) The efficiencies of Canna flaccida and Cyperus alternifolius are better than the typha latifolia and Juncu effuses because they have a longer growing period during the course of test and a developed root system. Egeria has the best effect of depurating wastewater in submerged plants. (5) The macrophytes have different ability to depurate wastewater in different seasons. The efficiency in winter is lower than that in summer and autumn. (6) For the performance of removal nitrogen and phosporus of submerged plants the effect of season is notable. Furthermore, some questions about appilication of aquatic macrophytes were put forward for the sake of avoiding problems and deficiencies appeard in above tests.