Study On The Construction Technology Of The Ecological River And It's Purification Efficiency

Associated with Demonstration project on techniques about water quality purification of plain river network and water body ecological restoration, which is supported by the National High Technology Research and Development Program of China (863 Program), many problems are studied in this paper. The main contents include:(1) Survey on construction technologies of ecological river; (2) Discussion on ecological restoration technologies in canalized river in china; (3) Comparative study on two kinds of filler materials; (4) Study on purification efficiency of optimum filler materials to polluted river water; (5) Comparative study on purification efficiency between the startup period of engineering and the initial period when Micro-ecosystem sets up; (6) Study on purification efficiency of optimum filler materials to polluted water in winter.The results show that: (1) Both kinds of channel models, which are constructed by gravel and detritus respectively, have high removal efficiency in treating polluted water. In the 30 days' experiment, which simulate startup period of the restoration engineering, the total removal rates of TN, TP, NH₄⁺-N and COD_Mn of the gravel channel model are 32.1 %, 93.8%, 80.8% and 99.0%, while those of the detritus channel model are 36.5%, 99.1%, 85.0% and 98.6%; (2) The purification efficiency of the detritus channel model is better than that of the gravel channel model during the startup period of the channel experiment; (3) In the first week of the startup period of the channel experiment, there are remarkable removal rates in treating polluted water. The adsorption of filler and the touching sedimentation function are the main mechanism during mis period; (4) The temperature has great influence on the removal of the contaminations. When the water temperature is approaching to and above 30 ℃ in the detritus channel model experiment in summer, the alga increases fast, the concentration of NH₄⁺-N decreases sharply, while the concentration of TN, TP and COD_Mn rises up. But in low temperature experiment condition of winter, except that TP is disturbed easily by the flow, there is no evident removal result in the two channel models. The total removal rates of TN, NH₄⁺-N and COD_Mn of the gravel channel model are 48.0%, 10.1 % and 14.9%; while those of the detritus channel model are 17.4%, -3.6% and 9.8%; (5) During the establishing period of micro-ecosystem, the detritus channel model has high removal efficiency in treating polluted water. In the 54 days'experiment, the total removal rates of TN, TP, NH/-N and CODMnare 90.6%, 98.4%, 98.7% and 74.0%, the water quality was ameliorated from inferior standard V to standard II or III; (6) During the establishing period of micro-ecosystem, the change of micro-organism indicator inform that the water quality changes in the rule of Coprozoic zone- a -Polysaprobic zone- P -Polysaprobic zone-O1igosaprobic zone; (7) The high removal efficiency in treating polluted water in the detritus channel model is short-term. Compared with the startup period of the channel experiment, only the removal efficiency of TN increases rapidly, but that of TP, NH/-N and CODmii does not increase, even decreases; (8) hi the low temperature condition of winter, the gravel channel model, which has been amended by fixing packing material and domesticated by the microorganism in natural river or lake water, shows better purification efficiency than the detritus channel model; (9) The former three experiments conclusions show that without the external pollution resource immitting the river, both the gravel channel model and the detritus channel model can purify the water quality to a high degree within 30days. It is concluded that controlling the external pollution resource is the key factor to guarantee self-purification ability of river.