Study On Urban Polluted River Water At Low Temperature By Biological Technology

Dianchi Lake watershed, which locates in the central of YunNan-GuiZhou plateau, plays an important role in the development of economic in the region. It is located in the watershed zones of the Yangtze River, Pearl River and Red River and lower in north than south. Dianchi Lake is in the lowest point of the watershed, and has nearly thirty rivers into the heart-shaped Lake. Most of these rivers go though towns, farmlands, phosphate rock and sewage area and accept the input of rural areas with rainfall scouring rubbish into the Dianchi Lake, which the natural supply of water is less, thus it is polluted very serious and is the typical of most heavily polluted lakes. One of the main causes of the eutrophic Dianchi Lake is the reduction of river pollution load not enough. In the paper, one of the most polluted river of Xin Yunliang River which into the Dianchi Lake is studied.The target is to explore an effective treatment process to reduce the pollution load into the Dianchi Lake and provids theory and technology for improving the Dianchi Lake water quality and ecological restoration.Xin Yunling River is the main flood control and drainage channel in the west of Panlong River in the main city of Kunming. Currently, the river of Xin Yunling River is seriously polluted, and the water body smelly and black, which belongs to badⅤ. In the river, the main pollutions are ammonia nitrogen and organic matter. The effective two-stage biological aerated filter process is studied to remove the organic matter and ammonia nitrogen, while the study, the TN(Total Nitrogen), nitrite, nitrate nitrogen and pH value were observed. In the study, the developed running load and operating conditions are founded, and which provid theoretical and technical support for the following demonstration projects.In Kunming, it is cold in winter, and the advantages of BAF, strong Ability to adapt to temperature changes, low capital coast, small area required, flexible and modular design and the efficient nitrification rate, are suitable for the urban polluted river, which both sides have little fields can be used. This study uses two-stage biological aerated filter technology and ceramisite as filler under the condition of the main pollution matters are ammonia and organic of the Xin Yunliang River. In the study, the cultivation of biofilm, the normal operation and the effect of pollution removal are discussed. After nearly three months of continuous normal operation at low temperature, achieves the following results:(1) The BAF biofilm is cultivated in the way of inoculating with activated sludge first and then with three days of intermittent water culture and aeration, and the following is continuous aeration with continuous influent of 2.4 m3/d. After more a month of training, it can draw a conclusion that the BAF biofilm is successfully cultivated when the concentration of ammonia influent 25 mg/L and effluent less than 6 mg/L;(2) The BAF always has a high removal efficiency of ammonia nitrogen under the following hydraulic loading:2.4 m3/d,3.0 m3/d,3.6 m3/d and 4.8 m3/d. Under the hydraulic loading of 2.4 m3/d, the volume load is reached to 0.197 kgNH3-N/(m3 filler·d), and the average effluent ammonia concentration is 3.3 mg/L; The BAF also has a high removal efficiency of organic pollutant in any condition of the four hydraulic loading, and the average effluent CODCr is 35.57 mg/L; The higher volume ability of the BAF needs further study;ln the two-stage filter, there is little nitrite nitrogen accumulation, and the nitrate nitrogen has a high increase in the effluent of the second stage;(3) The organic pollutant is removed mainly in the place of carbon oxidation section (the first stage) and the ammonium nitrogen is in the nitrification section (the second stage). Both stages of the two-stage BAF have its separately functions, and both are high removal effiency. (4) The two-stage BAF still has a high removal efficiency in the low temperature of 9～10℃. Under the condition, the average removal efficiency of ammonium nitrogen and CODCr are separately 65.44% and 46.12%. The low temperature in winter of Kunming does not affect the normal operation of the BAF.(5) The TN(total nitrogen) average removal is only 15.21% by the BAF, which can be considered the contribution of the simultaneous nitrification and denitrification. The effective removal of TN needs the following solid-phase carbon source denitrification.(6) During the experiment, the pH value changes between 7 and 8 in both stages and there is no need to add alkalinity. The pH value increases in the carbon oxidation section and decreases in the nitrification section.The study is only a small part of the project. With the development of sold carbon source, the next step is the application of the appropriate and cost-effective solid carbon source in the study of nitrogen removal. The cost-effective sold carbon source will replace the traditional expensive liquid carbon source in the field of low C/N ratio sewage and will be a new method in the nitrogen removal.