| Non-point pollution in Dianchi Lake Basin is one of the important factors in resulting in water body eutrophication. It is significant to develop techniques for purifying non-point source sewage in order to control eutrophication of Dianchi Lake In the present study, two typical villages, Liang-jia village and Xinyi village, located on north bank of Dianchi Lake were selected to develop and integrate techniques for purifying non-point source sewage based local viliage entironmental characteristics The purifying efficiencies of projects were investigated during studying periods from July 2006 to April 2008.Liang-jia village is the resident-farmland mixing area, sewage from residents area and drainage from farmland flowes into the agro-ditches.Two existed ditches were modified to become the ecological ditches (one ditch with adding microbologansim, and another without adding microbiologanism) to order to enlarge the ditches' ecological capacities and strengthen their abilities of sewage purification, the purifying efficiencies of ecological titches were investigated compared to a traditional ditch The Major results were summarized as bellow:In dry days, the average removal efficiency of TN, TP, COD were 70.3% and 66.6%, 73.7% for the ecological ditch with adding microorganism; 48.3 %, 60.6 %, 58.0% for the ditch without adding microorganism, while 30.1%, 23.8%, 18.4% for traditional ditch. The removal rates of pollutants were higher by 20-30% for the ecological ditches than for traditional ditch. The average removal efficiency of TN, TP, COD were lower in rain days than in dry days because of the large flux, fast velocity of flow in rain days, but which were yet higher for ecological ditches than for traditional ditch during rain days.The differences of the removal rates of pollutants were determined in dependence on purifying units, which were observed in following a decreasing order as below: interception of bamboo charcoal> desilting of> interception of gravel> ceramic block of> anaerobic paragraph. Although the anaerobic units had the lowest removal rates of pollutants, but these units had also played an important role on other units. The invest for reconstructing ecological ditch based on trandition ditches costed 1000yuan/m~3, and the runing cost was 0.19yuan/m~3. So, farmland ecological ditch has great value for application and spread because of its prominent sewage purification effect without using additional land.Xinyi village is one of the new residential area, parts of rimland were used to construct integrated ditch-substrates system to purify sewage. The the water quality parameters of influent and effluent were investigated to characterize the purifying efficiency. The major results were reported as bellow:The average removal rates of SS, COD, TP, TN were 58.8%, 36.6%, 25.2%, 12.2% for the pretreatment units, which were 58.31%, 68.91%, 80.08%, 47.16% for matrix percolation beds. The pretreatment units had a high removal rates of SS and COD due to sedimentation and anaerobic condition, which ensure the better purification of the sewage in the matrix infiltration bed. After the integrated ditch-substrates system kept continuous operation, the average removal rates of SS, COD, TP, TN decreased in the fisrt 12hrs, subsequently removal rates kept stabilization. The average removal rates of SS, COD, TP, TN increased with increasing intermittent running time.The hydraulic loading rate was 0.83m~3 /m~2·d, pollution loading rate was 0.172kg/m~2·d for COD, 0.031kg/m~2·d for TN, 0.003kg/m~2·d for TP, 0.120kg/m~2·d for SS; its construction costs was 802.8/m~3·d, operating costs was 0.13yuan/m~3.
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