Effect of comprehensive river sewage closure treatment project on water quality in Chuanfang River,Kunming

In this study,the water quality of Chuanfang River,sewage pumping station and effluent from the first,seventh and eighth sewage treatment plants in Kunming,Yunnan Province was evaluated after a comprehensive river sewage closure project was implemented. The results indicated that the water quality of Chuanfang River was remarkably improved by the river sewage closure project. In contrast to the control point in Lanhua ditch,the dissolved oxygen( DO) content and oxidation reduction potential( ORP) value increased significantly in Chuanfang River,while electrical conductivity( EC) value decreased obviously and pH value did not change much. The concentrations of TN,NH+ 4-N,TP,PO3-4-P,BOD 5 and COD Cr in Lanhua ditch were 2. 00,4. 87, 7. 68,6. 28,59. 95 and 12. 81 times higher than Chuanfang River,respectively. Compared with the water quality in 2004,the concentrations of TN,TP and CODCr in Chuanfang River decreased by 45. 44%, 88. 84% and 74. 85%,respectively. It is estimated that this project would reduce 1121. 36 kg·d- 1 of TN, 831. 05 kg·d- 1of NH+ 4-N,111. 67 kg·d- 1of TP,15. 37 t·d- 1of BOD 5,and 22. 43 t·d- 1of COD Cr, which would have significant environmental benefit on decreasing the pollution load in Dianchi Lake.