Water Pollution Characterization by Pathogenic Indicators in Water Runoff in the Downtown of Hanoi, Vietnam

In Hanoi, the capital of Vietnam, lakes and rivers are polluted by both point pollution sources such as discharge from sewerage system; and by non-point pollution sources such as washoff from land surface and leakage from septic tanks. Several studies had mentioned about water pollution but were mainly focusing on organic pollution, feacal contamination and pollutant sources from surface runoff were not considered. To investigate the characteristics of pollutant variation in runoff water and feacal contamination by pathogenic indicators, water samples were collected in August and September 2008, by the roadside and at the inflows of lakes under wet weather condition in the downtown of Hanoi. Monitoring results showed high pollutant concentration, especially pathogenic indicators as E.coli and total coliform (TC), both in road runoff and water that flowed into lakes. Runoff water quality was much different depending on the sampling locations and patterns of rainfall. Pollutant concentration collected by the roadside tend to increase at the end of rainfall. It might be attributed to the discharge of domestic wastewater from individual households or leakage from septic systems. Time and spatial variation were much different for each event that made urban runoff water to be more difficult to control in comparison with domestic wastewater. Cluster analysis was applied to find the similarities of water quality among sampling locations. It was a useful method to find the spatial variation of pollutants and their level of pollution.