Sewage Water Quality of Phnom Penh City

Sewage water quality from Phnom Penh City in Cambodia was studied from December 1997 to September 1999. Samples were collected from the outfalls of sewer pipes to Tonle Sap River, channels, lakes, and pumping stations.As a result, concentrations of chemical oxygen demand (COD), total nitrogen (T-N) and total phosphorus (T-P) in dry season were much higher than those of surface water in Cambodia, possibly due to the domestic wastewater. In rainy season, these amounts decreased due to attenuation by the rainwater. In dry season, 56% of suspended solid (SS) in sewage deposited as sediments in channels and lakes. The levels of Cd, Zn, Cu and Pb in the sediments of these channels and lakes were higher than those in other points of the area studied. In rainy season, SS and heavy metals were flushed outside by the rainwater. Levels of anionic and nonionic surfactants, total organic halogen (TOX) and Bisphenol-A were found to those in Japan. Both surfactants mainly came from domestic wastewater while TOX and Bisphenol-A came from specific emission sources. Daily pollutant loads of SS, COD, T-N, T-P, anionic surfactant and nonionic surfactant were 13, 53, 8.2, 1.1, 1.4 and 0.3 (g/person-day), respectively.