Assessment of water quality changes in Saigon and Dong Nai rivers under the influence of domestic wastewater discharges

Abstract

The study was conducted to evaluate the impact of domestic wastewater discharges on surface water quality (BOD5 and DO) at pumping stations on Sai Gon – Dong Nai river during the dry season and the wet season using the MIKE 21FM model. The results indicated that the water quality in Dong Nai river is rated better than the Sai Gon River. Specifically, the BOD5 concentration was high, and the DO concentration was low at Hoa Phu station in Sai Gon River. However, the surface water quality at pumping stations on Dong Nai river, namely Hoa An and Binh An was up to standard compared to column A2 for domestic water supply purposes according to QCVN 08- MT:2015/BTNMT. Specifically, the wastewater source from Thu Dau Mot city on the Sai Gon river was about 4 km from Hoa Phu pumping station with a discharge volume of 0,66 m3/s, and another source from Bien Hoa city on the Dong Nai river reached a discharge volume of 2,15 m3/s, which was about 4.7 km and 5.5 km from Hoa An and Binh An intakes, respectively. The outcomes proved that Hoa Phu and Hoa An pumping stations were not affected by the wastewater from these cities. Otherwise, there was markedly degraded water quality at Binh An intake in the dry season, which was unsatisfied with QCVN 08- MT:2015/BTNMT (A2 type).