Water Pollutant Discharge Indicator Estimation and Water Quality Prediction in Pak Kret District, Bangkok, Thailand

Abstract

After several decades of water and sanitation sector development in developing countries, ambient water pollution is still one of the major environmental problems. Safe and convenient sanitation, toilet use, public health issues, hygiene behavior and ambient water quality improvement are purposes and benefits of sanitation. The sanitation indicator of Millennium Development Goals (MDGs) showed that the proportion of population with access to improved sanitation in Thailand was 99 % in 2004, however, ambient water quality deterioration is still a major environmental problem. Therefore, pollutant discharge and affordability should be discussed in a quantitative manner. In this paper, municipal wastewater pollutant discharge contribution to ambient water pollutant loads was given attention. The pollutant load per capita flowing into water body (PLC wb) were estimated as 7.2 g-BOD person-1 day-1 , 9.2 g-TN person-1 day-1 and 1.2 g-TP person-1 day-1 , in Pak Kret Municipality, a peri-urban area of Bangkok, Thailand. PLC wb can evaluate both anthropogenic pollutant removal effects of wastewater treatment systems and natural purification effects in ambient water. Scenario-based analysis showed water quality improvement in the Chao Phraya River to be 0.12-0.26 mg-BOD l-1 , 0.19-0.33 mg-TN l-1 and 0.03-0.05 mg-TP l-1 compared to the current annual average water quality of 1.94 mg-BOD l-1 , 1.19 mg-TN l-1 , and 0.22 mg-TP l-1. Pollutant discharges per capita (PDCs) estimation results and cost-benefit comparison results showed the effectiveness of PDCs to evaluate various municipal wastewater treatment systems.