ASSESSMENT OF EFFLUENT QUALITY FROM DRAINAGE PIPES IN PHITSANULOK MUNICIPALITY

Abstract

This study aimed to assess the quality of effluent discharged directly into the Nan River from drainage pipes within the Phitsanulok Municipality, Phitsanulok Province. Effluent samples were collected from 10 locations along both sides of the Nan River in April 2023. The analysis covered 11 parameters, including pH, DO, BOD, total solids, total dissolved solids, total suspended solids, oil and grease, nitrite, heavy metals, coliform bacteria, and fecal coliform bacteria, to evaluate the wastewater quality index (WQI). The results showed that the majority of wastewater was classified between acceptable to very poor quality classes, with WQI values ranging from 154.86 to 218.62. Notably, location 10 had the highest WQI of 218.62, indicating a very poor quality class. Key effluent quality parameters such as total solids (57.04±1.22 mg/L), BOD (32.28±22.54 mg/L), oil and grease (114.01±5.92 mg/L), iron (0.77±0.06 mg/L), total coliform bacteria (5,477±5,221 MPN/100mL), and fecal coliform bacteria (3,006±3,504 MPN/ 100mL) exceeded the effluent quality standards by 80%, 100%, 100%, 100%, 40%, and 90% of the sampling points, respectively. The findings highlight the urgent necessity to develop effective wastewater treatment systems and implement efficient wastewater management strategies to mitigate the long-term impacts on the Nan River and its ecosystem.