Bioremediation of heavily polluted Bagmati River water in Kathmandu Valley, Nepal, using Moringa oleifera seed extract

The precious Bagmati River water is deteriorating continuously due to the loading of effluents from different sources. The water quality of the Bagmati River water was determined by collecting water samples from Pashupati (B-1) and Balkhu (B-2) sites of the Bagmati River in Kathmandu Valley. The observed water quality parameters indicated that the Bagmati River is extremely polluted, and pollution was more pronounced downstream after the confluence of its tributaries. The total coliform count was extremely high, and bacteria levels exceeded the limit of counting, indicating fecal pollution from domestic influents. After treatment with indigenous Moringa oleifera (MO) seed extract, the black-colored water became clear. Most probable number and spread plate count of coliform progressively decreased with increasing concentrations of MO seed extract. The hardness, turbidity, iron, and chromium concentrations were reduced to below the World Health Organization standard after treatment with 100 mg/L MO and citric acid-treated seed extracts. The results suggest that the treated and untreated MO seed extracts could be a good natural coagulant for polluted river water treatment to reduce physicochemical and microbial pollutants.