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Asian Journal of Water, Environment and Pollution. Vol. 22, No. 1 (2025), pp. 42-51.
doi: 10.36922/ajwep.8434

ORIGINAL RESEARCH ARTICLE

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

extract

Mandira Pradhananga Adhikari* , and Manisha Neupane
Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal
*Corresponding author: Mandira Pradhananga Adhikari (mandira43@hotmail.com)

Received: January 7, 2025; 1st revised: February 14, 2025; 2nd revised: February 19, 2025;
Accepted: February 19, 2025; Published Online: March 6, 2025

Abstract: 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.

Keywords: Coagulant; Chromium; Iron; Moringa oleifera; Water pollution

1. Introduction as dysentery, diarrhea, cholera, and skin disease. The
2,3
Bagmati River is precious and important in the geography,
Clean and safe water plays a dynamic role in human culture, hydrology, and socioeconomic development
life. The use of surface water for drinking and domestic of Nepal. Recently, the effluents from various
purposes is a common practice in communities of sources degraded the Bagmati River water, mainly in
developing countries like Nepal. The rapid population Kathmandu Valley, increasing the levels of harmful
growth, industry, and the excessive use of chemical chemicals and undesirable biological contaminants.
4
fertilizers are increasingly polluting surface water. Thus, the treatment and purification of surface water
Therefore, obtaining safe drinking water is one of the using effective and inexpensive techniques is essential
biggest problems for people, especially those living in for safe domestic use and for preventing casualties from
developing countries. People from poor communities waterborne diseases. Among the techniques used for
1
are using polluted river water without any purification water disinfection, chlorination is the most effective
or pre-treatment, leading to waterborne diseases, such and cheap technique. However, residual chlorine can

Volume 22 Issue 1 (2025) 42 doi: 10.36922/ajwep.8434