International Journal of Research in Environmental Science Volume 4, Issue 2, 2018, PP 42-49 ISSN No. (Online) 2454-9444 DOI: http://dx.doi.org/10.20431/2454-9444.0402005 www.arcjournals.org International Journal of Research in Environmental Science (IJRES) Page | 42 Comparative Study of Untreated and Ozonated Well Water from Bhaktapur Municipality, Nepal Sarita Lawaju 1 , Dr. Raju Bhai Tyata 2 , Tej Kumar Shrestha 3,4 , Dr. Ram Prasad Lamsal 5 , Anish Parajuli 6 1 Khwopa College, Department of Environmental Science, Dekocha, Bhaktapur, Nepal. 2 Khwopa College of Engineering, Professor, Head of Department, Science & Humanities, Nepal. 3 Khwopa College, Lecturer, Department of Environmental Science, Nepal. 4 Lumbini Environmental Services Pvt. Ltd, Managing Director, Kathmandu, Nepal. 5 Chief, Climate Change & Management Division, Ministry of Forests & Environment, Nepal. 6 Lumbini Environmental Services Pvt. Ltd., Program Director, Kathmandu, Nepal. 1. INTRODUCTION Availability of water for human consumption is decreasing everyday, eventually growing pollution and discharge of more than 80% of sewage without treatment results water pollution despite the effort to improve its quality in developing countries (WWAP, 2009). Dielectric Barrier Discharge (DBD) is one of the emerging technologies suitable for wastewater treatment (Eliasson et al., 1978). Water purification by conventional methods are either costly or have limited efficiency, similarly researches have revealed that many years of chlorine use for water disinfection has been concluded to be harmful for human health. This has raised concern for an effective method of water treatment (Subedi et al., 2012). Water purification by ozone synthesis is an industrially accepted application of electrical discharges (Bubnov et al., 2004; Chang & Wu 1997; Eliasson et al. 1987). Conventional chlorination process is being replaced by ozonation process due to its strong oxidising and effective disinfectant nature without any side effect (Kurica et al., 2004, Malik et al., 2001). This technology avoids chemical storage and handling; its by-products have no adverse effects to human health and environment, it safely destroys broader range of organic contaminants and removes colour, odour and suspended solid materials (Rajeshwari et al., 2001). Moreover, ozone is highly efficient in killing bacteria, viruses, spores and cysts (Malik et al., 2001). Abstract: This study is based on comparison of the quality of well water before and after ozonation. The study was conducted in eight different sites of Bhaktapur Municipality in November 2016 to February 2017. Different water quality parameters such as Temperature, pH, Electric Conductivity, Dissolved Oxygen, BOD, Total hardness, Ca-hardness, Mg-hardness, Iron, Total coliform, Fecal coliform and Non-coliform were analyzed. The study determined physico-chemical and microbial quality of well water sources before and after treatment. There were no significant changes in conductivity of water from eight different sources before and after treatment. Conductivity values remained stable before and after treatment. pH of water after treatment varied slightly with respect to pH of untreated water. DO of all samples increased significantly after ozonation. BOD of samples decreased after ozonation. There was overall decrease in Total hardness, Magnesium hardness and Calcium hardness after treatment. Iron in its ferrous state had charge of 2+. When ozone was passed through the solution containing ferrous salts, it contributed oxygen atom that reacted with Fe 2+ resulted to ferric salt and hence concentration of Fe 2+ decreased. There was overall decrease in microbial parameters (Total coliform, Fecal coliform and Non-coliform). Keywords: Ozonation, water, ozone. *Corresponding Author: Tej Kumar Shrestha, Khwopa College, Lecturer, Department of Environmental Science, Nepal. Lumbini Environmental Services Pvt. Ltd, Managing Director, Kathmandu, Nepal.