ARSENIC BIOSAND FILTER:
“STUDY ON THE EFFECT OF AIR SPACE BETWEEN THE RESTING WATER AND
THE DIFFUSER BASIN ON ARSENIC REMOVAL AND DETERMINATION OF
GENERAL FLOW CURVE” (A case study of Nawalparasi district, Tilakpur V.D.C.)
A Thesis
Submitted for partial fulfillment for the Bachelor Degree in Environmental Science (Honor’s
Degree) to the department of Biological Science and Environmental Science
School of Science, Kathmandu University
By
Shashank Pandey
Abstract
The study attempt to investigate the effect of air space between the diffuser basin and the
resting water level on removal of arsenic by the Arsenic Biosand Filter. In addition, the study
focused on the determination of general flow curve for the filter , determination of time
required for volume of water to be filtered and also to comprehend the social acceptance of
the filter.
Four filters from Tilakpur VDC of Nawalparasi district were selected for the research..
Altogether 150 water samples were collected and flow rate of each sample was taken. The
collected samples were tested for arsenic by using ENPHO arsenic field test kit. Besides this,
the social acceptance of the filter was evaluated through questionnaire and informal survey.
To accomplish the objective some hypothesis was set. And the result obtained from the
research was compared with the hypothesis set. And according to the comparison the result
and conclusion were made. And thus the result obtained from the research was not according
to the hypothesis set and this thesis describes the different reasons not satisfying the
hypothesis
Acknowledgement
I would like to express my sincere gratitude to Dr. Rana Bahadur Chhetri, Associate
Professor, and Head of Department of Biological Sciences and Environmental Science for
allowing me to undertake this work.
I am grateful to my supervisors Associate Professor Dr. Sanjay Nath Khanal Department of
Biological Sciences and Environmental Science for his continuous guidance advice effort and
invertible suggestion throughout the research.
I am also grateful to my supervisor Dr. Roshan Raj Shrestha Executive chairman of
Environment and Public Health Organization ENPHO for providing me the logistic support
and his valuable suggestion to carry out my research successfully.
My utmost gratitude to Mr. Bipin Dongol, Environmental Engineer (ENPHO), Binod Mani
Dahal (ENPHO), Mr. Prajwol Shrestha and Mr. Tommy Ka Kit Ngai, Lecturer Research
affiliate at Massachusetts Institute of technology (MIT) without their continuous support this
study would not have been possible. I would also like to thank members of ENPHO for
helping to carry out my research.
I would also like to thank Mr. Sandeep Shrestha Lecturer, Kathmandu University and Juna
Shrestha (ENPHO) for encouraging me to carryout this project.
I would also like to thank my friends of Environmental Science batch 2000 and my friends
Sushil Tuladhar , Yogendra Jung Khadka, Neelesh Man Shrestha of Environmental Science
IInd Year for there help throughout the study.
Lastly I would like to express my sincere appreciation to my parents especially my Mamu for
encouraging and supporting me throughout the study.
CHAPTER 1 HISTORICAL BACKGROUND
Water resource, water supply and water quality in Nepal
Nepal is the 2nd richest country in water resource in the world, possessing about 2.27% of the
world water resource (CBS 1999). Despite this fact planned water supply was stated only in the
fourth plan (1970-1975). The national coverage of water supply system was only about 4% in
1970. A separate institution, the Department of Drinking Water Supply and Sewerage (DWSS)
was established during that period. By the end of water supply and sanitation decade (1990), the
coverage substantially increased to 36% of the total population, with the rural population and
urban population at 33% and 67% respectively. The recent Between Census Households
Information, Monitoring and Evaluation System (BCHIMES) report-2000 indicates water
coverage at 78% for rural and 92.3% for the urban population (Shrestha, 2003).
Sanitation facility is very poor condition having only 29% national coverage and issue on water
quality has not been given proper attention (Shrestha et.al, 2203). Rural communities continue to
use the most convenient source of water irrespective of quality. Regular outbreaks of water borne
epidemics and increasing number of patients being admitted to hospitals due to water related
diseases indicates that only supplying of drinking water is not sufficient to improve public health
status unless continued effort is made both on water supply and sanitation.
Nepal water resources are considerable with surface run-off in the order of 200 km3 annually. In
general, there is very little rainfall from November to January. In addition to surface water,
Nepal’s ground water resources are also extensive.
In Nepal, the guideline value for national drinking water quality standard has been suggested by
Pyakural (1994) and Task Force (1995)