The State of Arsenic in Nepal - 2003 - Harvard University ...

Bangladesh and solves the problem of chemical powder.
Oxidation, adsorption, precipitation and filtration is the
process for removal of arsenic, iron in this filter. This filter
system can remove up to 95% of the arsenic, even when the
water is highly contaminated. Retardation of filtration
process due to clogging and presence of microbes in the
treated water limits the filter’s performance. Therefore,
techniques for improvement of microbiological quality
should also be used while providing this option.
Improved Bio-sand filter
The Bio-sand filter as a point-ofuse
drinking water treatment
option that was initially designed
by Dr. David Manz of the
University of Calgary. Recently, a
joint research study that included
MIT, ENPHO and RWSSSP
improved this filter for removal of
Figure 5.5 Biosand Filter
arsenic by combining the concepts
of three gagri and bio-sand filter. Now it can be used for
removal of arsenic, iron, bacteria and turbidity. This filter
uses the process of aeration, adsorption and filtration. As
this system has a high flow rate of 30 litres per hour, the biosand
filter has become in high demand in communities, not
only for arsenic removal, but also due to higher flow rate.
Due to its enhanced performance and durability, the NRCS
replaced all other filters (two gagri and three gagri) with
improved bio-sand filter in their program area. Field test shows
that this filter removes more than 95% arsenic on average
and up to 99% in some cases (ENPHO/NRCS/4, 2003; Ngai
and Walewijk, 2003). The filter also removes high levels of
iron—up to 99%, with an average of 95%. Microbiological
quality of this treated water is satisfactory. NRCS, RWSSSP,
RWSSFDB, and DOE are implementing this system in their
arsenic affected districts. Recently, World Bank has awarded
“Development Market Place – 2003 (DM2003) to MIT/
ENPHO/RWSSSP for the promotion and implementation of
this filter in arsenic affected communities in Nepal.
Arsenic Iron Removal Plant (AIRP)
This plant is designed to serve a group of households that
9
share a single tube well. The main concept behind this
system is the removal arsenic by extracting iron from
contaminated water.
It is good for only
those tube wells
where arsenic
concentrations are
more than 50 ppb
Figure 5.6. Arsenic Iron Removal Plant
but less than 101
ppb and the iron content is more than 3 mg/l. About 20 units
of AIRP have already been installed under NRCS program in
Nawalparasi and Rautahat districts.
5.4. Media and arsenic contamination
Within the last decade, Nepal has seen an exponential
increase in the different forms of media such as FM radios,
private television channels, and the print media. The media,
especially the radio is held in high regard in Nepal, mostly in
the rural areas, because it is frequently the only link to current
news. There is a perception that anything aired in the radio,
television and in the printed form is correct. Coverage in
media is mostly related to politics. There is little news on
social and development issues, and sometimes reporting is
not completely accurate. Potential disasters related to water
get some attention, but is commonly limited to the number
of deaths of people from floods and landslides. The issue
of arsenic contamination in the ground water of Nepal has
not been given much attention in the media at the present
time.
The NASC, during its early period, had decided that issue
on arsenic contamination might create some fear in the people,
especially because there was very limited detailed information
to share. The committee believed that there would be more
harm done in terms of increased publicity without solid
information to describe the severity of the arsenic issue. At
first, the results of arsenic testing in groundwaters from tube
wells were not made accessible to the media. This restriction
was later on finally made public through an organized press
meet. Most of the coverage in the media took place after
this press conference. Almost all media forms then
highlighted the issue of arsenic contamination. This event