Efficacy of aqueous plant extract in disinfecting water of
different physicochemical properties
J. K. Kirui, K. Kotut and P. O. Okemo
ABSTRACT
This study explored the possibility of disinfecting water using aqueous extracts of medicinal plants.
Seven medicinal plants used by Samburu herbalists for the treatment of stomach illnesses were
investigated for water disinfection. Aqueous extracts of the dried powdered plant material were
directly used to treat the water samples collected. Efficacy of water treatment with medicinal plants
expressed as percentage reduction in bacterial colonies revealed that Acacia nilotica extract with a
mean percentage reduction of 99.86% was the most effective at reducing the number of bacterial
colonies. Albizia anthelmintica extract with a mean of 9.47% was the least effective at reducing the
number of bacterial colonies. The study also revealed a possible interaction between plant extracts
and water source (P < 0.05, df ¼ 54). The results obtained in this study point out a possibility of using
aqueous extracts from A. nilotica in disinfecting water of different physicochemical properties.
J. K. Kirui (corresponding author)
K. Kotut
P. O. Okemo
Department of Microbiology,
Kenyatta University,
P.O. Box 43844,
Nairobi 00100,
Kenya
E-mail: kiruibii@yahoo.com
Key words | aqueous extract, bacterial colonies, disinfection, medicinal plants
INTRODUCTION
Samburu district is one of the most remote regions of Kenya. The
area lacks proper infrastructure such as roads and conventional
medical facilities. The area is semi-arid savannah grassland with
an annual rainfall of 250–500 mm. Because of the low and erra-
tic rainfall, this region experiences frequent shortages of water.
During periods of low water availability, competition for water
between humans, livestock and wildlife is common. The
pressure for use combined with a diversity of users may result
in contamination of water in various sources. Human and
animal wastes that may get into water sources through surface
runoff may contain pathogenic bacteria that cause diarrhea.
The World Health Organization estimated that around
1.1 billion people in low income countries lack access to
improved water sources (United Nations Report ) and
that diarrheal diseases cause 2.2 million deaths a year
(World Health Organization ). Studies have shown
that water treated with flocculent-disinfectant reduces diar-
rhea (Crump et al. ). The methods for treatment of
drinking water that have been proved to reduce waterborne
diarrheal diseases include the addition of sodium hypochlor-
ite solution (Quick et al. ) and solar disinfection
(Conroy et al. ), combined with safe storage of water
in narrow-mouthed containers (Mintz et al. ).
Reller et al. () found that while high doses of sodium
hypochlorite render water microbiologically safe, such
levels adversely affect the taste of water and therefore
decrease the willingness of people to treat the water. In
addition to the mentioned limitation, the commercial disin-
fectants are not readily available in remote settings, and if
availed, the Samburu community, which is marginalized,
may not be able to afford to buy them. In response to these
limitations, an alternative local technology for water disinfec-
tion was explored. We hypothesized that this treatment could
be useful to treat water in remote areas where the commercial
water treatment methodologies are not readily available.
Through interviews with herbal medicine practitioners,
seven medicinal plants commonly used by the Samburu com-
munity were identified. The Samburu community uses these
plants to manage diarrhea related to consumption of contami-
nated water. Aqueous extracts of these plants were used to
treat model contaminated water of different physicochemical
properties. This study focused mainly on the efficacy of the
848 © IWA Publishing 2015 Journal of Water and Health | 13.3 | 2015
doi: 10.2166/wh.2015.002
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