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HEALTH AND SANITATION
Household rainwater
disinfection options
The selection of appropriate household water treatment
(HWT) systems requires prior knowledge of the quality of
the water, as well as how various HWT options work and
their effectiveness against different contaminants.
Water is exposed to sunlight
for about six to eight
hours and pathogens are
inactivated by the synergistic
effect of both temperature
and sunlight radiations.
By Water Research Commission
DISINFECTION METHODS
A traditional approach to treating water at
household level is to kill or inactivate pathogens
through disinfection (WHO, 2013). The most
common methods used by households around the
world to disinfect their drinking water are: chlorine
disinfection, solar disinfection (SODIS), ultraviolet
(UV) disinfection and boiling. These disinfection
methods can be effectively applied at household
level (Jordan et al., 2008).
harvested rainwater with disinfection has proved to be
successful as illustrated in a number of studies (Despins
et al., 2009; Mendez et al., 2011; Ahmed et al., 2012).
Solar disinfection (SODIS) has been shown to be an
effective treatment method at household level. In SODIS
treatment, water is exposed to sunlight for about six
to eight hours and pathogens are inactivated by the
synergistic effect of both temperature and sunlight
radiations (Sichel et al., 2007; Ubomba-Jaswa et al.,
2009; Dayem et al., 2011).
However, the common disadvantage associated with
most disinfection methods is reduced treatment
efficiency on turbid water (Sobsey et al., 2002).
Filtration is often required when using disinfection
methods to reduce turbidity which can shield certain
microorganisms, thereby resulting in treatment
inefficiency (Qualls et al., 1983). The volume of water
that can be treated during solar disinfection is also of
concern as it can only treat small volumes of water
(Jordan et al., 2008). Ahammed and Meera (2008) studied the effectiveness
of SODIS in the treatment of roof-harvested rainwater
and reported that complete inactivation of total
coliforms was observed after six hours when solar
radiation exceeded 500W/m 2 . Limitations of SODIS
include inefficiency in treatment of large volumes of
water, its ineffectiveness during cloudy or rainy days
and it is recommended the method not be used on
turbid water (> 30 NTU) (EAWAG, 2012).
Three disinfection methods common to RWH systems
are chlorination, UV light, and ozonation. Treatment of Amin and Han (2009) investigated the benefits of solar
collector disinfection (SOCO-DIS) as a potential treatment
September 2018 Volume 24 I Number 7
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