Subsurface Iron and Arsenic Removal

1 Introduction
sulfate or ferric chloride) and arsenic adsorption
to media, like activated alumina and granular iron
oxide/oxide (GFH; Banerjee et al., 2008). In all cases
the arsenic binds to the positively-charged surface
of the (iron hydroxide) matrix. Especially at low to
moderate arsenic concentrations, the technology
of arsenic adsorption is relatively effective. Other
arsenic removal technologies include ion exchange,
coagulation/filtration and reverse osmosis (AWWARF,
2000; EPA, 2007; Johnston et al., 2001). Most processes
are, however, not designed for household application
in a developing country context. The sustainability
of a HWTS can be addressed based on five criteria
(van Halem et al., 2009): accessibility, water quality,
water quantity, functionality, and environmental
footprint. Accessibility entails both the affordability
and availability of the technology and should be
expressed in money, time or distance. A product can be
accessible through a local shop or organization, but in a
globalizing world, also through an ordering system on
the internet. The criteria of water quality and quantity
are formulated by the World Health Organization
(WHO, 2006; WHO, 2007), being 2L per person per day. Functionality depends on
the operation and maintenance activities for the users,
which strongly determines the social acceptance of a
technology. The environmental footprint is generally
not the main concern of most users, but long-term
1
brick
chips
coarse sand
cast iron
coarse sand
coagulation and
flocculation bucket
cloth filter
scooping net
coarse sand
charcoal
fine sand
brick
chips
media
media
perforated plate
covered with
cotton filter
sand
cloth filter
sand
EVOH resin
geo textile
synthetic cloth
scooping net
scooping net
charcoal
Figure 1.2 Arsenic household water treatment and storage (from left to right): Sono Filter, Alcan Filter, Shawdesh Filter and Read-F
(BETV-SAM, 2011)
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