Mwabi, JK; Adeyemo, FE; Mahlangu, TO; Mamba, BB; Brouckaert, BM; Swartz, CD; Offringa, G; Mpenyana-Monyatsi, L; Momba, MNB
One of the United Nations Millennium Development Goals is
to reduce to half by 2015 the number of people, worldwide, who lack access to safe water. Due to
the numerous deaths and illnesses caused by waterborne pathogens, various household water
treatment devices and safe storage technologies have been developed to treat and manage water at
the household level. The new approaches that are continually being examined need to be durable,
lower in overall cost and more effective in the removal of the contaminants. In this study, an
extensive literature survey was conducted to regroup various household treatment devices that are
suitable for the inexpensive treatment of water on a household basis. The survey has resulted in
the selection of four household treatment devices: the biosand filter (BSF), bucket filter (BF),
ceramic candle filter (CCF) and the silver-impregnated porous pot filter (SIPP). The first three
filters were manufactured in a Tshwane University of Technology workshop, using modified designs
reported in literature. The SIPP filter is a product of the Tshwane University of Technology. The
performance of the four filters was evaluated in terms of flow rate, physicochemical contaminant
(turbidity, fluorides, phosphates, chlorophyll a, magnesium, calcium and nitrates) and microbial
contaminant (Escherichia coli, Vibrio cholerae, Salmonella typhimurium, Shigella dysenteriae)
removals. The flow rates obtained during the study period were within the recommended limits (171
l/h, 167 l/h, 6.4 l/h and 3.5 l/h for the BSF, BF, CCF and SIPP, respectively). Using standard
methods, the results of the preliminary laboratory and field studies with spiked and
environmental water samples indicated that all filters decreased the concentrations of
contaminants in test water sources. The most efficiently removed chemical contaminant in spiked
water was fluoride (99.9%) and the poorest removal efficiency was noted for magnesium (26-56%). A
higher performance in chemical contaminant removal was noted with the BF. For pathogenic
bacteria, the mean percentage removals ranged between 97% and 100%. Although the concentrations
of most chemical parameters were within the recommended limits in raw surface water, poor removal
efficiencies were recorded for all filters, with the poorest reduction noted with fluorides
(1648%). The average turbidity removals from surface water ranged between 90% and 95% for all
filters. The highest bacterial removal efficiency was recorded by the SIPP (99-100%) and the
lowest by the BF (20-45%) and the BSF (20-60%). Extensive experimental studies with various types
of raw surface water will still determine the long-term performance of each filter, as well as
the filters that can be recommended to the communities for household treatment of drinking water.
(C) 2011 Elsevier Ltd. All rights reserved.