Removal of waterborne bacteria from surface water and groundwater by cost-effective household water treatment systems (HWTS): A sustainable solution for improving water quality in rural communities of Africa

Abstract

In this study 5 household water-treatment devices/systems (HWTS) were constructed using inexpensive local materials (sand, gravel, zeolites and clays). They included the silver-impregnated porous pot filter (SIPP), the ceramic candle filter (CCF), the conventional biosand filter (BSF-S), a modified biosand filter with zeolites (BSF-Z), and a bucket filter (BF). Their ability to remove turbidity and pathogenic bacteria (Vibrio cholerae, Salmonella typhimurium and Shigella dysenteriae) from synthetic sterile water, groundwater and surface-water sources was evaluated. The flow rates ranged from 0.05 ℓ·h ) and lowest (14% to 76% (2.91 to 7.19 NTU)) average percentage turbidity removals were noted for SIPP and BF, respectively. The SIPP was the only device that consistently removed 100% of all target pathogens throughout the study. Its performance was found to be significantly superior (p<0.05) compared to that of the other four devices. Sixty (60%) to 100% bacterial removals were observed for BSF-S; 90% to 100% for BSF-Z; 90% to 100% for CCF; and 40% to 99.9% for BF. Based on the findings of this study the SIPP can be recommended for use by rural communities as it consistently produced high-quality water that complied with the SANS 241 turbidity and microbiological limits for drinking water.

Efficiency of Slow Sand Filter in Purifying Well Water

“…However, the removal efficiency of sand bed depends more upon the maturity of the schmutzdecke than upon its depth (AWWA, 1991). Within the filter bed, the presence of protozoa, bacteria, algae and other forms of life contributes to the removal of pollutants (Banda, 2011;Bonnefoy, 2002) including the E. coli (Mwabi et al, 2013). Two-way ANOVA reveals that there is no significant difference on the removal of E. coli among the three different sand filter depths and flow-through rates (p<0.05).…”

“…Each layer of the graded gravel is 100-mm thick or a total gravel depth of 300 mm. The gravel layer holds the sand filter to prevent it from displacement during filtration (Liabwel et al, 2001;Mwabi et al, 2013). After grading and before placing in the filter set-up, both sand and gravel were washed again thoroughly with clean water to assure that both materials were free of any foreign matter.…”

“…Protozoa, bacteria, algae and other forms of life within the filter bed contribute to pollutant removal (Banda, 2011;Hsieh et al, 2010;Joubert et al, 2008Bonnefoy, 2002 including E. coli (Mwabi et al, 2013).…”

Do low-cost ceramic water filters improve water security in rural South Africa?

“…Other studies concentrated on costefficient POU water treatment techniques. BSF with plastic housing was found to be as efficient as its concrete counterparts (Fabiszewski de Aceituno et al, 2012) and various researchers reported the success of locally produced, low-cost CWF Simonis and Basson, 2011;Mwabi et al, 2013). Recent reviews of reduction of diarrhoea by different POU interventions found filtration techniques superior to solar or chemical water disinfection (Wolf et al, 2014;Clasen et al, 2015).…”

“…However, comparisons were blurred by a high risk of bias, since the data relied on self-reported diarrhoea and placebo POU interventions were missing. For rural South Africa, low-cost ceramic water filters have been advocated for POU water treatment (Du Preez et al, 2008;Mwabi et al, 2013), andDu Preez et al (2008) reported on their high acceptability. The need for improved drinking water supply in South Africa was recently manifested for two communities in the Municipality of Mutale (Rananga and Gumbo, 2015): 95 % of the households were willing to pay for reliable drinking water supply; those with tertiary level education would afford ZAR 150 per month.…”