Design for sustainable development—Household drinking water filter for arsenic and pathogen treatment in Nepal

Abstract

In the last 20 years, the widespread adoption of shallow tubewells in Nepal Terai region enabled substantial improvement in access to water, but recent national water quality testing showed that 3% of these sources contain arsenic above the Nepali interim guideline of 50 microg/L, and up to 60% contain unsafe microbial contamination. To combat this crisis, MIT, ENPHO and CAWST together researched, developed and implemented a household water treatment technology by applying an iterative, learning development framework. A pilot study comparing 3 technologies against technical, social, and economic criteria showed that the Kanchan Arsenic Filter (KAF) is the most promising technology for Nepal. A two-year technical and social evaluation of over 1000 KAFs deployed in rural villages of Nepal determined that the KAF typically removes 85-90% arsenic, 90-95% iron, 80-95% turbidity, and 85-99% total coliforms. Then 83% of the households continued to use the filter after 1 year, mainly motivated by the clean appearance, improved taste, and reduced odour of the filtered water, as compared to the original water source. Although over 5,000 filters have been implemented in Nepal by January 2007, further research rooted in sustainable development is necessary to understand the technology diffusion and scale-up process, in order to expand access to safe water in the country and beyond.

Iron oxide amended biosand filters for virus removal

“…Since then, BSFs have been chosen by hundreds of humanitarian groups as the best method for improving water quality in developing countries and, as of 2009, it is estimated that over 200,000 BSFs have been implemented in over 70 countries [12]. Surveys reveal its wide acceptance by users due to the improved appearance, smell, and taste of the treated water [17]. Considering the criteria of water quantity produced, water quality, ease of use, and ease of access, BSFs have been identified as the point-of-use technology having the most potential to deliver sustainable potable water treatment to the developing world [11].…”

Dimensioning metallic iron beds for efficient contaminant removal

“…The remarkable efficiency of 3-Kolsi filters has prompted researchers to further develop the system for improved sustainability [9,10,31,[34][35][36][37]. The best product is the SONO arsenic filter in which the 100 % Fe 0 layer is replaced by a proprietary porous Fe 0 -based material (termed as Composite Iron Material -CIM) [32,33].…”

“…Fe 0 -based materials are used in particular (i) as reducing agents in permeable reactive walls [5][6][7][8], and (ii) as reagents to assist biofiltration in household filters [3,9,10]. The fundamental process responsible for contaminant removal in both contexts is necessarily the oxidative dissolution of Fe 0 (iron corrosion) which may be coupled with contaminant reduction (reactive walls) or the subsequent precipitation of iron hydroxides which may be coupled with contaminant adsorption and co-precipitation (household filters).…”

Filtros ecológicos: um estudo da remoção de produtos farmacêuticos e de cuidados pessoais e do efeito da contaminação no biofilme

“…Isto indica que o aumento do tempo de detenção aumenta o crescimento da biomassa (P = 0,79 para S1 e P = 0,11 para S2) e melhora a remoção de absorbância. Há melhora na eficiência dos filtros lentos de areia domésticos em relação aos parâmetros de qualidade de água conforme o amadurecimento dos filtros, fato este que tem sido relatado em vários trabalhos (KAISER et al, 2002;NGAI et al;, MWABI et al, 2012.…”

“…No geral, as remoções de coliformes totais e E. coli estão de acordo com trabalhos publicados sobre filtros lentos de areia para uso doméstico (NGAI et al, 2007;MWABI et al, 2012).…”