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Evidence of Economically Sustainable Village-Scale Microenterprises for Arsenic Remediation in Developing Countries Michael German, Todd A Watkins, Minhaj Chowdhury, Prasun Chatterjee, Mizan Rahman, Hul Seingheng, and Arup K. Sengupta Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b02523 • Publication Date (Web): 08 Jan 2019 Downloaded from http://pubs.acs.org on January 9, 2019
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Evidence of Economically Sustainable Village-Scale Microenterprises for Arsenic
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Remediation in Developing Countries
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Michael S. German A,B, Todd A. Watkins C, Minhaj Chowdhury B, Prasun Chatterjee D,
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Mizan Rahman E, Hul Seingheng F, and Arup K. SenGupta A,B,G*
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A Department
of Civil and Environmental Engineering, Lehigh University (USA, 18015); B
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WIST, Inc. (USA, 75063); C Department of Economics, Lehigh University (USA, 18015);
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D WIST
Water Solutions Pvt. Ltd. (Kolkata, 700039, India); E Drinkwell Bangladesh Ltd.
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(Motijheel, Dhaka, 1000, Bangladesh); F Institute of Technology of Cambodia (PO Box
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86, Russian Federation Blvd, Phnom Penh, 12100, Cambodia); G Society for
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Technology with a Human Face (STHF, NGO, Kolkata, 700061, India)
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Corresponding author:
[email protected]; 1 W. Packer Ave, Bethlehem, PA
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18015; 610-758-6405 (fax); 610-758-3534 (office)
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TOC/Abstract Art
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Abstract
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Although unknown 25 years ago, natural arsenic contamination of groundwater affects
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over fifty countries and up to 200 million people. The economic viability was analyzed and
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modelled of eighty-eight community-based arsenic mitigation systems existing for up to
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20 years in India and Bangladesh. The performances of three community-based arsenic
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mitigation systems that are ethnically different and separated across two different
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countries were monitored closely for 24 months of self-sustainable, long-term operation
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at WHO standards through local, paid caretakers.
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Based on data from the use of hybrid ion exchange materials (HIX-Nano) and the broad
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set of field operations, Monte Carlo simulations were used to explore the conditions
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required for self-sustainable operation and job creation in low-income communities
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(100 million people across rural India, Bangladesh, Nepal, Burma, Vietnam, Cambodia
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and Laos remain at high risk of drinking water well above the WHO arsenic limit (0.010
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mg/L).21-25 An additional 100 million people are at risk of high fluoride consumption (WHO
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limit: 1.5 mg/L) throughout the Indian subcontinent and East Africa after 40 years of
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treatment efforts.26,27 Although technological innovations are highly desirable for efficient
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removal of both arsenic and fluoride from contaminated groundwater, their integrations 3 ACS Paragon Plus Environment
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with the social and economic framework of the affected communities pose serious
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challenges. In 2010, Johnston et al. reviewed treatment systems in Bangladesh and noted
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that household-based treatment systems faced logistical and operational challenges and
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community-based systems faced financial sustainability challenges.28 In response, they
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recommended arsenic avoidance.29,30 and the controlled use of water from deep aquifers
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for non-agricultural applications.31-34 Water from deep aquifers does not necessarily
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eliminate the treatment requirement because many deep aquifers across the Indian
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subcontinent have been found with significant hardness, iron and salinity. One salient
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question that evolved during the same period was: Can a robust mitigation technology,
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combined with an appropriate economic model and villagers’ participation, including both
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men and women, transform the crisis into an economic opportunity? This inquiry and
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sustained follow-up efforts led to the installation of tens of community mitigation systems
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since 2000 through various forms of local and international collaborations.
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Community-Scale vs. Point of Use (PoU) Treatment
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Lacking strong central water governance, decentralized systems based on
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household point of use (PoU) treatment emerged as an acceptable option in arsenic-
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affected communities in South and Southeast Asia. However, coordinating consistent
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operation and collection of arsenic-laden sludge from individual families to ensure safe
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disposal posed insurmountable hurdles.26 In addition, the PoU model was deemed
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economical solely because all associated labor for its installation and day-to-day
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operation were considered free of cost. Consequently, this approach, where human labor
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was
never
compensated,
did
not
create
employment
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opportunities
beyond
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manufacturing. Quality control and maintenance of the treated water in individual
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households posed major difficulty regarding concurrent iron and arsenic removal.26-30
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In comparison, centralized community-based village-scale water treatment
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systems designed to serve 100-200 families (i.e., 500-1000 individuals), can produce high
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quality water when operated by paid plant operators (caretakers) and water transported
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to individual households by delivery personnel. Net uncompensated labor hours are thus
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significantly reduced while new jobs are created in the community as shown in
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supplementary information (SI) Figure S1.38,39 Systems were managed by a village-
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selected committee comprising both men and women. Most importantly, every
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participating family was viewed as a stakeholder and required to pay a monthly tariff to
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cover the maintenance cost of the plant and compensation of the trained operator, as
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agreed by the villagers’ committee. Water delivery was a separate paid service that was
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highly valued for the elimination of the physical burden of carrying water over 500m. Key
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elements of the community-based systems are presented in Figure 1A, while Figure 1B
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exhibits one community-based system in existence with water delivery through local
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vehicles (e.g., rickshaw or tuk-tuk). The fundamental tenet of the economic model that
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evolved over a decade in arsenic-affected rural communities is that all human labor
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needed to sustain safe water supply must be financially compensated from tariffs received
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from participating villagers. Details and photographs of past, active arsenic treatment
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systems are included in SI Table S1.
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Figure 1. A) A general overview of a sustainable, interconnected water system that can
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produce safe water with sustainable financial growth (top); B) One community treatment
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system with rickshaw delivery service of safe water to individual households in the Indian
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subcontinent (bottom).
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Choice and Implementation of Technology
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Activated alumina is a widely used adsorbent for both arsenic and fluoride but it
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suffers from the following major shortcomings: first, it is unable to remove As(III) or
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arsenite; second, it is chemically unstable at acidic and alkaline pH; and, third, it is not
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reusable for more than 1-2 cycles, thus generating hazardous waste in rural communities
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lacking proper solid waste management.38,39 Reverse Osmosis or RO is a non-specific
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treatment that requires continuous supply of electricity and discards 50-80% of the feed
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water as waste with elevated concentrations of arsenic and fluoride. From an
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environmental sustainability viewpoint, the Department of Drinking Water and Sanitation
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(DDWS) of the Government of India, now the Ministry of Drinking Water and Sanitation
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(MDWS), strongly discouraged indiscriminate use of RO to mitigate the arsenic and
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fluoride crisis.40 Other adsorbents, namely, granular ferric hydroxide/oxide (GFH or GFO),
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naturally occurring laterite and titanium dioxide doped chitosan are not amenable to reuse
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or not available commercially.41-44
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Hybrid ion exchangers or HIX-Nano materials are comprised of a polymeric anion
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exchange resin support that is dispersed with metal oxide nanoparticles (e.g., iron,
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zirconium) both within the macropores and the gel phase.45-50 HIX-Nano
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commercialized over a decade ago because of its synergy of high capacity, high
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reusability and consequent reduction in the cost of treated water for arsenic, fluoride and 7 ACS Paragon Plus Environment
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phosphate removal.38,39,44-52 Arsenic removed from groundwater is converted into solids
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(sludge) of ferric hydroxide that are contained over an aerated coarse filter under an
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oxidizing environment. Continued research and field-scale applications in India,
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Cambodia, Bangladesh and Nepal have created robust and simple-to-apply sludge
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containment protocols in rural communities to ensure environmental compatibility and
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public safety.50-60 In addition to robustness and high capacity, the reusability of HIX-Nano
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makes the process conducive to long-term application in developing countries due to
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lesser dependence on supply of the adsorbent material. Several community-based
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systems are in operation for more than a decade and HIX-Nano materials are now
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produced in India.
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The central goals of this investigation were to evaluate whether community-based arsenic mitigation systems in developing countries, once installed, can:
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i)
Operate long-term while generating positive operating earnings;
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ii)
Create employment opportunities in affected communities without outside subsidies;
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iii)
accordance with national/WHO standards;
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Operate and maintain HIX-Nano to achieve treated water quality in
iv)
Maintain self-sustaining operation in affected communities.
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ECONOMIC ANALYSIS METHODS A
cash-flow
model
of
community-based
systems
was
developed
for
microenterprise operations to account for process economics: capital expenses or CapEx 8 ACS Paragon Plus Environment
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[e.g., site preparation cost (S), HIX-Nano resin (R), system equipment (E), construction
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(C)]; wages (W); non-wage operational expenses including regeneration cost or OpEx
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[e.g., electricity expense (Z), operation and maintenance including chemicals (M), delivery
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(D), marketing (K), overhead (Ov)]; financial expense or FinEx [e.g., amount borrowed
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(B), loan interest rate (I), amortization term period (T)]; and revenue or REV [e.g., price
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of water (P), quantity of water processed (Q) and number of customers (N)].
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Net monthly cash flows (CFit), i.e., monthly operating profit or loss, in location i during month t, were then: CFit = REV(Pit , Nit) – {CapExit(Sit , Rit , Eit , Cit) + Wit + OpExit(Qit , Zit , Mit , Dit , Kit , Ovit) + FinExit(Bi , Ii , Ti)}
(1)
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Three critical sustainability questions are whether village communities can 1) have
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sustainable operational economics, i.e., monthly revenues exceeding monthly expenses;
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2) generate employment opportunities in affected communities; and, 3) can provide safe
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drinking water in compliance with the WHO standards without any significant violation.
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Operations are cash flow positive monthly when CFit > 0. Since monthly cash flows vary
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and are dependent on external factors like ambient weather, religious fasting and other
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similar constraints, cumulative cash flows (CCFit) over a two-year period is a more
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objective global indicator of sustainability and economic health of the community system
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and presented as follows: 𝑡
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𝐶𝐶𝐹𝑖𝑡 = ∑ 𝐶𝐹𝑖𝑡 𝑡=0
(2)
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Cumulative operating cash flows (COCFit) may be considered when CapEx is fully
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subsidized, i.e., government-funded installations, where CapExit is excluded from CFit
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calculations by starting time at t=1.
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Self-sustaining operations were explored via Monte Carlo analysis with 2000
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simulations in Palisade’s @RISK 56,57 under various scenarios to determine periodic cash
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flows and operational breakeven periods. Instead of making assumptions about variable
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parameter distributions and correlations58,59 among them, as is typical in Monte Carlo
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applications, financial data from actual system implementations was used to inform the
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input distributions and correlations. Probability distributions for key input variables in the
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cash flow simulations (CapEx, W, non-wage OpEx, P, N, Q, B, I, T) were best fit
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distributions from data collected, in some cases for more than a decade, at nine HIX-
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based arsenic treatment systems in India and Bangladesh (a total of 103 observations)
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or from national surveys (W, I),62 as shown in SI Figure S2A-E. Additionally, price and
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quantity data was also collected for seventy-nine further sites (Table S1), and used to
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inform correlations.
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Community-Based Systems Investigated and Other Input Data
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Three community-based treatment systems in arsenic affected rural communities,
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namely, Ballia, Manikganj and Supaul, were specifically identified for detailed analysis in
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the present study; they were part of the eighty-eight total systems used for Monte Carlo
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modelling. These three communities are geographically far apart from each other and
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ethnically different.
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Ballia (25°44'27.2"N 84°18'27.9"E) is a district in the most populous state of Uttar
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Pradesh in India, along the bank of the River Ganges. The entire district is affected by
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widespread arsenic contamination of groundwater and confronted with adverse health
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impacts on rural population. In 2013, the Society for Technology with a Human Face or
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STHF (NGO) installed a community-based treatment system using HIX-Nano as the
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primary sorbent.
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Manikganj (23°30'28.4"N 90°13'15.2"E) is one of the arsenic affected districts in
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Bangladesh with hundreds of defunct household PoU systems. In February 2015, an HIX-
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Nano system was installed in Manikganj with the support of STHF and WIST, Inc.
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Although Bangladesh is the worst arsenic-affected country, Manikganj has been the
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longest-running community-based arsenic treatment system there.
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In Supaul, Bihar, India (26°05'14.2"N, 86°30'30.7"E), STHF installed an HIX-Nano
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community drinking water system in late 2015 to remove arsenic and iron at a community
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toilet block operated by Sanitation and Health Rights in India (SHRI, NGO). SHRI
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purchased the system to use water sales revenue to offset operational costs of their toilet
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block.
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These three low income communities (