Subsurface Iron and Arsenic Removal

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3 Small-scale subsurface iron and arsenic removal in Bangladesh but have also indicated that the success of this technology may be site-specific. For this technology to be considered a safe arsenic mitigation solution it is inevitable that more knowledge needs to be gained about the operational conditions that control the efficacy of SIR/SAR. The objective of this study was to investigate the performance of small-scale SIR/SAR in rural Bangladesh. Materials and methods Household shallow tube wells with suction hand pumps are widely distributed in Bangladesh and the aim of the subsurface iron/arsenic removal technology is to use the existing infrastructure optimally. The Manikganj district, just west of Dhaka, was selected for this study, since this area is known to have high iron, arsenic and manganese concentrations in the groundwater. After testing numerous wells, two sites (A and B) were selected with the same arsenic concentrations (1.94 μg.L -1 ). The groundwater pH at the two test locations was 6.85 and the groundwater composition is illustrated in Table 3.1. The initial iron concentrations at location A and B was 0.018 mmol.L -1 and 0.27 mmol.L -1 , respectively, resulting in molar Fe:As ratios of 9 and 140. Manganese concentrations also differed at the two locations, namely, (A) 0.045 mmol.L -1 and (B) 0.006 mmol.L -1 . The experimental set-up (Figure 3.4) was connected to an existing hand pump with tube well in the upper aquifer. The 1.5-inch tube-well had a depth of 31 meters and a perforated well length of 3 meter. As an added precaution, the set-up was placed with families who already had arsenic treatment since 2001 (SIDKO system; BETV-SAM, 2011). For the purpose of subsurface treatment, the existing situation was modified with a pipe and valve for injection. After subsurface treatment, the groundwater was pumped (electrical suction pump) into the SIDKO system for aeration, sand filtration and Granular Ferric Hydroxide filtration (AdsorpAs, Harbauer GmbH). The treated water, low in arsenic (
Subsurface iron and arsenic removal for drinking water treatment in Bangladesh 3 water meter pump valve inline monitoring sampling tap iron filter aeration tank storage tank SIDKO system arsenic filter oxygen concentrations were reached by aerating the water with a combination of a shower head (installed in the SIDKO system) and subsequent bubble aeration in the storage tank. Analysis of the water samples was done with field test kits (Wagtech International: Palintest and Arsenator) and confirmed in the laboratory (Perkin-Elmer Flame AAS 3110; Perkin- Elmer GF-AAS 5100PC). Duplicates or triplicates were taken to check the method of sampling and accuracy of analysis. Arsenic speciation was done with a field method (Clifford et al., 2004) using anion exchange resin columns (Amberlite IRA400). Multimeters (HACH 340i) were fixed inline to the experimental setup to monitor pH (WTW SenTix 41), dissolved oxygen (WTW Cellox 325), ORP (WTW SenTix ORP) and electric conductivity (TetraCon 325). Measurements were registered on a computer with Multilab Pilot v5.06 software. The injection and abstraction volumes were monitored using water meters. Operation started in October 2008, just after the monsoon season, and continued until May 2009. At both locations, the families shared their arsenic treatment facility with the community and the weekly water consumption was 5.7-8.7 m 3 and 2.4-2.9 m 3 for location A and B, respectively. Operational conditions, such as injection frequency and production discharge, varied due to irregular operation. Normally the set-ups were used for the families’ water production, however, during research periods the operation was intensified. In this paper, all results are presented using the ratio between abstracted volume (V) and injected volume (Vi), V/ Vi. This volumetric ratio determines the efficiency of the system. Every period of injection-abstraction starts at V/Vi=0 and is referred to as a cycle, with the first injection-abstraction period being cycle 1. Injection was done the night before, so abstraction was started at 12-16 hours after injection. Figure 3.4 Experimental set-up for subsurface iron and arsenic removal at existing SIDKO system 42
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6 Characterization of accumulated d
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7 Catalysis by accumulated deposits
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8 Influence of groundwater composit
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Concluding remarks9
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9 Concluding remarks outlook is giv
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9 Concluding remarks with SIR in th
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9 Concluding remarks have the tende
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9 Concluding remarks Sharma S.K. (2
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Summary Subsurface iron and arsenic
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Summary Apart from adsorptive-catal
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Samenvatting Ondergrondse ijzer-en
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Samenvatting Fe 3+ oxiden. Niettemi
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Samenvatting drinkwaterkwaliteit, m
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List of publications List of public
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List of publications Disaster Relie
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