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Table 17 Maintenance of coagulation, co-precipitation and filtration technologies

From: Are interventions to reduce the impact of arsenic contamination of groundwater on human health in developing countries effective? A systematic review

Intervention Comments
DPHE/Danida two bucket system Negative - For the two kolshi, problems with the distribution of the chemical coagulant packet, as it had to be shipped from Kathmandu over unreliable road networks. Some users complained about the amount of work necessary to perform the coagulation process (add chemical, stir, wait 30 mins) and the clogging in the ceramic candle vessels, post coagulation (Ngai et al., 2007).
Alum treatment of contaminated water Negative - The water held a residual smell, therefore, people did not accept or use the water (Hoque et al., 2000).
Stevens Institute technology Negative - Main concerns were the technology was difficult to move and produced slow flow rates (Sutherland et al., 2002).
Household co-precipitation and filtration system Maintenance - Washing of clogged filter sand.
STAR -
CIWPL -
Procter & Gamble flocculant-disinfectant powder Maintenance - Disposal of residual flocculant. 10L/sachet. Stir five min and settle five min (Norton et al., 2009).
Negative - Problems with cooking reported on 28% of visits – primarily associated with preparation of rice and included development of a yellowish discolouration, a bad smell and stickiness. Difficulties with water treatment were reported next most frequently (24%) and included difficulties with flocculant disinfectant floating on top of the water during treatment rather than settling which made filtration difficult (Norton et al., 2009).
Household arsenic removal system Maintenance - Sand bed resuspended in well water and washed twice a week. Issue with disposal of orange sludge (Meng et al., 2001).
Ferric chloride coagulation Maintenance - Requires daily addition of chemicals to water and regular supply of chemicals. Washing of straining cloth and sand from twice a week to every two weeks (Ashraf Ali et al., 2001).
Positive - People generally very eager to use units, particularly among those more aware of the adverse effects of arsenic. People were willing to pay for chemical packets. Easy operation and maintenance appears to have made units popular. Impressed with clarity of water – identified by households as primary reason for using the unit (Ashraf Ali et al., 2001).
Negative - Some of the households did not use treated water during the winter because the water was very cold and the tubewell water was much warmer. Also noted that it was difficult for women to stir upper bucket. Observations suggest instructions not strictly followed. Too much work for the mixing and too long for iron flocs to settle (Ashraf Ali et al., 2001).
Chlorinating agent (BP) + ferric alum Maintenance - Requires periodical sludge removal and/or cleaning (Hossain et al., 2005).