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Roles of microbial community on arsenic removal in drinking-water

A.B.M.Rafiqul Islam, M.Abdul Jalil, KazueTazaki

The objective of the study is to evaluate the feasibilityof biogenic removal ofAs inBangladesh. The study had been conducted at Hazigonj, a highly As contaminated areas in the south east ofBangladesh in the period of May, 2001 to June, 2011. As-contaminated Tube-wellsWater (TW) (n=16),microbial mats (MM) (n=16)mainly composed of autotrophic and heterotrophic bacteria associatedwith photosynthetic algae that have grown in front ofAs-contaminated TW, and urine (n=95) samples were collected from the locality. HG-AAS analysis of TWshowed the high ranges 0.31- 2.45 mg/LAs, (r =0.999) with an average of 1.53±0.77 mg/LAs. Besides this, the average of 0.60±0.70 mg/LAs, had been detected in urine samples that alsomight showthe higher intake of As from the TW. Neutron activation analysis (NAA) indicated the higher concentrations ofAs (390 and 550mg/kgAs,) accumulated in twoMMobtained near (0.3m) two of the tube-wells, which were several hundred times higher than those of corresponding TW(1.70 and 1.61 mg/LAs). Further, in a series of in situ sampling, highestAs (390mg/kg) accumulated inMM, at the upstreamnear the tube-well faucet (1.70mg/L). Reduced concentrations (0.74mg/ LAs and 0.18 mg/LAs) were detected in the downstream, around 4 and 8m apart from the TW, while MMof same spots concentrated 124 mg/kg and 38 mg/kg ofAs respectively. This study provides the evidence ofmicrobialAs accumulation, whichmay help in designing an effective and economicAs bioremoval procedure.