Abstract
Maintenance of existing household arsenic (As) removal technologies are comparatively difficult due to the use of the sand beds as a filter. Moreover, pre-aeration of groundwater is avoided during filter operation that may affect the removal efficiency. This study investigated the effect of pre-aeration on the efficacy of simple iron nested ceramic filter (CF) for the removal of As and Fe from the natural groundwater. Five CFs at 5 households in the Bagerhat district of Bangladesh were tested for 31 days with pre-aerated groundwater (AGW system) and non-aerated groundwater (NAGW system). Pe-aeration of groundwater significantly improved (p > 0.5) the removal efficiency of As and Fe in the CFs. The filters effectively removed As in the groundwater from 203 - 231 μg/L to 29–40 μg/L in the AGW system whereas the effluent As were >50 μg/L in the NAGW system. Iron (Fe) was also removed effectively and the overall As and Fe removal efficiency were more than 82% and 99%, respectively in the AGW system. Removal of Mn and PO4–P were significantly enhanced achieving more than 56% and 99% removal, respectively in the AGW system. X-ray absorption fine structure (XAFS) analysis indicated that the oxidation of Fe2+ and As(III) and subsequent adoption/precipitation are the main processes controlling the removals of As and Fe in the CFs. Two stages oxidation of Fe2+ and As(III) in the AGW system facilitated to increase As and Fe removal efficiency. The findings of this study suggest that the iron net nested ceramic filters with pre-aeration step is an effective method and can be employed at the household level in As contaminated region.
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•Pre-aeration of groundwater facilitated two stage Fe2+ and As(III) oxidation.•Groundwater Fe2+ fully oxidized to Fe3+ during pre-aeration step.•As and Fe removal enhanced significantly in ceramic filter.•As(V) was the dominant species adsorbed onto the HFO flocs.•Ca, Mn and PO4–P removal increased by the pre-aeration step.