CSIRO Publishing blank image blank image blank image blank imageBooksblank image blank image blank image blank imageJournalsblank image blank image blank image blank imageAbout Usblank image blank image blank image blank imageShopping Cartblank image blank image blank image You are here: Journals > Environmental Chemistry   
Environmental Chemistry
Journal Banner
  Environmental problems - Chemical approaches
 
blank image Search
 
blank image blank image
blank image
 
  Advanced Search
   

Journal Home
About the Journal
Editorial Boards
Contacts
Content
Online Early
Current Issue
Just Accepted
All Issues
Virtual Issues
Special Issues
Research Fronts
Sample Issue
For Authors
General Information
Notice to Authors
Submit Article
Open Access
For Referees
Referee Guidelines
Review Article
For Subscribers
Subscription Prices
Customer Service

blue arrow e-Alerts
blank image
Subscribe to our Email Alert or RSS feeds for the latest journal papers.

red arrow Connect with us
blank image
facebook twitter youtube

 

 Just Accepted

This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.


Solid-phase characterization of an effective household sand filter for As, Fe and Mn removal from groundwater in Vietnam

Andreas Voegelin, Ralf Kaegi, Michael Berg, Katja Nitzsche, Andreas Kappler, Vi Lan, Pham Trang, Joerg Goettlicher, Ralph Steininger

Abstract

Household sand filters are widely used in Vietnam to remove As, Fe and Mn from anoxic groundwater used as drinking water resource. To expand the mechanistic knowledge on filter functioning, we investigated the bulk and micrometer-scale distribution of Fe, As, P, and Mn and the speciation of Fe, Mn and As in a sand filter after eight years of operation using bulk and micro-focused X-ray fluorescence spectrometry (XRF) and X-ray absorption spectroscopy (XAS) and scanning electron microscopy coupled with an energy dispersive X-ray detection system (SEM-EDX). Effective oxygenation of the anoxic groundwater enables the oxidative removal of Fe, As and Mn in the filter sand. Our results show that Fe is retained in the filter as a 2-line ferrihydrite-like Fe(III)-precipitate that coats sand grains, and that As accumulates dominantly as pentavalent arsenate. The very close spatial correlation of accumulated As and P with Fe throughout the filter sand and down to the micrometer-scale and the effective Fe, P and As retention at an estimated average water residence time of only 30 min suggest that their uptake is governed by a combination of fast sorption reactions, surface-catalyzed Fe(II) oxidation, and mediated As(III) co-oxidation. In contrast, Mn is retained in separate Mn(IV/III)-(oxyhydr)oxide coatings and concretions, probably as a result of coupled surface-catalyzed and microbial Mn(II) oxidation. Silicate sorbed to the ferrihydrite-like Fe(III)-coatings inhibits their crystallisation and associated remobilization of P and As. The periodic drainage and aeration of the filter promote the oxidation of any residual Fe(II) and As(III) and the formation of dense Fe precipitates and thereby contribute to effective filter operation over several years.

EN14011  Accepted 05 May 2014
 
© CSIRO 2014



Legal & Privacy | Contact Us | Help

CSIRO

© CSIRO 1996-2014