Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations

Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations

Arsenic removal by passive treatment, in which naturally present Fe(II) is oxidized by aeration and the forming iron- (III) (hydr)oxides precipitate with adsorbed arsenic, is the simplest conceivable water treatment option. However, competing anions and low iron concentrations often require add...

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Main Authors: Roberts, Linda C., Hug, Stephen J., Reuttimann, Thomas, Billah, Md. Morsaline, Khan, Abdul Wahab, Rahman, Mohammad Tariqur
Format: Article
Language:English
Published: American Chemical Society 2004
Subjects:
TD895 Industrial sanitation. Industrial wastes
Online Access:http://irep.iium.edu.my/29703/
http://irep.iium.edu.my/29703/
http://irep.iium.edu.my/29703/
http://irep.iium.edu.my/29703/1/Env_Sci_Technol.pdf
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spelling iium-297032013-04-26T09:30:23Z http://irep.iium.edu.my/29703/ Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations Roberts, Linda C. Hug, Stephen J. Reuttimann, Thomas Billah, Md. Morsaline Khan, Abdul Wahab Rahman, Mohammad Tariqur TD895 Industrial sanitation. Industrial wastes Arsenic removal by passive treatment, in which naturally present Fe(II) is oxidized by aeration and the forming iron- (III) (hydr)oxides precipitate with adsorbed arsenic, is the simplest conceivable water treatment option. However, competing anions and low iron concentrations often require additional iron. Application of Fe(II) instead of the usually applied Fe(III) is shown to be advantageous, as oxidation of Fe(II) by dissolved oxygen causes partial oxidation of As(III) and iron(III) (hydr)oxides formed from Fe(II) have higher sorption capacities. In simulated groundwater (8.2 mM HCO3 -, 2.5 mM Ca2+, 1.6 mM Mg2+, 30 mg/L Si, 3 mg/L P, 500 ppb As(III), or As(V), pH 7.0 ( 0.1), addition of Fe(II) clearly leads to better As removal than Fe(III). Multiple additions of Fe(II) further improved the removal of As(III). A competitive coprecipitation model that considers As(III) oxidation explains the observed results and allows the estimation of arsenic removal under different conditions. Lowering 500 íg/L As(III) to below 50 íg/L As(tot) in filtered water required >80 mg/L Fe(III), 50-55 mg/L Fe(II) in one single addition, and 20-25 mg/L in multiple additions. With As(V), 10-12 mg/L Fe(II) and 15-18 mg/L Fe(III) was required. In the absence of Si and P, removal efficiencies for Fe(II) and Fe(III) were similar: 30-40 mg/L was required for As(III), and 2.0-2.5 mg/L was required for As(V). In a field study with 22 tubewells in Bangladesh, passive treatment efficiently removed phosphate, but iron contents were generally too low for efficient arsenic removal. American Chemical Society 2004 Article PeerReviewed application/pdf en http://irep.iium.edu.my/29703/1/Env_Sci_Technol.pdf Roberts, Linda C. and Hug, Stephen J. and Reuttimann, Thomas and Billah, Md. Morsaline and Khan, Abdul Wahab and Rahman, Mohammad Tariqur (2004) Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations. Environmental Science & Technology, 38 (1). pp. 307-315. ISSN 0013-936X http://pubs.acs.org/doi/abs/10.1021/es0343205 10.1021/es0343205
repository_type Digital Repository
institution_category Local University
institution International Islamic University Malaysia
building IIUM Repository
collection Online Access
language English
topic TD895 Industrial sanitation. Industrial wastes
spellingShingle TD895 Industrial sanitation. Industrial wastes
Roberts, Linda C.
Hug, Stephen J.
Reuttimann, Thomas
Billah, Md. Morsaline
Khan, Abdul Wahab
Rahman, Mohammad Tariqur
Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations
description Arsenic removal by passive treatment, in which naturally present Fe(II) is oxidized by aeration and the forming iron- (III) (hydr)oxides precipitate with adsorbed arsenic, is the simplest conceivable water treatment option. However, competing anions and low iron concentrations often require additional iron. Application of Fe(II) instead of the usually applied Fe(III) is shown to be advantageous, as oxidation of Fe(II) by dissolved oxygen causes partial oxidation of As(III) and iron(III) (hydr)oxides formed from Fe(II) have higher sorption capacities. In simulated groundwater (8.2 mM HCO3 -, 2.5 mM Ca2+, 1.6 mM Mg2+, 30 mg/L Si, 3 mg/L P, 500 ppb As(III), or As(V), pH 7.0 ( 0.1), addition of Fe(II) clearly leads to better As removal than Fe(III). Multiple additions of Fe(II) further improved the removal of As(III). A competitive coprecipitation model that considers As(III) oxidation explains the observed results and allows the estimation of arsenic removal under different conditions. Lowering 500 íg/L As(III) to below 50 íg/L As(tot) in filtered water required >80 mg/L Fe(III), 50-55 mg/L Fe(II) in one single addition, and 20-25 mg/L in multiple additions. With As(V), 10-12 mg/L Fe(II) and 15-18 mg/L Fe(III) was required. In the absence of Si and P, removal efficiencies for Fe(II) and Fe(III) were similar: 30-40 mg/L was required for As(III), and 2.0-2.5 mg/L was required for As(V). In a field study with 22 tubewells in Bangladesh, passive treatment efficiently removed phosphate, but iron contents were generally too low for efficient arsenic removal.
format Article
author Roberts, Linda C.
Hug, Stephen J.
Reuttimann, Thomas
Billah, Md. Morsaline
Khan, Abdul Wahab
Rahman, Mohammad Tariqur
author_facet Roberts, Linda C.
Hug, Stephen J.
Reuttimann, Thomas
Billah, Md. Morsaline
Khan, Abdul Wahab
Rahman, Mohammad Tariqur
author_sort Roberts, Linda C.
title Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations
title_short Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations
title_full Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations
title_fullStr Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations
title_full_unstemmed Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations
title_sort arsenic removal with iron(ii) and iron(iii) in waters with high silicate and phosphate concentrations
publisher American Chemical Society
publishDate 2004
url http://irep.iium.edu.my/29703/
http://irep.iium.edu.my/29703/
http://irep.iium.edu.my/29703/
http://irep.iium.edu.my/29703/1/Env_Sci_Technol.pdf
first_indexed 2023-09-18T20:43:38Z
last_indexed 2023-09-18T20:43:38Z
_version_ 1777409530506772480

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