Repurposing spent filter sand from iron and manganese removal systems as an adsorbent for treating arsenic contaminated drinking water

• Published in: Journal of environmental management Vol. 302; no. Pt B; p. 114115
• Main Authors: Watson, Malcolm, Nikić, Jasmina, Tubić, Aleksandra, Isakovski, Marijana Kragulj, Šolić, Marko, Dalmacija, Božo, Agbaba, Jasmina
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15-01-2022
• Subjects: Arsenic - analysis; Arsenic adsorption; Drinking Water; Iron; Manganese; Sand; Spent filter sand; Waste reuse; Water Pollutants, Chemical - analysis; Arsenic adsorption; Drinking water; Spent filter sand; Waste reuse
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2021.114115

Waterworks which utilise river bank filtration water sources often have to apply aeration and sand filtration to remove iron and manganese during the drinking water treatment process. After some time, the sand becomes saturated and the spent filter sand (SFS) must be disposed of and replaced. In order to valorize this waste stream, this paper investigates the reuse of SFS as an adsorbent for the treatment of arsenic contaminated drinking water. The arsenic removal performance of SFS is compared with two synthetic iron oxide coated sands (IOCS). The sorbents were first characterized by SEM, EDS, BET specific surface area, and point of zero charge (pHpzc) measurements, and then investigated under a variety of conditions. The surface of the SFS was revealed to be coated with iron manganese binary oxide. The Freundlich model best described the isotherm experiment data, indicating a non monolayer adsorption model for arsenic adsorption on the three IOCS investigated. As(III) and As(V) removals were negatively effected by the presence of PO43− and HA anions as they competed with the arsenic species for adsorption sites. However, given the status of SFS as a waste material, the results obtained in this paper suggest it may be successfully reused as a very economically and environmentally sustainable solution for small waterworks requiring both As(V) and As(III) removal during drinking water treatment.
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•Spent filter sand (SFS) from an iron removal process was investigated as an adsorbent.•The SFS was found to be coated with a mixture of Fe and Mn oxides.•This waste material was effective at removing both As(III) and As(V) from water.•Phosphate and humic acid anions competed for arsenic adsorption sites on SFS.•Reuse of SFS as an adsorbent is a promising sustainable solution for arsenic removal.