IRON BIOMINERALIZATION: IMPLICATIONS ON THE FATE OF ARSENIC IN LANDFILLS

Persistent Link:
http://hdl.handle.net/10150/195404
Title:
IRON BIOMINERALIZATION: IMPLICATIONS ON THE FATE OF ARSENIC IN LANDFILLS
Author:
Alday, Fernando Javier
Issue Date:
2010
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The new Maximum Contaminant Level (MCL) of arsenic in drinking water has caused a significant increase in the volume of arsenic-bearing solid residuals (ABSR) generated by drinking water utilities. Iron sorbents are being widely utilized for water treatment and comprise the bulk of the waste generated. Based on Toxicity Characteristic Leaching Procedure (TCLP) results, these ABSR may be disposed in municipal solid waste (MSW) landfills. However unlike the conditions in the TCLP, a mature landfill is a biotic, reducing environment where iron and arsenic may be reduced and, as a consequence, arsenic may be released to the leachate. The primary route of iron reduction in landfills is microbially mediated and biomineralization is a common by-product. In this case, biomineralization is the transformation of ferric (hydr)oxides into ferrous iron crystalline forms, such as siderite, vivianite and iron sulfide, and into mixed valent mineral forms, such as magnetite and green rust. In this work, biomineralization is evaluated as a possible process to control arsenic leaching from ABSR in landfills. Understanding biomineralization impacts, however, requires a precise knowledge of the various mechanisms of arsenic release under landfill conditions. To this end, we describe flow-through laboratory column experiments in which controlled conditions similar to those found in a mature landfill prevail. In these simulated landfill column experiments, the results show that biomineralization would naturally occur in typical non-hazardous MSW landfills. Without any intervention, As leaching was higher than 80% of the initial quantity loaded, in contrast to Fe leaching values, which were less than 10% of the initial quantity loaded. Phosphate and bicarbonate played an important role in the experiments, as probably arsenic competitors for sorption sites and as components of the secondary iron mineral phases, vivianite and siderite respectively. Although these minerals have less surface area and adsorption capacity than AFH, they were a key constituent on the retention of the As that was left in the columns by re-adsorbing As species, and more important by coating the AFH with some of the initially loaded As.
Type:
text; Electronic Dissertation
Keywords:
Arsenic; Biomineralization; Siderite; Vivianite
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Environmental Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Ela, Wendell P.; Saez, Eduardo
Committee Chair:
Ela, Wendell P.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleIRON BIOMINERALIZATION: IMPLICATIONS ON THE FATE OF ARSENIC IN LANDFILLSen_US
dc.creatorAlday, Fernando Javieren_US
dc.contributor.authorAlday, Fernando Javieren_US
dc.date.issued2010en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe new Maximum Contaminant Level (MCL) of arsenic in drinking water has caused a significant increase in the volume of arsenic-bearing solid residuals (ABSR) generated by drinking water utilities. Iron sorbents are being widely utilized for water treatment and comprise the bulk of the waste generated. Based on Toxicity Characteristic Leaching Procedure (TCLP) results, these ABSR may be disposed in municipal solid waste (MSW) landfills. However unlike the conditions in the TCLP, a mature landfill is a biotic, reducing environment where iron and arsenic may be reduced and, as a consequence, arsenic may be released to the leachate. The primary route of iron reduction in landfills is microbially mediated and biomineralization is a common by-product. In this case, biomineralization is the transformation of ferric (hydr)oxides into ferrous iron crystalline forms, such as siderite, vivianite and iron sulfide, and into mixed valent mineral forms, such as magnetite and green rust. In this work, biomineralization is evaluated as a possible process to control arsenic leaching from ABSR in landfills. Understanding biomineralization impacts, however, requires a precise knowledge of the various mechanisms of arsenic release under landfill conditions. To this end, we describe flow-through laboratory column experiments in which controlled conditions similar to those found in a mature landfill prevail. In these simulated landfill column experiments, the results show that biomineralization would naturally occur in typical non-hazardous MSW landfills. Without any intervention, As leaching was higher than 80% of the initial quantity loaded, in contrast to Fe leaching values, which were less than 10% of the initial quantity loaded. Phosphate and bicarbonate played an important role in the experiments, as probably arsenic competitors for sorption sites and as components of the secondary iron mineral phases, vivianite and siderite respectively. Although these minerals have less surface area and adsorption capacity than AFH, they were a key constituent on the retention of the As that was left in the columns by re-adsorbing As species, and more important by coating the AFH with some of the initially loaded As.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectArsenicen_US
dc.subjectBiomineralizationen_US
dc.subjectSideriteen_US
dc.subjectVivianiteen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineEnvironmental Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorEla, Wendell P.en_US
dc.contributor.advisorSaez, Eduardoen_US
dc.contributor.chairEla, Wendell P.en_US
dc.contributor.committeememberArnold, Robert G.en_US
dc.contributor.committeememberField, James A.en_US
dc.contributor.committeememberChorover, Jonen_US
dc.identifier.proquest11136en_US
dc.identifier.oclc752260994en_US
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