Masters Theses

Alternative Title

Leaching of As and Se from fly ash in the simulated field systems

Keywords and Phrases

Arsenic; Selenium; Fly Ash; Leaching; Calcium; Adsorption; NOx; Hg

Abstract

"Fly ash accounts for nearly 60% of coal combustion products produced in the United States. Although fly ash is beneficially used in the cement and concrete industries, in waste stabilization, and as a structural fill, about 60% is disposed in landfills or ponds. Trace elements of major environmental concern such as As, Se, Hg, Cr, Cd, Ni, Pb, Cu, Co etc end up on fly ash particles as a result of coal combustion, which may be potentially released to the environment. For utilization purposes, fly ash is classified as class C or class F, depending primarily on its Si+Al+Fe content. The westernsub-bituminousminous coal typically produces class C fly ash, which is also higher in calcium than class F fly ash typically produced from eastern bituminous coal. Due to the differences in ash composition, the leaching behavior of trace elements varies between different types of fly ashes. In addition, activated carbon and ammonia may be used in power plants to control mercury and NOx emission, which also may affect trace element leaching. This study focused on the leaching potential of two major oxyanions of concern, arsenic and selenium, from different fly ashes under simulated field conditions. The results indicated that As and Se, which occur primarily as anionic species in water, were less leachable from the class C ash compared to the class F ash, at least partially due to the higher calcium content in the class C ash. Results also indicated that the mixing of class C ash and class F ash can significantly reduce the leaching of arsenic compared to the Class F ash alone. Activated carbon and ammonia based technologies do not seem to change the leaching characteristics of both arsenic and selenium from fly ash under natural conditions"--Abstract, page iv.

Advisor(s)

Wang, Jianmin

Committee Member(s)

Burken, Joel G. (Joel Gerard)
Chusuei, Charles C.

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Environmental Engineering

Sponsor(s)

Electric Power Research Institute

Publisher

University of Missouri--Rolla

Publication Date

Spring 2006

Journal article titles appearing in thesis/dissertation

  • The Leaching Behavior of Arsenic and Selenium from Class F Fly Ash under Different Conditions
  • Impacts of Mercury and NOx Control on the Leachability of Arsenic and Selenium from Fly Ash

Pagination

x, 61 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2006 Lenin Prabu Kasthuri, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Subject Headings

ArsenicCoal -- CombustionFly ash -- Environmental aspects -- United StatesLeachingSelenium

Thesis Number

T 8945

Print OCLC #

83277393

Electronic OCLC #

905854678

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