Civil Engineering ETDs

Publication Date

Summer 7-15-2019

Abstract

Flue gas emitted from coal-fired power plants is one of the major sources of sulfur and nitrogen oxides emissions to the atmosphere in the world today. Although coal use has decreased, it is still a major contributor to such emissions. The Clean Air Act in the United States established regulations for coal-fired power plants to limit SOx and NOx emissions into the atmosphere. To meet regulatory requirements, power plants have been using scrubbers to limit their air emissions. Flue-gas desulfurization (FGD) is a pollution prevention method that is employed to limit sulfur dioxide emissions directly in the environment using scrubbers.

The wastewater coming out of FGD scrubbers is high in salinity and can cause pollution when discharged to the environment unless it is treated. FGD wastewater contains high concentrations of dissolved salts which limit options for recycling and reuse. This research project focuses on treating FGD wastewater with a combination of ion exchange (IX), precipitation, and nanofiltration (NF) to improve the recovery of marketable materials and the recycling of water to minimize the disposal of wastewater. Laboratory experiments to support model development were focused on the ion exchange and nanofiltration processes.

For IX, the commercially available resin was used to perform laboratory batch and column experiments to determine the selectivity of the resin, design parameters and limitations for the removal of calcium. Nanofiltration (NF) was used for the removal of sulfate ions from the wastewater using commercially available NF membranes. Removal of Trace contaminants, such as arsenic, mercury, nitrate, and selenium using Ion Exchange and Nanofiltration, were also studied in this process. The performance of these physical-chemical processes depends on the total dissolved solids of the wastewater, so wastewaters of varying TDS were analyzed.

This research has practical applications for coal-fired power plants. The benefit of the study will be the development of a process with improved opportunities for recovering materials and reusing wastewater.

Keywords

Ion Exchange, Nanofiltration, Flue Gas Desulfurization, Wastewater, Gypsum, Brucite

Sponsors

Department of Energy

Document Type

Thesis

Language

English

Degree Name

Civil Engineering

Level of Degree

Masters

Department Name

Civil Engineering

First Committee Member (Chair)

Dr. Kerry Howe

Second Committee Member

Dr. Bruce Thomson

Third Committee Member

Dr. Abdul-Mehdi S. Ali

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