Date of Award

1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Yang Deng

Committee Member

Huan Feng

Committee Member

Dibyendu Sarkar

Committee Member

Yueqiang Liu

Subject(s)

Sewage--Purification--Organic compounds removal, Ferrites (Magnetic materials), Water reuse, Mefenamic acid

Abstract

Rapidly expanding population, escalating water consumption, and dwindling water resources make water shortage a crisis on a global level, particularly in arid and semi-arid areas or where water sources are highly contaminated. Water reuse, accomplished by a variety of water reclamation technologies, is a strategically sound approach to this crisis. In practice, secondary effluent that is the treated wastewater discharged from municipal wastewater treatment plants (WWTPs) is a preferred reclaimed water source due to its high quality and stable quantity. However, various pollutants, effluent organic matters (EfOM) and emerging contaminants in particular, are still present in secondary effluent. They should be effectively removed before the reclaimed water is safely used.

In this dissertation study, ferrate (Fe(VI)) is proposed as a new treatment agent for treatment of secondary effluent, with an emphasis of removing EfOM and emerging contaminants. Fe(VI) is an environmentally friendly treatment agent with multiple treatment mechanisms including oxidation, coagulation, adsorption, precipitation and disinfection. Bench-scale studies were performed to investigate ferrate(VI) treatment of secondary effluent for the purpose of water reclamation. Special attention was paid to EfOM and a model emerging contaminant, i.e. mefenamic acid (MEF), which represent two challenging traditional and emerging contaminants in secondary effluent, respectively. Initial efforts were made to preliminarily evaluate the treatment performance of ferrate(VI) for the removal of different secondary effluent contaminants under different operating conditions. Thereafter, ferrate(VI) reactions with EfOM and MEF were mechanistically investigated. All the aforementioned experiments were carried out in a batch mode. Afterwards, the treatment performance of ferrate(VI) treatment of secondary effluent was studied in a continuous-flow reactor, which is more commonly selected in engineering practices. Besides removal of the common wastewater contaminant, focus would be specially on coagulative behaviors of ferrate(VI) resultant particles, which could not be studied in a batch mode due to a different hydraulic flow state. Moreover, preliminary cost analysis was made to compare ferrate(VI) treatment and ozonation (a common chemical oxidation option in water reuse) for water reclamation. Finally, implications of ferrate(VI) for environmental management were discussed and future research suggestion was identified.

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