Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Madhumita Bhowmick Ray

Abstract

Estrogenic compounds are most significant endocrine disrupting compounds (EDC), which are of primary concern due to their widespread presence in the aqueous environment and also due to their adverse impact both on aquatic life and potential risk to human health. Conventional wastewater treatment plants are not designed to remove EDC, with biosorption on biosolids as the predominant removal mechanism. Anaerobic digestion is one of the most preferred processes employed for sludge stabilization in wastewater treatment plants. Advanced oxidation processes (AOPs) are seen as promising technologies for removal of estrogens from the environment. In this research, a controlled degradation study of estrogenic compounds in anaerobic digestion was undertaken. Anaerobic digestion of estrogens was not observed under any circumstances and pretreatment only played the role of reducing the estrogen loading on the anaerobic digesters. Digestion led to increase in estrogenicity which may be attributed to biotransformation of E1 to E2, and as expected most of the estrogens partitioned onto the solid phase and remained there during digestion. In this work, a comprehensive study was conducted to determine the relative efficiency of various advanced oxidation processes such as O3, H2O2, UV, and combinations of UV/O3, UV/H2O2 for the removal of estrone (E1) from pure water and secondary effluent. In addition, to the parent compound (E1) removal, performance of the AOPs was characterized using removal of total organic carbon (TOC) and estrogenicity of the effluent. Intermediate analysis indicated that UV photolysis produces recalcitrant intermediates, affecting slow TOC removal. Energy calculations and cost analysis indicates that UV processes are best in terms of operating costs (mainly electrical), although ozonation is optimum when both capital and operating water treatment costs are taken into account ($ 0.34/1000 gallon) in light of its superior removal of E1, TOC, and estrogenicity relative to other AOPs. The rate of TOC degradation was low for all the AOPs including ozonation. The rate of E1 removal decreased linearly with the background TOC in water, although E1 degradation in the secondary effluent was not affected significantly due to the low COD concentration.

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