Date of Award

8-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Engineering and Earth Sciences

Committee Member

Sudeep Popat, Committee Chair

Committee Member

David A. Ladner

Committee Member

David L. Freedman

Abstract

Anaerobic membrane bioreactors (AnMBRs) offer a potentially energy efficient

means of treating domestic wastewater, but their performance with seasonal temperature

variations must be understood to determine their feasibility in replacing conventional

activated sludge processes. A bench-scale AnMBR treating primary clarifier effluent

from a WWTP in Greenville, SC was found to achieve a similar chemical oxygen

demand (COD) removal during operation at 35°C, 25°C, and 15°C, with average

permeate COD concentrations of 70.5 mg/L, 60.7, and 77 mg/L respectively. Methane

yields averaged 109 L CH4/kg CODremoved at 35°C, 114 L CH4/kg CODremoved at 25°C,

and 64 L CH4/kg CODremoved at 15°C. Reduced methane yield is attributed to a decrease

in methanogen abundance, seen by an almost 3-fold decrease in mcrA gene abundance

during operation at 15°C. The conclusion that the AnMBR achieves similar methane

yields at 35°C and 25°C is significant because substantial energy savings could be

obtained from not heating the reactor to 35°C as is common in conventional anaerobic

processes. Energy savings could especially be significant if the wastewater is already

near 25°C for a portion of the year. By understanding the microbial components of

AnMBR treatment through molecular microbial analysis and relating them with the

performance of the AnMBR at different temperatures, we can better understand the

functionality of specific microbial communities and therefore better inform, operate, and

design anaerobic resource recovery processes for maximum effectiveness.

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