Date of Award

Spring 1-1-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil, Environmental & Architectural Engineering

First Advisor

Sherri M. Cook

Second Advisor

JoAnn Silverstein

Third Advisor

Scott Summers

Abstract

Given the gap between water supply and demand, recycling of wastewater, including nonpotable applications, can improve water availability. Mainstream anaerobic processes are gaining importance due to reduced energy and cost demands as compared to conventional process. This study’s goal is to compare mainstream aerobic and anaerobic water reuse treatment trains to identify criteria for improving the sustainability of water recycling. The functional unit is the production of nonpotable reuse water over 40 years from 20 million gallons per day of medium strength wastewater. The comparison of water reuse systems consisting of anaerobic (ANA) and aerobic (AER) processes were focused on the different chemical and energy demands for each treatment scenario. These demands were translated into 10 aggregated environmental impact categories using life cycle inventory data and the Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts (TRACI) assessment method. When comparing ANA and AER baseline scenarios, it was found that using chlorine disinfection had the largest impacts, compared to UV. Therefore, UV disinfection was used for further study. The AER scenario was best in 6 out of 10 environmental impact categories as compared to ANA, mostly due to offsetting chemical fertilizer production with biosolids land application, and negative impacts mostly due to aeration energy. ANA had benefits from energy production during mainstream wastewater treatment but large negative impacts due to high alum doses for coagulation. Additional scenarios included evaluating high strength wastewater, which showed the significance of alum dosing on environmental performance; maximum dissolved methane recovery, which showed great improvements in ANA performance; and best and worst case ANA operations, which showed that ANA could be better than AER if optimized. These results were used to set criteria for technology performance and support model-based experimental design. Overall, the advancement of ANA technologies and employment of resource recovery can minimize the relative environmental impacts of conventional nonpotable reuse treatment systems.

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