Civil Engineering

 

Date of this Version

Spring 5-2011

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor John S. Stansbury. Lincoln, Nebraska: May, 2011

Copyright 2011 Derek J. Gardels

Abstract

The objective of this study was to determine the environmental sustainability and economic feasibility of five water reuse designs using economic input-output life cycle assessments and benefit/cost analyses. These five water reuse designs were evaluated for four regions of the United States including the Northwest (Seattle), Southwest (Scottsdale), Midwest (Omaha), and Southeast (Tampa). The water reuse designs include a greywater reuse system with no treatment for sub-surface landscape irrigation for a single-family residential house (Model 1), an indoor greywater reuse system with treatment for toilet flushing and laundry washing for a single-family residential house (Model 2), a hybrid untreated greywater system for landscape irrigation with a rainwater reuse system for toilet flushing and laundry (Model 3), a rainwater reuse system for toilet flushing and laundry washing for an apartment building (Model 4), and a community dual distribution system with water reclamation for non-potable uses (Model 5).

The results of this study indicate that there are trade-offs with each of the designs. Models 1 and 5 had the best results in terms of environmental sustainability and economic feasibility. Models 1 and 5 reduced greenhouse gas emissions and energy consumption compared to the baseline scenario. However, with both of these designs, there are additional environmental impacts and additional systems to operate and maintain. Overall, Models 2 and 3 were not environmentally sustainable or economically feasible as designed. Model 4 had mixed results based on regional variability in prices and precipition. In Seattle and Tampa, this design performed favorably in terms of environmental sustainability and economic feasibility due to plentiful amounts of rainfall and relatively high prices for water. However, this design did not have positive results in Scottsdale due to low availability of water. Even though a large amount of rainwater was collected and used in Omaha, Model 4 was determined to be not economically feasible due to the current low prices for water in Omaha.