Graduation Year

2021

Document Type

Thesis

Degree

M.S.E.V.

Degree Name

MS in Environmental Engr. (M.S.E.V.)

Degree Granting Department

Civil and Environmental Engineering

Major Professor

Mauricio M. Arias, Ph.D.

Committee Member

Qiong Zhang, Ph.D.

Committee Member

Nancy Diaz-Elsayed, Ph.D.

Keywords

Desalination, Energy Recovery, Environmental Impacts, Life Cycle Assessment, Life Cycle Cost Assessment, Techno-economic Assessment

Abstract

Desalination has the potential to provide a stable supply of clean fresh water and meet the increasing water demands; however, this process does come with a few challenges such as high energy consumption, high energy cost, and a discharge of a highly concentrated brine. Pressure retarded osmosis (PRO) is a technology that could work as an efficient energy recovery technology for desalination since it can significantly reduce the energy consumption and dilute the brine before discharge. Studies have assessed the economic feasibility of PRO systems; however, these studies have not addressed the environmental sustainability of the systems. Thus, there is a prominent need for studies evaluating both the economic and environmental sustainability of PRO systems in order to determine the feasibility. The overall goal of this research is to provide a holistic sustainability assessment on a hypothetical full-scale PRO system by performing a life cycle assessment (LCA) and life cycle cost analysis (LCCA). The area of focus for the case study will be the City of Tampa, Florida where the PRO system would be located at the Tampa Bay Seawater Desalination Plant (TBSWDP). The brine would be obtained from TBSWDP and two scenarios were evaluated for the transfer of the treated wastewater from two wastewater treatment plants.

Sima Pro V8 was used to model the impacts of the PRO LCA scenarios. Generated energy had significant negative impact contribution across the majority of the categories, which indicates that the overall environmental impact will be lowered when integrated with a desalination plant. PRO outflow had a significant impact contribution to terrestrial ecotoxicity, marine ecotoxicity, human toxicity and marine eutrophication. PRO System ( Equipment) had a high impact contribution to ozone depletion. The LCCA was performed using various cost equations from extensive literature review and personal communications with treatment plants and manufacturers. The levelized cost of energy (LCOE) resulted to be a high cost of $0.62/kWh and $0.69/kWh due to the transmission and pretreatment costs. The PRO LCOE was not economically competitive compared to mainstream renewable energy generation sources such as wind ($0.23/kWh) and solar ($0.13/kWh). Obtaining the feed solution from a wastewater treatment plant within 1 km and using high quality treated wastewater to avoid pretreatment is recommended to lower the LCOE to $0.14/kWh, making the system economically feasible.

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