Application of life cycle assessment in seawater desalination plants

In this thesis, the environmental impacts of 1 m3 treated seawater produced by a seawater reverse osmosis (RO) desalination plant in Marmara Region were revealed and evaluated using Life Cycle Analysis (LCA) method with a door-to-door approach. 1 m3 treated seawater has been selected as the functional unit and system boundary includes the supply of raw seawater, treatment of seawater, distribution to the network and supply to the end user. In addition to the LCA application performed with the plant data, a raw seawater sample taken from a point close to the water intake structure of the treatment plant was analyzed in a laboratory to determine the characteristics of the water. In order to evaluate the treatibility of the water, treatibility studies were carried out with both reverse osmosis (RO) and nanofiltration (NF) membranes. The experimental data obtained from these studies were modeled with a commercial process design software and a life cycle inventory (LCI) of the experimental system was created. This inventory was modeled in SimaPro and analyzed with the ReCiPe 2016 method. The environmental impact results obtained were evaluated by comparing with the real plant data. Analyses were performed with ReCiPe2016 method in SimaPro9.1.1.7 Educational version; as midpoint categories; Global Warming Potential (GWP), Ozone Formation, Human Health (OF, HH), Ozone Formation, Terrestrial Ecosystems (OF, TE), Terrestrial Acidification Potential (TAP), Fine Particulate Matter Formation Potential (FPMFP), Freshwater Eutrophication Potential (FEP), Marine Eutrophication Potential (MEP), Terrestrial Ecotoxicity Potential (TEP), Freshwater Ecotoxicity Potential (FEP), Marine Ecotoxicity Potential (MEP), Human Carcinogenic Toxicity (HCT), Human Non-Carcinogenic Toxicity (HN-CT), Land Use (LU), Mineral Resource Scarcity (MRS), Fossil Resource Scarcity (FRS), Water Consumption (WT); Human Health, Ecosystems and Resources were considered as endpoint categories. IMPACT2002+ and CML IA Baseline methods were applied for sensitivity analysis, and Monte Carlo simulation was applied for uncertainty analysis. The results showed that the RO process was the dominant contributor in all impact categories due to energy consumption. In order to improve the environmental impacts of the plant, two alternative scenarios with renewable and non-renewable energy were modeled; it was mathematically proven that the use of renewable resources provides significant reductions in impact levels, and therefore, in order to prevent emissions caused by high energy requirements, the transition to renewable energy in the plant is inevitable. As a result, it is recommended to increase the energy efficiency of energy-intensive processes and accelerate the transition to renewable energy sources in order to reduce environmental impacts in drinking water production by desalination.