Optimizing renewable energy-powered seawater desalination treatment process for zero-waste and improved productivity

Abstract

Desalination has become essential for supplying freshwater in arid regions, yet it presents a significant environmental challenge due to the generation of concentrated brine waste. For every liter of freshwater produced by a typical seawater reverse osmosis (SWRO) plant, approximately 1.5 liters of hypersaline brine are produced. The water recovery rate is typically around 25% – 40% for conventional SWRO, meaning over half of the intake water exits as brine. This brine, about twice as salty as seawater, often contains harmful treatment chemicals and heavy metals. Its discharge into marine environments significantly increases local salinity, lowers oxygen levels, and adversely affects marine ecosystems. This thesis aims to optimize renewable energy-powered SWRO processes to achieve zero brine waste and improve water production efficiency, thus aligning closely with several United Nations Sustainable Development Goals (SDGs). Specifically, it supports SDG 6 (Clean Water and Sanitation) by ensuring sustainable freshwater supply, SDG 7 (Affordable and Clean Energy) by utilizing renewable energy sources, SDG 13 (Climate Action) through greenhouse gas (GHG) emissions reduction, and SDG 12 (Responsible Consumption and Production) by converting brine waste into valuable products, promoting a circular economy. The research adopts a broad sustainability approach integrating renewable energy sources, zero-waste principles, brine resource recovery, life cycle environmental impact assessment, and Artificial Neural Network (ANN)-based process simulation. Renewable energy sources such as solar photovoltaics and wind turbines completely offset the high energy demands of RO, drastically reducing operational GHG emissions. Case studies, such as the solar-powered SWRO facility in Al Khafji, Saudi Arabia, and Australia’s wind-powered Perth Seawater Desalination Plant, demonstrate the feasibility and benefits of renewable-powered desalination at scale. Zero-waste brine management is addressed through innovative recovery methods, turning brine into valuable resources. The concentrated brine, rich in sodium, magnesium, calcium, potassium, and trace elements like lithium and bromine, is processed through methods like evaporation ponds, electrodialysis, and chemical precipitation. This process significantly reduces environmental pollution while creating additional economic benefits. A thorough Life Cycle Assessment (LCA) is employed to evaluate the environmental impacts of the desalination system systematically. Metrics such as carbon footprint, energy intensity, and marine ecotoxicity are analyzed, confirming that renewable integration and brine recovery significantly enhance sustainability compared to conventional methods. An advanced ANN model is developed using operational data from real-world plants, such as the Victoria & Alfred Waterfront Desalination Plant in Cape Town. This model predicts freshwater production rates, energy consumption, and brine composition based on varying operational parameters, facilitating precise optimization and enhanced productivity. Real-world data validate the ANN model’s predictive accuracy, enabling precise, proactive adjustments in operational strategies. The thesis further examines global case studies to reinforce its strategies and demonstrate practical feasibility. Renewable-powered desalination projects and brine utilization initiatives globally provide actionable insights, ensuring the optimized approach is grounded in practical applications and scalable solutions. In conclusion, this research delivers significant improvements in SWRO performance, achieving intensely higher water recovery rates of 45.7%, minimal environmental discharge, valuable by-product generation, reduced energy consumption, and significantly lower carbon footprints. By presenting a detailed and validated framework, this thesis supports global water security efforts by proposing a sustainable and practical desalination solution, transforming an environmental challenge into an opportunity for economic and ecological resilience.