Life cycle analysis of seawater biodesalination using algae

This study assesses environmental impacts of reverse osmosis and algae-based biodesalination in four scenarios using a life cycle assessment (LCA) approach. These scenarios encompass (1) a multistage conventional pre-treatment desalination system, (2) immobilized algae-based hybrid desalination system, (3) suspended algae pre-treatment hybrid system, and (4) an attached growth algae-based hybrid system with a low-pressure reverse osmosis (LPRO) system. The assessment integrates the ReCiPe and USEtox 2.0 methods, examining diverse phases such as construction, operation, waste treatment, and chemicals. The impact analysis unveils waste treatment as a significant contributor in Scenario 1. In Scenarios 2 and 3, the operational phase, driven by chemical consumption, emerges as a major factor by 60–70 %, causing environmental damage. Scenario 4 showcases superior environmental performance, notably in global warming potential, freshwater eutrophication, marine eutrophication, ozone layer depletion, and fossil resource scarcity. Results highlight that Scenario 2 and Scenario 3, utilizing immobilized and suspended growth biodesalination, do not align with favorable LCA outcomes. Overall, Scenario 4 displays the least environmental impact and a favorable carbon footprint. The study advocates pipeline brine disposal due to its greater convenience and lesser environmental damage. A sensitivity analysis emphasizes the advantages of shorter transportation distances for optimal brine disposal from the desalination plant to the sea. •Assessed environmental impacts using LCA for algae-based seawater desalination•By consuming CO2 during photosynthesis, algae help reduce GHG emissions.•Biodesalination presents three energy-efficient scenarios for seawater treatment.•Algal biomass is hydrothermally liquefied, generate electricity in last 3 scenarios.•Decreasing brine disposal distance reduced terrestrial ecosystem impact by 20 %.