Desalination methods such as distillation and reverse osmosis face several challenges. Which option lists these challenges?

• A. Distillation and reverse osmosis; challenges include high energy use, brine waste management, infrastructure costs, and membrane fouling.
• B. Electrolysis is a desalination method.
• C. Desalination has no environmental impacts.
• D. Distillation and reverse osmosis; challenges include low energy use and no waste.

Answer: (C)

Desalination relies on pushing or separating salt from seawater, which demands substantial energy and creates byproducts that must be managed over the system’s life. Distillation needs large amounts of heat to evaporate water, while reverse osmosis uses high-pressure pumps to push water through membranes, both of which translate into high operating costs and a sizable energy footprint. Along with energy use, producing a highly concentrated brine stream is a major challenge because discharging or disposing of that brine can harm marine environments if not properly treated or diluted. The infrastructure for these processes is capital-intensive, including pretreatment to protect equipment and ongoing costs for maintenance, membrane replacement, and handling of other wastes. Membrane fouling and scaling reduce efficiency, require more energy, and shorten the life of components, complicating operation and increasing downtime and expenses.

Statements that claim there are no environmental impacts, or that desalination uses low energy with no waste, run counter to this reality. While other processes like electrochemical approaches exist in some contexts, the traditional and most common methods—distillation and reverse osmosis—face these energy, waste, and infrastructure-related challenges.