Water is essential for life on Earth, therefore ensuring sufficient freshwater resources for all life and human activities are vital to sustainable development. Progressively, we have focused our attention on the problem of water scarcity. Demand for freshwater is therefore a high priority worldwide.

All water supplies are used by technology, but in many instances, the absence of accessible, affordable energy makes their use costly, time-consuming, and highly harmful. Researchers assume that by raising energy consumption to generate more water with the same amount of electricity, there are realistically easier ways to conserve more water. In this respect, renewable energy will play an important role in powerful and safe seawater desalination. However, it is predicted that wastewater can produce large amounts of new and complicated pollutants that are always harder to handle. Advanced oxidation processes are interesting contaminant removal techniques. Nevertheless, there are still some disadvantages such as cost, by-product developments, and residual toxicity.

The aim of this Special Issue is to collate original research articles from researchers working in scientific disciplines related to water and wastewater treatment. We hope to receive submissions that highlight emerging materials and technologies related to this topic. Review articles discussing the state of the art are also welcome.

Potential topics include but are not limited to the following:

• Water and wastewater treatment
• Membrane separation technology
• Nanotechnology in water treatment
• Desalination by various renewable energy-driven processes
• Environmental-friendly desalination processes
• Hybrid materials for water desalination
• Renewable energy for driving wastewater technologies
• Industrial wastewater treatment technology
• Smart catalytic materials for water treatment
• Photocatalytic membranes for water treatment
• Carbon-based materials for water treatment
• Improvements in water treatment using adsorption technology