Water scarcity is one of the most severe resource problems facing humanity in the 21st century. Only 1/4 of the world's population has access to standard drinking water, and 1/3 of the population does not have access to safe water supply. The water crisis is a global problem. Strengthening water resource protection, accelerating water pollution control and sewage resource utilization, and achieving sustainable utilization of water resources have become a common task for all mankind. The sacred mission of our water supply and drainage workers is to popularize water supply, save water, treat sewage, and improve water quality. Cross basin water transfer, seawater desalination, sewage reuse, and rainwater storage are currently widely valued open-source measures. They can all alleviate the contradiction between water supply and demand, and sewage reuse is often the first choice. The reason is that sewage is available nearby, the water volume is stable, and is not affected by climate. The so-called sewage reuse refers to the deep technical treatment of domestic sewage (or urban sewage) or industrial wastewater to remove toxic and harmful substances and certain heavy metal ions from polluted water bodies, and then disinfect and sterilize. The treated water is colorless and odorless, meeting or better than the national standards for miscellaneous water use. With the continuous improvement of living standards, people have higher requirements for greening in residential areas. Establishing supporting small sewage treatment plants in residential areas for reclaimed water reuse can develop new water sources and reduce the investment cost of supporting facilities in residential areas.
