Coal gasification wastewater zero-emission treatment method, treatment system and application thereof

The invention provides a coal gasification wastewater zero-emission treatment method, a treatment system and an application thereof. The treatment system provided by the invention can respectively perform biochemical treatment, desalting and concentrated saline treatment on coal gasification wastewater through a biochemical treatment unit, a desalting unit and a concentrated saline treatment unit, clear water produced by each step can be reused, the produced high-salinity concentrated water can enter the next step for treatment, evaporation is finally performed through an evaporation unit, the clear water produced after evaporation can be used for water supply of a boiler, and the produced concentrated water can be used for flushing ash and slag. The treatment system provided by the invention can realize wastewater zero-emission treatment so as to achieve the purpose of saving water resources.