Zero-wastewater discharge system and method for preparing ultrapure water

The invention discloses a zero-wastewater discharge system for preparing ultrapure water. The system comprises a pretreatment subsystem, a desalination subsystem, a precision treatment subsystem and a regenerated wastewater pretreatment subsystem. The pretreatment subsystem comprises a raw water storage tank, a water pump, a softening filter, a pH value regulating tank, a quartz sand filter, an active carbon filter, a zeolite filter and a pretreatment water storage tank which are sequentially connected through pipelines. The desalination subsystem comprises a primary reverse osmosis main machine and a secondary reverse osmosis main machine. The precision treatment subsystem is a mixed bed system. The regenerated wastewater pretreatment subsystem comprises a regenerated wastewater neutralization pond and an evaporative crystallization device. By means of the system and method for preparing the ultrapure water, zero-wastewater discharge in the preparing process of the ultrapure water is realized; the system for preparing the ultrapure water comprises a mixed bed, a large amount of acid-alkali wastewater produced in the regeneration process of cation resin and anion resin in the mixed bed is treated in the system instead of being discharged into a sewage pipe network just like in an existing treatment mode, and the ultrapure water is obtained ultimately.