The technology of the closed circulation and zero discharge in paper mills with waste paper as raw material is a mature one.

Non－ deinking recycled paper mills are easy to achieve closed cycle,while deinking recycled paper mills are difficult to achieve closed cycle because of adding many chemicals in the process.

Talking about the design of closed cycle system on handling waste water by the absorption of slag,smoking dust and smoking_gas.

,occurred,which affected seriously the regular working of the heat exchanger in one closed cycle and phase-change heat transfer system.

Its germicidal and ameliorative actions in close system of whitewater are researched.

The practice of waste water close circulation in our paper mill is discussed.

System closure has become the trend of the paper industry.

White water closure was simulated in laboratory using the white water of a commercial newsprint plant was investigated． The relations among some wet end factors were probed in different closure levels， a method for characterizing the degree of the white water closure was suggested

Operational tests show this product is technologically mature, reasonable in design, and has improved performance and reliability with non open box maintenance during an overhaul interval especially thanks to the application of the technique of closed circulation circles researched and developed in house.